Dietary recommendations have been made for n-3 fatty acids, including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) to achieve nutrient adequacy and to prevent and treat cardiovascular disease. These recommendations are based on a large body of evidence from epidemiologic and controlled clinical studies. The n-3 fatty acid recommendation to achieve nutritional adequacy, defined as the amount necessary to prevent deficiency symptoms, is 0.6-1.2% of energy for ALA; up to 10% of this can be provided by EPA or DHA. To achieve recommended ALA intakes, food sources including flaxseed and flaxseed oil, walnuts and walnut oil, and canola oil are recommended. The evidence base supports a dietary recommendation of approximately 500 mg/d of EPA and DHA for cardiovascular disease risk reduction. For treatment of existing cardiovascular disease, 1 g/d is recommended. These recommendations have been embraced by many health agencies worldwide. A dietary strategy for achieving the 500-mg/d recommendation is to consume 2 fish meals per week (preferably fatty fish). Foods enriched with EPA and DHA or fish oil supplements are a suitable alternate to achieve recommended intakes and may be necessary to achieve intakes of 1 g/d.

Diets with increased protein and reduced carbohydrates (PRO) are effective for weight loss, but the long-term effect on maintenance is unknown. This study compared changes in body weight and composition and blood lipids after short-term weight loss (4 mo) followed by weight maintenance (8 mo) using moderate PRO or conventional high-carbohydrate (CHO) diets. Participants (age = 45.4 +/- 1.2 y; BMI = 32.6 +/- 0.8 kg/m(2); n = 130) were randomized to 2 energy-restricted diets (-500 kcal/d or -2093 kJ/d): PRO with 1.6 g x kg(-1) x d(-1) protein and <170 g/d carbohydrates or CHO with 0.8 g x kg(-1) x d(-1) protein, >220 g/d carbohydrates. At 4 mo, the PRO group had lost 22% more fat mass (FM) (-5.6 +/- 0.4 kg) than the CHO group (-4.6 +/- 0.3 kg) but weight loss did not differ between groups (-8.2 +/- 0.5 kg vs. -7.0 +/- 0.5 kg; P = 0.10). At 12 mo, the PRO group had more participants complete the study (64 vs. 45%, P < 0.05) with greater improvement in body composition; however, weight loss did not differ between groups (-10.4 +/- 1.2 kg vs. -8.4 +/- 0.9 kg; P = 0.18). Using a compliance criterion of participants attaining >10% weight loss, the PRO group had more participants (31 vs. 21%) lose more weight (-16.5 +/- 1.5 vs. -12.3 +/- 0.9 kg; P < 0.01) and FM (-11.7 +/- 1.0 vs. -7.9 +/- 0.7 kg; P < 0.01) than the CHO group. The CHO diet reduced serum cholesterol and LDL cholesterol compared with PRO (P < 0.01) at 4 mo, but the effect did not remain at 12 mo. PRO had sustained favorable effects on serum triacylglycerol (TAG), HDL cholesterol (HDL-C), and TAG:HDL-C compared with CHO at 4 and 12 mo (P < 0.01). The PRO diet was more effective for FM loss and body composition improvement during initial weight loss and long-term maintenance and produced sustained reductions in TAG and increases in HDL-C compared with the CHO diet.

There are multiple adverse effects of trans fatty acids (TFA) that are produced by partial hydrogenation (i.e., manufactured TFA), on CVD, blood lipids, inflammation, oxidative stress, endothelial health, body weight, insulin sensitivity, and cancer. It is not yet clear how specific TFA isomers vary in their biological activity and mechanisms of action. There is evidence of health benefits on some of the endpoints that have been studied for some animal TFA isomers, such as conjugated linoleic acid; however, these are not a major TFA source in the diet. Future research will bring clarity to our understanding of the biological effects of the individual TFA isomers. At this point, it is not possible to plan diets that emphasize individual TFA from animal sources at levels that would be expected to have significant health effects. Due to the multiple adverse effects of manufactured TFA, numerous agencies and governing bodies recommend limiting TFA in the diet and reducing TFA in the food supply. These initiatives and regulations, along with potential TFA alternatives, are presented herein.