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AJCN Sep, 2006

[Vitamin D is extremely important - Must it be absolutely proven?] Nutrition, chronic disease, and the problem of proof Am J Clin Nutr 2006 84: 471-472.[http://www.ajcn.org/cgi/content/full/84/3/471] "...the likelihood of nursing home admission was inversely related to baseline vitamin D status. The trend in risk was approximately linear up to the highest values measured (ie, >75 nmol/L). After various adjustments, persons with values <25 nmol/L had nearly 4 times the risk of being admitted to a nursing home as did persons with values >75 nmol/L. The true risk may be even higher,... This finding has biological plausibility, inasmuch as low vitamin D status impairs lower-extremity function and contributes significantly to the risk of falling (3, 4)...The high prevalence of vitamin D deficiency mandates that physicians assess and correct vitamin D status in their elderly patients (5)...Persons are, of course, always free to act on available information, but individual initiative is rarely an efficient way of changing public health status. Food fortification is an obvious alternative (7), but any such proposal bumps up squarely against the problem of proof. Most of the studies concerned (including the study by Visser et al) are observational in character. Do such studies constitute sufficient evidence for a population-level intervention? The randomized controlled trial (RCT), which has become the gold standard for establishing the efficacy of pharmacologic agents, is poorly suited to the evaluation of nutritional effects, ... First, whereas a drug-free state exists that can be contrasted with a drug-added state, with respect to nutrients, the only contrast can be between different intakes, both usually well above zero. Second, most nutrients have what is known as threshold behavior, ie, some physiologic measure improves as intake rises up to a level of sufficiency, above which higher intakes produce no additional benefit. Third, most nutrients have beneficial effects on multiple tissues and organ systems, and thus a focus on a single or "primary" outcome measure, which is favored by RCTs, is often procrustean. Such circumstances raise 2 related questions: 1) to what extent should current standards of proof be relaxed for nutrient benefits? and 2) what alternative investigational design might be used to produce results that could be used as a basis for nutritional policy? ...Public policy has long been comfortable in using a more relaxed standard of proof for potentially harmful effects. " [Note in the article it states that there is general agreement that white postmenopausal women should get 1000-1500 mg Calcium/day.]

[Genes and environment each play a major role in obesity.] Genetics of obesity in Hispanic children Am J Clin Nutr 2006 84: 473-474[http://www.ajcn.org/cgi/content/full/84/3/473] "An epidemic of overweight and obesity is occurring in both industrial and developing societies. According to the National Health and Nutrition Examination Survey (NHANES), the prevalence of obesity doubled in the adult population, and the prevalence of overweight tripled in children and adolescents between 1982 and 2002 (Internet: www.cdc.gov/nchs/nhanes.htm)...18.2% of boys and 16.0% of girls between the ages of 2 and 19 y are now overweight (1). Prevalence estimates differ by ethnicity, eg, 22.0% of Mexican American boys and 16.2% of Mexican American girls are overweight (1)... As reviewed by Comuzzie and Allison (4), 40–70% of the within-population variation in obesity is due to genetic variation. ..genetic influences contributed 0.75–0.80 of the variation in percentage body fat in a pediatric twin study (6)...Energy and macronutrient intakes have heritability coefficients ranging from 0.54 to 0.69, and indicators of physical activity have heritability coefficients ranging from 0.32 to 0.60. Risk factors for metabolic diseases have heritability coefficients of 0.25 to 0.73, the highest being that for serum total cholesterol concentrations. ..[This]suggests the presence of single major genes with large effects (7)."

The underappreciated role of muscle in health and disease Am J Clin Nutr 2006 84: 475-482.[http://www.ajcn.org/cgi/content/abstract/84/3/475] " Muscle plays a central role in whole-body protein metabolism by serving as the principal reservoir for amino acids to maintain protein synthesis in vital tissues and organs in the absence of amino acid absorption from the gut and by providing hepatic gluconeogenic precursors. ... Nonetheless, the maintenance of adequate muscle mass, strength, and metabolic function has rarely, if ever, been targeted as a relevant endpoint of recommendations for dietary intake. It is therefore imperative that factors directly related to muscle mass, strength, and metabolic function be included in future studies designed to demonstrate optimal lifestyle behaviors throughout the life span, including physical activity and diet. " [The article states that a young healthy male typically has 35 to 50 kg of muscle, while an elderly woman may have only 13 kg. The man uses 485 kcal/day to maintain his muscle, the woman only 120. The force of those muscles on bones prevents osteoporosis. The article points out that therre is no consideration of muscle mass or physical activity in the Daily Values. The article points out the 15 g of essential amino acids provides the maximal response of the body for building muscles for a 55 kg woman.]

[Waist circumference is main danger]Body fat distribution and risk of type 2 diabetes in the general population: are there differences between men and women? The MONICA/KORA Augsburg Cohort Study Am J Clin Nutr 2006 84: 483-489 [http://www.ajcn.org/cgi/content/abstract/84/3/483] " ...waist circumference (WC), or waist-hip ratio (WHR) is a better risk predictor of type 2 diabetes...Conclusions: Both overall and abdominal adiposity were strongly related to the development of type 2 diabetes. Because there was an additive effect of overall and abdominal obesity on risk prediction, WC should be measured in addition to BMI to assess the risk of type 2 diabetes in both sexes. "

Inflammatory proteins are related to total and abdominal adiposity in a healthy adolescent population: the AVENA Study Am J Clin Nutr 2006 84: 505-512 [http://www.ajcn.org/cgi/content/abstract/84/3/505] "Background: In adults, obesity is characterized by a state of chronic low-grade inflammation accompanied by moderately high concentrations of acute phase inflammatory proteins. Recent results regarding C-reactive protein (CRP) point to a similar status in adolescents; ...Conclusions: Total body fat seems to be associated with a chronic low-grade systemic inflammation in apparently healthy adolescents...."

[tea extract looks promising for the treatment of obesity or diabetes] An extract of black, green, and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers Am J Clin Nutr 2006 84: 551-555[http://www.ajcn.org/cgi/content/abstract/84/3/551]"Background: In vitro studies suggest that extracts of black, green, and mulberry teas could interfere with carbohydrate and triacylglycerol absorption via their ability to inhibit -amylase, -glucosidase, sodium-glucose transporters, and pancreatic lipase...Conclusion: This study provides the basis for additional experiments to determine whether the tea extract has clinical utility for the treatment of obesity or diabetes."

[tomatoes protect your heart] Effects of antiplatelet components of tomato extract on platelet function in vitro and ex vivo: a time-course cannulation study in healthy humans Am J Clin Nutr 2006 84: 570-579[http://www.ajcn.org/cgi/content/abstract/84/3/570] "Background: Natural antithrombotic agents that influence platelet function are of potential interest for primary prevention of cardiovascular disease. Previous reports showed that tomato extracts inhibit platelet aggregation in vitro, but little is known of the active components, their mode of action, or their efficacy in vivo. ..Conclusions: The ingestion of tomato components with in vitro antiplatelet activity significantly affects ex vivo platelet function. The reported cardioprotective effects of tomatoes are potentially linked to a modulation of platelet function."

[soy reduces fibroids] Lignan and isoflavone excretion in relation to uterine fibroids: a case-control study of young to middle-aged women in the United States
Am J Clin Nutr 2006 84: 587-593.[http://www.ajcn.org/cgi/content/abstract/84/3/587] "Background: Uterine fibroids are hormonally responsive; estradiol and progesterone stimulate their growth, and gonadotrophin-releasing hormone agonists shrink them. Phytoestrogens, including isoflavones and lignans, can act as weak estrogens or antiestrogens...Conclusions: Our findings suggest a modest inverse association between lignan excretion and uterine fibroid risk. Whether this relation represents an effect of lignans per se or of other constituents of lignan-containing foods on the development of uterine fibroids remains to be determined. No association was found between isoflavone excretion and uterine fibroids; however, the intake of soy foods, the primary source of isoflavones, was low in this population."[Article mentions a study of Japanese women showing increased soy intake reduced the risk of premenopausal hysterectomy, so eating soy is good.]

Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men
Am J Clin Nutr 2006 84: 623-632 [http://www.ajcn.org/cgi/content/abstract/84/3/623] "Background: The progressive loss of skeletal muscle mass with aging is attributed to a disruption in the regulation of skeletal muscle protein turnover...Conclusions: Co-ingestion of protein and leucine with carbohydrate after activities of daily living improves whole-body protein balance, and the increase in muscle protein synthesis rates is not significantly different between lean young and elderly men."

[Medical students learn not to tell us about good nutrition] Predictors of nutrition counseling behaviors and attitudes in US medical students Am J Clin Nutr 2006 84: 655-662. [http://www.ajcn.org/cgi/content/abstract/84/3/655] "Conclusions: The perceived relevance of nutrition counseling by US medical students declined throughout medical school, and students infrequently counseled their patients about nutrition. Interventions may be warranted to improve the professional nutritional practices of medical students."

 

 

 

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