Title: Nutritional Factors that Influence Peak Bone Mass

 

Key words: genetic factors, peak bone mass, PBM, osteoporosis, calcium, Vitamin D, rickets, phytates, obesity, teenage girls, anorexic, weight-reducing diet, hormonal imbalances, protein, salt, acidic ash, high fibre, oxalate, caffeine, alcohol, iron deficiency, social factors, smoking, vitamin C, vitamin K, bone matrix, zinc, magnesium, copper, exercise, low body weight, protein, chappatis, malnutrition, 

 

Date: Sept 2006

 

Category: The body

 

Nutrimed Module:

 

Type: Article

 

Author: Morgan, G.

What Nutritional Factors Influence Peak Bone Mass?

 

Although genetic factors account for some 80% of the peak bone mass (PBM), it has been estimated that as much as 50% of the osteoporotic burden of later life could be prevented by appropriate dietary measures taken before the PBM reached its peak in the 20ís or 30ís. This is largely in the form of adequate calcium and vitamin D intake (Heaney 1966). As the incidence of osteoporosis is increasing with increasing age of the population and other factors this is obviously a great cause of concern.

 

Though rickets, the major nutritional bone disease of childhood, still occurs in the Asian immigrant community in this country due to vitamin D deficiency and a high phytate diet (Stephens et al. 1982), the major cause of concern relates to the white Caucasian population of a later age group as this age group is more at risk than the Asian or Afro-Caribbean population. 25% of the PBM is acquired during the teenage years and girls are particularly at risk at this time in the UK due to the following factors.

 

1) Although obesity is protective against osteoporosis there is a

significant subpopulation (30% according to a survey by Shepherd  and Dennison 1966) amongst teenage girls who are on a weight-reducing diet. The combination of low body weight and poor    nutritional intake of calcium and other nutrients would lead to a lowering of PBM. Particularly at risk are anorexic patients who are predisposed to food fads and are likely to have hormonal imbalances favouring the development of osteoporosis?

 

2) A diet high in protein, salt and acidic ash producing foods causes an increase of calcium in the urine and a negative calcium balance, all important factors in this group (Heaney 1966). Other subgroups may be taking a high-fibre, -phytate or -oxalate diet, all of which impede the absorption of calcium.

 

 

3) Caffeine and alcohol consumption may be high. Both affect bone metabolism.

 

 

4) Iron deficiency, common in this group due to dietary factors and high rate of teenage pregnancy, indirectly affects the PBM by producing weakness and lack of exercise. Social factors also militate against an active and healthy lifestyle in this group. Conversely iron therapy for the treatment of these problems counteracts the absorption of calcium and may compound the problem.

 

 

5) Smoking, an increasing problem, impacts on bone metabolism,    possibly by affecting the local circulation.

 

Other factors such as vitamin C, vitamin K, zinc, magnesium and copper are known to be essential in the process of normal bone metabolism. Protein forms the bone matrix and accounts for some 40% of bone mass. Though not seen frequently in this country, all of these factors come into play in malnutrition and would impact on the eventual PBM of the growing skeleton a susceptible population. Low body weight, lack of exercise and the female sex are the main additional factors involved in the problem though some of these may be related to dietary and social factors.

 

The consumption of chappatis, a common staple diet in Indian communities, which are rich in calcium-binding phytates, is a good example of a dietary custom which might impinge on the metabolism of young growing bone and affect the PBM. In developed countries an adequate intake of calcium continues to be the single most important factor in bone growth and many studies have shown the benefits of supplementation in compromised groups.

 

 

 

References

1.  Lodge JK  (2001)  Lecture Notes.  Surrey University

2.  Golden BE  (2000)  In: Human Nutrition and Dietetics, 10th edn. London

3.  Stephens WP, et al.  (1982)  Observations on the natural history of vitamin D deficiency amongst Asian immigrants.  Quarterly J Med

51: 171-88

4.  Shepherd R, Dennison CM  (1996)  Influences on adolescent food choice.  Proc Nutr Soc  55: 345-57

5.  Heaney RP  (1996)  Bone mass, nutrition and other lifestyle factors.  Nutrition Reviews  54 (April) 11: S3-S10