Life Extension Magazine October 2009
Ask The Doctor
Vitamin D Supports Healthy Blood Sugar
By Steven V. Joyal, MD
Q: I am 52-years-old and I consume 5,000 IU of vitamin D a day because I want to maintain my bone health and support my immune system. Diabetes runs in my family (my father and mother developed type 2 diabetes), and I know that diabetes increases the risk of heart attack and stroke. Can vitamin D help with blood sugar (and heart health)?
A: The scientific support for vitamin D continues to impress our organization!
In addition to beneficial effects on cell growth and maturation, bone integrity, and immune health, we discussed the important link between cardiovascular health and vitamin D in our September, 2007 magazine article titled “Vitamin D’s Crucial Role in Cardiovascular Protection.”
Studies suggest that people who are vitamin D deficient are far more likely to suffer from high blood pressure, which is a risk factor for heart attack and stroke. For example, a study showed that in middle-aged men, serum vitamin D levels correlate with blood pressure and other cardiovascular risk factors.1 Another study showed that vitamin D and calcium supplementation improve blood pressure in aging women.2
Of further interest, diabetes is significantly more prevalent in people with low serum levels of vitamin D.3
In a recent double-blind, randomized, controlled trial published in 2009, one hundred male volunteers over the age of 34 were given either 120,000 IU of vitamin D3 or a placebo every fourteen days for six weeks to study the impact of vitamin D supplementation. Metabolic function was then evaluated by a variety of measurements and tests. Seventy-one trial participants completed the study.
The results indicated that supplementation with the equivalent of about 8,500 IU of vitamin D3 daily significantly increased serum 25-hydroxy vitamin D levels and improved insulin sensitivity (p=0.038; per protocol analysis). No significant changes in insulin secretion or lipid levels were found.4
An increase in blood sugar disposal by target tissues including skeletal muscle and liver may help explain the results of this placebo-controlled, double-blind trial. In the future, larger, longer studies need to be conducted to see if the results obtained in this clinical study are consistent.
“... diabetes is significantly more prevalent in people with low serum levels of vitamin D.”
However, it is important to note that the positive results observed in this 2009 placebo-controlled trial are consistent with the results of a 2007 double-blind, randomized, controlled trial involving supplementation with vitamin D and calcium in healthy older (≥ 65 years of age) adults with impaired fasting blood sugar. This 2007 trial showed a lower rate of insulin resistance in the group supplemented with calcium and vitamin D compared with the placebo group.5
Although clearly more research needs to be done, several recent clinical studies show intriguing, beneficial effects on blood sugar and insulin sensitivity associated with vitamin D supplementation.
Our organization will continue to report on the amazing, broad-spectrum health benefits of this remarkable pro-hormone—vitamin D!
Steven V. Joyal, MD, is the Vice President of Scientific Affairs at the Life Extension Foundation®.
If you have any questions on the scientific content of this article, please call a Life Extension Health Advisor at 1-866-864-3027.
1. Am J Hypertens. 1995 Sep;8(9):894-901.
2. J Clin Endocrinol Metab. 2001 Apr;86(4):1633-7.
3. Arch Intern Med. 2007 Jun 11;167(11):1159-65.
4. Diabet Med. 2009 Jan;26(1):19-27.
5. Diabetes Care. 2007 Apr;30(4):980-6.