Vitamin D, Calcium and osteoporosis prevention

Dr Merlin Thomas

Merlin Thomas is a physician and a scientist. His research laboratory is at the JDRF/ Danielle Alberti Memorial Centre for the study of Diabetes Complications at the Baker IDI Heart and Diabetes Institute in Melbourne.
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Bone density testing and aging bones

It is recommended that everyone over the age of 65 have bone density measures performed to see how they are tracking. Even earlier tests may be warranted for those women with an increased risk of fracture, such as those with a small build, a family history of fractures, those with diabetes, steroid users and those who experienced premature menopause.

It may seem ages away, but small (slow) changes to make stronger bones today can make a big difference as to whether, or if, we develop osteoporosis. There a number of things we can do in our adult life to keep our bones stronger for longer.

Weight-bearing activities, such as walking, running and jumping, and strength-training exercises can reduce our risk of fracture in a number of ways. Exercise builds muscle strength and improves our coordination, which can reduce our risk of falling in the first place. Repeated pulling and pushing of muscle on bone also stimulates growth of stronger bone and slows bone thinning. By contrast, an inactive lifestyle means idle muscles and a faster rate of bone thinning.

Calcium to protect aging bones

Calcium is stored in enormous quantities in our bones. If calcium in our diet is insufficient to offset normal losses, bone is broken down to retrieve its stored calcium. Equally, if calcium intake is increased, bone re-absorption will slow and more calcium will be deposited as an insurance against hard times.  Dairy products are usually suggested as the major dietary source of calcium.  But calcium can also be obtained from low-fat sources, including seaweed, nuts, seeds, legumes and green leafy vegetables such as kale and okra.

Vitamin D to protect aging bones

Vitamin D is an important regulator of bone metabolism. The ability to get the most calcium from our diet is critically dependent on Vitamin D, so even if we consume lots of calcium in our diet or in supplements, they won’t work if our Vitamin D levels are low. Most Vitamin D is synthesized inside the body in an inactive form. This is transformed in the skin by ultraviolet light and subsequently by the liver, before being stored in the fat for later use. Getting our stores up in the warm light of summer is how we get through a dark winter.

With changes in Vitamin D synthesis and less outdoor activities, our stores of Vitamin D often decline as we age. In fact, even in the sunny states, over half of all retirees have Vitamin D levels sufficiently low to denote vitamin deficiency. When Vitamin D levels fall to this extent, re-absorption of bone is sped up, while formation of new bone is slowed. This accelerates bone thinning, weakens muscles and contributes to bony aches and pains.

Keeping our Vitamin D levels optimal as we get older can be simply achieved by regular, sensible sun exposure. Vitamin D is also widely available in fortified products, such as cereals, bread and milk. A number of Vitamin D supplements are also available over the counter to help maintain healthy levels. These include Vitamin D2 (from plants or yeast), which is less potent than Vitamin D3 (from animal sources), so it needs to be taken in three times higher doses to achieve the same effect (i.e. 10μg of Vitamin D3 is equivalent to 30μg of Vitamin D2). Vitamin D should always be taken in combination with calcium supplements or increased calcium intake for maximum effect.