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AJCN May 2005

[A low sugar diet helps your circulatory system, while a low fat diet hurts it.] Jennie Brand-Miller Optimizing the cardiovascular outcomes of weight loss  Am J Clin Nutr 2005 81: 949-950

The past 2 y have seen a steady stream of reports indicating that restriction or modification of carbohydrate intakes can favorably affect weight loss and cardiovascular disease (CVD) risk factors (16). The article by Ebbeling et al (7) in this issue of the Journal represents one more in favor of diets with a low glycemic index (GI) or glycemic load (GL). Serum triacylglycerol concentrations in young overweight adults with similar weight loss fell nearly twice as far with the ad libitum low-GL diet as with the energy-restricted low-fat diet, whereas concentrations of plasminogen activator inhibitor 1, an important measure of thrombogenicity, significantly worsened (ie, rose) in subjects who were following the energy-restricted low-fat diet. The study was small (n = 23) and from a group at Harvard that had published other studies on the same topic, but it was long-term (12 mo) and carefully carried out.

[Lack of B6, folate, and B12 cause your brain to get progressively worse.] Stein Emil Vollset and Per Magne Ueland B vitamins and cognitive function: do we need more and larger trials? Am J Clin Nutr 2005 81: 951-952.

Observational studies, including a recent investigation in 2871 subjects (7), have consistently reported that an elevated concentration of tHcy in serum or plasma is a risk factor for dementia and impaired cognitive function (8). This association has been explained by neurotoxic effects of homocysteine or the ability of elevated homocysteine to cause vascular lesions. Alternatively, the effects are mediated by the impaired function of the B vitamins involved in homocysteine metabolism, including vitamin B-12, folate, and vitamin B-6. Impaired vitamin B-12 status is known to be prevalent among the elderly, and vitamin B-12 deficiency may cause severe myelopathy and also prominent mental symptoms and memory loss (9). Poor folate status has been associated with depression and dementia in the elderly, and folate metabolism is linked to a variety of neurochemical processes (10). Vitamin B-6 status declines with age, and low blood concentrations of vitamin B-6 have been associated with impaired cognitive function and Alzheimer disease. Such associations could be explained by the involvement of vitamin B-6 in the synthesis of several neurotransmitters (11).

[Keeping fit is important to healthy aging.] K Sreekumaran Nair Aging muscle Am J Clin Nutr 2005 81: 953-963

Age causes structural and functional changes in skeletal muscle in a wide range of species, including humans. Muscle changes in humans start in the fourth decade of life and cause frailty and disabilities. Associated changes in body composition form the basis of many metabolic disorders, such as insulin resistance, type 2 diabetes, hypertension, and hyperlipidemia, which result in an increased incidence of cardiovascular death. Decreases in the synthesis rates of many muscle proteins, specifically of myosin heavy chain and mitochondrial proteins, occur with age…Both aerobic exercise and resistance exercise enhance muscle protein synthesis and mitochondrial biogenesis…Voluntary physical activity is regulated by cognitive centers and could attenuate the progressive decline in mitochondrial functions that occurs with age.

[Exercise predicts how fat you will become.] Ulf Ekelund et al, Physical activity energy expenditure predicts changes in body composition in middle-aged healthy whites: effect modification by age Am J Clin Nutr 2005 81: 964-969

Background: It is unclear whether physical activity energy expenditure (PAEE) predicts changes in body composition…

Design: This was a prospective population-based study conducted in 739 (311 men and 428 women) healthy middle-aged (median age: 53.8 y) whites. The median follow-up was 5.6 y. PAEE (MJ/d) was assessed by heart rate monitoring…Fat mass (FM) and fat-free mass (FFM) were assessed by bioimpedance…

Conclusions: Baseline PAEE predicts a change in FM in younger adults, who as a group gained weight in this study. In contrast, baseline PAEE in older adults—who were on average weight stable—is associated with a gain in BW, which was explained by an increase in FM and FFM.

[Atkin's diet works!] Cara B Ebbeling et al, Effects of an ad libitum low-glycemic load diet on cardiovascular disease risk factors in obese young adults  Am J Clin Nutr 2005 81: 976-982

Conclusion: An ad libitum low-glycemic load diet may be more efficacious than a conventional, energy-restricted, low-fat diet in reducing cardiovascular disease risk.

Caryl A Nowson et al, Blood pressure change with weight loss is affected by diet type in men Am J Clin Nutr 2005 81: 983-98

Background: Weight loss reduces blood pressure,…

Objective: Our goal was to assess the effect on blood pressure of 2 weight-reduction diets: a low-fat diet (LF diet) and a moderate-sodium, high-potassium, high-calcium, low-fat DASH diet (WELL diet).  Design: After baseline measurements, 63 men were randomly assigned to either the WELL or the LF diet for 12 wk, and both diet groups undertook 0.5 h of moderate physical activity on most days of the week…Conclusions: For a comparable 5-kg weight loss, a diet high in low-fat dairy products, vegetables, and fruit (the WELL diet) resulted in a greater decrease in blood pressure than did the LF diet. This dietary approach to achieving weight reduction may confer an additional benefit in reducing blood pressure in those who are overweight.

Gong Yang et al,  Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women  Am J Clin Nutr 2005 81: 1012-1017

Objective: Our aim was to examine the association between usual intake of soy foods and BP.  Design: The usual intake of soy foods was assessed at baseline, and BP was measured 2–3 y after the baseline survey among 45 694 participants of the Shanghai Women's Health Study aged 40–70 y… Conclusion: Usual intake of soy foods was inversely associated with both systolic and diastolic BPs, particularly among elderly women.

[about 1 g Tryptophan at night aids sleep.]C Rob Markus et al, Evening intake of -lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention Am J Clin Nutr 2005 81: 1026-1033

Background: Brain serotonin function is thought to promote sleep regulation and cognitive processes, whereas sleep abnormalities and subsequent behavioral decline are often attributed to deficient brain serotonin activity. Brain uptake of the serotonin precursor tryptophan is dependent on nutrients that influence the availability of tryptophan via a change in the ratio of plasma tryptophan to the sum of the other large neutral amino acids… Conclusion: Evening dietary increases in plasma tryptophan availability for uptake into the brain enhance sustained alertness early in the morning after an overnight sleep, most likely because of improved sleep. [Diet contained addition of about 1 g tryptophan at night]

Henry C Lukaski Low dietary zinc decreases erythrocyte carbonic anhydrase activities and impairs cardiorespiratory function in men during exercise  Am J Clin Nutr 2005 81: 1045-1051

[About 20% of men and 40% of women from age 19-50 have low zinc intakes.] Objective: This study determined the effects of low zinc intake on carbonic anhydrase activity in red blood cells (RBCs) and cardiorespiratory function during exercise. Design: In this double-blind, randomized crossover study, 14 men aged 20–31 y were fed low-zinc and supplemented (3.8 and 18.7 mg/d) diets made up of Western foods for 9-wk periods with a 6-wk washout… Conclusion: These findings indicate that low dietary zinc is associated with significant reductions in zinc status, including RBC carbonic anhydrase activities, and impaired metabolic responses during exercise.

Supplement: Women and Micronutrients: Addressing the Gap Throughout the Life Cycle: Barbara A Underwood, Richard J Deckelbaum, and Sharon R Akabas Preface  Am J Clin Nutr 2005 81: 1187S.

Ed. notes: 1. overweight increases risks of various birth defects 50 to 250% 2. 400 mcg folic acid are essential to get during pregnancy 

3. Theresa O Scholl Iron status during pregnancy: setting the stage for mother and infant Am J Clin Nutr 2005 81: 1218S-1222S

…iron supplements and increased iron stores have recently been linked to maternal complications (eg, gestational diabetes) and increased oxidative stress during pregnancy. Consequently, while iron supplementation may improve pregnancy outcome when the mother is iron deficient it is also possible that prophylactic supplementation may increase risk when the mother does not have iron deficiency or IDA…

4. menopause  5. Jeri W Nieves Osteoporosis: the role of micronutrients Am J Clin Nutr 2005 81: 1232S-1239S - Higher doses than the current US recommendation (600 IU) of vitamin D in the elderly (age 65 y) may actually be required for optimal bone health (800–1000 IU/d). The elderly can clearly benefit from increased vitamin D intakes; however, the potential importance of vitamin D in peak bone mass is just being investigated. Vitamin D has been related to falls, with supplementation reducing the number of falls. 6. Ronni Chernoff Micronutrient requirements in older women Am J Clin Nutr 2005 81: 1240S-1245S - Among the micronutrients, the significant ones that may be associated with deficiencies in elderly women include vitamin B-12, vitamin A, vitamin C, vitamin D, calcium, iron, zinc, and other trace minerals. In old and very old women, these are micronutrients of interest but there is a great need for research to determine appropriate recommendations. 7. Sharon R Akabas and Karen R Dolins Micronutrient requirements of physically active women: what can we learn from iron? Am J Clin Nutr 2005 81: 1246S-1251S

"It is clear that iron supplementation should never be initiated without prior determination of iron status, as iron overload presents serious health issues."

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