Cardiovascular disease and vitamin D (some strange claims)

Potential Impact of the Steroid Hormone, Vitamin D, on the Vasculature: Vitamin D-hormones and cardiovascular disease

American Heart Journal. online 27 May 2021, https://doi.org/10.1016/j.ahj.2021.05.012

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The role of vitamin D in the cardiovascular system is complex because it regulates expression of genes involved in diverse metabolic processes. Although referred to as a vitamin, it is more accurately considered a steroid hormone, because it is produced endogenously in the presence of ultraviolet light. It occurs as a series of sequentially activated forms, here referred to as vitamin D-hormones. A little-known phenomenon, based on pre-clinical data, is that its biodistribution and potential effects on vascular disease likely depend on whether it is derived from diet or sunlight. Diet-derived vitamin D-hormones are carried in the blood, at least in part, in chylomicrons and lipoprotein particles, including LDL.

Since LDL is known to accumulate in the artery wall and atherosclerotic plaque, diet-derived vitamin D-hormones may also collect there, and possibly promote the osteochondrogenic mineralization associated with plaque.

Also, little known is the fact that the body stores vitamin D-hormones in adipose tissue with a half-life on the order of months, ++raising doubts about whether the use of the term “daily requirement” is appropriate . Cardiovascular effects of vitamin D-hormones are controversial, and risk appears to increase with both low and high blood levels . Since low serum vitamin D-hormone concentration is reportedly associated with increased cardiovascular and orthopedic risk, oral supplementation is widely used, often together with calcium supplements.

However, meta-analyses show that oral vitamin D-hormone supplementation does not protect against cardiovascular events, findings that are also supported by a randomized controlled trial. These considerations suggest that prevalent recommendations for vitamin D-hormone supplementation for the purpose of cardiovascular protection should be carefully reconsidered.

Table of Contents

Types of vitamin D-hormones

Activation and storage of D vitamins

Half-lives and levels of inactive and activated D vitamins

Dietary requirements: daily or seasonal?

Dependence of carrier and bio-distribution on source

Dependence of hydroxylation rate on source

Pleiotropic effects of vitamin D-hormones

Vitamin D-hormones supplementation and cardiovascular outcomes

Effect of D vitamins on vascular cells and atherosclerotic calcification

Vitamin D-hormone activity in adipose tissue

Influence of obesity on vitamin D-induced vascular calcification

Inhibition of osteoclastic resorption