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The ‘ABCs’ of Vitamin D

October 04, 2019 by Kimberly Drake

I have heard the horror stories of cod liver oil. Back in the day, my grandmother would line up all 10 of her children, and each one would get a spoonful of the most wretched tasting stuff ever put on earth. 

Some would persevere through the horrendous taste and choke it down, and some, well, didn’t fare so well. There was a method to grandma’s madness, as the reason she forced her children to endure this nightmare on a spoon was to ensure they got enough Vitamin D to prevent rickets. However, as it turns out, this sunshine vitamin may be critical for overall health. But just how critical?

According to a fact sheet for health professionals published by the Office of Dietary Supplements of the National Institute of Health, Vitamin D is a fat-soluble vitamin naturally present in a limited number of foods, often added to cereals and other products, available as a dietary supplement and produced by the body when the skin is exposed to sunlight. This vitamin is considered biologically inert and must go through processes in the liver and kidneys to become activated.

What does it do for the body?

Vitamin D assists in calcium absorption in the intestines to help with bone growth and mineralization, and when there’s a deficiency, bones can become thin, brittle or distorted. It also helps prevent rickets in children and osteoporosis in older adults. In addition to bone health, Vitamin D is also involved in cell growth, neuromuscular and immune function, and the reduction of inflammation.

What are the known health benefits?

Although research is emerging that Vitamin D may help in the prevention and treatment of type 1 and type 2 diabetes, hypertension, depression, glucose intolerance, multiple sclerosis and other medical conditions, it is mostly associated with bone health, heart health and cancer prevention. Adequate levels of Vitamin D might help prevent osteoporosis in older adults, postmenopausal women, those who have difficulty exercising and individuals on long-term steroid therapy, but the jury is out on whether it helps prevent cancer or heart disease.

In a 2017 paper published in the journal, Epidemiologic Reviews by Oxford Academic, researchers found higher circulating levels of Vitamin D appear to be associated with reduced risk of colorectal and bladder malignancies, but a higher risk of prostate and possibly pancreatic cancers. In addition, one of the latest clinical trials looking into the effects of Vitamin D supplements on the prevention of cancer, the newly published VITamin D and OmegA-3 TriaL (VITAL) from Brigham and Women’s Hospital, concluded that according to trial results, Vitamin D supplementation did not reduce the risk of cancer or major cardiovascular events like heart attacks, but did appear to reduce the risk of overall cancer-related death.

How much do you need?

Those at risk for D deficiency include older adults, those with limited sun exposure, people with darker skin pigmentation and individuals with diseases that prevent fat absorption in the intestines. There is a blood test available to check your levels, and although there is no formal clinical definition of vitamin D deficiency, most medical professionals consider a normal level to be higher than 20 ng/mL (50 nmol/L).

Getting vitamin D naturally is challenging, as very few foods contain enough to meet daily requirements. It is found in fatty fish such as salmon, tuna or mackerel, with the highest amounts contained in fish liver oils, which is why previous generations had to live through the daily battle with the dreaded cod liver oil-filled spoon. Today, most of our vitamin D intake comes from fortified foods like cereal or milk.

Sunlight is another natural source, but because of variables like the season, cloud cover, smog, skin melanin content and sunscreen use, this is not always a reliable source. The UVB radiation needed for absorption of vitamin D does not penetrate glass, so those stuck inside due to work or other factors may not get enough exposure for adequate D production. Some researchers say that approximately five to 30 minutes of sun exposure between 10 a.m. and 3 p.m. at least twice a week to the face, arms, legs or back without sunscreen is usually enough exposure to produce adequate vitamin D.

What about supplements?

To the relief of many, gone are the days when this vitamin only came out of an obnoxious bottle of cod liver oil. These days, the sunshine vitamin comes in pills containing either D2 (ergocalciferol) or D3 (cholecalciferol). 

Which is better? According to experts, D3 may be superior because it is more potent, yet less toxic in higher amounts, and has been the form used in most clinical trials. In general, depending on needs, most medical organizations recommend people with no deficiency should take 600 to 800 IU of vitamin D3 daily and consider 4000 IU a day as the upper limit for safe supplementation. Of course, this recommendation varies widely among health care providers in both Western and Alternative medicine.

Like with most vitamins, minerals and supplements, the controversy rages on about whether the sunshine vitamin is indeed a miracle pill. One thing not contested, and in fact celebrated, is that in order to get adequate amounts, you no longer have to stand in grandma’s “cod liver oil firing line” to get the supplementation you need.

Kimberly Drake can be reached at [email protected]

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