Last week a study was published online in the JAMA Network Open. The researchers compared the health benefits of vitamin D in two groups – normal weight and those overweight/obese. https://jamanetwork.com/journals/jamanetworkopen/article-abstract/2800491
The 2019 Vitamin D and Omega-3 Trial (VITAL) was the most extensive randomized placebo-controlled clinical trial focused on vitamin D and cardiovascular health. I remember the headlines at the time stating that vitamin D did not reduce the risk of cardiovascular disease. I thought it was strange; however, I did no further investigation then.
A new set of headlines caught my attention today. The original study is included in my current review and assessment. I had dived into the initial research and found several interesting things. First, the vitamin D supplements given to the test patients were 2,000 IUs a day. Initially, I thought this was far too little to produce beneficial results. The study confirmed there was no improvement in cardiovascular health.
Vitamin D3 Pathways
As I look at cardiovascular health, vitamin D is one part of the equation. In addition, we think of vitamin D improving bone or skeletal health – and many articles support that. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257679/ is one of them. Vitamin D can enter the body through sunshine, food, or supplements and is converted in the liver to 25-hydroxyvitamin D3. It can be stored in the liver, muscles, and fat tissue or sent to the skin, colon, brain, lymph nodes, and pancreas.
The primary path of 25-hydroxyvitamin D3 is to the kidneys, where it is converted into 1,25 dl-dihydroxyvitamin D3 to regulate calcium metabolism – depositing calcium in bones, for example. However, calcium is not deposited in the bones without vitamin K2. The study did not include any analysis of vitamin K2. Once calcium enters the bloodstream, it can be deposited in the bones when vitamin K2 is present or in the heart valves and arteries (calcium plaques).
I believe that 2,000 IUs of vitamin D3 is too little to be effective in testing the health benefits of vitamin D3 (1,25 dl-hydroxyvitamin D3). However, the study did impress me with the level of vitamin D3 testing – employing multiple biomarkers of vitamin D3 metabolism (total vitamin D3, bioavailable vitamin D3, free 25-hydroxyvitamin D, and vitamin D binding protein). In addition, the study focused on those with a healthy weight (BMI less than 25) and those overweight.
One noteworthy result was that cancer incidence was reduced in the healthy weight group but not in the overweight group. Why? Did weight, or excess fat, impact vitamin D’s ability to deliver the necessary benefits regarding cancer?
Vitamin D3 Levels
https://www.lifeextension.com/magazine/2021/5/vitamin-d-deficiency Part of the dilemma I see is the use of vitamin D threshold for health. The National Academy of Medicine defines vitamin D insufficiency as below 20 ng/dL. Other medical and health organizations suggest that 30 ng/dL is the minimum level to achieve health benefits from vitamin D. Regardless, the sufficient/insufficient levels of vitamin D3 for effectiveness have been bandied about for quite a while.
The study mentioned at the beginning of this article recorded an average vitamin D3 level of 28 ng/dL for all patients. The study also opined that anything above 30 ng/dL did not appear to protect against bone fractures. The upper limits of vitamin D3 testing were not defined in the study.
I keep my vitamin D3 levels above 80 ng/dL. However, it took years for me to determine the level of vitamin D3 supplementation to achieve 80 ng/dL by months of specific supplementation and then a blood test to confirm the results.
Life Extension Magazine has been following vitamin D3 research for over two decades. https://www.lifeextension.com/magazine/2010/9/michael-holick-the-pioneer-of-vitamin-d-research and http://drholick.com/askHolick/questions.html recommend 40-60 ng/dL for everyday health and above 60 ng/dL when a disease like cancer is being treated. However, whether you take 2,000 IUs or 8,000 IUs per day, the level of 1,25 dl-hydroxyvitamin D is not known. This is because everyone processes vitamin D differently.
Getting Back to the Study
https://www.newsmax.com/health/health-news/vitamin-d-absorption/2023/01/24/id/1105672/ Vitamin D is a fat-soluble vitamin. Is circulating vitamin D stored in adipose (fat) tissue more in obese patients than in average weight? That is one conclusion. Another is that obesity causes vitamin D to be eliminated from the body faster than it can be used. Another theory is that fat tissue suppresses enzymes and receptors responsible for vitamin D. All theories sound plausible.
Regardless, vitamin D does not provide overweight people with the same health benefits as those within normal weight standards. For example, the risk of cancer was notably lower in patients with normal weight than those overweight.
A question about increasing the vitamin D3 supplementation levels in overweight patients was met with skepticism and non-agreement. The study did not recommend overweight people increase their daily dosage of vitamin D3 to improve the health benefits of vitamin D3 in their bodies.
I have been following the debates about vitamin D3 for years. It is one of the reasons I planned regular increases in my vitamin D3 supplementation over time with follow-up blood tests to determine how much vitamin D3 is needed to achieve specific levels of vitamin D3 in my body. Yet, the researchers and scientists mentioned in this, and many other research articles, do not address a body level of vitamin D3 to maintain and testing to achieve it. Life Extension is an organization I regularly use for reference.
Articles in Life Extension continually refer to circulating blood levels rather than 2,000 IUs or 8,000 IUs. When you do not know the internal levels of vitamin D3, how can you make general statements about the efficacy of higher dosages of vitamin D3? My wife’s oncologist regularly tested her vitamin D3 levels and wanted her to maintain levels between 80-100 ng/dL to assist with the chemotherapy treatments.
Vitamin D3 testing is relatively inexpensive and available. Before publishing this article, my quick pricing check found that four different laboratories priced vitamin D3 tests between $39 and $99, with most of the tests under $58. I always add vitamin D3 tests to my annual physical, and my insurance pays for it. If it did not, I would pay that cost myself.
Supplementation is the most realistic way to gain adequate levels of vitamin D3. However, sun exposure time, latitude, age, time of year, clothing, and other factors restrict the amount of vitamin D processing that can occur naturally inside your body when relying only on the sun as your source of vitamin D.
Live Longer & Enjoy Life! – Red O’Laughlin – RedOLaughlin.com