Don’t be Distracted, Vitamin D is Essential for Strong Bones, Muscles, and More
Osteoporosis, the result of accelerated bone loss, leads to brittle, weak bones which are susceptible to fracture. An estimated 8.2 million women over 55 years have osteoporosis in the US (Frost and Sullivan, 2013). According to the International Osteoporosis Foundation, osteoporosis causes more than 8.9 million fractures worldwide annually. The combined lifetime risk of hip, forearm and vertebral fractures is equivalent to the risk for cardiovascular disease. In the US, Frost and Sullivan estimate the total health care expenditure on managing and treating osteoporosis-attributed bone fractures among women over 55y at $14 billion per year.
Vitamin D is needed for calcium absorption and to maintain strong bones. Having adequate amounts of one but not the other will not maintain healthy bones. People who are deficient in one, or both, are at greater risk of osteoporosis.
The recent meta-analysis by Reid and associates on vitamin D and osteoporosis confirms the problems inherent in using a pharmacologic mentality that treats nutrients like drugs. The authors searched the literature for randomized, controlled trials (RCTs) conducted in adults comparing vitamin D2 or D3 against a placebo. The endpoint of interest was bone mineral density. Dietary nutrient intakes, physical activity, and sun exposure were not included in the analysis. In some studies, people had very low serum 25(OH)D status at baseline. 15 studies (65%) had mean baseline serum 25(OH)D concentrations defined as optimal (≥50 nmol/L) and several were >70nmol/L. Two studies used annual high-dose intramuscular injections; a strategy which would not yield stable year-long blood and tissue 25(OH)D levels. Finally, the meta-analysis evaluates only one health outcome – bone mineral density.
Nutrient-health relationships are complex. Nutrients are rarely consumed in isolation. As consumers, we adopt a myriad of lifestyle behaviors and genetic predispositions. Most importantly, nutrients are essential to the healthy functioning of many parts of our bodies. As MedLine Plus, a service of the US National Library of Medicine and NIH suggests in ‘What is it?’ (using much stronger language than this blog can use), vitamin D is important for the health of many organs and tissues – heart, blood vessels, muscles, joints, respiratory system, immune system, and skin.
In an accompanying editorial, Dr C Rosen emphasizes the importance of vitamin D stores to maintain healthy bones and prevent hip fractures. Few foods are good or excellent sources of vitamin D. It is important for physicians and other healthcare practitioners to embrace the advice of Duffy MacKay ND, vice president of scientific and regulatory affairs at the Council for Responsible Nutrition to continue to test vitamin D levels to accurately guide their patients.
Chao and colleagues examined plasma 25(OH)D levels in 2,714 volunteers with 4,224 blood draws and questionnaires on dietary supplement use. Age, summer season and high levels of physical activity were associated with statistically higher vitamin D levels. They report that 400 IU daily may be too little to see health benefits. 39% of the studies (n = 9) evaluated by Reid and colleagues were supplementing at 400 IU/d. Even 1000-2000 IU vitamin D once or twice per month was insufficient to raise plasma 25(OH)D levels. Using regression analyses, the authors show that vitamin D status is a reflection of three factors: dose, frequency and duration of supplementation.
Bottom line. Vitamin D is important for our health. Have your serum 25(OH)D levels checked. And remember, if you live in toward the poles of the earth and/or infrequently expose skin to direct sunlight, meeting vitamin D and calcium nutrient requirements is healthy advice.
Reid IR, Bolland MJ, Grey A. Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysis. 2013 Lancet doi:10.1016/S0140-6736(13)61647-5
Chao Y-S, Brunel L, Faris P, Veugelers PJ. The importance of dose, frequency and duration of vitamin D supplementation for plasma 25-hydroxyvitamin D. 2013 Nutrients doi:10.3390/nu5104067
Rose C. Vitamin D supplementation: bones of contention. 2013 Lancet doi:10.1016/S0140-6736(13)61721-3
Shanahan C, de Lorimer R. Smart Prevention – Health Care Cost Savings Resulting from the Targeted Use of Dietary Supplements. An Economic Case for Promoting Increased Intake of Key Dietary Supplements as a Means to Combat Unsustainable Health Care Cost Growth in the United States. Frost & Sullivan. 2013.