HEALTH

Vitamin D vital to keeping away disease

Evidence linking low vitamin D to disease is mounting.

In Summary
  • Clinical studies have demonstrated that improving calcium and vitamin D levels substantially reduces the risk of developing many cancers.
  • Why is vitamin D deficiency rising? Our indoors lifestyle and fat-shy diets may be to blame.
Vitamin D vital to keeping away disease
Vitamin D vital to keeping away disease
Image: STAR ILLUSTRATED

A couple of weeks ago, I discussed the resurgence of interest in vitamin D, a vitamin of such vital importance that it is now regarded as a hormone, ie, a chemical messenger.

Vitamin D research has expanded to include the extra-skeletal domain. In the last decade, the resurgence of interest has largely been birthed following a deluge of evidence linking vitamin D deficiency to a variety of diseases and disorders—from viral infections to cancer.

This is only the beginning of the vitamin D story. Let’s not forget that vitamin D is a proxy for the sun. It is probable that the benefits of the sun go beyond vitamin D, and a dose-response relationship appears to be the norm.

 

As the critical roles of vitamin D unravel, the evidence linking low vitamin D to disease is mounting. There currently exists compelling evidence correlating low vitamin D status to heart disease, breast and colon cancer, and multiple sclerosis – reflecting vitamin D’s actions on the cells of the immune system, and in controlling growth, multiplication and death of cells.

There have been a number of well-designed clinical studies that have demonstrated that improving calcium and vitamin D levels substantially reduces the risk of developing many cancers. With colon cancer in particular, scientists have observed an exceedingly strong correlation, with higher vitamin D levels being associated with a lower risk of colon cancer. This evidence largely consists of observational studies, which cannot show cause and effect. What they can, and are being used for, is to frame a causal hypothesis.

Sunshine is our best source of vitamin D, which is made from a form of cholesterol that resides under our skin. We can also get vitamin D from an animal-based diet, one rich in eggs, oily fish and full-fat dairy products. These are also rich in calcium, vitamin K and phosphorous, key nutrients for bone health.

Other associated vitamin D deficiency disorders include infections (TB, influenza, general infections), blood disorders, type 2 diabetes, bone diseases, autoimmune diseases (multiple sclerosis, type 1 diabetes, asthma), heart disease, thyroid disease and inflammation; as well as obesity and the metabolic syndrome.

Prior to the discovery of anti-tuberculosis medication, patients with TB used to be nursed in the fresh air and sunlight. We know that more cases of TB are diagnosed in the summer than in the winter, because winter dips in sunshine correlate with peaks of TB incidence in the summer.

Studies have accurately mapped out falling vitamin D levels in the winter with rising respiratory infections. Influenza is particularly interesting. A strong correlation has been noted between increasing latitude from the equator and influenza outbreaks. Remember that we’ve gone, ancestrally, from year-round sunshine to seasonal sunshine.

It has been hypothesised, rather compellingly, that influenza is influenced by vitamin D status. When the population’s vitamin D goes down in the autumn and winter, their natural defences are down and certain strains of the flu virus are able to replicate and spread easily. In the summer, with rising vitamin D levels, flu seems to disappear.

It is not a coincidence that nutrients that need to be consumed together, tend to be provided together. Omena, also known as the Lake Victoria sardine, is small enough to be eaten whole. It’s packed with all these nutrients, with a single serving providing one’s entire daily vitamin D requirement.

Influenza appears to break out at the same level of latitude, seemingly unconnected. This was observed even before there was widespread air travel. While these studies cannot tell us, for certain, that low vitamin D causes the flu, the association is very strong, and the mechanisms of how this happens are currently being looked into. Perhaps humans were never meant to migrate away from their equatorial origins?

 

Now let’s try to answer the question everyone is asking. Why is vitamin D deficiency rising? Why is it that supplementation is now recommended for almost everyone? Our indoors lifestyle and fat-shy diets may be to blame.

Sunshine is our best source of vitamin D, which is made from a form of cholesterol that resides under our skin. We can also get vitamin D from an animal-based diet, one rich in eggs, oily fish and full-fat dairy products. These are also rich in calcium, vitamin K and phosphorous, key nutrients for bone health.

It is not a coincidence that nutrients that need to be consumed together, tend to be provided together. Omena, also known as the Lake Victoria sardine, is small enough to be eaten whole. It’s packed with all these nutrients, with a single serving providing one’s entire daily vitamin D requirement.

Vitamin D may also play a crucial role in the development of type 2 diabetes, one of the fastest-growing life-limiting diseases on earth. Join me next time as I continue to unravel the mysteries of this sunshine vitamin.

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