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Nutrition and Osteoporosis
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Prepared for World Osteoporosis Day 2006
Year of Bone nutrition - "Bone Appétit"
NUTRITION
AND OSTEOPOROSIS
WHAT IS OSTEOPOROSIS?
Osteoporosis is a disease in which the density and quality of bone are
reduced, leading to weakness of the skeleton and increased risk of fracture,
particularly of the spine, hip and wrist. Osteoporosis is a global public
health problem which currently affects approximately one in three women
and one in five men, and is increasing in significance as the population
of the world both grows in size and is living longer (1, 2, 3). Bone loss
doesn’t have any symptoms, and often the first sign of having osteoporosis
is a fracture. For all these reasons, osteoporosis is often referred to
as the "silent epidemic".
Although genetic factors largely determine whether an individual is at
heightened risk of osteoporosis, lifestyle factors such as good nutrition
and exercise play a key role in building bone during youth, and helping
to slow down bone loss in adults and the elderly. The importance of these
‘lifestyle’ factors is that they are amenable to modification
– individuals can take positive steps to strengthen their bones
and reduce their risk of osteoporosis.
NUTRITION AND BONE HEALTH
Like any organ in the body, the skeleton needs a balanced diet containing
both macronutrients (energy, protein, fat and carbohydrate) and micronutrients
(vitamins and minerals) for its normal development and maintenance. However,
in generally well nourished individuals, the two key nutrients to consider
for bone health are the mineral calcium, and vitamin D. Calcium is a major
structural component of bone tissue, and the skeleton also acts as a reservoir
of calcium for maintaining calcium levels in the blood. Recommended
daily calcium intakes for populations vary between countries. The FAO/WHO
(2002) recommendations, based on data from several countries, are as follows:
500-700 mg/day during childhood, 1300 mg/day from age 10-18 years, 1000
mg/day from age 19-65 years (1300 mg/day in women postmenopause), and
1300 mg/day from age 65 years onwards (4). Milk and other dairy foods
are among the richest and most readily available sources of calcium in
the diet. Two or three servings of dairy foods a day (e.g. a
serving would be a glass of milk, a slice of cheese, or a pot of yoghurt)
would ensure that virtually all children and adults would achieve this
level of calcium intake. Dairy foods have the additional advantage of
being good sources of protein and other micronutrients (besides calcium)
that are important for bone and general health. Other food sources of
calcium include certain green vegetables (e.g. broccoli, curly kale, bok
choy): whole canned fish with bones such as sardines or pilchards; nuts
(almonds and Brazil nuts in particular); and tofu set
with calcium. Calcium-fortified foods and drinks, including breads, cereals,
orange juice and soy beverages are also available in some countries. Vitamin
D is also essential for the development and maintenance of bone, both
for its role in assisting calcium absorption from the gut, and for ensuring
the correct renewal and mineralization of bone tissue. Vitamin D is synthesized
in the skin when it is exposed to sunlight, and although this is usually
sufficient for most individuals, dietary or supplemental vitamin D becomes
especially important during the winter months for populations in northern
latitudes, and for elderly people who do not go outdoors much and in whom
the capacity for skin synthesis of vitamin D is reduced. Vitamin D deficiency
in older adults can increase the risk for osteoporosis, falls and fractures.
Food sources of vitamin D include oily fish such as salmon, sardines and
mackerel, and in some countries fortified foods such as margarine, dairy
foods and cereals.
Table: Approximate calcium levels in foods
Food / Serving size / Calcium (mg)
Milk, semi-skimmed 236 ml / 8 fl oz 283
Yoghurt (low-fat fruit) 150 gm / 5 oz 210
Cheese, cheddar- type 28 gm / 1 oz 205
Cheese, cottage 112 gm / 4 oz 142
Cheese, mozzarella 28 gm / 1 oz 101
Ice cream, dairy, vanilla 112 gm / 4 oz 112
Tofu, soya bean, steamed 100 gm / 3.5 oz 510
Broccoli, cooked 112 gm / 4 oz 45
Curly kale, cooked 112 gm / 4 oz 168
Almonds 26 gm / 12 almonds 62
Sardines, canned in oil, drained, whole 100 gm / 4 sardines 500
Bread, white, sliced 30 gm / 1 medium slice 53
Reference:
Food Standards Agency (2002) McCance and Widdowson’s.
The Composition of Foods, Sixth summary edition.
Cambridge: Royal Society of Chemistry
RESEARCH STUDIES INVESTIGATING THE EFFECTS OF CALCIUM, VITAMIN
D AND DAIRY FOODS ON BONE MASS AND FRACTURE RISK
The importance of nutrition to bone health has been demonstrated in a
number of research studies, in human subjects across the age range. Studies
carried out over one to three years in children and adolescents have shown
that supplementation with either calcium, dairy calciumenriched foods,
liquid milk, or a calcium-enriched milk powder enhances the rate of bone
mineral acquisition, compared with un-supplemented (or placebo) control
groups (5-8). In general, these intervention trials increased the habitual
calcium intake of the supplemented children from about 600-800 mg/day,
to around 1000-1300 mg/day. Although these studies were short term, if
the higher calcium intakes were maintained into the third decade (the
time of achievement of peak bone mass), such an increment could possibly
account for as much as a 5-10% difference in peak bone mass. At the population
level, it is estimated that a 10% increase in peak bone mass could reduce
the risk of osteoporotic fractures during adult life by 50% (9). In studies
among adults, one three-year study in healthy young women aged 30-42 years
showed that enriching the diet with dairy foods prevented bone loss in
the spine, compared with control subjects who did not increase their dietary
calcium intake (10). In postmenopausal women and the elderly, several
studies have shown that calcium or milk supplementation slows the rate
of bone loss (11-18). In a study carried out in healthy, elderly women
living in nursing homes, calcium (1200 mg/day) and vitamin D (800 IU/day)
supplementation over 18 months reduced the risk of hip fractures and other
non-vertebral fractures (13). A similar intervention over three years
(500 mg/day calcium, 700 IU/day vitamin D) was shown to reduce bone loss
and the incidence of non-vertebral fractures in elderly men and women
living at home (12). In comparative intervention studies, dairy food supplements
and calcium supplements were equally effective in preserving hip bone
mass in postmenopausal women (15, 16), although these studies were not
designed to evaluate reductions in fracture rates.
In summary, adequate calcium intake is an important component of maintaining
bone health, and should be encouraged in all age groups. Dairy foods provide
the richest dietary sources of calcium, and also improve the nutrient
density of the diet in other respects (19, 20). However, the typical recommended
calcium intake of 1300 mg/day for older adults may be difficult to achieve
through the diet, particularly in the frail elderly who may have reduced
appetite, or medical conditions. Supplementation might therefore be required
where dietary intake is inadequate. In addition, in patients diagnosed
with osteoporosis and receiving a drug treatment, calcium and vitamin
D supplements are also usually prescribed, to ensure adequate intakes
and also maximum effectiveness of the drug therapy.
SELECTED FACTS ON NUTRITION AND OSTEOPOROSIS FROM THE LITERATURE
• Studies over one to three years in children and adolescents have
shown that supplementation with calcium, dairy calcium-enriched foods,
milk or a calcium-enriched milk powder, enhances the rate of bone mineral
acquisition (5-8).
• Adequate levels of calcium intake can maximize the positive effect
of physical activity on bone health during the growth period of children
(21).
• Calcium supplementation has been shown to have a positive effect
on bone mineral density
in postmenopausal women (11).
• Calcium and vitamin D supplementation reduces rates of bone loss
and also fracture
rates in older male and female adults, and the elderly (12-14). In institutionalized
elderly women,
this combined supplementation reduced hip fracture rates (13).
• A three-year study in healthy young women aged 30-42 years showed
that enriching the diet with dairy foods prevented bone loss in the spine,
compared with control subjects who did not increase their dietary calcium
intake (10).
• In comparative intervention studies, dairy food supplements and
calcium supplements were equally effective in preserving hip bone mass
in postmenopausal women (15, 16).
• Supplementation with both vitamin D and calcium, compared with
calcium alone, reduced body sway in elderly women, suggesting that correction
of vitamin D deficiency may improve neuromuscular function and reduce
the propensity to fall (22).
• Supplementing the diets of postmenopausal women with milk powder
improved the nutrient density of their diets compared with calcium-supplemented
women (19), and supplementing the diets of elderly healthy men andwomen
(with habitually low dairy intakes) with liquid milk improved parameters
of skeletal metabolism (23).
• In a study in elderly men and women, higher dietary protein intake
was associated with a lower rate of age-related bone loss (24).
• Poor nutritional status, especially with respect to protein intake,
is an important risk factor for hip fracture, and can also contribute
to poor recovery. In the NHANES I Study, hip fracture rates were higher
in women with low energy (calorie) intake, low body weight, low serum
albumin levels and indices of low muscle strength (25).
• Randomized, clinical trials in patients with hip fracture have
demonstrated the beneficial effects of giving protein supplements on the
clinical outcome following acute orthopedic management. Protein supplementation
resulted in fewer deaths, shorter hospital stays, and a greater likelihood
of return to independent living (26-28).
• Dairy foods, calcium-set tofu, some green vegetables, and small
canned fish with soft bones (e.g. sardines) provide the most readily-available
sources of dietary calcium. Although some plant foods also contain appreciable
amounts of calcium, some contain substances that substantially lower the
calcium bioavailability, e.g. oxalates in spinach and rhubarb, and phytates
in dried beans. Good plant sources of calcium, which are low in such substances,
include broccoli, kale and bok choy (29).
REFERENCES:
1. Melton LJ, 3rd, Atkinson EJ, O'Connor MK, et al. (1998) Bone density
and fracture risk in men. J Bone Miner Res 13:1915-23.
2. Melton LJ, 3rd, Chrischilles EA, Cooper C, et al. (1992) Perspective.
How many women have osteoporosis? J Bone Miner Res 7:1005-10.
3. Kanis JA, Johnell O, Oden A, et al. (2000) Long-term risk of osteoporotic
fracture in Malmo. Osteoporos Int 11:669-74.
4. FAO/WHO. (2002) Human Vitamin and Mineral Requirements.
5. Johnston CC Jr, Miller JZ, Slemenda CW, et al. (1992) Calcium supplementation
and increases in bone mineral density in children. N Engl J Med 327:82-87.
6. Bonjour JP, Carrie AL, Ferrari S, et al (1997) Calciumenriched foods
and bone mass growth in prepubertal girls: a randomized, double-blind,
placebo-controlled trial. J Clin Invest 99:1287-94.
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on bone accretion in Chinese children. Osteoporos Int 15:654-58.
9. Bonjour P. (2001) Invest in Your Bones: How diet, lifestyles and genetics
affect bone development in young people. International Osteoporosis Foundation.
10. Baran D, Sorensen A, Grimes J, et al. (1990) Dietary modification
with dairy products for preventing vertebral bone loss in premenopausal
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for postmenopausal osteoporosis. VII. Meta-analysis of calcium supplementation
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12. Dawson-Hughes B, Harris SS, Krall EA and Dallal GE (1997) Effect of
calcium and vitamin D supplementation on bone density in men and women
65 years of age or older. N Engl J Med 337:670-76.
13. Chapuy MC, Arlot ME, Duboeuf F, et al. (1992) Vitamin D3 and calcium
to prevent hip fractures in the elderly women. N Engl J Med 327:1637-42.
14. Chapuy MC, Pamphile R, Paris E, et al. (2002) Combined calcium and
vitamin D3 supplementation in elderly women: Confirmation of reversal
of secondary hyperparathyroidism and hip fracture risk. The Decalyos II
study. Osteoporos Int 13:257-64.
15. Prince R, Devine A, Dick I, et al. (1995) The effects of calcium supplementation
(milk powder or tablets) and exercise on bone density in postmenopausal
women. J Bone Miner Res 10:1068-75.
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prevents seasonal bone loss and changes in biochemical markers of bone
turnover in elderly New England women: a randomized placebo-controlled
trial. J Clin Endocrinol Metab 83:3817-25.
17. Lau EM, Lynn H, Chan YH, et al. (2002) Milk supplementation prevents
bone loss in postmenopausal Chinese women over 3 years. Bone 31:536-40.
18. Lau EM, Woo J, Lam V, et al. (2001) Milk supplementation of the diet
of postmenopausal Chinese women on a low calcium intake retards bone loss.
J Bone Miner Res 16:1704-09.
19. Devine A, Prince RL, Bell R. (1996) Nutritional effect of calcium
supplementation by skim milk powder or calcium tablets on total nutrient
intake in postmenopausal women. Am J Clin Nutr 64:731-37.
20. Barr SI, McCarron DA, Heaney RP, et al. (2000) Effects of increased
consumption of fluid milk on energy and nutrient intake, body weight,
and cardiovascular risk factors in healthy older adults. J Am Diet Assoc
100:810-17.
21. Specker B and Binkley T (2003) Randomized trial of physical activity
and calcium supplementation on bone mineral content in 3- to 5-year-old
children. J Bone Miner Res 18:885-92.
22. Pfeifer M, Begerow B, Minne HW, et al. (2000) Effects of a short-term
calcium and vitamin D supplementation on body sway and secondary hyperparathyroidism
in elderly women. J Bone Miner Res 15:1113-18.
23. Heaney RP, McCarron DA, Dawson-Hughes B, et al. (1999) Dietary changes
favorably affect bone remodeling in older adults. J Am Diet Assoc 99:1228-33.
24. Hannan MT, Tucker KL, Dawson-Hughes B, et al. (2000) Effect of dietary
protein on bone loss in elderly men and women: The Framingham Osteoporosis
Study. J Bone Miner Res 15:2504-12.
25. Huang Z, Himes JH, McGovern PG (1996) Nutrition and subsequent hip
fracture risk among a national cohort of white women. Am J Epidemiol 144:124-34.
26. Schurch MA, Rizzoli R, Slosman D, et al. (1998). Protein supplements
increase serum insulin-like growth factor-I levels and attenuate proximal
femur bone loss in patients with recent hip fracture. A randomized, double-blind,
placebo-controlled trial. Ann Intern Med 128:801-09.
27. Delmi M, Rapin CH, Bengoa JM, et al. (1990) Dietary supplementation
in elderly patients with fractured neck of the femur. Lancet 335:1013-16.
28. Tkatch L, Rapin CH, Rizzoli R, et al. (1992) Benefits of oral protein
supplementation in elderly patients with fracture of the proximal femur.
J Am Coll Nutr 11:519-25.
29. Weaver CM, Proulx WR, Heaney R (1999) Choices for achieving adequate
calcium with a vegetarian diet. Am J Clin Nutr 70 (Suppl):543S-48S.
The National Osteoporosis Foundation of South Africa wishes to thank the
International Osteoporosis Foundation for preparing this report for World
Osteoporosis Day 2006
Published on 2006-10-05