If you’re like us, you’ve probably been hearing a lot recently about the perils of vitamin D deficiency. Suddenly, we’re all lacking it – and it can be linked to a variety of diseases including osteoporosis, cancer, heart disease and many more.
Is Vitamin D deficiency real or just a fad?
Our analysis is that yes, it is real, but a lot depends on how you define deficiency. It’s likely that many of us become deficient to some degree – especially at the end of winter – but what remains to be determined is what that actually means for your health.
What is Vitamin D?
Vitamin D, while named a vitamin, is actually a prohormone, which means it is converted by the body into a hormone and does not act like a typical vitamin.
Functionally, it works mainly to regulate calcium in your body, but receptors for it are present in more than 30 tissues, including your thyroid and certain immune and heart cells.
Most of the production of Vitamin D occurs in the skin in response to sunlight, after which it travels to the liver and kidneys to be processed further. We don’t get much Vitamin D from our diet, unless you’re eating oily fish several times a week.
Our concern with Vitamin D deficiency began about 100 years ago. At the turn of the 20th century there was an epidemic of the disease rickets.
Childrens’ bones were not developing properly and were weak and misshapen. It was very common. As much as 80-90% of children in the city of Boston, for instance, had rickets.
Research into the treatment of rickets in part focused on the fact that cod liver oil seemed to help treat and prevent it. By boiling and treating cod liver oil in different ways, researchers were eventually able to isolate the active ingredient in it that helped treat rickets – Vitamin D.
Vitamin D has a variety of effects. The most obvious ones are in regulating various aspects of calcium in the body. It helps you take calcium from your food, regulates the balance of calcium in bones, and helps you keep it in your body.
Remember how important calcium is to maintaining good bone health, which explains why lack of vitamin D led to rickets.
Why were children Vitamin D deficient?
The answer seemed to be the following – children were now living in big cities where environmental standards were poor. Smog filled the air, blocking the sun.
Beyond that, an increasingly large amount of time was spent indoors. Research showed that sunlight was essential to maintain vitamin D levels and that the lack of it led to rickets and other problems.
To fight this rising epidemic of childhood Vitamin D deficiency, we started fortifying milk and certain foods with Vitamin D. This helped a lot but trouble was not far. In the 50s in England there was an outbreak of hypercalcemia, which can be caused by high Vitamin D levels. In response, many European countries changed their fortification strategies.
Why are we suddenly Vitamin D deficient?
Recently it seems that there is a new outbreak of Vitamin D deficiency. The modern day outbreak is because of several things. First, we now strongly believe that any exposure to sunlight is a bad idea and that we should always be protected with sunblock. This is due to skin cancer specialists who want to reduce the incidence of melanoma.
Unfortunately, a sunblock that stops 99% of UV light will also stop 99% of Vitamin D production.
One of the most important factors in Vitamin D deficiency is that during the winter, we simply don’t get the sun we need to produce it adequately.
But the main reason for what may seem to be a sudden concern about vitamin D is this – we now hold that you need to have more Vitamin D than we used to. A lot of this comes from being better able to measure it than we used to. The reason this is important is because Vitamin D deficiency is unlikely to have obvious symptoms.
Most of us have enough to avoid obvious problems like rickets.
The problem is that low levels of Vitamin D might play a role in many chronic diseases ranging from those that make sense, osteoporosis (which is calcium related), to those that seem more of a stretch – like autoimmune disorders, cancer and even schizophrenia. Also diabetes.
Since many of these conditions are complex and multifaceted it is very hard to know what factors cause them.
How common is Vitamin D deficiency?
If you believe the research coming out, very, very common. One study of 18-29 year olds with healthy dietary habits showed that 36% had a Vitamin D deficiency by the end of winter. Another study showed that around half of preadolescent girls in Maine had a deficiency at end of winter.
What can we do?
Some researchers say that anywhere from 5-30 minutes of exposure to sunlight between 10am and 3pm during the summer will give you a good amount of Vitamin D. But to recommend that you go and get sun exposure will attract the wrath of skin cancer specialists.
Most likely, we’re going to be recommended to start taking Vitamin D supplements – which is a story in and of itself.
1) Overview of general physiologic features and functions of vitamin D
2) Vitamin D Intake: A Global Perspective of Current Status
3) Vitamin D: a D-Lightful health perspective
4) Vitamin D in preventive medicine: are we ignoring the evidence?