Melbourne Holistic Health Group

Published in Articles - Bone health on 31 July 2011 by Melbourne Holistic Health Group

Improving bone density through diet

A balanced diet high in vegetables, whole grains, beans, some dairy products and fruit in moderation, supplies the key nutrients required for optimal bone health. Typically our western diet contains insufficient calcium, too few vegetables and fruit, coupled with excessive amounts of salt, caffeine and alcohol - all of which can contribute to poor bone mineral density. Below is a list of specific foods and nutrients which should be increased or avoided in order to maintain optimal bone health.

Increase:

Fruits and vegetables

•  Including adequate serves of vegetables and fruits in the diet is an important way of attaining the complete spectrum of minerals and vitamins necessary for good bone health. It is recommended that adults consume 5-7 serves of vegetables (1 serve = 1/2 cup cooked vegetables or 1 cup of salad vegetables), and 2-3 serves of fruit (1 serve = 1 medium-sized piece of fruit like an apple), per day.

Calcium

• Maintaining an adequate intake of calcium throughout life can reduce the risk of osteoporosis. Calcium is the most abundant mineral in the human body with about 99% incorporated into bones and teeth. The physiological functions of calcium are so vital that the body demineralises bone in order to maintain blood calcium levels. Adequate dietary calcium is therefore critical in maintaining a healthy skeleton.
• Australian women have been found to have a below adequate calcium intake. A study in 2000 found that 76% of women consume less than the recommended daily intake of calcium and are therefore at risk of bone loss.
• Requirements for calcium vary between age groups and are usually greater than the amount found in a typical western diet. Women of all ages should be encouraged to assess their dietary calcium intake. Your practitioner can quickly and easily assess your average daily intake. If the intake is below the recommended level, a supplement may be required to replace the missing portion. The chart ‘Maintaining good bone health across the life span’ below shows the recommended daily calcium intakes for different age groups. Your practitioner can help you to assess your calcium intake.

Magnesium

• Magnesium is as important as calcium in maintaining bone health. As the magnesium content of the bone mineral decreases, bone crystals become larger and more brittle. Magnesium increases calcium absorption form food and enhances calcium retention in the body. While dairy foods are a good source of calcium they are often not a good source of magnesium, which is why large intakes of dairy products should not be relied upon for bone health. The recommended daily intake for magnesium is 320-400mg/day. Good sources of magnesium include green leafy vegetables, nuts, legumes and whole grains.

Vitamin D

• Vitamin D plays an important role in maintaining serum calcium levels and the modelling and remodelling of bone. Without vitamin D bones become thin, brittle and misshapen. See the section on vitamin D on how to source vitamin D through sunlight and diet and a discussion on why vitamin D supplementation may be necessary.

Potassium

• Potassium is another mineral important for bone health maintenance, and one which is typically low in Western diets. The best source of potassium is from fresh fruits and vegetables, in particular bananas and potato skins. The alkalising effect of a high fruit and vegetable diet, brought about by bicarbonate ions, also reduces calcium excretion in the urine.

Boron

• Boron is another key mineral involved in maintaining the bone mineral matrix. Fruits, vegetables and nuts are the best sources of boron. Particularly rich sources include prunes almonds and raisins. Other sources include parsley, dates and hazelnuts.

Chromium

• Chromium may help improve bone mineral density indirectly by increasing insulin sensitivity and controlling blood sugar levels, Chromium has been found to reduce excretion of hydroxylproline and calcium in post-menopausal women. Good sources of dietary chromium include brewer’s yeast, parsley, olives and spinach.

Vitamin K

• Vitamin K plays a role in bone protein synthesis such as osteocalcin, which is involved in bone mineralisation. Great food sources of vitamin K include green leafy vegetables such as spinach, broccoli, kale, watercress and parsley.

Other minerals

• Other minerals such as zinc, manganese, copper, silicon and strontium are important to one health and are involved in collagen synthesis and the processes of bone mineralisation. Research has shown that when zinc, manganese and copper were added to a calcium supplement, post-menopausal bone loss slowed more than with calcium alone.

Dietary phyto-oestrogens

• Dietary phyto-oestrogens can be found in foods such as soy milk, tofu and tempeh. While the isoflavones in soy are considered to have a protective effect on bone density, questions remain as to how much must be consumed for beneficial effects, and as yet there is no research showing a reduction in fracture risk from soy consumption.

Dietary factors which may negatively affect bone health:

High Protein

• As dietary protein increases, the urinary excretion of calcium also increases. It is estimated that there is a 1mg loss of urinary calcium per 1gram of protein ingested. Calcium balance is not considered to be affected unless dietary protein intake is greater than 75 grams per day. People on high protein diets for weight loss, should have their calcium intake assessed and calcium supplementation may be necessary.

Caffeine

• Caffeine consumption results in increased urinary excretion of calcium for up to 3 hours after ingestion. It is estimated that one cup of brewed coffee (~ 230mg caffeine) causes a urinary loss of up to 2-3mg of calcium. One study found that daily consumption of caffeine in amounts equal to, or greater than that obtained from about 2-3 servings of brewed coffee may accelerate bone loss from the spine in women with calcium intakes below 800mg.

Alcohol, sugar and salt

• Alcohol, sugar and salt all increase urinary loss of minerals including calcium. Limiting intake of these foods in the diet is generally advisable.

High fibre diets

• High fibre diets can reduce calcium absorption, as the phytates in fibre bind to calcium ions. However Australians generally consume less than adequate dietary fibre, so this is unlikely to be a problem for most.

Soft drinks

• Soft drinks are high in phosphorous and excessive intake of phosphorous can increase calcium loss from the bone.

Improving bone density through lifestyle factors

The two most important lifestyle factors in maintaining bone health and preventing osteoporosis is to stop smoking and to undertake regular exercise.

Smoking

Smoking is a risk factor in developing osteoporosis for several reasons. Smokers often have a lower body weight and bone mineral density. Smoking decreases oestrogen production and increases oestrogen metabolism, or the breakdown of oestrogen. This is important as oestrogen in known to be protective to bone density. Coupled with this, women who smoke reach menopause 1.5-2 years earlier than non-smokers, and therefore reduce the protective effects oestrogen has on the bone even further. A review of osteoporosis found that women who stop smoking before menopause reduce their risk of hip fracture by about 25 per cent compared to those continuing to smoke.

Exercise

What does the research say?

The effects of calcium, oestrogen and exercise tend to be cumulative. Exercise has the most beneficial effects on bone during the years when oestrogen is available and the dietary intake of essential nutrients is adequate. Despite this an exercise related increase in BMD is seen at all ages, including after menopause.

Exercise maximises the attainment of peak bone mass and bone strength and attenuates age- and menopause related bone loss

Epidemiological studies suggest that regular exercise is associated with a reduction in osteoporotic fracture risk of up to 50% in both men and women over 65 years of age

What kind of exercise is best

Weight-bearing exercise

• Weight bearing exercises refer to any exercises where your bones and muscles work against gravity. Examples include running, skipping, walking, jogging, dancing, tennis, volleyball, lifting weights, and netball. Swimming or cycling is NOT considered weight-bearing.

High intensity and/or high impact activities

• Running, jogging, jumping and rope skipping are more stimulating to bone cells than sustained, low impact activity such as walking.

Resistance exercise

• Resistance exercise includes exercising with weights or lifting weights. Evidence suggests that this type of exercise along with high intensity/impact exercise probably provides the most benefit for improving bone mineral density.

Tips for a good bone-health exercise program

These tips come from the Osteoporosis Society, see (www.osteoporosis.org.au):

• To have an effect on bone, exercise needs to be regular and fairly vigorous.
• Doing a variety of different exercises is best because it exercises bone in different ways.
• Short intense bursts of exercise (e.g. 15 minutes of lifting weights or very brisk walking), is probably better for bones than a leisurely one hour walk.
• Two short exercise sessions (20 minutes) separated by 8 hours is better for bone, than one long session.
• Start slowly and progress gradually.
• Activities that promote muscle strength, balance and co-ordination, help to prevent falls. Pilates, gentle yoga and Tai Chi are all good activities to help prevent falls.

‘Maintaining good bone health across the life span’

Key lifestyle and dietary advice for all ages: Eat a diet high in fruits and vegetables Ensure adequate calcium intake Ensure adequate vitamin D through regular sunlight or supplementation Smoking and alcohol avoidance Exercise regularly

Age (years)	Calcium requirements (mg/day) (RDI)	Key advice
Children (1-3)	500	If children are dairy intolerant ensure adequate intake of calcium from other sources ie fortified soy products
Children (4-8)	800
Girls and boys (9-11)	1000
Girls and boys (12-18)	1200	Smoking and alcohol avoidance 15 minutes 4 times week of weight bearing exercise Girls with absent/irregular menstruation should consult a health professional
Men and women >18	800- 1000	Smoking and alcohol avoidance 15 minutes 4 times week of weight bearing exercise
Women (51-70)	1500	Assess medication use if any and affect on calcium status 15 minutes 4 times week of weight bearing exercise Choose low-fat dairy options
Women and Men >70	1300	Assess medication use if any and affect on calcium status 15 minutes 4 times week of weight bearing exercise Specific advice for falls prevention
Pregnancy and lactation <18	1500	Calcium and vitamin D supplementation is often required during pregnancy and lactation
Pregnancy and lactation >18	1500

Be sure to check with your nutritional requirements for good bone health with your practitioner during your next consultation.