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Background/objectives: We examined the associations between carbohydrate substitutions (total; low-, medium-, high-glycemic index (GI) carbohydrates) for fat or protein and risk of type 2 diabetes., Subjects/methods: The cohort comprised 25,943 male smokers among whom 1098 diabetes cases were identified from a national register during a 12-year follow-up. Diet was assessed by a validated food frequency questionnaire. The relative risks (RR) and confidence intervals (CI) for diabetes were analyzed using Cox proportional hazard modeling, and multivariate nutrient density models were applied to examine the associations between substitutions of macronutrients and diabetes risk., Results: The risk of diabetes was lower when fat or protein was replaced with an isoenergetic amount (2% of energy intake) of carbohydrates, the multivariate RRs were 0.96 (95% CI: 0.94, 0.99) and 0.85 (95% CI: 0.80, 0.90), respectively. The lower risks were due to replacing saturated plus trans fatty acids, and meat, milk or plant protein with carbohydrates, respectively. Low-, medium- or high-GI carbohydrates did not associate with lower diabetes risk when replacing fat or fatty acids, except when total fat was replaced with medium-GI carbohydrates. Low-, medium- and high-GI carbohydrates had similar inverse associations with diabetes risk when they replaced total, meat or milk protein., Conclusion: Higher carbohydrate intake at the expense of fat, attributable to trans and saturated fatty acids, or protein was associated with decreased diabetes risk. Replacing fat or protein with lower-GI carbohydrates was not more beneficial than replacing it with higher-GI carbohydrates.

Objective: To compare the effects on serum lipoproteins of three isocaloric diets with reduced total fat and saturated fatty acid (SFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA)., Design: A low-fat diet (LF) provided 20 en% fat, 7.9% SFA, 7.8% MUFA, 3.0% PUFA; a high-PUFA diet (HP) 26 en% fat, 7.5% SFA, 8.2% MUFA, 8.1% PUFA; and a high-MUFA diet (HM) 26 en% fat, 7.3% SFA, 14.1% MUFA, 3.2% PUFA. Diets were consumed for 8 weeks in a parallel design, after 2 weeks on a habitual diet with 33-34 en% fat, 13-14% SFA, 12% MUFA, 6% PUFA, and followed by an 8-week period on habitual diet. Compliance to diet was monitored by repeated food records and weekly visits to a nutritionist., Subjects: 45 free-living, middle-aged couples who were randomly allocated into the three diet groups; 43 men and 44 women completed the study., Results: During the diet periods, a small but significant reduction in body weight of 0.4-1.0 kg was observed in all groups. Similar and significant reductions of mean weight-adjusted serum total cholesterol (4-8%), low-density lipoprotein (LDL) cholesterol (7-11%), and high-density lipoprotein (HDL) cholesterol (8-11%) were observed during the diets. HDL2-cholesterol and apoprotein (apo) A-I levels were reduced whereas HDL3-cholesterol and apoA-II increased. ApoB was significantly decreased during the HM diet only. Serum triglycerides increased significantly during diets LF (25%, P < 0.01) and HP (19%, P < 0.05) but not during diet HM (5%, NS)., Conclusions: Reduction in the intake of total fat and saturated fatty acids reduced serum LDL-cholesterol and HDL2-cholesterol concentrations irrespective of the relative proportions of MUFA and PUFA in the diets. The results suggest that there might be some advantage in increasing the proportion of MUFA in low-fat diets, since the HM diet rich in MUFA reduced apoB and slightly attenuated the increase in serum triglycerides that is commonly associated with dietary fat reduction.

Objective: To assess the effects of high-fish and low-fish diets on plasma concentrations of fatty acids and selected antioxidants., Design and Subjects: The effects of fish consumption on dietary and plasma antioxidant levels and fatty acid composition were studied as part of a large dietary survey of Finnish adults (n = 1861). High-fish consumers were matched with low-fish consumers and 41 pairs were identified. The members of each pair were of the same sex, from the same 10 y age group, and from the same or adjacent areas. There were 21 men and 20 women in each group, with a mean age of 54.3 y., Methods: The fish consumption of the subjects was investigated with a qualitative food questionnaire. Additionally, a 3 d food record was used to estimate the diet. Two indices were defined to describe the oxidation potential of the diets. The plasma alpha-tocopherol, gamma-tocopherol, and beta-carotene concentrations and various fatty acids were analysed., Results: The mean fish intake was 103 g/d in the high-fish and 5 g/d in the low-fish group. The dietary intakes of vitamin C, protein, total n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid, docosahexaenoic acid, mercury, selenium, and salt and the theoretical oxidative potential were higher (P < 0.05) and the saturated fatty acid intake lower (P < 0.01) in the high-fish than in the low-fish group. The dietary vitamin E intake was similar in both groups but the ratio of dietary vitamin E/PUFA was higher (P < 0.01) in the high-fish than in the low-fish group (0.85 and 0.75, respectively). The plasma n-3 PUFAs were higher (P < 0.001) and n-6 PUFAs lower (P < 0.001) in the high-fish than in the low-fish group. There were no differences in plasma antioxidant levels between the groups., Conclusion: This study shows that extreme fish consumption does not affect plasma antioxidant levels.

The effects of dietary fatty acid composition on the endogenous formation of DNA adducts of malonaldehyde (MA), the major product of lipid peroxidation, were investigated in humans. A group of 59 healthy individuals of both sexes and different ages was initially fed a milk fat-based diet rich in saturated fatty acids for 14 days. Following this initial period, after which the group was considered homogeneous with respect to diet, 30 randomly chosen subjects were given a sunflower oil-based (rich in polyunsaturated fatty acids) (SO) diet and the remaining 29 individuals a low erucic acid rapeseed oil-based (rich in monounsaturated fatty acids) (RO) diet for 25 days. The fatty acid composition of plasma lipid fractions and the level of DNA adducts of MA in total white blood cells were then determined at the end of the SO and RO dietary periods. DNA adduct levels were measured by 32p-postlabelling using reversed-phase HPLC with on-line detection of radioactivity. Higher concentrations of polyunsaturated fatty acids in plasma triglycerides and higher levels of DNA adducts of MA were found in the subjects on the SO diet when compared with those in the RO dietary group. A large inter-individual variation in adduct levels was observed. The average adduct level in the SO diet group was 7.4 +/- 8.7 adducts/10(7) nucleotides (n = 23). This level was 3.6-fold higher than that found in individuals in the RO diet group (P < 0.001). Our results, in conjunction with the mutagenic and carcinogenic properties of MA, thus suggest the interaction of lipid peroxidation products such as MA with DNA as one plausible mechanism explaining the involvement of dietary fat in carcinogenesis.

We compared the effects on blood pressure (BP) of three isocaloric diets with reduced total fat and saturated fatty acid (SAFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Diet LF (low fat) provided 20 en% fat (7.9% SAFA, 7.8% MUFA, 3.0% PUFA); diet HP (high PUFA) 26 en% fat (7.5% SAFA, 8.2% MUFA, 8.1% PUFA), and diet HM (high MUFA) 26 en% fat (7.3% SAFA, 14.1% MUFA, 3.2% PUFA). The diets were consumed for 8 weeks (intervention) preceded by 2 weeks and followed by 8 weeks on a habitual diet (baseline/ switchback) with 33-34 en% fat (13-14% SAFA, 12% MUFA, 6% PUFA). Forty-five free-living couples were randomly allocated into the three diet groups, and 43 men and 44 women completed the study. BP was measured weekly with an automatic device. Compliance to diet was monitored by repeated food records, serum fatty acid compositions, and weekly visits to a nutritionist. Both systolic BP (SBP) and diastolic BP (DBP) remained unchanged throughout the study in all three groups. The weight-adjusted mean (s.e.m.) BP values showed changes in SBP of +1.7 (1.8), -0.4 (1.7), and +1.9 (1.9) mm Hg on the LF, HP, and HM diets, respectively (difference NS), and DBP of +0.1 (1.0), +0.6 (1.0), and -0.3 (1.0) mm Hg, respectively (difference NS) between the last 2 weeks of the baseline and intervention periods. The expected fatty acid intakes were achieved, and there were no between-group differences in change of body weight, intake of dietary fibre and potassium, and 24-h sodium excretion. A reduction in total fat and SAFA intake and changes in the proportions of dietary MUFA and PUFA did not affect the BP levels of this normotensive population with an adequate intake of PUFA at baseline. [ABSTRACT FROM AUTHOR]