Osteoporosis: A Nutrition Fact Sheet for Health Professionals

Nutrition has long been established as a key factor in building and maintaining bone strength. While calcium and vitamin D are crucial nutrients for bone health, energy, protein and other vitamins and minerals all play a role. The risk of developing osteoporosis is influenced by life-long dietary intake of these nutrients in combination with regular weight-bearing activity and not smoking.

Dietary calcium

Calcium is essential for bone health and the recommended intake (RDA) is 800 mg/day for children, adults and older people, increasing to 1200 mg for teenagers, pregnant and lactating women¹ . Unfortunately, 16% of women in Ireland are consuming less than the estimated average requirement of calcium². The National Children’s Food Survey also found that 28% boys and 37% girls aged 5-12 years have inadequate calcium intakes³.

The richest sources of calcium in the diet are milk, cheese and yogurt. Three servings a day will help meet calcium needs of an adult or child; five servings are recommended during adolescence and pregnancy. Smaller amounts of calcium may be obtained from other food sources, such as green vegetables, bread and sardines. It should be noted however that the bioavailability of calcium from non-dairy sources is lower. Foods fortified with calcium and vitamin D such as milk and yoghurt can also be useful.

Vitamin D

Vitamin D is primarily produced by the action of UVB light on the skin, with a limited number of foods also providing vitamin D (oily fish, egg yolks, liver and fortified dairy products). Due to Ireland’s northerly latitude (and the use of sunscreens) production from UVB light is compromised. This, together with poor dietary intakes, has contributed to wide-spread sub-optimal vitamin D status. Recent research has confirmed that low vitamin D status (25 hydroxyvitamin D < 50nmol/l) is more prevalent than previously believed, particularly in postmenopausal women⁵. Dietary sources should therefore be encouraged in all ages.

Calcium and vitamin D supplements

If it is not possible to achieve adequate calcium and vitamin D intake through diet, supplements may be recommended. A meta-analysis of calcium and vitamin D supplementation found that calcium and vitamin D supplementation reduced bone loss and fracture risk in adults aged 50 years and older⁶. The National Osteoporosis Foundation in the USA recommends 1000mg-1200mg calcium and 800-1000IU of vitamin D for adults (aged 50 years and older)⁷.

Vitamin D given alone has not been found to reduce risk of fracture⁸ but has been shown to reduce falls if vitamin D status was low at baseline⁹.

Note: Recent studies have investigated a possible link between supplemental calcium intake and cardiovascular disease^{10 11}. This is an area of ongoing research with no consensus at present^{12 13}.

Other Dietary Factors

Alcohol

High alcohol intakes increase risk of osteoporosis; some research suggests that even 2-4 drinks per day may be harmful to bone tissue and the authors advise that one drink per day for women and two drinks per day for men is a safe level¹⁴.

For overall health the recommended limits in Ireland are:

• Up to 11 standard drinks a week for women

• Up to 17 standard drinks a week for men

A high alcohol intake will also increase risk of falls and injury and should be a consideration when assessing falls risk.

Caffeine

It has been suggested that a high caffeine intake is a risk factor for osteoporosis, with some groups advising a consumption of no more than 4 strong cups of coffee a day or less^{15, 16}. Caffeine is found in coffee, tea, cola-type drinks, energy drinks and chocolate. Consumption of fizzy drinks has been found to displace milk intake in teenagers and may contribute to sub-optimal bone development in this age group.

Soy

There is inconclusive evidence that soy has a beneficial effect on bone health. The available evidence does not support a recommendation for the use of soy for this purpose¹⁷.

Other vitamins and minerals

Various research studies suggest a role for different vitamins and minerals in bone health¹⁸. The evidence suggests that vitamin C and K may have positive effects on bone. However it is recommended that these nutrients are obtained from a balanced diet with adequate fruit and vegetables as the evidence is not sufficient to recommend supplementation¹⁹.

Omega 3 fatty acids

It has been suggested that omega 3 fatty acids have a beneficial effect on bone health but the evidence at present is limited by the small number of studies. From the studies to date it appears that any potential benefit of omega 3 fatty acids on bone may be enhanced by concurrent administration of calcium²⁰.

Groups at increased risk

Low Body Mass Index (BMI)

Low BMI and low body weight have been identified as risk factors for osteoporosis^21. Frail older people, those with eating disorders and some athletes may have a low BMI and are therefore at greater risk of developing osteoporosis.

Malnourished adults

Malnourished adults particularly those with an inflammatory condition are at increased risk of bone loss²². Nutritional screening tools can be used to identify those at risk who may require some intervention or referral to a dietitian. Tools include the Malnutrition Universal Screening Tool (MUST) devised by BAPEN²³. In older people there are many factors which may contribute to poor nutritional status, including- difficulties eating (e.g. badly fitting dentures), poor appetite, loneliness, social isolation, difficulties accessing and preparing food and ill health. Identifying and managing any problems can have a significant impact on nutritional status²⁴.

Older people should also be assessed for dehydration, as this can exacerbate dizziness and increase risk of falls and injury. A minimum of 8 glasses of fluid daily will improve these symptoms²⁵.

Those on weight reducing diets

Bone loss has been shown to be accelerated during weight loss ²⁶. This may increase risk of osteoporosis in dieters, particularly in those following restrictive diets. In addition, dieters may be excluding sources of calcium in the diet, such as dairy foods, in the belief that they are fattening. Whereas evidence shows that weight reducing diets higher in dairy foods, dietary calcium, and protein with daily exercise protect bone during weight loss27.

Other medical conditions

Particular attention should be paid to the calcium intakes of individuals at risk of osteoporosis due to conditions such as coeliac disease, malabsorption or inflammatory bowel disease. Those on long-term corticosteroids are also at greater risk of osteoporosis²⁸.

Healthy eating advice

A healthy balanced diet will ensure that all nutrients necessary for bone health are provided in the diet. This can be achieved by following the principals of the food pyramid. Those at low risk of osteoporosis should be given general health and well being advice, including information on alcohol, caffeine, smoking, calcium and vitamin D. Those identified to be at high risk may need further assessment and dietary advice to improve nutritional status and reduce risk of fracture.

Updated by Laura Keaskin, MINDI, October 2013

Review date: October 2015

© 2013 Irish Nutrition and Dietetics Institute, INDI. All rights reserved. May be reproduced in its entirety provided source is acknowledged. This information is not meant to replace advice from your medical doctor or individual counselling with a dietitian. It is intended for educational and informational purposes only.

References:

1. Food Safety Authority of Ireland (FSAI) (1999) Recommended Dietary Allowances for Ireland, Dublin: FSAI.