Can Vitamin D Prevent Diabetes?

variety of fruit with vitamin C
Vitamin D may help prevent diabetes in people at high risk of developing he condition, researchers report.

The study does not prove cause and effect. “But if confirmed, there are huge implications because vitamin D is easy and inexpensive,” Anastassios Pittas, MD, of Tufts Medical Center in Boston.

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In a study of over 2,000 people with prediabetes, the higher the level of vitamin D in the blood, the lower the risk of developing type 2 diabetes.

Pittas presented the results here at the annual meeting of the American Diabetes Association.

Tracking Vitamin D Levels

The three-year study involved 2,039 people with high blood sugar levels. Their vitamin D levels were measured at the start of the study and six months, one year, two years, and three years later.

For every 5 nanograms per milliliter (ng/mL) increase in vitamin D levels, the risk of developing diabetes dropped by 8%, Pittas says. Levels of 30 or higher are considered normal.

The participants were divided into three groups. Participants in the group with the highest third of vitamin D levels (average reading of about 30 ng/mL) were 38% less likely to develop diabetes than those in the lowest third (average vitamin D level of 13 ng/mL).

A strength of the study is that vitamin D levels were measured at various time points, Pittas says. Past studies often relied on one measurement at the start of the study, which may not accurately reflect their vitamin D status over time.

The analysis also took into account a person’s body weight, physical activity, and other factors known to decrease diabetes risk. Nonetheless, there could be some unmeasured variable that affected risk, Pittas says. He says a robust clinical trial in which half the people get vitamin D and half get placebo is needed to determine if supplements can stave off diabetes.

Diabetes Prevention

Sheena Kayaniyil, a PhD candidate at the University of Toronto, says that her research also supports a role for vitamin D in the prevention of diabetes.

In a study of nearly 500 people at high risk of diabetes, higher vitamin D levels at the start of the study were associated with lower blood sugar levels three years later.

Higher vitamin D levels also predicted better function of the body’s own insulin-producing beta cells at follow-up, she says. “Our research supports a potential role for vitamin D in the [development] of diabetes.”

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the “peer review” process, in which outside experts scrutinize the data prior to publication in a medical journal.

We bet you’re wondering…how can you get in more Vitamin D, right?

1. Incorporate vitamin D-rich food

Wild salmon 3 oz = 420 IU
Atlantic mackerel 3 oz = 320 IU
Sardines 1 can = 250 IU
Shrimp 3 oz = 150 IU
Skim and 1% low-fat milk 1 cup = 100 IU
Shittake mushrooms 4 items = 260 IU
Fortified yogurt 1 cup = 80 IU
Fortified cereals 1 cup = 40 – 80 IU

2. Supplement daily with vitamin D. Because food sources are limited, it’s a good idea to consider supplements. After first consulting with your doctor to discuss your specific needs, consider taking a multivitamin which provides at least the Daily Value, 400 IU.

For women taking extra calcium, buy a brand that also provides vitamin D — optimally, D3 (cholcalciferol), the most potent form.

For men who would like to take additional vitamin D, look for a supplement that provides 400-1000 IUs of D3, also called cholcalciferol. It’s important to note that men should not take supplemental calcium (some research suggests excessive calcium may increase the risk for prostate concerns).

3. Enjoy “a little” safe sun. 15 minutes, a few times each week, should do the trick. Our bodies produce their own vitamin D through exposure to the sunlight.

That’s good news, considering that too much sun can damage the skin and increase your risk of skin cancer. Remember to ALWAYS apply sunscreen year-round (even during the winter months).