Can Vitamin D Prevent Type 1 Diabetes?

Can Vitamin D Prevent Type 1 Diabetes?

Julian Whitaker, MD

I recently attended a conference at the University of California, San Diego School of Medicine and heard presentations from some of the world’s experts on vitamin D. I’ve been writing about the diverse benefits of vitamin D for more than a decade, and we’ve been testing blood levels of this vitamin and prescribing 2,000 to 4,000 IU to patients at Whitaker Wellness for years. So you might ask, “What’s the big deal?”

Well, I was astounded at the breadth of new research on this subject. Vitamin D has long been known to prevent rickets (malformation and weakness of bones), but its benefits go far beyond bone health. For example, did you know that vitamin D supplementation during pregnancy and infancy may reduce the risk of a child developing type 1 (juvenile) diabetes by 80 to 90 percent? Or that most of the world’s population—including 85 percent of Americans—can be deficient in vitamin D during the cold, dark fall and winter months?

Deficiencies Are Widespread

Let’s look at deficiencies first. It’s hard to get enough vitamin D from food. You’d need to eat two or three daily servings of salmon or sardines, drink five glasses of fortified milk, or take a spoonful of cod liver oil just to get the meager RDA of vitamin D, which isn’t nearly enough. In fact, it’s almost impossible to get optimal levels from food alone. The reality is, we get most of our vitamin D from sunshine.

When ultraviolet-B (UVB) radiation from the sun penetrates the skin, it reacts with cholesterol to form vitamin D. UVB makes up a very small portion of the spectrum of sunlight, and the angle of the sun during the winter makes it impossible for UVB to reach much of the Earth. As a result, people living in northern latitudes are unable to produce vitamin D from November through February. Even if you sunbathed for hours on a cold, sunny day, you wouldn’t get enough UVB to enable your skin to make this vitamin. So unless you take vitamin D supplements, your levels plummet during the winter months.

A wide variety of diseases have distinct seasonal and geographic patterns, and the common link in each and every one of them is vitamin D. One of the most dramatic associations is type 1 diabetes.

The D–Diabetes Connection

At the vitamin D conference, Frank Garland, PhD, of the University of California, San Diego, presented research showing that Finland has the highest incidence of type 1 diabetes in the world. Before the 1960s, however, disease rates in that country were near the worldwide average. What changed?

In 1964, Finnish health authorities lowered the vitamin D recommendation for infants from 4,500 IU to 2,000 IU per day. Cases of type 1 diabetes began to creep up. A decade later, it was reduced to 1,000 IU, and the incidence climbed even faster. Then in 1992, for no reason other than ignorance, the suggested intake was cut back to 400 IU. Not surprisingly—or, rather, predictably—the rate of type 1 diabetes shot up like a rocket and has continued on this upward trend ever since.

Type 1 diabetes is now epidemic in Finland, affecting about 65 out of 100,000 children. That’s four times what it was 50 years ago. On the other hand, childhood diabetes in sun-drenched countries is so rare that it’s considered an oddity. Cuba, for instance, has only 2 cases per 100,000 kids. I don’t know if Cuba has a recommended intake of vitamin D, but that country does have sunshine—and lots of it all year long. And there’s no question it’s all that sunshine that slashes the rate of type 1 diabetes!

Vitamin D Keeps Tissues Healthy

How does vitamin D prevent type 1 diabetes? Dr. Garland explained that the cells in various tissues and organ systems work together. Strong, healthy interfaces among similar cells allow them to function as a unit, share resources, and maintain tight barriers that screen out microbes, immune cells, and the like. Proteins called cadherins play a key role in holding cells together, and their proper function is dependent on ample amounts of vitamin D.

When D levels are low, these intercellular junctions become weak and leaky. In the case of type 1 diabetes, breaks in the barriers allow immune cells to slip through and attack insulin-producing cells, or islet cells, in the pancreas. This interaction creates antigens that spur the immune system to attack more vigorously, and a full-fledged autoimmune reaction ensues. Sufficient levels of vitamin D simply tighten up the junctions and stop leakage and islet cell destruction, thus preventing diabetes. It’s that simple!

Let’s Turn the Tide on Type 1 Diabetes

Type 1 diabetes is a devastating condition that requires lifetime use of insulin. Stem cell therapy and islet cell transplants are expensive and therefore lucrative avenues of treatment. Yet compared to the preventive power of vitamin D, they seem downright silly. If we can reduce the incidence of disease by 80 to 95 percent with an inexpensive nutrient, don’t you think we should?


  • Start taking vitamin D—it’s sunshine in a capsule.
  • The recommended daily dose of vitamin D3 (the best supplemental form) for infants is 1,000–1,800 IU; for children ages 1 to 12, 2,000 IU; and for adults, 2,000–5,000 IU—or more, if needed, to bring blood levels into the optimal range.
  • I strongly suggest having your vitamin D blood level tested and increasing your intake until your blood level is between 50 and 80 ng/mL.


  • Garland F. Can diabetes be prevented with vitamin D? Diagnosis and Treatment of Vitamin D Deficiency Seminar. December 2, 2008, San Diego, CA.

Modified from Health & Healing with permission from Healthy Directions, LLC. Photocopying, reproduction, or quotation strictly prohibited without written permission from the publisher. To subscribe to Health & Healingclick here.

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