bone health

by Alison Shepherd Registered Nutritionist & Nurse Tutor

Alison Shepherd is a Nurse Tutor at Florence Nightingale School of Nursing and Midwifery, Kings College University London. She is a Registered Nutritionist lecturing in nutrition and adult nursing with specialist interest in childhood obesity and clinical nutrition.

The role of nutrition in bone health through the lifespan

Part 2:

Bone health in later childhood and adolescence

Maximising bone strength in later childhood and adolescence is deemed to be critical for future adult bone health (15). The most rapid growth spurt after infancy is the pubertal growth spurt and research suggests that 37 percent of peak bone mass (PBM) is ac- crued during this time. Studies have shown that one fourth of bone mass is accrued between the ages of 12-14 year in girls and 13-15 years in boys (41). Lanham- New (42) also proposes that ap- proximately 90 percent of PBM is determined by around the age of 18 years for girls and in boys at aged 20 when the growth spurt has normally ended.

Suboptimal intake of nutrients dur- ing late childhood and adolescence can contribute to poor bone accre- tion (35). Therefore, it is crucial to en- sure that children develop a healthy lifestyle to maximise their chances of good bone health later on in adult- hood (3).

Factors influencing bone health in children and adolescents. (Adapted from 1 & 3)

Achieving adequate dietary calcium and vitamin D (43)

Weight bearing physical activity for 20 minutes two to three times per week

Maintaining a healthy body weight

Avoidance of smoking and excess alcohol consumption

Recent research from the Scien- tific Advisory Committee on Nutrition

14

(SACN) (44) has identified that the current dietary patterns in children and adolescents is a cause for concern. National data shows that children typically have diets high in energy dense foods, saturated fat and sugar (non-milk extrinsic sug- ars), and low in fibre and fresh fruit and vegetables (45). A diet high in energy dense foods can lead to obesity (1) and recent statistics show that obesity in children is on the rise (44) with three in 10 young people aged between two to 15 years who are classified as overweight or obese (46). This excess adiposity has been shown to lead to less bone accrual in preschool children (47). Further- more, a diet low in fruit and veg- etables can adversely affect bone health (48) as fruit and vegetable consumption has been shown to balance the excess acidity in the Western diet which can be detri- mental to bone health, particularly in the later adult years (49). Calcium and Vitamin D are two of the most important single nutrients that are attributed to maximising bone health (43). Data from SACN (2008) has identified that 12 percent of children aged between 11-18 years have low biochemical vitamin D status, with a higher prevalence of low vitamin D status in the UK adoles- cent population in the winter months (51). Most of the vitamin D intake in the UK is synthesised by the skin from absorption of sunlight, mainly during the summer months and very few foods actually contain vitamin D (3). Overt vitamin D deficiency will result in osteomalacia and can also affect general health (35). To date there

are no recommendations to set RNIs for the intake of vitamin D in the UK (1).

Adolescents do have a need for higher dietary calcium to sustain bone growth when compared to adults and furthermore, the ado- lescent skeleton is more responsive to calcium and protein before the onset of puberty (35). However, 22 percent of adolescent girls and 11 percent of adolescent boys have a significantly low calcium intake (50). Milk is high in calcium and other general growth promoting factors. A recent study (52) suggests that car- bonated drinks are thought to dis- place milk consumption during ado- lescence and therefore may have a negative effect on bone health. Indeed, Mc Devitt and Ahmed (35) suggest that a diet which is low in milk and high in carbonated drink consumption are independent risk factors for fracture in adolescence. Whilst the examination of these single nutrients is important, Chan et al (53) suggest that it is vital to con- sider the importance of whole diet quality when making recommenda- tions with regards to nutrition and bone health.

Exercise in adolescence

The Department of Health (54) suggests that children should par- take in at least 60 minutes of physi- cal activity per day as physical ac- tivity is particularly beneficial in bone development in adolescent boys (55). Brook-Wavell & Stensel (56) sug- gest that these targets are not being met, particularly by adolescent girls, which is also a cause for concern

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