Vitamin D

Updated: May 4, 2021


Vitamin D


Vitamin D is often called the sunshine vitamin due to our skin’s incredible ability to absorb ultraviolet light from the sun to form Vitamin D (cholecalciferol) in the skin from 7-dehydrocholesterol. We can also get vitamin D from our diet. Unfortunately, Vitamin D naturally occurs only in very few foods.


We need Vitamin D for:

· normal calcium homeostasis. Its action resembles that of parathyroid hormone, ultimately causing elevation of the serum calcium concentration. It does so by promoting absorption of Calcium (and phosphate) from the gut. It increases osteoclastic resorption (breakdown and absorption) of bone moving calcium from your bones to your bloodstream.

In children, lack of Vitamin D impairs mineralization of the growing skeleton, thus causing rickets. In adults, vitamin D deficiency results in osteomalacia.


· support the immune system and fight inflammation. Fascinating studies are now undertaken investigating the effect of Vitamin D on covid related illness.


· Oral health, lowering the risk of tooth decay and gum disease. Vitamin D is beneficial for oral health, due to its effect on bone metabolism and "its ability to function as an anti-inflammatory agent and stimulate the production of anti-microbial peptides."


· Vitamin D can help treat hypertension: According to a 2019 review published in the journal Current Protein & Peptide Science suggests that vitamin D may play a role in treatment of high blood pressure where they have found even short-term vitamin D deficiency may directly raise blood pressure which in turn may lead to organ damage.


· Weight management. Obesity is a risk factor for Vitamin D deficiency. On the flip side, one 2009 study in the British Journal of Nutrition found that, in overweight or obese women with low calcium levels, those who took a daily dose of calcium paired with vitamin D were more successful shedding pounds than those who took a placebo supplement


· Effect on mood: The sun can brighten up your mood, and so can vitamin D. According to a 2017 review article in the journal Neuropsychology, researchers found "a significant relationship between depression and vitamin D deficiency.”


· Multiple fascinating studies (which can be found on the National Cancer Institute website) provide some evidence that vitamin D may have cancer fighting powers. Furthermore, in experimental studies Vitamin D has been found to have several activities that might slow or prevent the development of cancer cells and tumors in mice, including promoting cellular differentiation, decreasing cancer cell growth, stimulating cell death (apoptosis), and reducing tumor blood vessel formation (angiogenesis).


Vitamin D deficiency is caused by:

· Lack of dietary vitamin D with inadequate sunlight

· Intestinal malabsorption of fat (vitamin D is fat-soluble)

· Our kidneys and liver are involved in Vitamin D metabolism as well. So many kidney or liver problems could impair hydroxylation. (The intermediate precursors of Vitamin D are activated by hydroxylation sequentially in the liver and kidneys to give 1,25-dihydroxy-cholecalciferol, a steroid hormone. Hydroxylation in the kidney is stimulated by the parathyroid hormone and low calcium levels.)


Skin pigmentation affect our body’s ability to synthesize Vitamin D. Furthermore, our skin’s ability to make vitamin D decrease as we age.


Our Canadian recommendation is to take a vitamin D supplement year-round and not only in the Winter months. Healthy adults require 1000iu Vit D3 (cholecalciferol) daily.


Here are some foods sources of vitamin D:

· Swordfish

· Rainbow trout

· Salmon

· Cod liver oil

· Snapper

· Egg yolk

· Tuna

· Mushrooms


Vitamin D fortified products:

· Cow’s milk

· Plant based milk substitutes

· Margarine

· Infant formula

· Formulated liquid diets/foods for use on a very low energy diet/meal replacements

· (Fortification of these products are mandated in Canada, fortification is voluntary for butter substitutes, condensed milk and goat’s milk)


In my Practice I generally prescribe 1000 iu VitD/day for healthy adults, 600iu daily for children. Some of my patients with osteoporosis, kidney or liver problems, or leaky-gut syndrome (malabsorption) needs much higher doses. At higher doses we monitor levels with blood testing, as vitamin D can become toxic in excess. It is very rare to get toxic levels of vitamin D, and unlikely to happen when staying within recommended guidelines. As always check in with your doctor before you decide to try vitamin D in supplement form.




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