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Background: Genetically engineered 'Golden Rice' contains up to 35 [micro]g [beta]-carotene per gram of rice. It is important to determine the vitamin A equivalency of Golden Rice [beta]-carotene to project the potential effect of this biofortified grain in rice-consuming populations that commonly exhibit low vitamin A status. Objective: The objective was to determine the vitamin A value of intrinsically labeled dietary Golden Rice in humans. Design: Golden Rice plants were grown hydroponically with heavy water (deuterium oxide) to generate deuterium-labeled [[sup.2]H][beta]-carotene in the rice grains. Golden Rice servings of 65-98 g (130-200 g cooked rice) containing 0.99-1.53 mg [beta]-carotene were fed to 5 healthy adult volunteers (3 women and 2 men) with 10 g butter. A reference dose of [[sup.13][C.sub.10]]retinyl acetate (0.4-1.0 mg) in oil was given to each volunteer 1 wk before ingestion of the Golden Rice dose. Blood samples were collected over 36 d. Results: Our results showed that the mean ([+ or -]SD) area under the curve for the total serum response to [[sup.2]H]retinol was 39.9 [+ or -] 20.7 [micro]g x d after the Golden Rice dose. Compared with that of the [[sup.13][C.sub.10]]retinyl acetate reference dose (84.7 [+ or -] 34.6 [micro]g x d), Golden Rice [beta]-carotene provided 0.244).94 mg retinol. Thus, the conversion factor of Golden Rice [beta]-carotene to retinol is 3.8 [+ or -] 1.7 to 1 with a range of 1.9-6.4 to 1 by weight, or 2.0 [+ or -] 0.9 to 1 with a range of 1.0-3.4 to 1 by moles. Conclusion: [beta]-Carotene derived from Golden Rice is effectively converted to vitamin A in humans. This trial was registered at clinicaltrials.gov as NCT00680355.

Background: Spirulina is a high-protein food supplement that contains carotenoids. Objective: The objective of the study was to determine the vitamin A equivalence of spirulina [beta]-carotene in humans. Design: Spirulina was grown in a 23 atom% [sup.2][H.sub.2]O cultural solution. Spirulina [beta]-carotene showed the greatest enrichment as [[sup.2][H.sub.10]]trans [beta]-carotene. Ten healthy Chinese men with a mean ([+ or -]SD) serum retinol concentration of 1.7 [+ or -] 0.3 [micro]mol/L and a body mass index (in kg/[m.sup.2]) of 23 [+ or -] 3 consumed 5.8 [micro]mol [[sup.13][C.sub.10]]retinyl acetate in oil as a reference dose with a breakfast containing 13 g fat. One week later, each subject consumed 7.9 [micro]mol trans [beta]-carotene in spirulina with a breakfast containing 22 g fat. All subjects followed diets low in carotenoid and vitamin A. Forty blood samples were collected from each subject over a span of 56 d. Concentrations and enrichments of retinol and [beta]-carotene in serum samples were determined by using HPLC and a mass spectrometer. Results: Compared with the serum response to [[sup.13][C.sub.10]]retinyl acetate dose, the mean conversion factor of spirulina [beta]-carotene to retinol was 4.5 [+ or -] 1.6 (range: 2.3-6.9) by weight. It was estimated that 80% of the conversion occurred within the first 24 h after spirulina administration. Conclusion: In a group of well-nourished, normal-weight Chinese men following low-vitamin A diets, 4.5 mg spirulina [beta]-carotene consumed with 22 g fat has the same vitamin A activity as does 1 mg retinyl acetate.

Background: Oxidative stress has been implicated in the pathogenesis of chronic diseases related to aging such as cancer and cardiovascular disease. Carotenoids could be a part of a protective strategy to minimize oxidative damage in vulnerable populations, such as the elderly. Objective: Our aim was to determine the protective effect of carotenoids against DNA damage. Design: A randomized, double-blind, placebo-controlled intervention study was conducted. Thirty-seven healthy, nonsmoking postmenopausal women aged 50-70 y were randomly assigned to 1 of 5 groups and were instructed to consume a daily dose of mixed carotenoids ([beta]-carotene, lutein, and lycopene; 4 mg each), 12 mg of a single carotenoid ([beta]-carotene, lutein, or lycopene), or placebo for 56 d. Plasma carotenoid concentrations were analyzed by using HPLC, and lymphocyte DNA damage was measured by using a single-cell gel electrophoresis (comet) assay. Results: At day 57, all carotenoid-supplemented groups showed significantly lower endogenous DNA damage than at baseline (P < 0.01), whereas the placebo group did not show any significant change. Significantly less (P < 0.05) endogenous DNA damage was found as early as day 15 in the mixed carotenoid (P < 0.01) and [beta]-carotene (P < 0.05) groups. Conclusions: The results indicate that carotenoid supplementation decreases DNA damage and that a combination of carotenoids (4 mg each of lutein, [beta]-carotene, and lycopene), an intake that can be achieved by diet, or a larger dose (12 mg) of individual carotenoids exerts protection against DNA damage. KEY WORDS Mixed carotenoids, lutein, [beta]-carotene, lycopene, DNA damage, comet assay, elderly women

Background: The vitamin A value of spinach and carrots needs to he measured directly. Objective: The objective was to determine the vitamin A value of intrinsically labeled dietary spinach and carrots in humans. Design: Spinach and carrots were intrinsically labeled by growing these plants in 25 atom% [sup.2][H.sub.2]O nutrient solution. Growth in this medium yielded a range of trans [beta]-carotene (t[beta]-carotene) isotopomers with a peak enrichment at molecular mass plus 10 mass units. Seven men with a mean ([+ or -] SD) age of 59.0 [+ or -] 6.3 y and a body mass index (in kg/[m.sup.2]) of 25.7 [+ or -] 1.5 consumed pureed spinach (300 g, 20.8 [micro]mol t[beta]-carotene equivalents) or carrots (100 g, 19.2 [micro]mol t[beta]-carotene equivalents) with a standardized liquid diet (no extra fiber) in random order 4 mo apart. Seven women with a mean ([+ or -] SD) age of 55.5 [+ or -] 6.3 y and a body mass index of 26.4 [+ or -] 4.2 consumed pureed spinach only (300 g, 20.0 [micro]mol t[beta]-carotene equivalents). A reference dose of [[sup.13][C.sub.8]]retinyl acetate (8.9 [micro]mol) in oil was given to each subject 1 wk after each vegetable dose. Blood samples were collected over 35 d. Results: Areas under the curve for total labeled serum [beta]-carotene responses were 42.4 [+ or -] 8.5 nmol x d per [micro]mol spinach [beta]-carotene and 119.8 [+ or -] 23.0 nmol x d per [micro]mol carrot [beta]-carotene (P < 0.01). Compared with the [[sup.13][C.sub.8]]retinyl acetate reference dose, spinach t[beta]-carotene conversion to retinol was 20.9 [+ or -] 9.0 to 1 (range: 10.0-46.5 to 1) and carrot t[beta]-carotene conversion to retinol was 14.8 [+ or -] 6.5 to 1 (range: 7.7-24.5 to 1) by weight. Conclusions: Spinach and carrots can provide a significant amount of vitamin A even though the amount is not as great as previously proposed. Food matrices greatly affect the bioavailability of plant carotenoids, their efficiency of conversion to vitamin A, or both. KEY WORDS Vegetables, stable isotope, hydroponics, spinach, carrots, mass spectrometry

Background: Nicaragua initiated a national program of vitamin A fortification of its domestic sugar supply starting with the 1999-2000 sugarcane harvest. Objective: This study was conducted to document any change in the vitamin A status of a cohort of children during the first year of the program. Design: The vitamin A status of 21 Nicaraguan schoolchildren (mean age: 6.7 y; range: 5.3-9.3 y) was assessed in March 2000 and in March 2001. Total-body vitamin A stores and liver vitamin A concentrations were estimated with the deuterated-retinol-dilution (DRD) technique at a dose of 5 mg [[sup.2][H.sub.4]]retinyl acetate at baseline and 5 mg [[sup.2][H.sub.8]]retinyl acetate during the repeat test 1 y later. Plasma retinol and carotenoids were measured by HPLC. Results: Median total-body vitamin A stores increased from 0.33 to 0.72 mmol (P = 0.0001), liver vitamin A concentrations from 0.52 to 0.78 [micro]mol/g (P = 0.0003), and plasma retinol concentrations increased from 0.97 to 1.17 [micro]mol/L (P = 0.01). Conclusion: The vitamin A status of Nicaraguan schoolchildren improved during the year after the initial distribution of vitamin A-fortified sugar in Nicaragua. KEY WORDS Vitamin A, total-body vitamin A stores, liver vitamin A, deuterated retinol dilution, stable-isotope dilution, retinol, carotenoids, [beta]-carotene, vitamin A-fortified sugar, Nicaraguan children

Background: The vitamin A requirements of elderly humans have not been studied. Objective: In a cross-sectional study of 60-88-y-old men (n = 31) and women (n = 31) in rural Philippines, we assessed the dietary intakes of elders with adequate ([greater than or equal to] 0.07 [micro]mol/g) or low (< 0.07 [micro]mol/g) liver vitamin A concentrations to estimate vitamin A requirements for this age group. Design: Total-body vitamin A was assessed by the deuteratedretinol-dilution technique; liver vitamin A concentrations were assessed by assuming that liver weight is 2.4% of body weight and that, in this marginally nourished population, 70% of total-body vitamin A is in the liver; serum retinol was measured by HPLC; and dietary intakes were assessed with 3 nonconsecutive 24-h dietary recalls. The mean vitamin A intake +2 SDs of subjects with adequate liver vitamin A concentrations was used to estimate an acceptable or sufficient vitamin A intake value for elders. Results: The mean ([+ or -] SD) vitamin A intakes of the men and women with adequate vitamin A in liver were 135 [+ or -] 86 and 134 [+ or -] 104 [micro]g retinol activity equivalents (RAE)/d, respectively; intakes of the men and women with low vitamin A in liver were 75 [+ or -] 53 and 60 [+ or -] 27 [micro]g RAE/d, respectively. Total-body vitamin A or liver vitamin A but not serum retinol correlated with dietary RAE, preformed vitamin A, [beta]-carotene, fat, and protein. An estimated acceptable or sufficient dietary vitamin A intake associated with adequate liver vitamin A concentrations in elders is 6.45 [micro]g RAE/kg body wt; for a reference 76-kg man and a 61-kg woman, these values are [approximately equal to] 500 and 400 [micro]g RAE/d, respectively. Conclusion: The dietary vitamin A intakes of elders with adequate or low liver vitamin A concentrations as estimated by use of the deuterated-retinol-dilution technique are useful for assessing vitamin A requirements. KEY WORDS Vitamin A, retinol, deuterated retinol dilution, stable-isotope dilution, carotenoids, [beta]-carotene, retinol activity equivalent, vitamin A requirements, elderly humans

Background: Quantitative information on the conversion of [beta]-carotene to vitamin A in humans is limited. Objective: We determined the short- and long-term conversion of labeled [beta]-carotene to vitamin A by using a stable-isotope reference method. Design: [[sup.2][H.sub.8]][beta]-Carotene (11 011 nmol, or 6 mg) in oil was given with a liquid diet (25% of energy from fat) to 22 adult volunteers (10 men, 12 women). Three days after the [[sup.2][H.sub.8]][beta]-carotene dose, the volunteers each took a dose of [[sup.2][H.sub.8]]retinyl acetate (8915 nmol, or 3 mg) in oil with the same liquid diet. Blood samples were collected over 56 d. Results: The 53-d area under the serum [[sup.2][H.sub.4]]retinol response curve (from the [[sup.2][H.sub.8]][beta]-carotene dose) was 569 [+ or -] 385 nmol * d, and the 53-d area under the serum [[sup.2][H.sub.8]]retinol response curve (from the [[sup.2][H.sub.8]]retinyl acetate dose) was 1798 [+ or -] 1139 nmol * d. With the use of [[sup.2][H.sub.8]]retinyl acetate as the vitamin A reference, the [[sup.2][H.sub.4]]retinol formed from [[sup.2][H.sub.8]]beta-carotene (11 011 nmol) was calculated to be equivalent to 3413.9 [+ or -] 2298.4 nmol retinol. The conversion factor of [beta]-carotene to retinol varied from 2.4 to 20.2, and the average conversion factor was 9.1 to 1 by wt or 4.8 to 1 by mol. This conversion factor was positively correlated with body mass index (r = 0.57, P = 0.006). The postabsorption conversion of [beta]-carotene was estimated as 7.8%, 13.6%, 16.4%, and 19.0% of the total converted retinol at 6, 14, 21, or 53 d after the [[sup.2][H.sub.8]][beta]-carotene dose, respectively. Conclusion: The quantitative determination of the conversion of [beta]-carotene to vitamin A in humans can be accomplished by using a stable-isotope reference method. This approach provides in vivo metabolic information after a physiologic dose of [beta]-carotene. KEY WORDS [[sup.2][H.sub.8]][beta]-Carotene, [[sup.2][H.sub.8]]retinyl acetate, humans, retinol equivalence, stable isotope, mass spectrometry

Background: The conventional deuterated-retinol-dilution (DRD) technique provides a quantitative estimate of total body stores of vitamin A in humans. The procedure requires equilibration of serum deuterated retinol with nondeuterated retinol after administration of an oral dose of deuterated vitamin A. Equilibration takes [approximately equal to] 3 wk to complete. Objective: Our goal was to develop a predictive mathematical formula for quantitative assessment of total body stores of vitamin A in adults by using a procedure that takes less time to perform because serum isotope equilibration is not required, so that blood drawing can be done 3 d, instead of [approximately equal to] 3 wk, after isotope dosing. Design: Ratios of serum deuterated to nondeuterated retinol (D:H retinol) were determined in Filipino adults (n = 68) 3 and 20 d after an oral dose of 0.015 mmol [[sup.2][H.sub.4]]retinyl acetate and in Guatemalan adults (n = 15) 3 and 21 d after a 0.030-mmol dose. D:H retinol values 20 or 21 d after the isotope dose were used in a mathematical formula to obtain quantitative estimates of total body stores of vitamin A that were then correlated with serum D:H retinol values 3 d after the isotope dose. Results: The relation between these variables was nonlinear and was described by the following equation: total body stores of vitamin A (in mmol retinol) = 0.00468 [10.sup.37(isotope dose in nmol)]/D:H retinol in serum 3 d after the isotope dose. Conclusion: A 3-d DRD technique could be used for quantitative assessment of total body stores of vitamin A; this technique takes less time than does the conventional DRD technique. KEY WORDS Deuterated retinol dilution, DRD, 3-d DRD, stable isotope dilution, vitamin A body stores, vitamin A status assessment, Phillipines, Guatemala

Background: After a dose of labeled vitamin A is given to humans for estimating body stores of vitamin A, blood is customarily drawn at pseudo-equilibration times ranging from 11 to 26 d. Objective: The objective was to determine whether a shorter sample collection interval (6 h or 3 d), which would be more realistic in field settings, can be used. Design: Correlations of enrichment at 6 h or 3 d with enrichment at 21 d were made after an oral dose of deuterium-labeled vitamin A was given to Chinese schoolchildren (aged 10-11 y; n = 58) with marginal-to-normal vitamin A status. A predictive equation was then derived and applied to data obtained from a separate group of children to verify that the calculated enrichment at 21 d (determined by using data obtained at an earlier time point to predict 21-d enrichment) reflected directly measured enrichment at 21 d. Results: Because 3-d isotope enrichment was found to correlate well with 21-d enrichment, a predictive equation was derived whereby 3-d data were used to predict isotope enrichment at pseudo-equilibration (ie, at 21 d). When the 3-d predictive equation was applied to a separate group of Chinese children, the calculated 21-d data (determined by using the 3-d data and the predictive equation) matched the directly measured 21 -d data. Body stores of vitamin A determined from either the calculated or directly measured 21-d enrichment data also showed agreement. Conclusion: Percentage enrichment at 3 d (but not at 6 h) can be used to evaluate vitamin A body stores in humans. KEY WORDS Deuterated vitamin A, retinol enrichment, total-body vitamin A stores, Chinese children, stable isotope

Background: Dietary pattern analysis is a unique approach to studying relations between diet and disease. Objective: Our objective was to describe the dietary patterns of an eastern Nebraska population and investigate the associations between those dietary patterns and risks of adenocarcinoma of the esophagus and distal stomach. Design: We recruited 124 subjects with esophageal adenocarcinoma, 124 subjects with distal stomach adenocarcinoma, and 449 control subjects in a population-based, case-control study. Results: Six dietary patterns were identified with the use of cluster analysis. The first dietary pattern represented healthy food choices and had higher energy contributions from fruit and vegetables and grain products and lower energy contributions from red meats, processed meats, and gravy than did the other dietary patterns. In contrast, a second dietary pattern was high in meats and low in fruit and cereals. The other 4 dietary patterns were each characterized by a concentrated energy source: salty snacks, desserts, milk, and white bread, respectively. The test of overall difference in cancer risk across dietary patterns was significant for distal stomach adenocarcinoma (P = 0.04) but not for esophageal adenocarcinoma. Risk of esophageal adenocarcinoma was inversely associated with intakes of dairy products, fish, all vegetables, citrus fruit and juices, and dark bread and was positively associated with gravy intake. Risk of distal stomach adenocarcinoma was positively associated with red meat intake. Conclusions: Our study suggests that a diet high in fruit and vegetables may decrease the risk of esophageal adenocarcinoma and that a diet high in meats may increase the risk of distal stomach adenocarcinoma. Am J Clin Nutr 2002;75:137-44. KEY WORDS Esophagus, stomach, neoplasm, dietary pattern, cluster analysis, cancer

Subjects taking a hydrogen pump blocking agent (omeprazole) develop bacterial overgrowth of the small intestine. We tested the hypothesis that this bacterial overgrowth produces menaquinones, which would meet the vitamin requirement in situations of vitamin K deficiency. In a crossover-type design, 13 healthy volunteers eating a phylloquinone-restricted diet for 35 d were randomly assigned to take omeprazole during the first period of study or starting on day 15 until the end of the study. Coagulation times, serum osteocalcin [total osteocalcin and undercarboxylated osteocalcin (ucOC)], plasma phylloquinone, urinary [Gamma]-carboxyglutamic acid, and plasma undercarboxylated prothrombin (PIVKA-II) were measured. Plasma phylloquinone concentrations declined 82% with dietary phylloquinone restriction (P [is less than] 0.05) and were not significantly different in the period when the diet was combined with omeprazole treatment (P [is greater than] 0.05). The mean value for PIVKA-II during the phylloquinone-restricted diet significantly increased 5.7-fold from baseline (P [is less than] 0.05); however, the combination of omeprazole treatment and the phylloquinone-restricted diet significantly reduced PIVKA-II values by 21% (P [is less than] 0.05) compared with the diet period alone. There were no alterations in total or percentage ucOC concentrations during the phylloquinone-restricted diet or during the period of diet plus omeprazole treatment. Our data support the hypothesis that bacterial overgrowth results in the synthesis and absorption of menaquinones. These menaquinones contribute to vitamin K nutriture during dietary phylloquinone restriction, but not enough to restore normal vitamin K status. Am J Clin Nutr 1998;68:699-704.

Nonsteroidal antiinflammatory drugs (NSAIDs), such as aspirin, frequently cause gastric mucosal injury in the elderly. Impairment of prostaglandin synthesis is a crucial step by which aspirin attenuates mucosal defense capacity. Vitamin E has been shown to decrease prostanoid concentrations, which implies an ulceropermissive effect of vitamin E. To assess the effect of vitamin E on aspirin-induced gastric injury and mucosal prostanoid concentrations, 20 male rats aged 20 mo were divided into two groups and fed diets containing either 30 (physiologic requirement) or 500 mg all-rac-[Alpha]-tocopheryl acetate/kg. After 6 wk, all rats received two intragastric doses of aspirin (1.4 [micro]mol/kg body wt). A third group of six animals fed the high-vitamin E diet received a vehicle solution without aspirin. Mucosal samples for vitamin E and prostaglandin [E.sub.2], 6-keto-prostaglandin [F.sub.1[Alpha]], and thromboxane [A.sub.2] measurements were collected. The prevalence and degree of mucosal lesions were not significantly different among all groups. Rats fed the high-vitamin E diet had significantly higher mucosal vitamin E concentrations than rats fed the low-vitamin E diet. Mucosal concentrations of all three prostanoids were 95% lower in aspirin-treated rats than in controls (P = 0.0001 in all instances). The high-vitamin E diet group had significantly lower mucosal 6-keto-prostaglandin [F.sub.1[Alpha]] concentrations (P = 0.02) than the low-vitamin E diet group, indicating decreased prostacyclin formation, whereas concentrations of prostaglandin E2 and thromboxane [A.sub.2] were similar in the aspirin-treated groups. Aspirin markedly reduced mucosal prostanoid concentrations in rats, without apparent effects on gastric injury, whereas vitamin E supplementation significantly reduced mucosal 6-keto-prostaglandin [F.sub.1[Alpha]] concentrations. Nevertheless, vitamin E supplementation did not result in more gastric injury in aspirin-treated rats than in controls. Am J Clin Nutr 1997;66:1218-23.

Supplementation of healthy elderly persons with [Beta]-carotene has been considered a way to enhance immune responses. In study 1 the short-term effect of [Beta]-carotene (90 mg/d for 3 wk) on immunity was assessed in a randomized, double-blind, placebo-controlled longitudinal comparison of healthy elderly women. In study 2 the long-term effect of [Beta]-carotene (50 mg every other day for 10-12 y) on immunity was assessed in a randomized, double-blind, placebo-controlled longitudinal comparison of men enrolled in the Physicians' Health Study. Subjects from both studies taking active supplements had significantly greater plasma [Beta]-carotene concentrations than did subjects taking placebo. The pre- to postintervention change in delayed-type hypersensitivity skin test responses between [Beta]-carotene and placebo groups in the short-term study was not significantly different, nor was the response between treatment groups in the long-term study. There were no significant effects due to [Beta]-carotene supplementation on in vitro lymphocyte proliferation, production of interleukin 2, or production of prostaglandin [E.sub.2] as a result of short- or long-term [Beta]-carotene supplementation. In addition, there were no differences in the profiles of Lymphocyte subsets [total T cells (CD3+), T helper cells (CD4+), T cytotoxic-suppressor cells (CD8+), and B cells (CD19+)] due to short- or long-term [Beta]-carotene supplementation, nor were there differences in percentages of CD16+ natural killer cells or activated lymphocytes (cells expressing interleukin 2 transferrin receptor) due to long-term [Beta]-carotene supplementation. Consistent results from these two trials show that [Beta]-carotene supplementation did not have an enhancing or suppressive effect on T cell-mediated immunity of healthy elderly.

A case-control study of the associations of retinoids and specific carotenoids with breast cancer using concentrations of these nutrients in breast adipose tissue was conducted among women attending a breast clinic in the Boston area in 1989-1992. Breast adipose tissue was collected during breast biopsy. Cases (n = 46) were women whose biopsies revealed invasive or in situ breast cancer; control subjects (n = 63) were women whose biopsies revealed benign disease. We observed inverse associations between breast adipose concentrations of retinoids and carotenoids and risk of breast cancer, although not all were statistically significant. The multivariate-adjusted odds ratio comparing women above the median value of the control group for retinol with those below or equal to the median was 0.71 (95% CI: 0.26, 1.93; NS); corresponding odds ratios were 0.61 (95% CI: 0.23, 1.64; NS) for retinyl palmitate, 0.30 (95% CI: [Beta]-carotene, 0.32 (95% CI: 0.11, 0.94) for lycopene, and 0.68 (95% CI: 0.27, 1.73; NS) for lutein/zeaxanthin. There was a nonsignificant positive correlation (r = 0.23, P = 0.15) between breast adipose tissue concentrations of retinol and dietary intake of preformed vitamin A, including supplements measured by using a food-frequency questionnaire. No correlation was found between breast adipose concentrations of carotenoids and intake of dietary carotenoids. These data suggest that higher breast adipose concentrations of retinoids and some carotenoids may be associated with decreased risk of breast cancer and that further examination of these relations is warranted.

The effect of gastric acidity on the blood response to a single dose of 120 mg [beta]-carotene in humans was investigated in 12 normal subjects (5 women, 7 men) aged 23-68 y. Omeprazole was used for 7 d to obliterate gastric acid secretion and to raise gastric pH to > 4.5. In a crossover design, six subjects were randomly assigned to take ,[beta]-carotene with omeprazole either at the beginning (day 9) or at the end (day 26) of the study. The [beta] response in blood was not altered by the experimental order. Results from the high-gastric-pH phase (ie, with omeprazole) were analyzed together and compared with the results from the low-gastric-pH phase (ie, without omeprazole). The increases of serum concentrations of both bans [beta] and cis [beta]-carotene 6 and 24 h after the ,[beta]-carotene dose were significantly greater at a low gastric pH (pH = 1.3 [+ or -] 0.1, ie, without omeprazole) than those at a high gastric pH (pH = 6.4 [+ or -] 0.3, ie, with omeprazole), P < 0.02. Similarly, 24 h after [beta]-carotene administration, the area under the blood ,6-carotene response curve (bans plus cis,[beta]-carotene) was significantly greater at a low gastric pH (6825 [+ or -] 760 nmol h/L) than at a high gastric pH (3390 [+ or -] 550 nmol h/L), P < 0.002. In investigations of bacterial overgrowth, gelatin capsule disintegration and isomeric profiles associated with high and low pH, we could not identify factors to explain the differences observed in the blood response curves between low-gastric-pH and high-gastric-pH conditions. A suppressed blood response of [beta]-carotene at a high intraluminal pH may have been due to the slower movement of negatively charged micelles through the unstirred water layer and cell membrane.

Plasma carotenoid responses were determined in 36 healthy men and women before and after being fed controlled diets with a moderate amount of fat (26% of total energy) and a high carotenoid content ([nearly equal to] 16 mg/d) for two 15-d periods. In addition, broccoli (205 g/d) was provided either during the first or the second 15-d residency period in a crossover design. Plasma was digested with lipase and cholesterol esterase, and carotenoids were extracted and measured by using HPLC. Three oxygenated carotenoids (lutein, zeaxanthin, and cryptoxanthin), three hydrocarbon carotenoids ([alpha]-carotene, all-trans-[beta]-carotene, and 13-cis-[beta]-carotene), and four geometric isomers of Iycopene (15-cis-, 13-cis-, 9-cis-, and all-trans-lycopene) were separated by using a C30 carotenoid column. A small unidentified peak coeluted with standard 9-cis-[beta]-carotene and was identified as [zeta]-carotene ([[lambda].sub.max] = 400 nm). The concentrations of plasma lutein, cryptoxanthin, [alpha]-carotene, 13-cis-[beta]-carotene, all-trans-[beta]-carotene, and cis- and trans-lycopenes were all significantly increased (P < 0.05) on days 6-16 by the high-fruit and -vegetable diets. The provision of additional broccoli for 5 d to t he basic high-carotenoid diet resulted in a further significant increase in the serum concentration of lutein compared with the feeding of the basic high-carotenoid diet alone. Most of the measurable carotenoids of human plasma can be increased by moderate alterations in diet within a short time, although the magnitude of the plasma response may be related to the baseline carotenoid concentrations.

Poor mineral nutrition reported in elderly people is attributed in large part to low dietary intake. Evaluation of the adequacy of mineral nutriture is limited for several minerals because of inadequate methods for assessing mineral status. In addition, there is a general lack of information about mineral nutriture and metabolism in very old people (> 85 y). Given these reservations, the 1989 recommended dietary allowance (RDA) for iron, zinc, and selenium appears adequate for elderly people, as does the estimated safe and adequate daily dietary intake (ES-ADDI) recommendation for copper. In contrast, the current RDAs for calcium and magnesium and the ESADDI for chromium need careful reevaluation. Current recommendations for calcium may be too low, whereas those for magnesium and chromium may be higher than necessary. For phosphorus, iodine, manganese, fluoride, and molybdenum the available data are insufficient to make a critical judgement about the appropriateness of the dietary recommendations for elderly people.

We evaluated the relation between [beta]-carotene intake and plasma and adipose tissue concentrations of carotenoids and retinoids. In Study 1, [beta]-carotene intakes were significantly greater in vegetarians than in nonvegetarians. Plasma concentrations of [beta]-carotene were also significantly higher in vegetarians than in nonvegetarians but only after two nonvegetarians with excessive intake of carrots were omitted. Plasma retinoid (retinol, retinyl esters, and retinoic acid) concentrations were not different between the two groups. In Study 2, female subjects ingested a daily placebo or 90 mg [beta]-carotene for 2 wk. In the group fed [beta]-carotene, plasma [beta]-carotene concentrations were significantly increased from baseline at 1, 2, and 3 wk. No [beta]-carotene changes were observed in the placebo-fed group. Plasma retinoid concentrations did not change in either group. In Study 3, adipose tissue [beta]-carotene and retinoid concentrations were measured in men after an oral [beta]-carotene dose (120 mg, experimental subjects) or no [beta]-carotene (control subjects). In the experimental subjects, adipose [beta]-carotene concentrations increased from baseline at 5 and 10 d post-dosing. The control group's adipose tissue [beta]-carotene concentration did not change over a 10-d period. Changes in retinoids in adipose tissue were not significant in either group. In conclusion, dietary and supplemental [beta]-carotene increased plasma [beta]-carotene concentrations but had no effect on plasma retinoid concentrations. There may be little tissue metabolism of [beta]-carotene to retinoids. Therefore, the anticarcinogenic effect of [beta]-carotene, if any, may be due to properties of the molecule itself.

Human subjects (n = 24) were supplemented with 100 mg [beta]-carotene/d for 6 d, either as synthetic all-trans-[beta]-carotene or a natural [beta]-carotene preparation derived from the alga Dunaliella salina, which consists of a 50:50 mixture of all-trans-and 9-cis-[beta]-carotene. This loading dose was followed by a 23-d maintenance dose consisting of alternate-day supplementation with 50 mg all-trans-[beta]-carotene or either 66 or 100 mg of the natural 50:50 isomeric mixture. The loading dose resulted in significant increases in plasma concentrations of both isomers, with the all-trans-[beta]-carotene-supplemented group showing a 7.2-and 5.0-fold increase in the all-trans and 9-cis concentrations in plasma, respectively. The group receiving the 50:50 mixture showed a 4.0- and 3.7-fold increase in the all-trans and 9-cis concentrations in plasma, respectively, without any apparent dose-dependency. However, even with the 50:50 mixture, the 9-cis concentrations were only a small fraction of the total plasma [beta]-carotene. Results after an additional 23-d period of alternate-day supplementation were not significantly different from those described above for the 6-d supplementation. Increases in low-density-lipoprotein concentrations of total [beta]-carotene correlated strongly with the increases seen in plasma concentrations. Lipid-soluble antioxidants vitamin E and ubiquinol were unaffected by [beta]-carotene supplementation. However, the amount of lycopene in the low-density lipoprotein decreased during this supplementation period. A strong discrimination between these two geometric isomers of [beta]-carotene was demonstrated, although the tissue site of discrimination was not determined.

The effect of the live bacterial yogurt cultures, namely Streptococcus thermophilus and Lactobacillus bulgaricus, and a mucosal adhering strain of Lactobacillus gasseri (ADH) on small intestinal and fecal bacterial characteristics was examined in 10 elderly subjects with atrophic gastritis and 23 elderly normal volunteers (11 received yogurt and 12 received ADH). Neither S thermophilus nor L bulgaricus was recovered from the stomach or small intestine of subjects fed yogurt or pasteurized yogurt. ADH was recovered from gastric or small intestinal aspirates in three of four subjects and in the stools of four of five subjects diagnosed with atrophic gastritis. In 11 of 12 normal subjects, ADH was isolated from stools. There was a significant reduction in fecal bacterial enzyme activity in both normal volunteers and subjects with atrophic gastritis after being fed with viable ADH. Adherent strains of bacteria such as ADH are likely to survive passage through the gastrointestinal tract and thus have greater metabolic effects.

Six groups of elderly subjects from central Guatemala were assessed for riboflavin status by using the erythrocyte glutathione reductase activity coefficient (EGRAC). The prevalence of riboflavin deficiency ranged from 50%, to 76% among the free-living rural elderly subjects. Milk intake data that were collected from some of the subjects showed a significant correlation (P < 0.0001) between frequency of milk intake and riboflavin status. In a short-term riboflavin supplementation experiment in which nine riboflavin-deficient subjects were given 10 mg riboflavin/d for 3 d, all the subjects' EGRACs were normalized by the supplementation. However, they returned to a state of deficiency within 2 wk while consuming their usual diets without supplementation. It appears that the high prevalence of riboflavin deficiency in elderly Guatemalan people is caused by inadequate intake of riboflavin-rich foods such as dairy products, and that sufficient amounts of riboflavin need to be ingested regularly to maintain satisfactory riboflavin status.

This article is an update of our 1987 literature review of vitamin requirements of elderly people (Am J Clin Nutr 1987;45:501-12). Poor dietary intake is the cause of much vitamin malnutrition in elderly people. Nevertheless, there is strong evidence that aging affects the requirement for certain vitamins. The 1989 recommended dietary allowances (RDAs) appear to be too low for elderly people for vitamin D, riboflavin, vitamin B-6, and vitamin B-12, and too high for vitamin A. For several vitamins there is enough information to establish an RDA for the category [greater than or equal to] 70 y.

This study examined postabsorptive plasma vitamin A after doses of retinyl palmitate in healthy men (n = 28) and women (n = 31). On consecutive days one physiologic [3000 retinol equivalents (RE)] and one pharmacologic dose (105 000 RE) were administered and blood samples collected. Plasma retinol and retinyl esters were measured by HPLC. Tolerance curves were constructed by plotting plasma retinyl ester concentration vs time. Postprandial retinyl ester response was measured as peak rise in retinyl ester concentration and area under the curve (AUC). Peak plasma retinyl ester concentration occurred earlier for females but the earlier peak was significant only for younger subjects ([is less than or equal to] 50 y, P < 0.02) given the low dose and older subjects ( > 50 y, P < 0.02) given the high dose. Peak rise and AUC were lower in females than in males, but this difference was significant for the high dose only (P < 0.05). In the high-dose experiment, when each age group was evaluated for sex differences the peak rise was significantly greater in males than in females in the older subjects (P < 0.05). Postabsorptive plasma retinol did not change from fasting concentrations. A lower plasma response in retinyl esters in women could be due to a more efficient chylomicron-remnant clearance. Am J Clin Nutr 1992;56:911-6.

We investigated the time course and the reproducibility of the relative-dose-response (RDR) test for assessing vitamin A status in older adults. The maximum plasma retinol response to 480 retinol equivalents (RE) of retinyl palmitate in abnormal responses was at 6 or 7 h after dosing compared with the 5-h sampling interval recommended by others for younger adults and children. With respect to reproducibility, the diagnostic concordance of two RDR tests at 7-d intervals in 14 elders was 71%. In 29% of tests, one test was abnormal and the other normal. Linear regression of the two RDR values in these 14 subjects gave a correlation coefficient of -0.08. We conclude that the procedure for the RDR should be modified when applied to persons > 60 y of age, and that multiple repetitions of the test are needed to provide a stable indication of vitamin A stores in an elderly individual.

Plasma and lipoprotein concentrations of [beta]-carotene (BC) were measured in men for 10 d after an oral dose of BC (120 mg) (experimental subjects, n = 11) or no BC (control subjects, n = 5). Lipoproteins were separated by sequential ultracentrifugation and BC was measured by HPLC. Plasma and lipoprotein BC concentrations in control subjects were steady. In experimental subjects, plasma BC content increased by 6 h postdosing (P < 0.015), peaked at 24 h (P < 0.05), and returned to baseline by 7 d. Maintenance of plasma BC concentrations suggests homeostatic control. Of the 11 experimental subjects, only 4 had a plasma response. Early increases in the BC content of chylomicrons, very-low-density lipoproteins, and intermediate-density lipoproteins were associated with decreases in the BC content of low-density lipoproteins and high-density lipoproteins. Intestinal input accounts for early rises in circulating BC concentrations whereas hepatic secretion is the source of later increases. Among all of the lipoproteins, transfer of BC may occur. Am J Clin Nutr 1992;56:128-35.

We evaluated vitamin A absorption in 50 healthy adults and 26 gastrointestinal-disease patients by measuring the postabsorptive response in plasma retinyl esters after oral doses of the vitamin. On 3 consecutive days, two physiologic-dose tests of 2000-2400 retinol equivalents (RE) and one pharmacologic-dose test (84 000 RE) were administered. The physiologic doses were given as an oil-soluble or a water-miscible preparation. In gastrointestinal -disease patients the physciologic-dose test was high correlated with the pharmacologic-dose test for the oil-soluble preparation as determined by peak rise (r = 0.50, P < 0.05) and area under the curve (r = 0.56, P

Previous studies have shown that the ability to absorb dietary calcium decreases as people grow older. This places the elderly at a greater risk for calcium deficiency and loss of bone mass (osteoporosis). The elderly are encouraged to eat high-fiber diets, but it has been demonstrated that dietary fiber can reduce the absorption of calcium. When fiber is present the calcium will bind to the fiber instead of being absorbed. When the gastric juice in the stomach becomes less acidic, as it commonly does in elderly people, more calcium will bind to the fiber. This suggests that high-fiber diets in elderly people with lower than normal amounts of acid in their stomach (achlorhydria) may greatly reduce the absorption of dietary calcium. To determine the effects of acid and dietary fiber on calcium absorption, a low-fiber meal, a high-fiber meal, and a high-fiber meal with hydrochloric acid added, were given to eight elderly subjects with achlorhydria and nine normal elderly subjects. When the low-fiber meal was consumed, 26 percent of the calcium from the meal was absorbed into the body. When the high-fiber meal was consumed, 19 percent of the calcium from the meal was absorbed into the body. The high-fiber meal plus acid resulted in a 18.9 percent absorption rate. The results were the same for the elderly subjects with achlorhydria and the normal subjects. These findings indicate that calcium absorption is reduced with high-fiber diets, and that the acidity of the stomach is not an important factor. (Consumer Summary produced by Reliance Medical Information, Inc.)

The immune system is the body's natural defense system against infection caused by microorganisms and foreign substances that enter the body. Previous studies have shown that the function of the immune system decreases with increasing age, and this may account for the increased susceptibility to infection and disease experienced by older people. These studies have reported that the production of interleukin 2 (a protein required for normal immune function) is reduced in elderly subjects. Studies performed in laboratory animals have reported that vitamin B-6 deficiency can impair the function of the immune system by reducing the production of antibodies and the number of cells (called lymphocytes) that make antibodies. Other studies have shown that elderly people have a high risk of developing vitamin B-6 deficiency. It is estimated that 50 percent of the elderly population has dietary intakes of vitamin B-6 that are lower than the Recommended Dietary Allowance (RDA). Therefore, a study was performed to determine the effects of vitamin B-6 deficiency on the immune system in elderly people. Eight healthy volunteers (average age of 64 years) followed a diet containing no vitamin B-6 for up to 20 days, followed by three separate 21-day periods in which vitamin B-6 was added back to the diet in increasing amounts. Following the period with no vitamin B-6, there was a significant reduction in the number of lymphocytes in the blood and in interleukin 2 production. When vitamin B-6 was added back to the diet, both the number of lymphocytes and interleukin 2 production returned to normal. It is concluded that vitamin B-6 deficiency impairs the function of the immune system in elderly people, and that adding vitamin B-6 to the diet can reverse the effects of vitamin B-6 depletion. (Consumer Summary produced by Reliance Medical Information, Inc.)

Cardiovascular disease, which affects the heart and blood vessels, is a major health problem among the elderly. Stroke is the most common cause of cardiovascular disease among elderly Chinese persons. Death due to stroke and myocardial infarction (heart attack) was estimated in 1976 at 138.7 and 29.6 per 100,000 Chinese, respectively, as compared with 87.9 and 301.0 per 100,000 Americans, respectively. Although the Chinese make up one quarter of the world's population, little is known about the various characteristics that may influence their risk of cardiovascular disease. The nutrition and health of 346 Chinese immigrants aged 60 to 96 years were assessed to determine cardiovascular risk factors. The elderly Chinese were physically active, rarely obese, and consumed a diet high in carbohydrate and low in fat and vitamin C. Thirty-nine percent of the men smoked cigarettes while few women did, and alcohol consumption was rare among both men and women. The elderly Chinese had lower blood pressures and levels of total, low-density lipoprotein, and high-density lipoprotein cholesterol, and ascorbic acid (vitamin C), as compared with elderly Americans. This group of Chinese immigrants was similar in these health measures to the urban population of mainland China, where hemorrhagic (due to bleeding) stroke is the primary cause of cardiovascular death. (Consumer Summary produced by Reliance Medical Information, Inc.)

Background: Serum retinyl ester concentrations are elevated in hypervitaminosis A. It was suggested that retinyl esters [is greater than] 10% of total serum vitamin A indicate potential hypervitaminosis, but this cutoff was derived from small clinical samples that may not be representative of the general population. Objective: We sought to examine the distribution of serum retinyl ester concentrations and associations between retinyl ester concentrations and biochemical markers of liver dysfunction in a nationally representative sample. Design: We assessed the associations between serum retinyl ester concentrations and 5 biochemical indexes of liver dysfunction by using multivariate linear and multiple logistic regression techniques and controlling for age, sex, use of supplements containing vitamin A, alcohol consumption, smoking status, and use of exogenous estrogens in 6547 adults aged [is greater than or equal to] 18 y in the third National Health and Nutrition Examination Survey (NHANES III), 1988-1994. Results: Thirty-seven percent of the sample had serum retinyl ester concentrations [is greater than] 10% of total serum vitamin A and 10% of the sample had serum retinyl esters [is greater than] 15% of total vitamin A. We found no associations between serum retinyl ester concentrations and 1) concentrations of any biochemical variable (multiple linear regression) or 2) risk of having biochemical variables above the reference range (multiple logistic regression). We did not find a serum retinyl ester value with statistically significant sensitivity and specificity for predicting increases in biochemical indexes of liver dysfunction. Conclusions: The prevalence of serum retinyl ester concentrations [is greater than] 10% of the total vitamin A concentration in the NHANES III sample was substantially higher than expected but elevated retinyl ester concentrations were not associated with abnormal liver function. Am J Clin Nutr 2001;73:934-40. KEY WORDS Retinyl esters, hypervitaminosis A, vitamin A, third National Health and Nutrition Examination Survey, NHANES III, liver dysfunction, liver function, vitamin A supplementation, retinol, vitamin A toxicity

Because elderly adults have distinct metabolic characteristics that alter various nutrient requirements, simple extrapolations of nutrient requirements for younger adults are not warranted. Gastrointestinal function is well preserved with aging regarding the digestion and absorption of macronutrients, but the aging gastrointestinal tract becomes less efficient in absorbing vitamin B-12, vitamin D, and calcium. The new dietary reference intakes considered recent studies in aging adults and concluded that the recommended dietary allowances (RDAs) should be 1200 mg and 15 [micro]g for calcium and vitamin D, respectively, for persons over the age of 70 y. The new RDAs for riboflavin, niacin, thiamine, folate, vitamin B-6, and vitamin B-12 are not different for persons in the oldest age category ([is greater than] 70 y) than for those aged 51-70 y. Because this is a quickly advancing field, it will be important to closely follow new research on nutrient requirements and aging over the next several years. Am J Clin Nutr 2000;72(suppl):529S-32S. KEY WORDS Aging, elderly, nutrient requirements, metabolism, dietary requirements, absorption, gastrointestinal function, dietary reference intakes, DRIs, recommended dietary allowances, RDAs

Background: It is important to understand the factors affecting strategies to improve the vitamin A status of populations. We reported previously that a 3-d deuterated-retinol-dilution (DRD) procedure might be used to indicate total body stores of vitamin A. Objective: We studied the ability of 3-d DRD to detect changes in the body pool size of vitamin A and the effect of vitamin A status on the bioconversion of plant carotenoids to vitamin A. Design: Two separate, unrelated studies were conducted in 7-13-y-old children with poor or marginal serum retinol concentrations (0.32-0.93 [micro]mol/L) by feeding them controlled diets daily for 5 d/wk for 12 wk, after treatment with an anthelmintic drug. In school 1 (n = 27), lunch and 2 snacks that were provided at school contained 2258 retinol equivalents/d (mostly from orange fruit and vegetables) and 5.3 MJ/d from 33 g fat, 37 g protein, and 209 g carbohydrates; in school 2 (n = 25), 2 snacks provided 2.5 MJ/d from 9.4 g fat, 9.6 g protein, and 119 g carbohydrates, but no carotenes. Results: In school 1, mean serum [Beta]-carotene increased from 0.12 to 0.62 [micro]mol/L (P = 0.0001) and serum retinol increased from 0.68 to 1.06 [micro]mol/L (P = 0.0001). In school 2, serum [Beta]-carotene increased from 0.06 to 0.11 [micro]mol/L (P = 0.0001) and serum retinol increased from 0.66 to 0.86 [micro]mol/L (P = 0.0001). In school 1, but not school 2, improvement in serum retinol varied inversely with baseline retinol (r = -0.38, P = 0.048). In both schools, 3-d DRD showed reductions in the ratio of serum deuterated to nondeuterated retinol (D:H retinol) postintervention, denoting improvements in vitamin A status; the higher D:H retinol (ie, the poorer the status) at baseline, the greater the reduction in D:H retinol postintervention (school 1: r = -0.99, P = 0.0001; school 2: r = -0.89, P = 0.0001). Conclusions: Three-day DRD can detect changes in the body pool size of vitamin A, although a predictive equation to quantitate total body stores of vitamin A with the use of 3-d data needs to be developed. Bioconversion of plant carotenoids to vitamin A varies inversely with vitamin A status; improvement in status after dietary interventions is strongly influenced by total body stores of vitamin A and is influenced little or not at all by serum retinol. Am J Clin Nutr 2000;72:455-65. KEY WORDS Vitamin A, retinol, [Beta]-carotene bioconversion, carotenoids, fruit, vegetables, anthelmintic drugs, deuterated retinol dilution, stable isotope dilution, school-age children

Background: Lutein and zeaxanthin are the only carotenoids in the macular region of the retina (referred to as macular pigment [MP]). Foods that are rich in lutein and zeaxanthin can increase MP density. Response to dietary lutein and zeaxanthin in other tissues has not been studied. Objective: The objective of this study was to examine tissue responses to dietary lutein and zeaxanthin and relations among tissues in lutein and zeaxanthin concentrations. Design: Seven subjects consumed spinach and corn, which contain lutein and zeaxanthin, with their daily diets for 15 wk. At 0, 4, 8, and 15 wk and 2 mo after the study, serum, buccal mucosa cells, and adipose tissue were analyzed for carotenoids, and MP density was measured. Results: Serum and buccal cell concentrations of lutein increased significantly from baseline during dietary modification. Serum zeaxanthin concentrations were greater than at baseline only at 4 wk, whereas buccal cell and adipose tissue concentrations of zeaxanthin did not change. Adipose tissue lutein concentrations peaked at 8 wk. Changes in adipose tissue lutein concentration were inversely related to the changes in MP density, suggesting an interaction between adipose tissue and retina in lutein metabolism. To investigate the possibility of tissue interactions, we examined cross-sectional relations among serum, tissue, and dietary lutein concentrations, anthropometric measures, and MP density in healthy adults. Significant negative correlations were found between adipose tissue lutein concentrations and MP for women, but a significant positive relation was found for men. Conclusion: Sex differences in lutein metabolism may be an important factor in tissue interactions and in determining MP density. Am J Clin Nutr 2000;71:1555-62. KEY WORDS Carotenoids, lutein, zeaxanthin, macular pigment, adults

Dark adaptation has been used as a tool for identifying patients with subclinical vitamin A deficiency. With this functional test it was shown that tissue vitamin A deficiency occurs over a wide range of serum vitamin A concentrations. However, serum vitamin A concentrations [is greater than] 1.4 [micro]mol/L predict normal dark adaptation 95% of the time. Other causes of abnormal dark adaptation include zinc and protein deficiencies. Stable isotopes of vitamin A and isotope-dilution techniques were used recently to evaluate body stores of vitamin A and the efficacy of vitamin A intervention programs in field settings and are being used to determine the vitamin A equivalences of dietary carotenoids. Vitamin A toxicity was described in patients taking large doses of vitamin A and in patients with type I hyperlipidemias and alcoholic liver disease. Conversely, tissue retinoic acid deficiency was described in alcoholic rats as a result of hepatic vitamin A mobilization, impaired oxidation of retinaldehyde, and increased destruction of retinoic acid by P450 enzymes. Abnormal oxidation products of carotenoids can cause toxicity in animal models and may have caused the increased incidence of lung cancer seen in 2 epidemiologic studies of the effects of high-dose [Beta]-carotene supplementation. Major issues that remain to be studied include the efficiency of conversion of carotenoids in whole foods to vitamin A by using a variety of foods in various field settings and whether intraluminal factors (eg, parasitism) and vitamin A status affect this conversion. In addition, the biological activity of carotenoid metabolites should be better understood, particularly their effects on retinoid signaling. Am J Clin Nutr 2000;71:878-84. KEY WORDS Vitamin A, retinoids, vitamin A deficiency, vitamin A toxicity, vitamin metabolism, stable isotopes, Robert H Herman Memorial Award in Clinical Nutrition

Background: Vitamin A activity of plant provitamin A carotenoids is uncertain. Objective: The objective was to determine whether plant carotenoids can sustain or improve vitamin A nutrition during the fall season in kindergarten children in the Shandong province of China. Design: The serum vitamin A concentration of 39% of the children was [is less than] 1.05 [micro]mol/L and of 61% of the children was [is greater than or equal to] 1.05 [micro]mol/L. For 5 d/wk for 10 wk, 22 children were provided [approximately equals] 238 g green-yellow vegetables/d and 34 g light-colored vegetables/d. Nineteen children maintained their customary dietary intake, which included 56 g green-yellow vegetables/d and 224 g light-colored vegetables/d. Octadeuterated and tetradeuterated vitamin A were given before and after the interventions, respectively, and their enrichments in the plasma were determined by gas chromatography-mass spectrometry. Serum retinol and carotenoid concentrations were measured by HPLC. Results: Carotenoid nutrition improved after consumption of green-yellow vegetables. Serum concentrations of retinol were sustained in the group fed green-yellow vegetables but decreased in the group fed light-colored vegetables (P [is less than] 0.01). The isotope-dilution tests confirmed that total-body vitamin A stores were sustained in the group fed green-yellow vegetables, but decreased 27 [micro]mol (7700 [micro]g retinol) per child, on average, in the group fed light-colored vegetables (P [is less than] 0.06). Conclusion: Green-yellow vegetables can provide adequate vitamin A nutrition in the diet of kindergarten children and protect them from becoming vitamin A deficient during seasons when the provitamin A food source is limited. Am J Clin Nutr 1999;70:1069-76. KEY WORDS Green-yellow vegetables, deuterated vitamin A, China, kindergarten children, total-body vitamin A stores

Background: Deuterated retinol dilution (DRD) gives quantitative estimates of total body stores of vitamin A. Objectives: In elderly people, we studied 1) the time when an oral dose of deuterated vitamin A equilibrates with body stores, 2) whether serum ratios of deuterated to nondeuterated retinol (D:H) at 3 or 6 d postdosing predicted body stores, and 3) the ability of DRD to detect changes in the size of the body vitamin A pool. Design: A 10-mg oral dose of [[sup.2][H.sub.4]]retinyl acetate was administered to 60-81-y-old Guatemalans (n = 47); percentage enrichment of serum retinol with deuterated retinol was determined at 1-3 time points per subject at 3, 6, 7, 14, 20, 21, and 54 d. In subjects from whom blood was obtained at 3 and 21 d (n = 15) and at 6 and 20 d (n = 9), total body stores were calculated by using the formula of Furr et al (Am J Clin Nutr 1989;49:713-6) with 21- or 20-d data and correlated with serum D:H at 3 or 6 d postdosing. Nine subjects received diets containing 982 [+ or -] 20 [micro]g RE ([bar] x [+ or -] SEM) plus 800 [micro]g RE as retinyl acetate supplements for 32 d. DRD, serum retinol, and relative dose response were used to assess vitamin A status before and after the intervention. Results: Deuterated retinol equilibrated with the body pool by 20 d postdosing. Vitamin A supplementation for 32 d increased body stores, although unexplained exaggerated increases were seen in some subjects. An inverse linear relation was found between estimates of body stores and serum D:H at 3 d postdosing (r = -0.75, P = 0.002); at 6 d postdosing, the correlation was weaker. Conclusions: DRD can detect changes in total body stores of vitamin A, although factors affecting serum D:H need to be elucidated. Serum D:H 3 d postdosing might be used as an early indicator of total body stores of vitamin A, although a predictive equation will need to be developed. Am J Clin Nutr 1999;69:278-84. KEY WORDS Vitamin A, deuterated retinol dilution, stable isotope dilution, body stores, elderly, retinol, relative dose response, Guatemala

Background: Epidemiologic studies have demonstrated that individuals who eat more fruits and vegetables and/or have high levels of serum [Beta]-carotene have a lower risk of cancer, especially lung cancer. However, recent human intervention studies using [Beta]-carotene supplements have shown an increase in the risk of lung cancer among smokers and asbestos workers. In this study, we used an animal model system to evaluate the hazard associated with a combination of high-dose [Beta]-carotene supplementation and tobacco smoking. Methods: Ferrets were given a [Beta]-carotene supplement, exposed to cigarette smoke, or both for 6 months. Cell proliferation and squamous metaplasia in lung tissue were assessed by examination of proliferating-cell nuclear antigen expression and histopathologic examination, respectively. [Beta]-Carotene and retinoid concentrations in lung tissue and plasma samples were analyzed by high-performance liquid chromatography. Expression of genes for retinoic acid receptors (RARs) and activator protein-1 (encoded by the c-Jun and c-Fos genes) in lung tissue specimens was examined by western blotting. Results: A strong proliferative response in lung tissue and squamous metaplasia was observed in all [Beta]-carotene-supplemented animals, and this response was enhanced by exposure to tobacco smoke. When compared with control groups, all three treatment groups had statistically significantly lower concentrations of retinoic acid in lung tissue, and they exhibited 18%-73% reductions in RAR[Beta] gene expression; however, RAR[Alpha] and RAR[Gamma] gene expression was not reduced. Ferrets given a [Beta]-carotene supplement and exposed to tobacco smoke had threefold to fourfold elevated expression of the c-Jun and c-Fos genes. Conclusions: Diminished retinoid signaling, resulting from the suppression of RAR[Beta] gene expression and overexpression of activator protein-1, could be a mechanism to enhance lung tumorigenesis after high-dose [Beta]-carotene supplementation and exposure to tobacco smoke. [J Natl Cancer Inst 1999;91:60-6]