Table of Contents
Osteoporosis, most commonly referred to as “thinning of the bones”, is a disease in which bone mineral density is reduced. This can cause the bones become brittle and fragile and easily fracture. Although there is no cure for osteoporosis, it can be prevented. Healthy diets, along with weight bearing exercise, are key factors in the prevention and treatment of osteoporosis. The focus of the osteoporosis diet is on optimising bone health at every stage in life and is based on a normal balanced diet with an emphasis on calcium rich foods and Vitamin D.
Osteoporosis is a worldwide health concern. 2007 figures (International Osteoporosis Federation (IOF) estimate it affects 75 million people in the United States (US), Europe and Japan and this is forecast to double in 50 years in line with increasing populations and increased life expectancy. In other parts of the world, such as Africa and Asia, the incidence is much lower, but according to the World Health Organisation (WHO), it is projected that the greatest increase in osteoporosis will take place in developing countries.Despite being one of the world's most common diseases, it is only now receiving international
FAO = Food and Agriculture Organization
WHO = World Health Organization
IU = International Unit
mcg = microgram
(Illustration by GGS Information Services/Thomson Gale.)
FAO = Food and Agriculture Organization
WHO = World Health Organization
mg = milligram
(Illustration by GGS Information Services/Thomson Gale.)
recognition. As recent as 30 years ago it was thought weak and broken bones was an unavoidable consequence of growing old.
In 1984 a Consensus Development Conference on Osteoporosis, held by the National Institute of Health (NIH) in the US, highlighted the need for more information on the prevention and treatment of osteoporosis. This led to the establishment of the National Osteoporosis Foundation (NOF) US in 1985, followed the United Kingdom (UK) National Osteoporosis Society (NOS) in 1986 both of which are now members of the much larger IOF, based in France, formed in 1998. In 2004, the first US Surgeon General’s Report on Bone Health & Osteoporosis listed vitamin D, calcium and exercise, as the three essential elements for optimal bone health. The importance of diet was further highlighted in 2006, by a report from the IOF “Bone Appetit:the role of food and nutrition in building and maintaining strong bones”, which shared its title with the theme of World Osteoporosis Day.
Calcium and osteoporosis
Research on recommended calcium intakes has focussed on either meeting requirements or on optimising bone density. Also calcium requirements for adults vary between geographic regions and cultures because of differing dietary, genetic and lifestyle factors, including physical activity and sun exposure. As such Calcium requirements vary from country to country.
In 1997, the American calcium guidelines were set significantly higher, than the previous recommendations set in 1989, following a 1994 National Institute of Health (NIH) conference on calcium intake. They recommended that calcium intakes in young people be increased to maximize peak bone mass and protect against osteoporosis. Calcium levels increased from 1,200 to 1,300 milligrams (mg) per day for adolescents and teens. Adults had an increase of 200mg to 1,000mg daily, while adults after 50 years were increased to 1,200 mg daily, 400 mg more than previously recommended.
In 2005, the United States Department of Agriculture (USDA) Dietary Guidelines for Americans increased the dairy serving for the first time from 2–3 a day to three a day (1 serving is approximately equal to 300 mg of calcium) since they were first published in 1980. This was to meet the higher recommended calcium intakes.
In contrast some other developed countries have lower recommended levels for example in the UK the 1998 recommended daily intakes are 550mg for children age 7 to 10, 800mg–1,000mg for age 15 to 18 ranges and 700–800mg for adults aged 19 to 50. The NOS also recommends 1200mg for those with osteoporosis. The UK Cambridge Bone Study, still on going in 2007, is determining whether young people aged 16 to 18 should increase calcium intakes to 1000 mg a day. In France for age 15 to 18, 1,200mg is recommended and in Nordic countries for boys the range is from 900mg.
Despite the higher recommendations surveys indicate that actual calcium intakes are often inadequate. According to the US National Health and Nutrition Examination Survey III (NHANES 1988–1994) all age groups, with the exception of young children, have an intake lower than the recommended level. The UK 2000 National Diet and Nutrition Survey (NDNS) of British young people aged 4 to 18, indicated only one in four girls is eating at least three portions of dairy products daily.
As a result of multiple factors influencing calcium requirements, in 2007 there is no single internationally accepted recommended calcium intake. In countries where osteoporosis is common, such as Western European, America and Canada and Japan, calcium intakes are based on the 2002 Food and Agriculture Organisation (FAO) and World Health Organization (WHO) recommendations.
Vitamin D and osteoporosis
and deposit it in the bone. A deficiency in Vitamin D can cause a softening of the bone. Rickets in children and osteomalacia in adults are examples of extreme vitamin D deficiency. Osteoporosis is an example of long-term low levels of vitamin D.
Similar to calcium, there are several factors that affect the required intake of Vitamin D, including exposure to sunlight and dietary intake. The Recommended Dietary Allowance (RDA) for adults was set in 1941 at 400 international units (IU) or 10 micro-gram (mcg) per day. This was the amount of vitamin D in a teaspoon of cod liver oil found to prevent rickets in infants. This RDA remained around this level until the National Academy of Sciences (NAS) released new guidelines in 1997. The new adequate intake (AI) was based on Vitamin D intakes required to achieve an optimal blood level of Vitamin D, 25-hydroxyvitamin D, in the absence of sun exposure.
Results suggested a level of at least 500 IU (12.5 mcg) from which an RDA could be set. As there is still no agreed definition of optimum 25-hydroxyvitamin D status, dietary Vitamin D recommendations vary from country to country.
Adequate intakes for vitamin D, in the US and Canada (2007), range from 200 IU (5 mcg) for 0 to 50 years, 400 IU (10 mcg) for 51 to 70 years and 600 IU (15 mcg) for over 70 years.
In the UK, Government’s Committee on Medical Aspects of Food Policy Panel on Dietary Reference Values says “No dietary intake (of Vitamin D) is necessary for adults living a normal lifestyle.” However, children up to the age of two years are recommended to receive a supplement containing 280 IU (7mcg) of vitamin D daily. Pregnant and lactating women and those age 65 and over are advised to take 400 IU (10 mcg).
As with calcium, evidence from surveys show that intake levels fall below the recommendations. In the USA, the NHANES (1999-2000), found a prevalence of vitamin D insufficiency in healthy adults living in Canada and the United States despite their Vitamin D food fortification programs. The UK NDNS (1998) of people aged 65 years and over found that approximately 98% had vitamin D intakes below the level. The same survey in 1990 of people aged 4 to 18 years also found a low vitamin D state in a significant proportion of those surveyed. In both sexes, this problem increased with age and thought linked to less time spent outside.
As of 2007, the IOF recommends the 2002 The Food and Agriculture Organisation (FAO) and the World Health Organisation (WHO) recommended Vitamin D intakes, which are based on Western European, American and Canadian data.
In addition to calcium and Vitamin D there is some evidence to suggest that other nutrients are beneficial to bone health such as magnesium, zinc, vitamins A, B, C, and K, however some of the evidence is weak and controversial as discussed below.
The osteoporosis diet focuses on maintaining or building strong bones throughout life. The emphasis is on Calcium and Vitamin D, but a balanced diet, with adequate protein and fresh fruits and vegetables and moderate intakes of alcohol, is also recommended. Other nutrients, which may promote or hinder bone health, are also included in this section.
Nutrients that promote bone health
CALCIUM. There are many foods that contain calcium, but not all are good sources because the calcium may not be well absorbed. Some non-dairy sources of calcium, such as cereals and pulses, contain compounds that bind to the calcium reducing its ability to be absorbed. For example, oxalates in spinach and rhubarb and phytates in pulses such as lentil, chickpeas and beans, and cereals and seeds. They do not however interfere with the absorption of calcium from other foods.
The most readily absorbed sources of dietary calcium include:
- Dairy products: These are rich sources of well-absorbed calcium and include foods such as milk, cheese, cream, yoghurt and fromage fraise. They are also a good source of other nutrients that that work together to help protect bone such as protein, Vitamin D, zinc and magnesium. Three servings of dairy foods daily is the recommendation. One serving is approximately 250ml milk, 200 g yoghurt and 40 g cheese, which provide 300mg calcium.
- Green leafy vegetables: These include broccoli, col-lard greens, mustard greens, kale and bok choy. Broccoli (85g) provides 34mg calcium
- Tinned fish: These need to fish with edible bones such as sardine, pilchards, and salmon. Tinned sardines (100g) provides 430mg calcium
- Nuts and seeds: Especially Brazil nuts and almonds. 6 almonds provides 31mg calcium
- Fruit: Especially oranges, apricots and dried figs. 1 orange provides 75mg calcium
- Tofu set with calcium: If it is prepared using calcium sulphate tofu (100g) contains 200-330mg calcium.
Some foods and drinks are fortified with calcium such as breads, cereals, orange juice and Soya milk (Soya milk doesn’t naturally contain calcium). These products should be specifically labeled as such.
VITAMIN D. It is made in the body by the action of the sun on the skin and a fifteen-minute walk each day usually provides all the vitamin D the body needs. Vitamin D is also fat-soluble vitamin found mainly in foods of animal origin.
Dietary sources of Vitamin D include:
- Oily fish: Salmon, tuna, mackerel, and sardines. Tinned sardine (100g) provides 260 IU Vitamin D
- Liver: Cooked liver (100g) provides 17 IU Vitamin D
- Egg yolk: 1 whole egg provides 20 IU Vitamin D
- Fish oil: 1 tablespoon provides 1360 IU Vitamin
In some countries vitamin D is added to breakfast cereals, grain products and pastas, milk, milk products, margarine, and infant formula. In the US milk has been fortified since the 1930’s, which almost eliminated rickets. In 2003 the Food and Drug Administration (FDA) approved the fortification of calcium-fortified juice and juice drinks. Canada has mandatory fortification of milk and margarine. In the UK, all margarine is fortified with vitamin D and it is added voluntarily to other fat spreads and some breakfast cereals. In Australia, margarine and some milk products are fortified. Finland introduced fortification of milk and margarines in 2003, while other European countries do not allow for any food fortification.
PROTEIN. During growth, low protein intakes can impair bone development increasing the risk for osteoporosis later in life. Protein is also important for maintaining muscle mass and strength. This is particularly important for the elderly to help prevent falls and fractures.
Protein sources include lean red meat, poultry, eggs, fish and diary as well as legumes (lentils, kidney beans), tofu, soymilk, vegetables, nuts, seeds and grains. There has been some conflict regarding the effect of animal versus vegetable protein on bone health. This will be discussed in the research and acceptance section.
FRUIT AND VEGETABLES. The Framington Heart Study (1948–1992) showed that lifelong dietary intakes of fruit and vegetables have beneficial effects on bone mineral density in elderly men and women. A 2006 British study also suggests that fruit and vegetable intakes may have positive effects on bone mineral in adolescents as well as older women. As of 2007, the nutrients, which are thought to improve bone mineral density, are still to be determined. It may be due to their alkaline nature, which neutralizes acids of digestion without using the buffering effects of calcium, or to their vitamin C, beta-carotene, vitamin K, magnesium or potassium content. As such the recommendations are to aim for at least five portions of fruit and vegetable a day.
VITAMIN K. Vitamin K is required for the production of osteocalcin, which is important for bone mineralisation. It seems Vitamin K may not only increase bone mineral density in osteoporotic people, but also reduce fracture rates. However, the mechanism is not well understood and in 2007, there is still inadequate evidence to show adding vitamin K would be effective in preventing or treating osteoporosis. Good dietary sources of Vitamin K are green leafy vegetables such as spinach, lettuce, cabbage, kale, liver and fermented cheeses and soybeans. Keeping to the recommendation of 5 portions of fruit and vegetables a day can help optimise Vitamin K intakes.
MAGNESIUM. Magnesium is a mineral that helps keep blood calcium levels constant. The elderly are at most risk of low magnesium levels, as magnesium absorption rates decrease and excretion rates increase with age. However, as of 2007, no studies recommend magnesium supplementation for preventing or treating osteoporosis. Good food sources of magnesium are green leafy vegetables, legumes, nuts, seeds and whole grains.
ZINC. Zinc is a constituent of hydroxylapatite, the main mineral component of bone. Dietary sources include whole grain products, brewer’s yeast, wheat bran and germ, seafood and meats and poultry. Zinc from animal sources are more easily absorbed than vegetable sources, so vegetarians may be at risk for low levels of zinc.
Nutrients that hinder bone health
ALCOHOL. Moderate alcohol intake of 2 units of alcohol /day is not thought to be harmful to bone health. However, studies show that more than 2 units/day are associated with a decrease in bone formation.
CAFFEINE. Caffeine has been implicated as a factor for osteoporosis, but without any convincing evidence up to 2007. Moderate consumption of caffeine, 400mg/d, the equivalent of 3 to 5 cups of coffee, depending on the size and strength, can be taken as part of a healthy diet.
SOFT DRINKS. In 2007 there were suggestions that the high phosphate content of carbonated cola drinks can result in low peak bone mass. However, there is no conclusive evidence that supports the claim. The problem tends to be the soft drinks displace milk in the diets of children and teenagers. The advice is to consume these drinks in moderation.
SALT. A high salt (sodium) intake increases excretion of calcium in the urine, so is considered a risk factor for bone loss and osteoporosis.
VITAMIN A. Vitamin A plays an important part in bone growth, but too much in the form of retinol, found in foods of animal origin such as liver, fish liver oils and dairy products, may promote fractures. Vitamin A as carotene, in green leafy vegetables and red and yellow fruits and vegetables, does not appear to cause problems. As of 2007, more studies are recommended.
BOTANICAL MEDICINES OR HERBAL SUPPLEMENTS. Herbalists and Chinese medicine practitioners believe that certain herbs can slow the rate of bone loss. Some commonly recommended products are ones containing calcium carbonate or silica such as horsetail, oat straw, alfalfa, licorice, marsh mallow, yellow dock, and Asian ginseng. Natural hormone therapy, using plant estrogens (from soybeans) or progesterone (from wild yams), may be recommended for women who cannot or choose not to take synthetic hormones. However, because the FDA does not regulate the manufacture and distribution of herbal substances in the United States, no quality standards currently exist. Individuals need to discuss use of these substances with their doctor or pharmacist or dietitian.
Once peak bone mass s is achieved, bone turnover is stable in both sexes until mid 1940s and so the nutritional requirement for calcium remains stable during this time. However, even after reaching full skeletal growth, adequate calcium intake is important because the body loses calcium every day through shed skin, nails, hair, sweat, urine and feces.
Bone loss begins from about 40 years. It is part of the normal ageing process and for women this bone loss is also accelerated further at the time of menopause. In addition, intestinal calcium absorption decreases and calcium excretion in the urine increases, so the body will compensate for low blood calcium levels by drawing on calcium in the bones. A decreased capacity of the skin to synthesize Vitamin D and less exposure to sunlight due to decreased mobility also makes the elderly high risk for low Vitamin D levels. Increasing calcium and Vitamin D from the diet therefore becomes more important.
The guidelines are important for age related bone loss as well as other groups at risk for developing osteoporosis such as:
- People allergic to diary products or with severe lactose intolerance avoid milk based products and foods containing milk products. Fortified soy or rice milks are adequate substitutes to meet calcium requirements, but they are not suitable for infants. Specialized milk substitute formulae are required for infant feeding. Green leafy vegetables, sardines, salmon, soymilk and calcium-fortified foods are all milk -free foods that are rich in calcium and vitamin D. Some lactose intolerant individuals may be able to tolerate some milk products as part of a meal, such as Swiss cheese and cottage cheese, which are naturally low in lactose.
- Vegans do not eat any products of animal origin, which includes milk and dairy products. Important calcium foods for Vegans include tofu, fortified Soya milk, green leafy vegetables, seeds, nuts and calcium fortified foods.
- Populations with limited exposure to sunlight, such as those in the northern latitudes, cover up for religious reasons or use sunscreen due to concerns about skin cancer and other skin diseases need to depend more on dietary sources of Vitamin D. Darker skinned people also make less Vitamin D from sunlight.
- Individuals who have problems with fat absorption may have low Vitamin D levels. As Vitamin D is fat-soluble, it requires some digestion of fat for absorption. A reduced ability to absorb fat is associated with conditions such as Cystic Fibrosis, Crohn’s Disease, and Celiac disease . Individuals on long-term oral corticosteroids, including those with asthma, arthritis or chronic obstructive pulmonary disease (COPD) have an increased risk of developing osteoporosis. Steroids contribute to increased osteoclast activity (bone break down) and inhibit osteoblast formation (bone building). Steroids also interfere with the absorption of calcium in the small intestine.
For those populations at risk for osteoporosis, calcium and Vitamin D supplements may be needed to meet daily requirement. The types of supplements available vary by country, so individuals should take medical advice before using them.
Three portions of low fat diary foods along with plenty of fruits and vegetables can help to lower blood pressure as shown in the DASH (Dietary Approaches to Stop Hypertension) study.
Research in 2003 looking at weight loss in over weight individuals showed diets high in low fat diary may contribute to lower body fat, especially in combination with a lower calorie intake. Increased dietary calcium is thought to bind more fatty acids in the colon, inhibiting fat absorption. It may also directly affect whether adipocytes store or break down fat.
Research supported by the U. S. National Cancer Institute and published in 2007 suggests diets rich in calcium, Vitamin D and diary foods may reduce the risk of colon cancer by 28%. The American Cancer Society encourages the inclusion of low-fat and fat-free dairy foods in a healthy diet, as part of their recommendations for cancer risk reduction.
For those who have high cholesterol, low-fat dairy products are recommended to meet their calcium requirements. Low fat alternatives have the same amount of protein and up to 20% higher in calcium, with less total and saturated fat than full fat products.
Calcium also has the potential to compete with the absorption of other important minerals, such as iron. Individuals with iron deficiency and taking iron supplements should avoid taking them at the same time.
servings of dairy reported a 27% lower incidence of kidney stones than those who did not. However, higher levels of supplemental calcium in older men and women may be associated with an increased risk of kidney stones.
High calcium intakes may also increase prostate cancer risk. A 2001 Harvard School of Public Health study showed that men consuming the most dairy products had about 32% higher risk of developing prostate cancer than those consuming the least.
The recommendation is not to avoid calcium, but keep to the recommended guidelines of 1000mg for adults and not to exceed the upper limit set at 2000– 2500mg of calcium per day.
Health concerns with too much Vitamin D are rare. Excess vitamin D is generally the result of taking high dose of supplements rather than from too much sunlight or food sources alone. The tolerable upper intake level (UL) for vitamin D at 1,000 IU (25 mcg) for infants up to 12 months of age and 2,000 IU (50 mcg) IU for children, adults, pregnant, and lactating women.
Adequate calcium and Vitamin D are key to reducing the risk of osteoporosis and this is the general acceptance all mainstream medical associations, member societies of the IOF, and part of the recommended dietary guidelines for many countries.
In 2007, The FDA is proposing to allow dairy processors and other food manufacturers to use new label language to promote the health benefits of calcium. Currently, a sample claim is “Regular exercise and a healthy diet with enough calcium helps teen and young adult white and Asian women maintain good bone health and may reduce their high risk of osteo porosis later in life”. Under a proposed new rule, milk cartons, yogurt packages and even some fat-free cheeses could soon display wording to the effect that Vitamin D and calcium can help reduce the risk of osteoporosis and promote bone health.
However, there is still the continued debate on the benefit of consuming the large amounts of calcium currently recommended for adults. Countries with high calcium intakes such as America and Sweden have some of the highest rates of osteoporosis. In contrast, countries such as the Gambia, China, Peru and India, have a much lower fracture incidence, despite an average calcium intake of 300mg/d, less than a third the amount recommended in the USA. Differing dietary, genetic and lifestyle factors, including physical activity and sun exposure may account for the low fracture rate, but there are some thoughts that the differences are related to high intakes of animal protein, of which diary is included. High protein increases the acid load in the body. In order to neutralize the acid, the body pulls calcium from bones, which may increase bone loss and increase the risk of osteoporosis. As such there are thoughts that the focus of the guidelines should be aimed at encouraging everyone to eat more calcium-rich plant-based foods, instead of consuming more dairy foods. Fruits and vegetables are considered alkali rich foods that do not need neutralizing and as such are more beneficial to bone health. In addition, they are low in calories, full of fiber and antioxidants. As of 2007, recommendations are that more studies are needed to understand the consequences of this acid- base balance for skeletal health in the long term.
Brown, Susan E. Better bones, Better Body: beyond Estrogen and Calcium McGraw-Hill; 2 edition (April 1, 2000). This book looks at osteoporosis from a wider perspective that includes lifestyle and exercise. It includes an osteoporosis risk assessment questionnaire and a step-by-step program for strengthening bones and improving overall health and well-being.
Celia J Pryrme, Gita D Mishra, Maria A O’Connell, et al.“Fruit and Vegetable Intakes and Bone Mineral Status: A Cross-Sectional Study in 5 Age and Sex Cohorts” American Journal of Clinical Nutrition 2006, 83: 1420-1428
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Dawson Hughes, B. Invest in Your Bones - Bone Appetit: The role of food and nutrition in building and maintaining strong bones 2006, International Osteoporosis Federation publication available online <http://www.iofbonehealth.org/>.
National Institute of Health Your guide to lowering high blood pressure with DASH 2006, National Institute of Health publication. Tells how to follow the eating plan with a week of menus and some recipes available on line <http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf/>
National Osteoporosis Society Healthy Eating for Strong Bones 2006, National Osteoporosis Society Leaflet. Available online at <http://www.nos.org.uk/.>
The Diary Council Fill your Bones with Calcium The Diary Council booklet 2006, available online <http://www.milk.co.uk/>.
United States Department of Heath and Human Services Bone Health and Osteoporosis: A Report of the Surgeon General 2004. Available on line at <http://www.surgeongeneral.gov/>
National Osteoporosis Foundation (NOF), 1232 22nd Street N.W. Washington, D.C 20037-1292 USA.Website <http://www.nof.org/>
National Osteoporosis Society (NOS), Camerton, Bath, BA2 0PJ UK. Website <http://www.nos.org.uk/>
International Osteoporosis Federation (IOF), 9, rue Juste-Olivier, CH-1260 Nyon, Switzerland. Website <http://www.nos.org.uk/>
National Diary Council USA. Website <http://www.nationaldairycouncil.org/nationaldairycouncil/>
The Diary Council, Henriettea House. 17/18 Henrietta Street, Covent Garden, London WC2E 8QH UK. Website <http://www.milk.co.uk/>
Tracy J. Parker, RD