According to research from the Vitamin D, Skin, and Bone Laboratory, Section Endocrinology, Diabetes, Nutrition, and Weight Management, Boston University School of Medicine, and the Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, “although it is still debatable what level of serum 25-hydroxyvitamin D is optimal, it is advisable to increase vitamin D intake and have sensible sunlight exposure to maintain serum 25-hydroxyvitamin D at least 30 ng/mL (75 nmol/L), and preferably at 40–60 ng/mL (100–150 nmol/L) to achieve the optimal overall health benefits of vitamin D.”
We opened with this definitive statement on what blood level of the tested form of Vitamin D – 25(OH)D – is necessary to achieve, since the Boston co-study author, Michael F. Holick, in my opinion, is the world’s leading expert on this topic.
Immunologic Effects of Vitamin D on Human Health and Disease – the study – which appeared in the December issue of Medicine & Science in Sports & Exercise, qualifies current recommendations of Vitamin D deficiency – a blood level of less than 20 ng/ml – and insufficiency – less than 30 ng/ml – with a specific blood range – “preferably 40-60 ng/ml” – for the, “optimal overall health benefits of Vitamin D.”
The research makes note that vitamin D, which regulates calcium and phosphate metabolism, is critical in maintaining skeletal integrity, while also functioning as an immunomodulatory hormone – a seco-hormone.
Holick and his fellow co-author, Nipith Charoenngam, note that there is a vitamin D link with the incidence and severity of many disorders such as psoriasis, multiple sclerosis, rheumatoid arthritis, type 1 diabetes, and infectious diseases – specifically, “experimental studies have shown that vitamin D has significant biologic activities on the innate and adaptive immune systems.”
Holick et al executed a review examining the biologic effects of vitamin D on the immune system and its association with several types of immune-related diseases and conditions, in addition to the impact that Vitamin D has relative to prevention and treatment of immune-related diseases.
Vitamin D gains access to the human system via sunlight exposure, diet, and supplements. The active forms include vitamin D2 – ergosterol – obtained in the diet from yeast, sun dried and irradiated mushrooms, and plants, while the active form – D3 – is manufactured internally from dietary sources, such as cod liver oil and oily fish.
Once in the system, the liver converts both D2&3 to 25(OH)D, then the kidneys complete the task by transforming the 25(OH)D to its active form – 1,25(OH)2D.
According to the research, “to maintain these blood levels (40-60 ng/ml) with minimal sunlight exposure, a person would require ingestion of 4000–6000 IUs of vitamin D daily, which would maintain serum vitamin D levels in the range of 20–40 ng/mL (50–100 nmol/L) and serum 25(OH)D levels in the range of 40–60 ng/mL (50–100 nmol/L).”
In order to meet the recommended vitamin D intake, the Endocrine Society guidelines state that adults, who are at risk for vitamin D deficiency, should strive for 1500-2000 iu’s per day – with an upper limit of 10,000iu’s.
The review concluded that, among other variables, “most of the evidence, to date, suggests that maintenance of a healthy vitamin D status is important for modulating the body’s immune function. Low serum levels of 25(OH)D are associated with multiple immune-related diseases, including autoimmune disorders and infectious diseases.”
However, Holick and Charoenngam point out that, “there is less convincing evidence that vitamin D is an effective treatment strategy for autoimmune diseases and infectious diseases with a few exceptions documented in this review. ‘
They go on to add that, “whether vitamin D therapy is effective as an adjunctive immunomodulatory agent for treatment of most diseases, it is still controversial based on heterogeneous findings from the clinical trials.”
Armed with this data, it makes good sense to work with your personal physician to determine the best approach to assess your vitamin D status – with appropriate intake guidelines, as the ultimate objective.
Interested in reading more? Check out COVID-19: Immune Support Update