Older men who are worried about insulin resistance can take heart from a Tufts University study which shows that higher than normal doses of vitamin K slow development of the condition. (Insulin resistance is a condition in which the body increasingly cannot use insulin properly and blood glucose levels rise. It is a major precursor to type 2 diabetes.)
The Tufts study, which was originally intended to assess the effect of vitamin K on bone mineral density and vascular calcification in older people, involved 355 non-diabetic Caucasian men and women ages 60 to 80 in a three-year clinical trial.
During the study, one group ate regular meals with supplements that included calcium, vitamin D, and 500 mcg of vitamin K daily, five times the dose recommended by the Food and Nutrition Board of the Institute of Medicine. A second group ate regular meals and ingested the same supplements except for the vitamin K.
By the end of the study, researchers noted that the progression of insulin resistance was slowed in the men who took the vitamin K supplement. Those men also had lower blood insulin levels.
The Tufts researchers did not see a similar result in the women who took the vitamin K or in the men and women who did not take the vitamin at all.
The researchers hypothesized that vitamin K failed to affect the women because the women tended to be more overweight than the men. Vitamin K is stored in the body’s fat tissues, and excess fat makes it harder for the body to access vitamin K for use in metabolizing glucose.
In any case, the study is not conclusive enough for scientists to say that vitamin K may provide an effective pre-diabetes therapy. The researchers called for further study to look at larger populations of pre-diabetic patients, including non-Caucasian populations.
Vitamin K is found in broccoli, Brussels sprouts, spinach, collard greens and other dark, leafy greens.