Vitamin D is the “sunshine vitamin” and has been produced on Earth for more than 500 million years. Phytoplankton, zooplankton and most plants and animals have the ability to manufacture vitamin D from the sun’s energy, and humans are no different. Vitamin D deficiency is becoming a major health problem though, due to a number of reasons, and this has a major impact on our health.

Health impact of vitamin D

This vitamin is really a hormone, and is critically important for many processes within the body. One of its major roles is in the development and maintenance of a healthy skeleton. It does this through the maintenance of calcium balance or homeostasis within the body.

This hormone increases the efficiency of the intestine to absorb dietary calcium. When the dietary calcium is inadequate to supply the body’s needs, then vitamin D communicates this to the osteoblasts. They then, in turn signal osteoclast precursors to mature, dissolving some of the calcium which is stored in the bone to meet the need elsewhere in the body.

The function of vitamin D is not limited to the intestine and the bone. There are “VDR” or vitamin D receptors in a number of other tissues, including the heart, brain, stomach, pancreas, skin, gonads and activated T and B lymphocytes or white blood cells. This leads to it being extremely important in a number of processes in the body.

Vitamin D deficiency has been implicated in being a risk factor for the development of osteoporosis, hypertension (high blood pressure), cancers of the colon, prostate, breast and ovary, type I diabetes, schizophrenia, depression and multiple sclerosis.

Why are we seeing a deficiency?

When the sun is so plentiful in our country, why are we finding that so many people are Vitamin D deficient? Our body converts UVB rays into vitamin D in our skin. Many factors influence this though. Due to our fear of developing skin cancer, we have reduced our exposure of our skin to the sun. Air pollution can dramatically reduce the effectiveness of our sun exposure, by absorbing UVB rays. Altitude plays a role, with more vitamin D conversion at a higher altitude. Sunblocks play a high role too, with a factor 30 blocking out between 95 and 98 percent of UVB rays.

Very few foods in nature provide Vitamin D. The best sources are fish oils and the flesh of fatty fish like salmon, tuna and mackerel, with smaller amounts being found in beef liver, egg yolks,cheese and some mushrooms. Whale blubber, seal and polar bear liver are also high in Vitamin D, but not highly likely unless you are an Inuit. Some dairy products, margarine, bread and cereals are fortified with vitamin D too, but are not the healthiest choices.

It is important to know your Vitamin D status. Vitamin D3 is the active form in the body and when tested in the blood should be above 33 ng/ml and ideally around 50 ng/ml for optimal health.

Sunshine may be our best medicine!

More reading:

Vitamin D fact sheet
Comprehensive article on Vitamin D
Development of new sunscreens to allow more vitamin D conversion