04 January 2006

Osteoporosis: milk or supplements?

During your teens, it's absolutely essential to increase your calcium intake in order to ensure bone health in later life. But what's the best source of this vital nutrient?

Osteoporosis is a particularly insidious disease that affects older adults of both sexes, although the incidence is generally higher in postmenopausal women.

As a larger percentage of our population who have a western lifestyle live longer, we can expect the incidence of osteoporosis in South Africa to escalate. One of the unanswered questions with regards to osteoporosis, is if we should be using milk and dairy products to supply the calcium and vitamin D required to prevent this disease, or if the solution lies in calcium supplementation.

Why there is still confusion
The reason why nutritionists are still unsure about this question is the fact that relatively few studies have investigated dietary treatment of osteoporosis on its own. Most of the prevention studies have made use of calcium and vitamin D supplements, plus a wide variety of other treatments such as oestrogen replacement therapy, fluoride, and/or medications like Fosamax.

There have been indications from studies that did not directly set out to study the effect of milk and dairy products on osteoporosis, but investigated other outcomes such as lowering of blood pressure with the DASH Diet, that found a positive increase in bone mineral density. This improvement in bone strength was attributed to the high intakes of low-fat milk and dairy products on the DASH Diet.

We also know that calcium reserves are laid down in the skeleton during the teenage years and early adulthood, and that girls and women who do not include adequate quantities of milk and dairy products in their diets, have low bone mineral densities which result in osteoporosis later in life.

New study
A recent study conducted in Malaysia with postmenopausal women has provided some proof that drinking two glasses of milk a day can prevent loss of calcium from the skeleton. In this study, 173 women completed the 24-month trial drinking 50 g of skimmed milk powder mixed with 400 ml of water a day. The skim milk powder provided 1 200 mg of calcium daily. The control group continued with a normal diet, which did not include the two glasses of skimmed milk a day.

At 24 months the results showed that the experimental group, when compared to the control group, had significantly higher dietary calcium intakes (1 440 vs. 450 mg/day), significantly higher serum vitamin D levels (89,4 vs. 71,2 nmol/L), and lower bone mineral loss rates.

This is an indication that dietary treatment of osteoporosis can play an important role in preventing bone loss in older women.

Why dietary calcium is important
The reasons why it may be more advantageous to counter bone mineral loss in the postmenopausal period with dietary calcium rather than calcium supplements, are as follows:

  • An integrated nutrition approach is always desirable and never more so than in the prevention of osteoporosis. Adequate bone health and strength is dependent on a variety of dietary factors such as protein, calcium, magnesium, zinc, vitamin K, vitamin D and fluoride intake. Milk and dairy products supply protein of good quality, magnesium, calcium and vitamin D, so one would achieve a number of important dietary goals by including these foods in the diet.
  • Because nutrient interactions are often complex, dietary treatment is often more effective than use of supplements. One example is the finding that calcium supplements may interfere with zinc absorption, which does not seem to occur when the calcium is derived from milk and dairy products.
  • Some less advantaged populations may find it difficult to afford calcium supplements, while skim milk powder is a relatively inexpensive food that most people can afford.
  • The fact that such good results were obtained in the Malaysian study show that a simple dietary intervention such as adding two cups of skim milk to the diet on a daily basis can make a dramatic difference to bone health.
  • Secondly, the skimmed milk used in the Malaysia study was low in fat. This should encourage people who avoid milk products because they are scared that it will cause weight gain, to consider this option. Skim milk can also be used for making your own yoghurt if you require greater variety in your diet.

Who is at risk?
The following individuals should consider adding two cups of skimmed milk to their daily diet:

  • Teenagers and young women who are perpetually on weight loss diets, who avoid milk because of its fat content - remember this is the time in your life when you need to lay down a large store of calcium in your skeleton to prevent osteoporosis in later life
  • Any woman who suffers from female hormone deficiencies - all postmenopausal women, or women who suffer from early menopause for whatever reason
  • People with eating disorders, especially young women who stop menstruating due to anorexia or bulimia
  • Men who have low calcium levels

Milk myths
There are plenty of ‘milk myths’ doing the rounds. Most of these are not scientifically proven, but let’s have a look at some of the most popular ones:

  • ‘Milk contains too much protein, which leaches calcium out of the bones’ - the warning that high protein intake can leach calcium out of bone is expressly directed at high meat protein intakes, not protein derived from milk and dairy products. If you drink two cups of skimmed milk a day, you won’t be burdening your body with excess protein. Just make sure that you are not eating large quantities of meat three times a day.
  • ‘Milk is responsible for too many allergies, and should be avoided’ - some individuals do suffer from milk allergies (they either react to one of the proteins in milk or to the milk sugar, lactose, which can cause lactose intolerance). If you have been tested by a pathology laboratory and have been scientifically diagnosed with milk allergy or lactose intolerance, then you do need to avoid milk. Try using soymilk substitutes, such as SoFresh which is also supplemented with calcium. If on the other hand, you have not been diagnosed by means of medical tests, and are cutting out milk and dairy products just because you think you may be allergic, you should have the tests done because you may be depriving yourself of a valuable source of readily available, inexpensive calcium and vitamin D.
  • ‘Milk is only for babies and adults don’t need it!’ This type of illogical reasoning could also apply to all other foods that human beings have been eating for thousands and thousands of years. In fact, if we take this reasoning to its extreme, then adults should not survive on anything but mother’s milk - which is of course an impossibility. The human race has had ample time to adjust to drinking cow’s milk and we have relied on this source of calcium for millennia. So, even if your blood group indicates that you are a ‘primitive’ member of modern humanity, remember that the theory of the Blood Group Diets is not scientifically proven (why every member of the human race with a specific blood group should be allergic to milk, or wheat, or food X, and that by cutting out this food you will lose weight, remains a mystery and smacks of another diet myth). Most adults can use milk with safety to boost their calcium and vitamin D intakes, unless they have a proven milk allergy.

The new study reported above shows that there is a simple and inexpensive, low-fat or fat-free solution to preventing osteoporosis. By having just two cups of skimmed milk a day you can protect your bones and teeth from deteriorating as you grow older. Simple, but effective. – (Dr Ingrid van Heerden, DietDoc)

Any questions? Ask DietDoc


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Healthy Bones

Tereza is the CEO of the National Osteoporosis Foundation and worked as a Nursing Sister in the field of Osteoporosis for 18 years prior to her appointment with the Foundation. She used to be the Educational Officer for the Foundation and co-wrote the patient brochure on Osteoporosis. Read more

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