Research Topic: Calcium and Vitamin D Supplements for Bone Health

Should Dietitians Be Recommending Calcium and Vitamin D Supplements to Optimise Bone Health?

It is well established that calcium is one of the fundamental minerals making up the bone matrix. Thus, it is important we are ensuring that our clients are consuming adequate dietary calcium to counteract natural calcium losses and bone turnover. If this balancing act between intake and losses is not maintained, our client’s bone health may suffer in consequence of maintaining calcium homeostasis. To address any deficits from oral intake, recommending clients supplement with calcium and vitamin D has been shown to be advantageous in supporting bone health and reducing the onset of fractures. 

Factors Which Contribute to Bone Mineral Density

60-80% of an individual’s ability to achieve peak Bone Mineral Density (BMD) is determined by genetics. Controllable factors such as diet, exercise, and lifestyle (including smoking status and alcohol intake) have a 20-40% contribution to the outcome. This provides a great opportunity for dietitians to advocate for seeing clients during their developing years to help them achieve an optimal peak BMD by age 25 for women and 30 for men. Studies have shown that when peak BMD is not achieved by this age, the likelihood of osteoporosis later in life is much greater.

How Can We Help Our Clients Optimise Their Absorption of Calcium?

Whilst the absorption rate for calcium is reported to be 30%, it can be increased if calcium is consumed in the absence of oxalic acid and phytic acid-containing food. High levels of these acids are widely seen in various healthy food items which would typically make up a balanced diet.

Foods with high levels of oxalic acid include:

  • Spinach and other green leafy vegetables, which are also sources of calcium
  • Sweet Potato
  • Rhubarb
  • Beans

Foods with high levels of phytic acid include:

  • Wheat Bran
  • Beans
  • Nuts and Seeds
  • Soy Isolates

Where possible, dietitians should be devising meal plans which avoid the combination of these above foods with rich calcium sources to optimise the absorption capacity. If dietary modification alone cannot meet the recommended nutritional targets, supplements are extremely valuable to address this deficit to ensure an ongoing and adequate supply of calcium and vitamin D are achieved. The dietitian’s decision to recommend supplements should be considered on a case by case basis. If supplements are necessary to offset dietary inadequacies, dietitians should be prioritising calcium citrate over calcium carbonate due to the superior 24% greater absorption capacity.

Evidence on The Efficacy of Supplementation for Bone Health

In a literature review by Van der Velde and colleagues, they summarised that elderly women were able to reduce their incidence of fractures by 30% when taking a combined daily supplement of calcium (500-1000mg/day) and vitamin D (250-1200 IU/day). A larger study which included 65-85-year-old male and female participants found similar positive outcomes when taking a combined calcium and vitamin D supplement over 5 years. It was concluded that this led to a 33% reduction in hip fractures. This illustrates that supplementation of calcium and vitamin D is a viable option which should be encouraged as required to promote bone health and reduce our client’s risk of developing osteoporosis and fractures in the future.

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