While vitamin D and calcium may get the lion’s share of the attention in the bone health segment – sales of calcium supplements totaled $1.2 billion in the US in 2009, while vitamin D sales came in at around $430 million, according to the Nutrition Business Journal – appreciation is growing for the role of other ingredients.
In the latest issue of Nutrition Reviews, Hala Ahmadieh and Asma Arabi from the American University of Beirut, Lebanon review the science and conclude that a range of nutrients are required:
“It is possible that nutrient patterns, and not individual foods or vitamins, are important in bone health, thus explaining some of the paradoxical results related to individual nutrients,” wrote Ahmadieh and Arabi.
“Indeed, all tissues need all nutrients, and bone should not be an exception. Therefore, well-balanced and adequate nutrition should be ensured in order to prevent adverse effects on bone health.”
According to the new review of the literature, the majority of studies concerning bone health have shown that “vitamin B complex and vitamins C, E, and K correlated positively with bone mineral density (BMD) at multiple skeletal sites and/or were associated with reduced risk of fracture, independent of BMD”.
The potential benefits of the B vitamins may be linked to their ability to reduce levels of homocysteine, an amino acid that, at elevated levels, has been linked to an increased risk of heart disease, cognitive decline and dementia, and osteoporosis.
The potential bone health benefits of vitamin C (ascorbic acid) are reportedly related to its role in the hydroxylation of lysine and proline, amino acids that are involved in formation of stable collagen structures and ultimately bone development.
Vitamin E may boost bone health via antioxidant mechanisms, said Ahmadieh and Arabi, with oxidative stress linked to the destruction of osteoblasts (cells responsible for bone formation). Oxidative stress is also linked to an increase in bone resorption linked to cells called osteoclasts.
Animal data has “confirmed” that vitamin E, and particularly the tocotrienol form of vitamin E, had anti-osteoporotic activities, they added.
Vitamin K has received a lot of attention for its bone health potential . Biological plausibility does exist for vitamin K, since osteocalcin is a vitamin K-dependent protein and it is essential for the body to use calcium in bone tissue. Without adequate vitamin K, the osteocalcin remains inactive, and this not effective.
While the majority of studies on the other vitamins support potential bone health benefits, the picture appears less clear cut for vitamin A, said the Beirut-based scientists. “Both excessive and insufficient intake of retinol may be associated with compromised bone health; however, data on vitamin A intake from dietary sources and from supplemental intake, as well as data on vitamin A status determined by serum retinol levels, showed inconsistent results”.
“The available data provide clear evidence that the effects of nutrition on bone health are not limited to those resulting from calcium and vitamin D intake. [Our] review highlights the importance of nutritional factors in preventing and reducing the risk of osteoporosis and fractures,” concluded Ahmadieh and Arabi.
According to Frost & Sullivan, the US bone and joint health market was estimated to be worth $178 million in 2008, and is predicted to be $246 million by 2015.
Source: Nutrition Reviews
October 2011, Volume 69, Issue 10, Pages 584–598, doi: 10.1111/j.1753-4887.2011.00372.x
"Vitamins and bone health: beyond calcium and vitamin D"
Authors: H. Ahmadieh, A. Arabi