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Study under review: Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D status
Vitamins are organic compounds (organic chemistry, not organic produce) which are required for an organism to live. They generally serve as cofactors, meaning they help proteins do their job. Vitamins also have the potential to form compounds similar to hormones.
Speaking of hormone-like compounds, previous issues of the ERD go into detail about various aspects of vitamin D research. Vitamin D deficiency is fairly common, even in developed countries, and a strong association between serum vitamin D levels and mortality has been repeatably observed.
Vitamin D is a fat-soluble vitamin, like vitamins A, E, and K. But unlike these other vitamins, mammals are able to synthesize vitamin D, specifically when exposed to UV-B light (which is shown in Figure 1). UV-B has a wavelength in the 280–315nm range and is produced by the sun, but not by most household lights. This light-induced synthesis has earned vitamin D the moniker “the sunshine vitamin”. While vitamin D is readily stored for rather long periods of time, serum levels of vitamin D can drop considerably during winter time, when UV intensity is low and duration of sunlight is short.
Vitamin D has several biological functions, including in the innate immune system, calcium absorption from the diet, modulating bone calcification, adjusting circulating phosphorous levels, and working with parathyroid hormone to maintain serum calcium levels. The majority of these functions are mediated by vitamin D binding to the vitamin D receptor (VDR). So, by examining how tissues in the body express this receptor, researchers can begin to determine which tissues vitamin D influences. Within the cardiovascular (CV) system, the endothelial cells (cells within the interior of blood vessels), smooth muscle cells (a type of muscle cell that is found around the blood vessels), and cardiomyocytes (heart muscle) all express VDR.
Thus, it is not surprising that several studies have observed an association between low serum levels of vitamin D and CV events and CV-related mortality. This is likely due to the role that vitamin D plays in preventing vascular calcification, reducing blood pressure via the renin-angiotensin-aldosterone system, lowering blood cholesterol levels, and reducing excess inflammation.
The study under review was designed to allow researchers to better understand the effect of vitamin D supplementation on CV health. Researchers provided individuals with a relatively low dose of vitamin D (20 micrograms (μg) or 800 IU) during the winter months while monitoring a rather comprehensive list of markers of CV health, including blood pressure, heart rate, serum lipids, vascular calcification, and several haematological variables. What separates this study from previous studies is this comprehensive analysis, that the participants were non-obese healthy adults, and a rather low dosage of vitamin D.
Serum vitamin D levels drop during winter months, as UV-B mediated synthesis is reduced. This may be detrimental to health, and several mechanisms (blood pressure, cholesterol, and vascular calcification) have been identified for how vitamin D specifically affects cardiovascular health. The objective of this study was to observe if low-dose vitamin D supplementation during winter months in healthy individuals has an impact on cardiovascular risk markers.
Other Articles in Issue #15 (January 2016)
DASH plus fat equals ...
The DASH diet is one of the most studied diets of all time, and was specifically formulated to curb chronic disease. But will DASH still do it’s thing if you add extra fat each day?
Wine and dine with diabetes
For some, wine is a daily or weekly indulgence. As those with type 2 diabetes must pay extra attention to the blood sugar and lipid impact of what they consume, this trial puts red and white wine to the test.
Better living through cherry juice
Cherries and berries (the former is not a type of the latter, by the way) have increasingly shown cognitive benefits. This trial specifically explores cherries for Alzheimer’s disease.
Interview: Victoria Prince, MD, PhD
Victoria Prince is passionate about ancestral health and evolutionary medicine, and has a particular interest in dietary fats and the role they play in health and disease, especially liver disease. She writes at principleintopractice.com.
The chocolate fountain of youth
Cocoa contains high levels of beneficial phytochemicals called “flavanols”, which may provide a variety of health benefits. This randomized trial tested cocoa for the specific purpose of wrinkle reduction and other skin-related improvements.
Beyond ‘eat less, move more’: treating obesity in 2016
By Spencer Nadolsky, DO
A fishy depression treatment
With many trials already conducted on the topic of fish oil and depression, the question of overall impact still remained. This is the latest update to the Cochrane systematic review on the topic.
A calorie is a calorie ... or is it?
Obesity research typically focus on what you eat, but less frequently touches on when you should eat it. Since animal models have shown strong results for meal timing, this study looked at potential weight-related benefits of eating earlier in humans.
Your probiotic may be lying to you
Take a gander at a probiotic bottle label and you may be astounded at the number of live bacteria, as well as the variety these supplements contain. But the labels may not be entirely accurate