The importance of Vitamin D in preventing osteoporosis

What is Vitamin D?

Vitamin D plays several vital roles. It helps absorb and maintain the amounts of calcium and phosphate in the body. These minerals are needed for strong bones and healthy teeth. In the introduction to my M.Phil thesis, I researched the factors that influenced bone formation and reported that “the build-up of bone during childhood and adolescence including genetic predisposition, diet, physical activity, body composition and smoking (Cooper, Westlake et al. 2006). Genetics factors have been reported to account for almost 80 per cent of the variance in peak bone mass (Davies, Evans et al. 2005; Bonjour, Chevalley et al. 2007). As far as diet is concerned, certain nutrition components have been extensively examined in the literature. Calcium and vitamin D have received particular attention and their associations with bone health in children and adolescents have been studied”.

Good sources of Vitamin D

Our skin is our vitamin D factory and it needs an adequate supply of sunlight in order to make vitamin D. Our diet is the second source of vitamin D which is present in:

• oily fish, such as salmon and sardines
• eggs
• fortified fat spreads
• fortified breakfast cereals
• powdered milk

The problem with vitamin D sources, oily fish excluded, is that they all come with additional risks. Cholesterol control is a risk with an egg-rich and fatty spread diets. Breakfast cereals are normally sugar loaded and contain considerable salt content.

Not enough Vitamin D and its consequences

In a BBC article, it was proposed that we do not have enough sunlight in this country. Hence our bodies fail to get the adequate dose needed to absorb Calcium and Phosphate which are crucial to building and maintaining healthier bones. Therefore, we could be exposing our children to higher risks in contracting Rickets and exposing our elderly (particularly women) to higher risks of Osteoporosis. In my M.Phil thesis I concluded that “Vitamin D deficiency has been reported as the cause of rickets among children and acts to exacerbate osteoporosis in later life (Holick 2004).”

What is Osteoporosis?

Osteoporosis is a medical complaint affecting the bones, whereby they become weak and breakable under strains normal bones can withstand. The most common fracture sites are the spine, wrist and hips. Other possible fracture sites are the arm or pelvis. It is vital to build bone strength at a younger age and I reported in my M.Phil. thesis that both nutrition and “impact” sports are crucial particularly in the bone formation years part of life.

The importance of bone formation

The following is published in my thesis and highlights the bone formation years and their connection on preventing Osteoporosis in later life:

“Childhood and adolescence is a particularly important period in bone formation as the skeleton undergoes accelerated growth with increasing annual deposits (also known as Bone mineral density accrual) that enhance the bone’s mineral density. The annual Bone mineral density accrual reach a peak in late adolescence (Bonjour, Chevalley et al. 2007). Bone mineral density accrual (growth per year) peaks at 12.54 years for girls and 14.05 years for boys. At these ages the maximum amount of bone mineral density is deposited per year. The annual deposits then decline until no further additions are made when girls reach approximately 17 years of age and boys reach approximately 18.5 years of age (Cooper, Westlake et al. 2006). These bone deposits act as a reserve that is depleted throughout life. The bigger the deposits the better the person is prepared for bone fracture prevention in later life. The bone mass of an individual in later life depends upon the peak attained during skeletal growth and the subsequent rate of bone loss (Cooper, Westlake et al. 2006). The rate of bone loss is stable throughout early to mid adulthood then bone is gradually eroded with age with an accelerated rate during the 3-6 years of menopause in women (Bonjour, Chevalley et al. 2007). The graph below shows BMD variation with age (Bhattacharya 2010). It shows that BMD values accelerate rapidly after birth and then start to slow down to a peak which occurs roughly around 20 years of age. A plateau is then maintained to the late 40s followed by a rapid decline.

Figure ‎1‑1 Variation of BMD with age

Bone loss in later years of life may lead to a condition known as Osteoporosis which is characterised by low bone mass and the deterioration of bone’s micro-architecture thus increasing the possibility of bone fracture (Jordan and Cooper 2002). Osteoporosis is a very common condition and is often undiagnosed in clinical practice leading to devastating health consequences with fractures in later life (Cooper, Westlake et al. 2006). In women, the occurrence of osteoporosis increases with age and has been reported to affect 2 percent at 50 years of age and over 25 percent at 80 years (Bayly, O’Neill et al. 2006).

The chief medical officer for England, Dame Sally Davies, recommended in January this year, that all pregnant and breastfeeding women, children aged six months to five-years-old and the over-65s should take vitamin D supplements. I quickly looked at Herbalife’s shake and the Multivitamin dose that I encourage my clients to take. As it turns out, they jointly provide almost 90% of Vitamin D’s RDA

and over 100% of Calcium’s and Phosphorous RDA.

Heba Al-Zuhair (M.Phil in Nutrition Physical Activity & Public Health)

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