Vitamin K cuts risk of diabetes in elderly by 50%.
It is inaccurate to suggest that vitamin K intake impacts on the risk of diabetes.
Vitamin K is a fat-soluble vitamin best known for its role in clotting. There are two main forms of vitamin K:
- Vitamin K1 (phylloquinone) found in leafy green vegetables.
- Vitamin K2 (menaquinone) found in poultry, meat, eggs and cheese.
There is growing interest in the potential role of vitamin K in human health and particularly diabetes.
An article in Natural News claims that vitamin K intake cuts the risk of diabetes by 50% in the elderly. This claim was based on a Spanish research publication in the American Journal of Nutrition (1). This study was a longitudinal research study, which followed 1065 people who were already enrolled in a larger clinical trial known as PREDIMED (Prevention with the Mediterranean Diet). This is a community-based study of Spanish men [age 55 to 80] and women [age 60 to 80]. The aim of the parent study is to evaluate the effect of the Mediterranean diet on cardiovascular disease in subjects at high risk of cardiovascular disease.
1,000 research subjects who were enrolled in the PREDIMED parent study but who did not have diabetes at baseline were enrolled in a vitamin K substudy of PREDIMED. The subjects were followed for an average of 5.5 years with lifestyle and dietary intake questionnaires, physical examination, and bloodwork.
During the period of follow-up, 131 new cases of diabetes were identified in the study cohort. There was a 17% reduced risk of developing diabetes for each extra intake of 100 mcg of phylloquinone per day.
Study participants who increased their dietary intake of vitamin K during the study had a 51% reduced risk of developing diabetes as compared to study participants who decreased or did not change their vitamin K intake.
This does not mean that we can simply extrapolate that vitamin K intake reduces overall risk of developing diabetes. There are a number of important reasons for this.
Firstly, the study cohort were elderly and were at high risk of cardiovascular disease. Results from the study cohort cannot be extrapolated to the general population.
Secondly, vitamin K blood measure levels were not measured in the study.
Thirdly, this study proves an association between vitamin K intake and risk of diabetes but does not prove that vitamin K was responsible for the reduced risk noted.
In summary, the study shows an association between vitamin K intake and lowered risk of diabetes in a very specific patient demographic. The results of this study cannot be extrapolated as proof that vitamin K directly reduces diabetes risk and certainly cannot be extrapolated to the general population.
- Am J Clin Nutr. 2012 Nov;96(5):1113-8. doi: 10.3945/ajcn.111.033498. Epub 2012 Oct 3. Dietary phylloquinone intake and risk of type 2 diabetes in elderly subjects at high risk of cardiovascular disease. Ibarrola-Jurado N1, Salas-Salvadó J, Martínez-González MA, Bulló M.