Maintaining Well-Being Through Stressful Times

Research from ASN Journals Hypertension is reduced by a high-nitrate beetroot juice extract

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Although hypertension is prevalent world-wide, it is an even greater problem in low- and middle-income countries, where nearly two-thirds of the hypertensive individuals reside.  In Africa, 46% of adults have hypertension and it is the sixth leading cause of disability within the Sub-Saharan region.  Because of the health care challenges associated with diagnosis and care in these regions, the use of a diet-based intervention may be received better than costly medications.  Inorganic nitrate, a precursor to nitric oxide, and folic acid are found in relatively high levels in certain leafy green vegetables and in beetroots. 

Existing literature suggests the potential utility of beetroot extracts and folic acid in the control of hypertension and endothelial function.  Because they partly operate through different mechanisms, it may be possible to affect an even greater control of hypertension by combining the interventions.  Siervo and colleagues conducted a study to explore this hypothesis and report the results of their study in the September 2020 issue of The Journal of Nutrition.

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NEWS FROM THE AMERICAN SOCIETY FOR NUTRITION

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Age-related skeletal muscle loss and function, known as sarcopenia, can lead to frailty and loss of mobility among older adults. Sarcopenia increases the risk of falls and often results in loss of independent living.  Healthy diets and physical activity are well known strategies that can help to maintain muscle strength and function.  However, metabolic disturbances associated with loss of skeletal muscle mass are not as well understood.  For example, the mechanisms by which vitamin C can affect skeletal muscle physiology during aging have not been extensively studied.

Given the lack of research investigating the relevance of vitamin C and skeletal muscle physiology in older populations, Ailsa Welch (University of East Anglia) and colleagues investigated associations between dietary and plasma vitamin C with indirect measures of skeletal muscle mass in a population of 13,000 free-living middle- and older-aged individuals. Fat-free mass was used as a proxy for skeletal muscle mass and estimated using bioelectric impedance analysis. Dietary vitamin C intakes were calculated from 7-day food diary data, and vitamin C was measured in the blood plasma.

Study results published in The Journal of Nutrition showed positive trends between dietary vitamin C and fat-free mass measures for both sexes.  Fat-free measures, expressed as a percentage of total mass or standardized by body mass index (BMI), were higher in participants with sufficient as opposed to insufficient plasma vitamin C by 1.6% and 2.0% in men, and 3.4% and 3.9% in women.  These findings of positive associations of both dietary and circulating vitamin C with measures of skeletal muscle mass in middle- and older-aged men and women suggest that dietary vitamin C intake may be useful for reducing age-related muscle loss.  Ensuring sufficient dietary vitamin C intake by promoting a diet rich in fruits and vegetables may help to reduce age-related loss of skeletal muscle and thus have a wide-reaching public health benefit.

References Lewis LN, Hayhoe RPG, Mulligan AA, Luben RN, Khaw K, Welch AA. Lower Dietary and Circulating Vitamin C in Middle- and Older-Aged Men and Women Are Associated with Lower Estimated Skeletal Muscle Mass. The Journal of Nutrition, Volume 150, Issue 10, October 2020, Pages 2789–2798, https://doi.org/10.1093/jn/nxaa221.

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ASN’s Themed Collection: Nutrition and Immune Support

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The editors of the American Society for Nutrition (ASN) journals have curated a themed collection of articles exploring the latest research and findings on the links between nutrition and immune system function.  With the COVID-19 pandemic devastating communities around the world, these articles underscore the role nutrition researchers and practitioners can play in helping people optimize and maintain healthy immune function, both to avoid infection and to support recovery from infection.
This themed collection includes 23 published studies that explore the many tools and approaches nutrition scientists use to understand how nutrition affects immune function.  Below are highlights from four studies included in the collection, one from each ASN journal. Some other studies from this collection were highlighted in a previous blog examining nutrition and viral infection.

Vitamin D and InfluenzaAdvances in Nutrition, July 2012

Evidence from both animal model studies and in vivo human studies indicate that there is a link between vitamin D status and the risk of influenza infection; however, the findings have not always been consistent.  In particular, observational human studies as well as randomized controlled trials have yielded mixed results.  Some studies, for example, have suggested that the reason influenza is more prevalent in the winter is the result of less sunlight and therefore less available vitamin D; however, not all studies have reached the same conclusion.

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Dietary Vitamin C may help reduce age-related muscle loss

Age-related skeletal muscle loss and function, known as sarcopenia, can lead to frailty and loss of mobility among older adults. Sarcopenia increases the risk of falls and often results in loss of independent living.  Healthy diets and physical activity are well known strategies that can help to maintain muscle strength and function.  However, metabolic disturbances associated with loss of skeletal muscle mass are not as well understood.  For example, the mechanisms by which vitamin C can affect skeletal muscle physiology during aging have not been extensively studied.

Given the lack of research investigating the relevance of vitamin C and skeletal muscle physiology in older populations, Ailsa Welch (University of East Anglia) and colleagues investigated associations between dietary and plasma vitamin C with indirect measures of skeletal muscle mass in a population of 13,000 free-living middle- and older-aged individuals. Fat-free mass was used as a proxy for skeletal muscle mass and estimated using bioelectric impedance analysis. Dietary vitamin C intakes were calculated from 7-day food diary data, and vitamin C was measured in the blood plasma.

Study results published in The Journal of Nutrition showed positive trends between dietary vitamin C and fat-free mass measures for both sexes.  Fat-free measures, expressed as a percentage of total mass or standardized by body mass index (BMI), were higher in participants with sufficient as opposed to insufficient plasma vitamin C by 1.6% and 2.0% in men, and 3.4% and 3.9% in women.  These findings of positive associations of both dietary and circulating vitamin C with measures of skeletal muscle mass in middle- and older-aged men and women suggest that dietary vitamin C intake may be useful for reducing age-related muscle loss.  Ensuring sufficient dietary vitamin C intake by promoting a diet rich in fruits and vegetables may help to reduce age-related loss of skeletal muscle and thus have a wide-reaching public health benefit.

References Lewis LN, Hayhoe RPG, Mulligan AA, Luben RN, Khaw K, Welch AA. Lower Dietary and Circulating Vitamin C in Middle- and Older-Aged Men and Women Are Associated with Lower Estimated Skeletal Muscle Mass. The Journal of Nutrition, Volume 150, Issue 10, October 2020, Pages 2789–2798, https://doi.org/10.1093/jn/nxaa221.

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