Are You Really Getting Enough Vitamin D?
Are You Really Getting Enough Vitamin D?
A new study on vitamin D, from Brigham and Women’s Hospital, is based on an analysis of data from the VITAL trial, which is a nationwide clinical trial that investigated whether taking vitamin D, or omega-3, supplements could reduce the risk of developing cancer, heart disease, or stroke.
Examining the Study
Now this study, based on over 25,000 U.S. participants over the age of 50 “found little benefit of vitamin D supplementation for preventing cancer, heart attack, or stroke in the overall cohort”.
This result I would disagree with and would suggest that the amounts of nutrients used in the study (daily intake of 2,000 IU vitamin D and 1,000 mg omega-3 fatty acids) was not sufficient to improve health outcomes.
Nonetheless, a recent re-analysis of the data provided by the VITAL trial found “there was a statistical correlation between BMI and cancer incidence, cancer mortality, and autoimmune disease incidence. Other studies suggest similar results for type 2 diabetes”. The new study we are looking at set out to investigate this correlation.
In over 16,000 participants from the original trial, researchers analyzed a wide range of vitamin D biomarkers, including levels of free and total vitamin D and its metabolites, along with levels of calcium, and parathyroid hormone (which helps the body utilize vitamin D).
“Most studies like this focus on the total vitamin D blood level. The fact that we were able to look at this expanded profile of vitamin D metabolites and novel biomarkers gave us unique insights into vitamin D availability and activity, and whether vitamin D metabolism might be disrupted in some people but not in others”, said senior author JoAnn E. Manson, MD.
Now here is where it gets a bit confusing. The researchers found that supplementing with vitamin D improved the biomarkers associated with vitamin D metabolism in most of the participants “regardless of their weight. However, these increases were significantly smaller in people with elevated BMIs.”
According to first author Deirdre K. Tobias, ScD, “The analysis of the original VITAL data found that vitamin D supplementation correlated with positive effects on several health outcomes, but only among people with a BMI under 25. There seems to be something different happening with vitamin D metabolism at higher body weights, and this study may help explain diminished outcomes of supplementation for individuals with an elevated BMI.”
So, the researchers concluded that vitamin D supplementation does reduce cancer and autoimmune disease rates, among “other outcomes”, in those with lower BMIs, but it provides minimal benefit for those with higher BMIs.
Therefore, they suggest that doctors should take into account a patient’s BMI when determining a dose of vitamin D to recommend, and researchers need to take this into account when analyzing the health benefits of vitamin D in clinical studies.
But, what I find confusing is the fact that vitamin D supplementation “improved the biomarkers associated with vitamin D metabolism in most of the participants regardless of their weight”.
I have always assumed that one’s BMI is nothing but an indication of their weight, so now we have to examine exactly what the BMI is, in order to fully understand this new research. Source Study
So, ostensibly, the Body Mass Index (BMI) is a simple formula which can be used to determine who has a high level of body fatness, allowing doctors to screen patients for weight categories that may be unhealthy. The math is simple: “a person’s weight in kilograms (or pounds) divided by the square of height in meters (or feet)”.
The higher the number the greater the body fat, “but it does not diagnose the body fatness or health of an individual”. Which is a little confusing as I assumed that “body fatness” was exactly what we were determining.
As far as diagnosing the health of an individual, if a patient does have a high BMI number the doctor will perform further testing to confirm that the person is indeed in a dangerous weight category. (“Such assessments include skinfold thickness measurements, evaluations of diet, physical activity, and family history.”)
It appears that the BMI, as nothing but an indicator of weight-for-height, is a simple, easy to use diagnostic tool, used commonly in nutrition and public health surveys as a way to roughtly monitor the weight status of the participants in such studies.
However, while “at the extremes of heaviness, BMI is probably a reasonable indicator of fatness in the general population”, it is now considered by progressive health professionals to be “a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age”.
Flawed or not, the BMI is still widely used in the medical community, as it was in the recent study we are examining. Many still consider it to be a reliable indicator of body fat in a large enough percentage of the population to be a somewhat acurate method for analyzing potential health status and problems.
Health Risks Related to BMI
If you have a high BMI then you are, likely, prone to certain health problems, including: “coronary heart disease; hypertension; osteoarthritis; sleep apnea and respiratory problems; some cancers; stroke; type 2 diabetes”.
Conversely, if you have a low BMI you may also be at risk for other health issues, including being predisposed to: “cardiovascular disease; depression; difficulty conceiving (in women); dry skin; hair loss; irregular menstruation; nutrient deficiencies; osteoporosis;poor immune system”.
If one’s BMI is below 18.5, then they are constituted as “underweight”; 18.5 – 24.9 represents a “healthy weight”; 25.0 – 29.9 signifies “overweight”; while 30.0 and above equals “obesity”.
Now here is where it gets confusing.
If my BMI is less than 25, even 24.9, then I have a healthy weight, but if I stray by .1, and slide up into that 25 category, I have become overweight. And, as we saw above, “vitamin D supplementation correlated with positive effects on several health outcomes, but only among people with a BMI under 25”.
I would have expected to see that anyone above 30, in the obese category, would show difficulty absorbing vitamin D and thus have negligible health benefits from supplementing with relatively low doses of vitamin D. However, since the benefits of low doses of vitamin D (2,000 IU daily in the study we are examining) only applied to those who are not even marginally overweight, we have to conclude that anyone carrying even a small amount of excess weight may need much more vitamin D to reap its benefits.
Based on my research over the years, I usually recommend most people to average about 25,000 IU of vitamin D weekly. This is roughly the amount recommended by scientists who study COVID-19 as well, as this study from June 2021 confirms: “A 5000 IU daily oral vitamin D3 supplementation for 2 weeks reduces the time to recovery for cough and gustatory sensory loss among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms.” (Source)
Now, as usual, I recommend the supplement be taken only five days a week, giving the body a chance to use up any excess if perchance we ingested more vitamin D than the body requires. So, my recommendation is slightly less than that of this COVID study, since they suggest 5,000 IU, seven days a week. In either case, this amount is most likely sufficient for most of us, including those who are slightly overweight since, as noted in the first study we examined, the subjects were only given 2,000 IU daily.
However, those who fall into the obese category would be well advised to regularly test their vitamin D levels, and ensure that they take enough supplemental vitamin D to keep within a healthy range. Since such people will likely be taking more than 5,000 IU daily, it is important that they also supplement with vitamins A, and K2, which are cofactors of vitamin D required when we ingest relatively high levels.
Finally, remember that the poorest absorbed form of vitamin D is tablets, so one should use softgels (which contain vitamin D in a matrix of fat), taken at a meal containing fat, or use liquid vitamin D drops, which do not require being taken with food. With liquid D (like our Quick D product), one can even just take 25 drops of the 1000 IU per drop product, or 10 drops of the 2,500 IU product, only once per week. This is a totally safe approach for those who dislike the daily approach.