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n-3 Fatty acids and cardiovascular disease: mechanisms underlying beneficial effects. Jung UJ, Torrejon C, Tighe AP, Deckelbaum RJ. Am J Clin Nutr. 2008 Jun;87(6):2003S-9S. PMID: 18541602 Dietary n-3 fatty acids, particularly eicosapentaenoic acid and docosahexaenoic acid, are important nutrients through the life cycle. Evidence from observational, clinical, animal, and in vitro studies indicates a beneficial role of n-3 fatty acids in the prevention and management of cardiovascular disease. Although the precise mechanisms are still unclear, clinical and preclinical studies indicate that the cardioprotective effects of n-3 fatty acids may be attributed to a number of distinct biological effects on lipid and lipoprotein metabolism, blood pressure, platelet function, arterial cholesterol delivery, vascular function, and inflammatory responses. Substantial evidence supports n-3 fatty acids as a practical, therapeutic adjuvant for promoting cardiovascular health and preventing and treating disease. n-3 Fatty acids modulate a number of important physiologic responses that can contribute to their cardioprotective effects. The multiple and complex mechanisms through which DHA and EPA exert their action appear to be distinct but also complementary. However, more studies are needed to quantify their protective effects and to define exact mechanisms of action.

Fish intake is associated with a reduced progression of coronary artery atherosclerosis in postmenopausal women with coronary artery disease. Erkkilä AT, Lichtenstein AH, Mozaffarian D, Herrington DM. Am J Clin Nutr. 2004 Sep;80(3):626-32. PMID: 15321802 Conclusions: Consumption of fish is associated with a significantly reduced progression of coronary artery atherosclerosis in women with coronary artery disease.

Measuring 25-hydroxyvitamin D in a clinical environment: challenges and needs. Hollis BW. Am J Clin Nutr. 2008 Aug;88(2):507S-510S. Review. PMID: 18689391 In this article, I provide an overview of the techniques available for measuring 25(OH)D, compare these techniques with one another, and assess their clinical utility. I also briefly discuss the stability of 25(OH)D in biological media and present an overview of the Vitamin D External Quality Assessment Scheme.

African Americans, 25-hydroxyvitamin D, and osteoporosis: a paradox. Aloia JF. Am J Clin Nutr. 2008 Aug;88(2):545S-550S. Review. PMID: 18689399

Plasma calcidiol, season, and serum parathyroid hormone concentrations in healthy elderly men and women. Dawson-Hughes B, Harris SS, Dallal GE. Am J Clin Nutr. 1997 Jan;65(1):67-71. PMID: 8988915 Plasma calcidiol and serum PTH concentrations were inversely related, with PTH rising slowly as calcidiol concentrations declined below 110 nmol/L (95 CI: 60, 168 nmol/L). More than 90% of the men and women had calcidiol concentrations below this value in the wintertime. The high prevalence of lower wintertime calcidiol values may increase risk of bone loss in elderly men and women.

Effects of chili consumption on postprandial glucose, insulin, and energy metabolism. Ahuja KD, Robertson IK, Geraghty DP, Ball MJ. Am J Clin Nutr. 2006 Jul;84(1):63-9. PMID: 16825682

Cholesterol, coconuts, and diet on Polynesian atolls: a natural experiment: the Pukapuka and Tokelau island studies. Prior IA, Davidson F, Salmond CE, Czochanska Z. Am J Clin Nutr. 1981 Aug;34(8):1552-61. PMID: 7270479 Two populations of Polynesians living on atolls near the equator provide an opportunity to investigate the relative effects of saturated fat and dietary cholesterol in determining serum cholesterol levels. The habitual diets of the toll dwellers from both Pukapuka and Tokelau are high in saturated fat but low in dietary cholesterol and sucrose. Coconut is the chief source of energy for both groups. Tokelauans obtain a much higher percentage of energy from coconut than the Pukapukans, 63% compared with 34%, so their intake of saturated fat is higher. The serum cholesterol levels are 35 to 40 mg higher in Tokelauans than in Pukapukans. These major differences in serum cholesterol levels are considered to be due to the higher saturated fat intake of the Tokelauans. Analysis of a variety of food samples, and human fat biopsies show a high lauric (12:0) and myristic (14:0) content. Vascular disease is uncommon in both populations and there is no evidence of the high saturated fat intake having a harmful effect in these populations.

Higher serum vitamin D concentrations are associated with longer leukocyte telomere length in women. Richards JB, Valdes AM, Gardner JP, Paximadas D, Kimura M, Nessa A, Lu X, Surdulescu GL, Swaminathan R, Spector TD, Aviv A. Am J Clin Nutr. 2007 Nov;86(5):1420-5. PMID: 17991655

Effects of n-3 long-chain polyunsaturated fatty acids on depressed mood: systematic review of published trials. Appleton KM, Hayward RC, Gunnell D, Peters TJ, Rogers PJ, Kessler D, Ness AR. Am J Clin Nutr. 2006 Dec;84(6):1308-16. Review. PMID: 17158410 Conclusions: Trial evidence that examines the effects of n-3 PUFAs on depressed mood is limited and is difficult to summarize and evaluate because of considerable heterogeneity. The evidence available provides little support for the use of n-3 PUFAs to improve depressed mood. Larger trials with adequate power to detect clinically important benefits are required.

Dietary protein and bone health: a systematic review and meta-analysis. Darling AL, Millward DJ, Torgerson DJ, Hewitt CE, Lanham-New SA. Am J Clin Nutr. 2009 Nov 4. [Epub ahead of print] PMID: 19889822

Safety of vitamin D3 in adults with multiple sclerosis. Kimball SM, Ursell MR, O'Connor P, Vieth R. Am J Clin Nutr. 2007 Sep;86(3):645-51. PMID: 17823429 Conclusions: Patients' serum 25(OH)D concentrations reached twice the top of the physiologic range without eliciting hypercalcemia or hypercalciuria. The data support the feasibility of pharmacologic doses of vitamin D3 for clinical research, and they provide objective evidence that vitamin D intake beyond the current upper limit is safe by a large margin.

Metabolic effects of conjugated linoleic acid in humans: the Swedish experience. Riserus U, Smedman A, Basu S, Vessby B. Am J Clin Nutr. 2004 Jun;79(6 Suppl):1146S-1148S. PMID: 15159248 CONCLUSIONS CLA and specifically the isolated isomers are interesting model fatty acids for studies of the effects of (structural differences of) unsaturated fatty acids in humans. Today, there is no clear indication for human use of CLA concentrates. The possible importance of the small reduction of body fat after supplementation with the commercially available CLA products, without evidence of an associated improvement in the metabolic profile, has to be weighed against the apparent reduction of HDL cholesterol and an increased lipid peroxidation. The possible health consequences of prolonged treatment periods are at present unknown. Human supplementation with high doses of the trans-10,cis-12 CLA isomer should be avoided while awaiting further information on possible effects and side effects. However, it cannot be excluded that future studies could point to clinical applications, eg, as a result of antitumorigenic properties or as a tool to prevent weight gain. This possibility certainly requires more research to increase the understanding of the mechanisms behind the effects of CLA and specific CLA isomers on a molecular level. More controlled studies in defined populations are needed, as are controlled studies for comparisons of the effects of different and well-defined (mixtures of) isomers and human studies of longer duration to secure long-term effects and safety.

Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Riserus U, Vessby B, Arnlov J, Basu S. Am J Clin Nutr. 2004 Aug;80(2):279-83. PMID: 15277146 CONCLUSIONS: A CLA preparation containing the purified c9,t11 CLA isomer increased insulin resistance and lipid peroxidation compared with placebo in obese men. Because c9,t11 CLA occurs in commercial supplements as well as in the diet, the present results should be confirmed in larger studies that also include women.

Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Cordain L, Miller JB, Eaton SB, Mann N, Holt SH, Speth JD. Am J Clin Nutr. 2000 Mar;71(3):682-92. PMID: 10702160 Our analysis showed that whenever and wherever it was ecologically possible, hunter-gatherers consumed high amounts (45-65% of energy) of animal food. Most (73%) of the worldwide hunter-gatherer societies derived >50% (> or =56-65% of energy) of their subsistence from animal foods, whereas only 14% of these societies derived >50% (> or =56-65% of energy) of their subsistence from gathered plant foods. This high reliance on animal-based foods coupled with the relatively low carbohydrate content of wild plant foods produces universally characteristic macronutrient consumption ratios in which protein is elevated (19-35% of energy) at the expense of carbohydrates (22-40% of energy).

Opposing effects of cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid on blood lipids in healthy humans. Tricon S, Burdge GC, Kew S, Banerjee T, Russell JJ, Jones EL, Grimble RF, Williams CM, Yaqoob P, Calder PC. Am J Clin Nutr. 2004 Sep;80(3):614-20. PMID: 15321800 Conclusion: Divergent effects of cis-9,trans-11 CLA and trans-10,cis-12 CLA appear on the blood lipid profile in healthy humans: trans-10,cis-12 CLA increases LDL:HDL cholesterol and total:HDL cholesterol, whereas cis-9,trans-11 CLA decreases them.

Effects of dairy products naturally enriched with cis-9,trans-11 conjugated linoleic acid on the blood lipid profile in healthy middle-aged men. Tricon S, Burdge GC, Jones EL, Russell JJ, El-Khazen S, Moretti E, Hall WL, Gerry AB, Leake DS, Grimble RF, Williams CM, Calder PC, Yaqoob P. Am J Clin Nutr. 2006 Apr;83(4):744-53. PMID: 16600923 CONCLUSION: Dairy products naturally enriched with cis-9,trans-11 CLA and trans-11 18:1 do not appear to have a significant effect on the blood lipid profile

Conjugated linoleic acid supplementation for 1 y does not prevent weight or body fat regain. Larsen TM, Toubro S, Gudmundsen O, Astrup A. Am J Clin Nutr. 2006 Mar;83(3):606-12. PMID: 16522907 CONCLUSION: A 3.4-g daily CLA supplementation for 1 y does not prevent weight or fat mass regain in a healthy obese population.

Egg consumption in relation to cardiovascular disease and mortality: the Physicians' Health Study. Djoussé L, Gaziano JM. Am J Clin Nutr. 2008 Apr;87(4):964-9. PMID: 18400720 Results: In an average follow-up of 20 y, 1550 new myocardial infarctions (MIs), 1342 incident strokes, and 5169 deaths occurred. Egg consumption was not associated with incident MI or stroke in a multivariate Cox regression. In contrast, adjusted hazard ratios (95% CI) for mortality were 1.0 (reference), 0.94 (0.87, 1.02), 1.03 (0.95, 1.11), 1.05 (0.93, 1.19), and 1.23 (1.11, 1.36) for the consumption of < 0.0001). This association was stronger among diabetic subjects, in whom the risk of death in a comparison of the highest with the lowest category of egg consumption was twofold (hazard ratio: 2.01; 95% CI: 1.26, 3.20; P for interaction = 0.09). Conclusions: Infrequent egg consumption does not seem to influence the risk of CVD in male physicians. In addition, egg consumption was positively related to mortality, more strongly so in diabetic subjects, in the study population.

Egg consumption in relation to cardiovascular disease and mortality: the story gets more complex. Eckel RH. Am J Clin Nutr. 2008 Apr;87(4):799-800. PMID: 1840069

Egg consumption, serum cholesterol, and cause-specific and all-cause mortality: the National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged, 1980 (NIPPON DATA80). Nakamura Y, Okamura T, Tamaki S, Kadowaki T, Hayakawa T, Kita Y, Okayama A, Ueshima H; NIPPON DATA80 Research Group. Am J Clin Nutr. 2004 Jul;80(1):58-63. PMID: 15213028 Results: The subjects were categorized into 5 egg consumption groups on the basis of their responses to a questionnaire (≥2/d, 1/d, 1/2 d, 1-2/wk, and seldom). There were 69, 1396, 1667, 1742, and 315 women in each of the 5 groups, respectively. Age-adjusted total cholesterol (5.21, 5.04, 4.95, 4.91, and 4.92 mmol/L in the 5 egg consumption categories, respectively) was related to egg consumption (P < 0.0001, analysis of covariance). In women, unadjusted IHD mortality and all-cause mortality differed significantly between the groups [IHD mortality: 1.1, 0.5, 0.4, 0.5, and 2.0 per 1000 person-years, respectively (P = 0.008, chi-square test); all-cause mortality: 14.8, 8.0, 7.5, 7.5, and 14.5 per 1000 person-years, respectively (P < 0.0001, chi-square test)]. In men, egg consumption was not related to age-adjusted total cholesterol. Cox analysis found that, in women, all-cause mortality in the 1-2-eggs/wk group was significantly lower than that in the 1-egg/d group, whereas no such relations were noted in men. Conclusion: Limiting egg consumption may have some health benefits, at least in women in geographic areas where egg consumption makes a relatively large contribution to total dietary cholesterol intake.