1.200 IU Vitamin D Won't Raise 25OH-D Levels Enough to See Beneficial Effects on Markers of Cardiovascular Health

In the course of the last weeks, I have refrained from posting each of the 1001 studies on vitamin D that appear in the myriad of medical magazines each month. It is simply too much, mostly very irrelevant information. A recent study by Maki et al. (Maki. 2011) is yet interesting insofar, as it provides some insight into the amounts of supplemental vitamin D one would probably need to see some cardiovascular benefits.

After supplementing the diets of their subjects with either a standard multi-vitamin or the multi-vitamin + 1,200IU of vitamin D for 8 weeks, the researcers measured serum 25-hydroxyvitamin D [25(OH)D] and high-density lipoprotein cholesterol (HDL-C) in subjects with high waist circumference and found:

There was a significant difference in mean change for 25(OH)D between the MVM and MVM+D treatment groups ( − 1.2 ± 2.5 nmol/l vs. 11.7 ± 3.0 nmol/l, respectively; P = 0.003). Vitamin D 1,200 IU/day did not increase 25(OH)D to a desirable level ( ≥ 75 nmol/l) in 61% of participants. There were no significant changes in cardiovascular disease risk markers. 

This is quite interesting, because even after all the fuss about vitamin D defiency that has even reached the mass media in the course of the last months, the general recommendation is not to take more than 1.000IU of vitamin D (sometimes even less) per day. For most people, this study seems to indicate, this is far too little to even get their vitamin D levels into the desirable ranges. Whether or not this would provide them with the beneficial results many scientists hope for, remains to be elucidated, though.

Opposing Effects of Resveratrol Depend on Dosage

While the hype about resveratrol appears to be over, it is still one of the cornerstones of many people seeking to improve health or promote longevity. If you belong to this group of people, you might find it interesting that without proper dosing, resveratrol may in fact do the exact opposite of what you were paying for.

A recent review published in Human and Experimental Toxicology (Calabrese. 2010) summarizes the literature as follows:

The current assessment indicates that low concentrations of resveratrol can be potentially beneficial or harmful, depending on the endpoint of interest. The data suggest that low doses of resveratrol would have the capacity to increase the risk of tumor development of a number of organs based on its capacity to enhance cell proliferation in multiple human tumor cell lines. In contrast, a strong case can be made that low doses of resveratrol can be significantly cardio-protective. It is likely that these general conditions could occur simultaneously within individuals. While the data are insufficient to answer this question, this type of conflict is not uncommon and we are likely to encounter it more often as investigators become more knowledgeable of the general nature of the hormetic dose response and its capacity to enhance potentially beneficial or harmful effects depending on the biological system, tissue and chemical agent.

Unfortunately, actual human data is sparse and it is still questionable in how far dosing schemes from in-vitro and animal studies are applicable to oral resveratrol supplementation in man. I will have an eye on future studies into that direction and let you know as soon as there is more reliable information out there, so stay tuned ;-)