I practice what I call “Functional Medicine” where the physician tries to determine and improve optimal function before pathology develops. This also requires that modalities used are prescribed in “just right” dosages. So like Goldilocks found the “just right” porridge, functional medical practitioners determine “just right” dosages for natural remedies.

Sue, age 56, came into the office boasting about the fact that she had been taking cod liver oil for several years now and probably getting enough vitamin D3 the active form of vitamin D, but she wasn’t sure. Her bone density scan results had improved over the years after taking the cod liver oil, among other therapies, but now that Vitamin D is hot in the news she wanted to make sure she was getting enough.

Almost every week lately, there are more news reports that most Canadians are probably not getting enough vitamin D due to the northern latitude and the lack of sunlight. Vitamin D is important in the prevention of many cancers including breast, pancreatic and prostate. It is important for preventing diabetes type II, treating and preventing depression (it modulates serotonin production), for the treatment and prevention of all anti-inflammatory diseases including cardiovascular disease, Alzheimer’s Disease, fibromyalgia’s and arthritis and of course for the treatment and prevention of osteoporosis.

I explained to Sue that her blood levels of vitamin D would be lowest in late winter ie February or March and highest in late summer around September. Optimally it would be good to measure it twice in one year to find out her body’s range and thus the optimal dosage required for her year round. The type of vitamin D measured in the blood is the 25(OH) vitamin D, not the 1,25 (OH) vitamin D. The optimal suggestion based on research from Dr. Holick M.D. author of “The UV Advantage” indicates that 120nmol/L is optimal not 20-50. The units are different in the United States so if you are reading American research a conversion needs to be made.

There are two forms of vitamin D provided in supplements: Vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). The vitamin D3 form is better absorbed in humans than the vitamin D2 form. Up until recently the dosage thought to prevent deficiency was 400IU’s per day. The American Journal of Clinical Nutrition published an article in 2001 indicating that the adult dosage of 1000IU’s of D3 per day may also be too low. For vitamin D to have its far reaching effects many researchers are stating that dosages twice or four times that amount may be required.

When we do Sue’s blood work we also keep an eye on her serum calcium as vitamin D can cause an excess of calcium if dosages are too high but this is rarely seen in clinical practice. Sue asked about kidney stones and vitamin D and I said to her that the research that concluded this statement used vitamin D and calcium carbonate in the research. Knowing that calcium carbonate is a poorly absorbed form of calcium, the conclusion is that it may have been the calcium carbonate causing the kidney stones and not the vitamin D. Toxicity of vitamin D is rarely found in his 30 year old clinical practice according to Dr.Jonathon Wright, MD author of Nutrition and Healing newsletter. Dr. Holick explains that winter sunlight in countries, such as Canada , is too slanted to provide vitamin D activation of the skin and that sunscreen also blocks the activation of vitamin D on the skin. Unprotected skin exposure to summer sun rays for 15 minutes during the middle of the day to receive a faint pink tinge will provide 10,000 IU’s of vitamin D proving that the body has a huge capacity to absorb and utilize vitamin D.

Sue’s 25(OH) in March was 80nmol/L and at the end of September was 110nmol/L indicating that the vitamin D she was getting in the summer was not providing the optimal range of 120nmol/L year round. She had been taking one tablespoon of Carlson’s Cod liver oil which provided 1200IU’s of vitamin D. Her mineral supplement also contained 1000IU’s. I suggested that during the summer when she did not get the pink tinge skin from the sun that she take an additional 1000IU’s vitamin D3 per day in the tablet form or take an extra tablespoon of cod liver oil that day and that she maintain this dosage through the non-summer months. Once she gets the pink tinge Sue should then protect herself from getting too much sun.

Now if Sue had been African-American I would have probably found her 25(OH) levels to be much lower as dark skin will not absorb vitamin D as readily so these people living in northern climates need to be especially careful to make sure they are getting enough. Is this why we see an increased risk of breast and prostate cancer in this population?