Search

Background: Short chain fatty acids (SCFAs; e.g., acetate, propionate, and butyrate) are produced by microbial fermentation of fiber in the colon. Evidence is lacking on how high-fiber diets that differ in macronutrient composition affect circulating SCFAs., Objectives: We aimed to compare the effects of 3 high-fiber isocaloric diets differing in %kcal of carbohydrate, protein, or unsaturated fat on circulating SCFAs. Based on previous literature, we hypothesized that serum acetate, the main SCFA in circulation, increases on all high-fiber diets, but differently by macronutrient composition of the diet., Methods: OmniHeart is a randomized crossover trial of 164 men and women (≥30 y old); 163 participants with SCFA data were included in this analysis. We provided participants 3 isocaloric high-fiber (∼30 g/2100 kcal) diets, each for 6 wk, in random order: a carbohydrate-rich (Carb) diet, a protein-rich (Prot) diet (protein predominantly from plant sources), and an unsaturated fat-rich (Unsat) diet. We used LC-MS to quantify SCFA concentrations in fasting serum, collected at baseline and the end of each diet period. We fitted linear regression models with generalized estimating equations to examine change in ln-transformed SCFAs from baseline to the end of each diet; differences between diets; and associations of changes in SCFAs with cardiometabolic parameters., Results: From baseline, serum acetate concentrations were increased by the Prot (β: 0.24; 95% CI: 0.12, 0.35), Unsat (β: 0.21; 95% CI: 0.10, 0.33), and Carb (β: 0.12; 95% CI: 0.01, 0.24) diets; between diets, only Prot compared with Carb was significant (P = 0.02). Propionate was decreased by the Carb (β: -0.10; 95% CI: -0.16, -0.03) and Unsat (β: -0.10; 95% CI: -0.16, -0.04) diets, not the Prot diet; between diet comparisons of Carb vs. Prot (P = 0.006) and Unsat vs. Prot (P = 0.002) were significant. The Prot diet increased butyrate (β: 0.05; 95% CI: 0.00, 0.09) compared with baseline, but not compared with the other diets. Increases in acetate were associated with decreases in insulin and glucose; increases in propionate with increases in leptin, LDL cholesterol, and blood pressure; and increases in butyrate with increases in insulin and glucose, and decreases in HDL cholesterol and ghrelin (Ps < 0.05)., Conclusions: Macronutrient composition of high-fiber diets affects circulating SCFAs, which are associated with measures of appetite and cardiometabolic health. This trial was registered at clinicaltrials.gov as NCT00051350., (Copyright © The Author(s) 2020.)

Broiler chicks at 2 wk of age were fed the following fats and oils at 4% in a corn-wheat-soybean basal diet: palm oil (PO); tallow (T1 and T2); tallow + soybean oil (50:50, TSO); tallow+acidulated soybean oil soapstock (50:50, TASO); soybean oil (SO); and linseed oil (LO). All of these, with the exception of T1, contained 5% soybean lecithin. The apparent fat availability (AFA) and AME of added fats ranged from 78.8 to 96.0% and from 7.32 to 8.95 kcal/g, respectively. Three fat sources (TSO, SO, and LO) resulted in the highest values for these two measurements, whereas PO, T1, T2, and TASO showed the lowest values. There was no difference for AME of diets among fat-supplemented treatments, regardless of the difference in the nutritive values of the fats and oils tested. The apparent availability of each fatty acid (AAFA) for C16:0, C18:0, C18:1, C18:2, and C18:3 was calculated from the analysis of the diets and excreta collected over a 4-d period. The results of the present study indicated that 2-wk-old chicks utilize TSO, SO, and LO more efficiently than PO, T1, T2, and TASO.

A food's hypercholesterolaemic-atherogenic potential lies in its cholesterol and saturated-fat content. To help understand the contribution of these two factors a cholesterol/saturated-fat index (CSI) has been calculated. This index is based on a modification of a regression equation computed from metabolic studies designed to lower plasma lipids. A low CSI indicates low saturated fat and cholesterol content and low atherogenicity. The CSI may be used to compare different foods and recipes and to evaluate daily intake quickly and easily.

Four diets, varying in kind and amount of fat, were calculated to meet the needs of adult men. Commonly available U.S.A. food were used. Fourteen days of menus, each with five caloric levels varying from 2,400 to 4,000 kcal, were calculated. Chemical analyses of composites were carried out to determine proximate composition, food energy, selected vitamins and minerals, sugars, fatty acids, and sterols. The diets were used in a controlled study of the effects of fat level and P:S on blood pressure, blood lipids, platelet aggregation, and other variables. In general, good agreement was found between calculated and analyzed nutrient contents. However, analyzed values for fiber, iron, cholesterol, and vitamin C showed larger than desirable differences from calculated values.

Twenty-five young couples consumed either a saturated or polyunsaturated fat diet for a 20-week period. The polyunsaturated beef, lamb and dairy products, high in linoleic acid, were produced by feeding ruminant animals "protected lipid" feeds which prevent hydrogenation of fats in the rumen. The experimental design provided for four dietary groups: A) saturated diet for 20 weeks; B) polyunsaturated diet for 20 weeks; C) saturated diet for 10 weeks then polyunsaturated diet for 10 weeks; and D) polyunsaturated for 10 weeks then saturated diet for 10 weeks. Polyunsaturated-to-saturated ratios (linoleic: total saturated fatty acids) for the diets were: prestudy, 0.43-0.56; saturated 0.11-0.14; polyunsaturated, 0.56-0.62. Factors other than diet that appeared to affect cholesterol responses were carefully considered. During the initial 3 weeks (regimentation period) plasma cholesterol concentration decreased in all groups irrespective of diet. This was followed by two experimental periods in which the effects of the prescribed diets were readily apparent (response periods I and II). The final 4 weeks of the study were characterized by diminishing compliance with the dietary discipline (abatement period). Subjects in each group (A,B,C,D) were subdivided into high and low on a basis of each group's initial median cholesterol level. Those in the high subgroups were very responsive to dietary changes whereas those in the low subgroups were not. Combined responses of high subjects were: polyunsaturated diet, -10.7 mg/dl (P less than 0.025), saturated diet, d8 mg/dl (P less than 0.05). Combined difference between saturated and polyunsaturated diets was 18.5 mg/dl or approximately a 10% cholesterol difference between the experimental polyunsaturated and saturated diets.

Two hundred and twenty-nine adolescent male pupils, attending two boarding schools, participated in a study, under free-living dietary conditions, designed to assess the effects on plasma lipids of altering only the type and not the amount of dietary fat. The students were monitored for 6 weeks on three different diets. During the first study period, dietary changes comprised substituting a polyunsaturated dried "filled" milk and products derived therefrom for conventional dairy products (diet A). The second dietary phase involved replacing all meat and dairy products with equivalent polyunsaturated ruminant fat products (diet B). The third period consisted of a control diet of conventional dairy and meat products. During both polyunsaturated diets a 14% reduction in plasma cholesterol was achieved compared with control levels. Low-density lipoprotein cholesterol was similarly suppressed. A greater decrease in plasma cholesterol of 19-21% was recorded in those pupils with initial cholesterol levels greater than 230 mg/dl. There was no significant difference in plasma triglycerides between diet A and the control diet whereas the triglyceride levels were 16.5% lower during diet B. The fall in plasma cholesterol coincided with an increase in plasma triglyceride linoleate from 8% to 19% of total triglyceride fatty acids. Dietary analysis of the pupils' diet indicated an increase in the ratio of polyunsaturates to saturates from 0.27 during the control period to 1.08 on the dried filled milk and 0.90 on the polyunsaturated ruminant fat products. A palatability survey showed that both the dried filled milk and the polyunsaturated ruminant fat products were as well accepted by the pupils as the conventional products. The results suggest that such products could, if introduced to the general population, play an important part in plasma cholesterol suppression in the hope that this would significantly reduce the incidence of coronary artery disease.

The apparent consumption of dietary fat in Australia is 115 g/person/day, of which two-thirds is contributed by ruminant-derived foods. Consequently, the polyunsaturated fatty acid/saturated fatty acid ratio of the Australian diet is low, approximately 0.2. Recently a process has been developed which allows modification of the fatty acid composition of ruminant body fat, and a range of foodstuffs (fat-modified foods) which have a substantially higher polyunsaturated fatty acid/saturated fatty acid ratio than their conventional counterparts has been produced and marketed. In the clinical trials in which there was complete substitution of fat-modified ruminant foods for conventional ruminant products the fall in serum cholesterol was approximately 10%. In the trial in which there was only partial substitution the fall in serum cholesterol was insignificant. Using the equation developed by Keys, the predicted fall in serum cholesterol resulting from varying degrees of substitution of fat-modified ruminant meats for their conventional counterparts in the Australian diet is shown to be negligible. The fat-modified products were marketed at approximately twice the price of their conventional counterparts and it is claimed that this will limit the degree of substitution. It is concluded that the public health significance of fat-modified foods is limited.

New methods of feeding low-birth-weight infants have been developed as a result of improved knowledge concerning the nutritional requirements of the premature infant. Breast milk may offer certain nutritional and non-nutritional advantages for immature babies. Preterm milk is theoretically more appropriate than term or pooled mature breast milk. However, some nutrients may be inadequate to support intrauterine rates of growth in small premature infants. New formulas specifically designed for preterm babies appear to be safe and to promote improved weight gain, fat absorption, bone mineralization, and nitrogen retention. Nutritional needs of growing preterm infants are better met by preamture formulas than by formulas designed for term babies.

This paper summarizes representative values for the fatty acid composition of unprocessed vegetable fats, vegetable oils, and animal fats. The data for these unprocessed fats and oils are identical with those of the processed, but unhydrogenated fats and oils. Calculations to convert the fatty acid methyl ester data to grams fatty acid per 100 gm. food are discussed, and the converted data are presented in tabular form. Climatic and cultivar effects on the fatty acid composition of some of these oils are reviewed.

The lipid composition of an egg substitute and fresh eggs was conpared. The total lipid was divided into fractions on a silicic acid column. Thin-layer-chromatographic analysis demonstrated that the egg substitute was practically void of cholesteryl esters. Gas-liquid-chromatographic analysis were used to ascertain the fatty acid composition of the various fractions. Eggs contained considerably higher concentrations of saturated and mono-unsaturated fatty acids than did the substitute. The polyunsaturated fatty acid concentration in the substitute was approximately three times that of eggs. In all fractions, the eggs contained several more individual fatty acids than did the egg substitute.

Highly purified preparations of mitochondria from bovine heart, liver, and kidney were isolated and characterized by electron microscopy, oxidative phosphorylation ability, cytochrome c reductase activity, and cytochrome content. Components of lipid extracts of the preparations were determined by thin-layer chromatography, diethylaminoethyl-cellulose column chromatography, and spectrophotometric procedures. The major phospholipids were identified by their chromatographic behavior, IR spectrometry, and paper chromatography of their hydrolysis products. The lipid content of the mitochondria paralleled that of the components of the electron transfer chain, heart mitochondria being richest and liver mitochondria poorest in lipid. Heart mitochondria contain equal concentrations of coenzyme Q and cholesterol (1%); the highest cholesterol content (4.7%) was found in mitochondria from kidney. The phospholipids of mitochondria from the three organs were qualitatively and quantitatively very similar. The major polar lipid components (cardiolipin, choline glycerophosphatides, and ethanolamine glycerophosphatides) were present in a molar ratio of 1:4:4. It is suggested that mitochondria from different sources contain characteristic lipids, mainly phospholipids, of which cardiolipin is particularly diagnostic of the source of the mitochondria.