Everyone seems to be rushing to the lab to find their ‘Vitamin D number’. This little vitamin cum hormone is being blamed for everything – from acne to hair loss, fatigue and insomnia..

The last 5 years have seen an exponential rise in the demand for expensive Vitamin D blood testing, both in the medical and general community. People are frantically asking for supplements in the hope that it will change their life. But will it??

Let us begin by getting some scientific background on Vitamin D.

There are two forms of Vitamin D – D2 and D3. Vitamin D2 is found commonly in foods like cheese, egg yolk, fatty fish, beef liver and raw shitake mushrooms. Vitamin D3 is produced naturally by the fat right underneath our skins, when exposed to sunlight. Oral supplements are generally in the D3 formulation which is easier for our bodies to absorb and utilize.

Both D2 and D3 are biologically inactive. When our body absorbs them either through our food or from the skin, they bind to a carrier protein in our blood called the D-Binding Protein (DBP). The DBP then carries D2 and D3 to the liver where it is transformed into 25 hydroxy (OH) Vitamin D. This is the major circulating form of Vitamin D in the blood, and this is form that is tested for, when you go to the lab. The biologically active form of Vitamin D, that is, the form which is ready available for utilization by the body, is 1,25 dihydroxy (DOH) Vitamin D. This is formed when 25 OH Vitamin D is carried from the liver to the kidney and further hydroxylated by the enzymes in the kidney. The synthesis of 1,25 DOH Vitamin D is tightly controlled by blood calcium and phosphate levels as well as the parathyroid hormone. This form is stored in our fat cells.

Interest in Vitamin D deficiency peaked about a decade ago when it was found that a vast majority of human kind are deficient. This led to a lot of discussion and panic about an emerging pandemic. Most dark-skinned races do not absorb sufficient amount of Vitamin D from sunlight due to the high level of sun-blocking melanin pigment in their skin. Vegetarians and vegans were worst affected as Vitamin D is only found in animal sources. The light-skinned races generally live in countries with very little sunshine and were also found to be deficient. As a thumb rule, children under 8 and adults over 60 need more Vitamin D compared to young adults. Those who are dark-skinned, vegetarian, underweight or living in cold countries need more Vitamin D, as do patients suffering from kidney or liver related ailments.

Vitamin D is necessary for healthy bones and deficiency is known to cause bone related ailments like Rickets and Osteoporosis. But it was also linked to a host of other ailments like high blood pressure, heart disease, diabetes, multiple sclerosis, autoimmune diseases, pimples, hair fall, depression, insomnia, infertility, Alzheimer’s disease and even cancer. These findings lead to over-testing, over-diagnosis and over-treatment with Vitamin D. Patients are coming in demanding for the test, curious to know their number, and there are days when physicians feel they are treating very little besides real or supposed Vitamin D deficiency. I have found fellow dermatologists testing patients with acne and hair fall for D deficiency! Vitamin D testing is more expensive than testing for anaemia, thyroid disorders and pelvic sonography to rule out ovarian cysts – tests that are medically established to have a cause-and-effect relationship with acne and hair fall.

The early advocates of D deficiency had us believe that even blood levels of 35 ng/ml is too little and there is no such thing as “too much” when it comes to the ‘sunshine vitamin’. They recommended a daily intake of 600-800 IU of Vitamin D, which is impossible to achieve through diet and sun exposure alone! Over-supplementation has made Hypervitaminosis and Vitamin D toxicity fairly common. This will never happen as a result of sun exposure alone, as our body can self-regulate Vitamin D synthesis from sunlight. But toxicity from over-supplementation can cause symptoms like nausea, loss of appetite, kidney failure and, ironically, fatigue and hypertension! Physicians are now starting to agree that in patients who have a minimum blood level of 20 ng/ml, diet and sun exposure is often sufficient to build up Vitamin D levels in the body. We have to start treating symptoms and not just a lab report.
Part of the problem is the inaccuracy and unreliability of various testing methodologies. There has also been a revision in the definition of Vitamin D “deficiency” and “insufficiency”. Physicians generally believed that 25 OH D3 values of less than 20 ng/ml indicated Vitamin D deficiency. But it is not as simple as that. A lot of patients might have values as low as 16 ng/ml and yet do not have any symptoms of Vitamin D deficiency. Ideally, one must also test for serum Calcium levels and the PTH hormone to correctly evaluate the state of deficiency.

Take the African-American population for instance. Vitamin D deficiency, as per test reports, is rampant and as high as 80% in the Black community. And yet, they are known to have higher bone and muscle mass compared to Caucasians, and rarely suffer any of the symptoms like muscle pain, joint pains, bone fragility, weakness or fatigue. Further study revealed that this is because these races also have lower blood levels of DBP – the Vitamin D binding protein, which locks away bio-available D3 and prevents the body from using it. DBP testing is neither easy nor inexpensive, and is mostly done for research purposes and rarely ever done in clinical practice. Lower levels of DBP means that the African population have higher levels of bio-available 1,25 DOH Vit D, even though they test low for the circulating 25 OH Vit D. Low blood levels of DBP in Africans compared to Caucasians is perhaps genetically ingrained.
Vitamin D deficiency has been linked to ailments like diabetes and hypertension. However, recent studies have not found any benefit of Vitamin D supplementation in preventing or treating these ailments. A lot of patients suffering from cancer, heart disease, diabetes and other chronic ailments have damaged liver and kidneys, which restricts their body’s natural ability to produce Vitamin D. Patients with arthritis, fibromyalgia, severe asthma and multiple sclerosis have severely restricted mobility, restraining them from outdoor activities and the accompanying sun exposure. The elderly might have several dietary restrictions as well (avoid eggs and meat, for instance) which predisposes them to nutritional deficiencies. So it is likely that Vitamin D deficiency in these populations is a symptom rather than a cause. When it comes to rickets, osteoporosis and osteopenia, there is a direct cause-and-effect relationship with Vitamin D deficiency. In these bony ailments, Vitamin D supplementation is indicated and disease recovery is well established. But Vitamin D supplementation is not medically indicated as a treatment for hypertension, acne, mental disorders and such, as the benefits have never been proven.

Vitamin D deficiency seems to be the fad of the decade. Physicians have historically noted such food and nutrition-related fads to arrive with a bang and fad away with a whimper. Take the excitement about Vitamin E in the 1990s. Research told us that high intake of Vitamin E can protect us from heart disease and prostate cancer. But when scientists tested the claims in large scale randomized clinical trials, they found no heart health benefit and a slightly higher incidence of prostate cancer! Similar hype and enthusiasm about Folic acid, B-complex vitamins and fish oil supplements have died a natural death. The public continues to understand the importance of these supplements and they remain widely popular, but we do not live in fear of a pandemic anymore. Sadly, these food and nutrition related frenzies often originate in medical papers, and not in the blogs of a nutritionist or the website of a health food store. The next few years will bring us closer to a conclusion, as there are several large, well-designed randomized studies underway, with results expected by 2020.

So does this mean we do not have a Vitamin D issue at all? Not entirely true. Take my country for instance. Millions of Indians are vegetarian, malnourished and do not have a proper understanding of dietary balance. Our obsession with light skin has made most of our women sun phobic. Our students are brilliant in maths and science but are poor at gym and sports. Vitamin D fortified milk would be an excellent idea in a country like mine. But based on my personal experience with patients and general public perception regarding nutrition, the D deficiency phobia is here to stay and patients are unlikely to heed our advice against unnecessary testing, anytime soon!