Author: Patrick O'Mara

Vitamin D supplementation has recently been evaluated in Switzerland in a small 1 year randomized clinical trial by Bischoff-Ferrari and colleagues. This study compared the effects of two “high” doses of vitamin D (60,000 IU of vitamin D3 per month or 24,000 IU vitamin D3 plus 300 mg of calcifediol per month) to a standard dose of 24000 IU per month (equivalent to 800 IU per day). The study did not include a control group receiving zero vitamin D supplementation. The study was completed in 200 men and women over the age of 70 yrs. The people enrolled in the study had at least 1 fall before entering the study.

High dose vitamin D did not result in improvements in strength in the lower limbs. In fact there were actually more falls in the high dose vitamin D groups in comparison to the standard dose 24,000 IU Vitamin D monthly. Therefore, increasing vitamin D intake above standard recommended intake levels provided no benefit with respect to muscle strength, and was actually associated with an increased risk of falling.

Although vitamin D is present in a few food groups, including fatty fish, eggs and D fortified milk and cereal, it is difficult to meet daily requirements with diet alone. Vitamin D in doses of 800-1000 IU daily will prevent vitamin D deficiency in most people.

Osteoporosis Canada recommends routine vitamin D supplementation for all Canadian adults year round. Healthy adults between19-50 years of age, including pregnant or breast feeding women, require 400 – 1,000 IU daily. Those over 50 or those younger adults at high risk (with osteoporosis, multiple fractures, or conditions affecting vitamin D absorption) should receive 800 – 2,000 IU daily.

Osteoporosis Canada advises Canadians to discuss their vitamin D requirements with their physician.

Osteoporosis Canada continues to advise Canadians to meet the Institute of Medicine established daily calcium requirement of 1000 -1200 mg, from dietary sources preferably, and to use supplements if this is not possible (in the form of calcium carbonate or calcium citrate). Every cell in our body requires calcium in order to function normally and inadequate calcium intake results in the release of calcium from the skeleton in order to meet daily requirements.

On the 29 of September 2015,Tai and colleagues published an article in the BMJ summarizing the careful assessment of 59 studies collectively evaluating the effects of calcium intake on bone mineral density in people over the age of 50 years . Small increases in bone mineral density (BMD) were noted with extra dietary calcium intake by 0.6 -1.8% over 1-2 years. Calcium supplements also were associated with increased BMD by 0.7-1.8%. Small decreases in total and spinal fractures were observed with calcium supplementation. The authors concluded that calcium intake from dietary sources and from supplements increase BMD similarly, however, the small effect on BMD is unlikely to reduce fractures.

Whether calcium could reduce fractures was explored in a second study by Bolland and colleagues, in the same issue of the BMJ. However, it did not demonstrate a significant reduction in fracture risk in the large randomized trials with calcium supplementation.

The studies which were evaluated did have significant variability with differences in the numbers of people evaluated as well as the quality of the assessments. In addition there were differences in how fractures were identified in the studies being evaluated.

Large well-designed controlled studies are required to determine the effects of calcium supplementation on skeletal health. There is no data supporting the use of calcium supplements alone as a treatment to prevent fracture in individuals with osteoporosis.

Individuals who have osteoporosis and are at increased risk for fractures may require medication, in addition to adequate calcium and vitamin D intake, in order to reduce their risk for fractures.

On Oct 28, 2014 a study on milk was published by Dr. Michaelsson of Uppsala University in Sweden. This study claims that high milk intake was associated with an increased rate of death.

In this study, over 61,000 women (ages 39-74) and over 45,000 men (ages 45-79) were followed for just over 11 years during which time they completed food questionnaires about their diet. After 20 years, it was observed that the death rate among the men and women appeared to be higher in those drinking three or more glasses of milk per day compared to those just drinking one glass per day. In addition, drinking more milk did not appear to reduce the risk of fractures (broken bones).

Although this study was published in The BMJ (originally called the British Medical Journal), its study design was not ideal for determining cause and effect between the high intake of milk and the increased risk of death. Other researchers have actually observed a lower rate of heart attacks in those with a diet rich in dietary sources of calcium. For example, in 2012 Li and colleagues evaluated a German cohort study of 23,980 people ages 35-64 who were followed over 11 years. This study found that a calcium enriched diet was associated with a lower rate of MI (heart attack) by 30%.

Clearly, further research is necessary before it can be concluded that a high intake of milk is harmful. In the meantime, Osteoporosis Canada still recommends that Canadians over age 50 consume 1200 mg of calcium daily through food and supplement, with food being the preferable source.

Strontium ranelate (Protelos) is a drug approved for the treatment of osteoporosis in Europe, but not in Canada. It is effective in reducing fractures . Recently the European Medicines Agency has completed their review regarding the safety of this drug and recommend that strontium ranelate not be taken by patients with heart or circulatory problems. Individuals who have had a heart attack, angina, stroke or uncontrolled blood pressure should not take this medicine and should discuss their osteoporosis therapy with their physician.

The safety of strontium citrate commonly available at health food stores in Canada has not been evaluated and its effects on fracture risk reduction are not known.

Osteoporosis Canada recommends that all patients with osteoporosis or at an increased risk of fracture discuss their treatment options with their physician.

In 15 of the studies the mean baseline vitamin D level was over 50 nmol/l which is higher than values seen in a significant number of Canadian men and women particularly during the winter months. In 1 study of adult Canadians who were not using vitamin D supplements, 34% had evidence of vitamin D insufficiency with vitamin D levels below 40 nmol/L.

The meta analysis completed by Reid and colleagues did not show an effect of vitamin D supplements on bone mineral density.

It is important to remember that vitamin D enables optimal calcium absorption from the bowel and inadequate vitamin D results in poor mineralization of the bone in addition to bone loss due to high levels of parathyroid hormone.

The majority of Canadians have inadequate vitamin D levels and do require approximately 400-2000 IU of vitamin D daily to reach a normal vitamin D level. Osteoporosis Canada’s guidelines for vitamin D are safe and are designed to prevent vitamin D deficiency, which is clearly harmful for bone health.

In those with osteoporosis it is necessary to take adequate calcium and vitamin D as well as drug therapy in order to significantly reduce fracture risk.