Population study links higher vitamin D levels to lower risk of pre-diabetic syndrome and healthier blood fat profiles
by Craig Weatherby

In June of this year we reported on a study that linked higher blood levels of vitamin D to reduced rates of metabolic syndrome… the cluster of physical signs that usually precedes diabetes.

Following on earlier studies, the authors of that joint Anglo-Chinese study linked deficient levels of vitamin D to a 52 percent higher risk of metabolic syndrome (See “Vitamin D Seen to Stall Pre-Diabetic Syndrome”).

Now, the authors of a U.S. study have linked higher blood levels of vitamin D to lower rates of metabolic syndrome, as well as improved cholesterol and triglyceride profiles in the blood (Maki KC et al 2009).

What the study found: heart and diabetes risks
Researchers analyzed vitamin D blood levels in 257 men and women.

The participants' intake of vitamin D from foods and supplements was estimated using diet questionnaires, and the results showed several things:
  • Almost one-third (31 percent) of people with the lowest average blood levels of vitamin D had metabolic syndrome, compared to only 10 percent of the people with the highest average levels ... a big, 64 percent reduction in risk of metabolic syndrome.
  • Higher vitamin D blood levels were associated with higher levels of HDL (“good”) cholesterol.
  • Higher vitamin D blood levels were associated with lower triglyceride (blood fat) levels.
  • Higher vitamin D blood levels were associated with having a lower body mass index and smaller waist.
    As the researchers noted, the cholesterol finding is important because every 1 mg/dL increase in HDL levels is associated with a five percent reduction in the risk of developing coronary heart disease (CHD).

    In other words, if you exclude the influence of all other risk factors, a 10 ng/mL increase in vitamin D blood levels could decrease the risk of CHD by about 20 percent.

    To help ensure optimal health, most vitamin D researchers recommend minimum blood levels ranging from 36 to 48 ng/mL (nanograms per milliliter), but three in four Americans fall well short of that mark.

    The most recent survey of Americans' blood levels pegged the average blood level in the U.S. at a subpar 24 ng/mL, while six percent had very unhealthy levels (i.e., lower than 10 ng/mL) and only 23 percent had healthy levels of 30 ng/mL or higher (Ginde AA et al. 2009).

    Does vitamin D lack make people overweight?
    The answer to that question is probably “no”.

    Instead, the researchers offered a more nuanced explanation for their observation that people with lower vitamin D levels had bigger waists and higher body mass indices.

    Vitamin D is fat-soluble and accumulated in fatty tissue. Thus, overweight and obese individuals have a greater storage capacity for vitamin D, which may result in reduced amounts circulating in the blood... and less vitamin D that is readily available for health-promoting purposes.

    So, in order to maintain a given blood level of vitamin D, an overweight or obese person may have to consume more vitamin D
    or get more sun exposurecompared with leaner folks.

    • Forouhi NG et al. Baseline serum 25-hydroxy vitamin d is predictive of future glycemic status and insulin resistance: the Medical Research Council Ely Prospective Study 1990-2000. Diabetes. 2008 Oct;57(10):2619-25. Epub 2008 Jun 30.
    • Ginde AA, Liu MC, Camargo CA Jr. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med. 2009 Mar 23;169(6):626-32. DOI: 10.1001/archinternmed.2008.604
    • Klein GL et al. Standard multivitamin supplementation does not improve vitamin D insufficiency after burns. J Bone Miner Metab. 2009 Mar 17. [Epub ahead of print]
    • Lu L et al. Plasma 25-hydroxyvitamin D Concentration and Metabolic Syndrome among Middle-aged and Elderly Chinese. Diabetes Care. 2009 Apr 14. [Epub ahead of print]
    • Maki KC et al. Serum 25-Hydroxyvitamin D is Independently Associated with High Density Lipoprotein Cholesterol and the Metabolic Syndrome in Men and Women. Journal of Clinical Lipidology. Published online ahead of print July 17, 2009. DOI: 10.1016/j.jacl.2009.07.003
    • Reis JP, von Mühlen D, Miller ER 3rd. Relation of 25-hydroxyvitamin D and parathyroid hormone levels with metabolic syndrome among US adults. Eur J Endocrinol. 2008 Jul;159(1):41-8. Epub 2008 Apr 21.