AJCN Jan, 2008
The American Journal of Clinical Nutrition offers many gifts of nutrition discoveries reported this January . So much news again that I start with the summary from the email you received.
SUMMARY – After this paragraph there are longer, clearer explanations. If you read the details and links to the journal articles below, these are conclusions you might reach with your doctor. 1. DIABETES – Glycemic index [GI] for diabetes – [Explanation of GI] “Views on the role of diet in the management of diabetes have undergone an evolution over the past 30 years…the role of low-GI foods in the prevention and treatment of diabetes remains unclear….Diastolic blood pressure was highest in the high-GI diet group … Soy/beans reduce diabetes risk 2.VITAMIN C– Eat fruits, veggies, vitamin C – “Consumption of carotenoid-containing fruit and vegetables was shown to be associated with a lower cardiovascular disease risk, yet β-carotene supplementation either had no effect or increased mortality…Several studies have shown that the higher the consumption of fruit and vegetables, the lower the incidence of cardiovascular disease (3-5), including strokes (6-11)… ” Low plasma vitamin C concentrations may be useful in identifying those at high risk of stroke. Does vitamin C decrease training efficiency? [Nutrition Investigator note: I include this vitamin C report despite my research justifying 500mg of vitamin C twice a day] 3. HIGH PROTEIN DIET – High protein diet more effective for weight loss – high-protein diet in this study provided 34% of energy “High protein diet essential in older (70+) people 4. OBESITY – Obesity is likely cause of metabolic syndrome – ” a lower prevalence of the metabolic syndrome associated with dietary patterns rich in fruit, vegetables, whole grains, dairy products, and unsaturated fats… The striking resolution of the metabolic syndrome with weight-reduction surgery (93%) as compared with lifestyle (25%) and drugs (19%) strongly suggests that obesity is the driving force “ Obesity causes inflammation which causes chronic disease – Obesity makes weight gain even easier 5. Vitamin D lowers blood pressure 6. Dieting in female athletes contributes to osteoporosis – ” in adolescent female runners, dietary restraint may be the disordered eating behavior most associated with negative bone health effects.” 7. Whole grains reduce heart disease risk 8. Yogurt benefit is unrelated to live bacteria 9. Saturated/trans fats harmful, some alcohol beneficial 10. chocolate risky?
DETAILS – 1. DIABETES – Glycemic index for diabetes – “Views on the role of diet in the management of diabetes have undergone an evolution over the past 30 years. For many years, a high-fat, low-carbohydrate diet was recommended (2); then, in 1979, the American Diabetes Association (ADA) issued a consensus statement suggesting that a high-carbohydrate, low-fat diet was best for most patients (3). This official position was subsequently modified to emphasize glucose and lipid control rather than weight loss; this change allowed the inclusion of more fat (primarily monounsaturated) in the diet (4). However, just as it is a topic for avid discussion in popular culture, diet remains a subject of lively debate with respect to diabetes treatment…the role of low-GI foods in the prevention and treatment of diabetes remains unclear….Diastolic blood pressure was highest in the high-GI diet group, and the difference was greatest between the high-GI diet group and the low-carbohydrate diet group.” Soy/beans reduce diabetes risk – “Conclusions: Consumption of legumes, soybeans in particular, was inversely associated with the risk type 2 diabetes.”
2.VITAMIN C– Eat fruits, veggies, vitamin C – “Consumption of carotenoid-containing fruit and vegetables was shown to be associated with a lower cardiovascular disease risk, yet β-carotene supplementation either had no effect or increased mortality…Several studies have shown that the higher the consumption of fruit and vegetables, the lower the incidence of cardiovascular disease (3-5), including strokes (6-11). These findings were attributed to many factors, including vitamin C. Others have shown that high plasma vitamin C concentrations are associated with a lower risk of stroke …The relation between stroke and vitamin C concentrations was independent of consumption of fruit and vegetables and supplements, although there were more supplement users in the highest quartile of plasma vitamin C concentrations. ” The full vitamin C report – “Conclusions: Plasma vitamin C concentrations may serve as a biological marker of lifestyle or other factors associated with reduced stroke risk and may be useful in identifying those at high risk of stroke.”Does vitamin C decrease training efficiency? – “Vitamin C also prevented the exercise-induced expression of cytochrome C (a marker of mitochondrial content) and of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. Conclusion: Vitamin C supplementation decreases training efficiency because it prevents some cellular adaptations to exercise.” [Nutrition Investigator note: I include this vitamin C report despite my research justifying 500mg of vitamin C twice a day as the saturating dosage. I have read the full article. The graphs show that various markers are substantially elevated after a training session by an athlete, but those markers do not change in a person who has not just trained, or in a person who takes vitamin C and then trains. I would argue that the vitamin C prevents free radical damage during training, and that is why those biomarkers do not change.”
3. HIGH PROTEIN DIET – High protein diet more effective for weight loss – high-protein diet in this study provided 34% of energy – ” A reported higher protein intake appears to confer some weight-loss benefit. ” Same finding for men – ” Conclusion: In the short term, high-protein, low-carbohydrate ketogenic diets reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.” High protein diet essential in older (70+) people – “Conclusion: Dietary protein may be a modifiable risk factor for sarcopenia in older adults and should be studied further to determine its effects on preserving LM in this population.” [This has been proven especially to prevent muscle wasting during bedrest in older people]
4. OBESITY – Obesity is likely cause of metabolic syndrome – “Whereas each risk factor of the metabolic syndrome (visceral obesity, atherogenetic dyslipidemia, elevated blood pressure, and dysglycemia) can be dealt with individually, the recommended initial therapeutic approach is to focus on reversing its root causes of atherogenetic diet, sedentary lifestyle, and overweight or obesity. No single diet is currently recommended for patients with the metabolic syndrome, although epidemiologic evidence suggests a lower prevalence of the metabolic syndrome associated with dietary patterns rich in fruit, vegetables, whole grains, dairy products, and unsaturated fats… The striking resolution of the metabolic syndrome with weight-reduction surgery (93%) as compared with lifestyle (25%) and drugs (19%) strongly suggests that obesity is the driving force for the occurrence of this condition.” Obesity causes inflammation which causes chronic disease – “Conclusion: During a 9-y period, an increase in weight is associated with an increase in systemic inflammation. This provides a mechanism that may explain some of the previously reported association of weight gain with an increased risk of both cancer and cardiovascular disease.” Obesity makes weight gain even easier – “Conclusion: The observed reduction in dietary fat oxidation [the poorer ability to burn dietary fat] in subjects with a higher percentage body fat may play a role in human obesity.”
5. Vitamin D lowers blood pressure – “Conclusions: Systolic blood pressure is inversely associated with serum vitamin D concentrations in nonhypertensive white persons in the United States.”
6. Dieting in female athletes contributes to osteoporosis – ” Conclusion: These findings suggest that, in adolescent female runners, dietary restraint may be the disordered eating behavior most associated with negative bone health effects.”
7. Whole grains reduce heart disease risk – “Conclusions: Both hypocaloric diets were effective means of improving CVD risk factors with moderate weight loss. There were significantly (P < 0.05) greater decreases in CRP and percentage body fat in the abdominal region in participants consuming whole grains than in those consuming refined grains.”
8. Yogurt benefit is unrelated to live bacteria – “Bacterial changes were not different after the consumption of fresh and heat-treated yogurt.”
9. Saturated/trans fats harmful, some alcohol beneficial – “Conclusion: Higher habitual intakes of saturated and trans fats are independently associated with increased subclinical atherosclerosis, and alcohol intake may attenuate the relation between saturated fat and subclinical atherosclerosis.”
10. Too much chocolate risky? – “Conclusions: Older women who consume chocolate daily had lower bone density and strength.” [Nutrition Investigator note: I include this report for full disclosure. I read the entire article. Women who ate chocolate six days a week had bones as strong as those who did not eat chocolate at all. Only those who ate it seven days a week had weaker bones. I suspect some women who eat chocolate every day have other risk factors, like lack of exercise, so the conclusion is a correlation rather than a causation.]
HAVE A HEALTHY NEW YEAR! TRY TO CUT DOWN ON STRESS AND ENJOY EATING, BECAUSE YOU ARE ONE OF THE WISE PEOPLE WHO KEEPS UP WITH GREAT NUTRITION THROUGH THESE COLUMNS, and are surely conscious of what you put in your body.
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