TIMES ONLINE
November 01, 2002
Dairy dilemma
by SUZANNAH OLIVIER
Has milk's wholesome image gone sour? Evidence suggests that you don't need it if you have a balanced diet
MILK has always enjoyed a wholesome reputation. However, the ?I don?t do dairy? brigade could be on the right track. In truth, there are not many established indisputable facts about the benefits of dairy intake.
Fact 1: animal milk was not introduced into the human diet until 7,000-10,000 years ago, at the point when animal herding was developed.
Fact 2: 70 per cent of people worldwide are unable to drink milk, and don?t. This is because, post-weaning, the milk enzyme lactase diminishes, making people unable to digest milk fully. Those of African, Asian, Jewish and southern Mediterranean descent are most likely to lack this enzyme. So is milk good or bad for you?
WEIGHT REDUCTION A study of 32 people over 24 weeks, conducted by Professor Michael Zemel, of Purdue University, Indiana, concluded that those who consumed three or four servings of low-fat dairy while on a 500-calorie-per-day restricted diet lost up to 70 per cent more weight than those who followed the low-calorie diet, or the same diet but with calcium supplements. This supports animal studies which have found that a high calcium intake increases metabolism and suppresses fat storage, but suggests that there is an X-factor in dairy which might accelerate weight loss even more. Yet countries with low dairy intakes have the lowest obesity problems.
BONE HEALTH Three portions of dairy (milk, yoghurt and cheese) achieves the 700mg of calcium that we are recommended to consume each day for strong bones. This may be important for people before their mid-twenties, when bone is reaching peak density.
However, Stephen Walsh, the Vegan Society?s vice-chair, says that milk acts as a stimulus generally ? rather than just because of the calcium ? due to the effect of IGF-1 (insulin-like growth factor 1) and he questions the advice to drink milk beyond the time of peak bone growth, as IGF-1 is linked with various cancers. The advantage of drinking milk in later years is not clear-cut. Calcium is not the only factor in bone health; magnesium found in grains and green leafy vegetables may also help. It?s possible that reducing calcium loss is more important than increasing calcium intake: a high consumption of salt, caffeine and phosphoric acid (from soft drinks) leads to calcium loss. Many non-Western cultures consume less calcium than we do and have lower levels of osteoporosis.
HEART DISEASE According to the Dairy Council, blood pressure and cholesterol levels are improved by dairy. They quote a study which recommends two or three portions daily of low-fat dairy products. But those results assumed the consumption of nearly ten portions of fruit and vegetables a day. One milk fatty acid, myristic acid, though not in fat-free dairy products, raises cholesterol.
BREAST CANCER Two Scandinavian studies offer evidence that milk intake reduces breast cancer risk. However, numerous previous studies have reached different conclusions. Even one of the positive studies says: ?The contradicting results may indicate that any association between milk and breast cancer is not strong.? Walsh, of the Vegan Society, believes it might be significant that the studies showing positive results were Nordic. Vitamin D, which helps calcium uptake by bones, and is implicated in lower breast cancer rates, is provided by sunlight on skin ? rarer in the north ? and by milk. Walsh says the safest bet is to get calcium and vitamin D from elsewhere.
THERE IS no strong evidence to say that you need to drink milk as long as you are eating a varied diet. If you eat dairy products, there seems to be little doubt that low-fat (skimmed, not semi-skimmed) is the only truly healthy option. Claims that dairy is a strong contender for preventing breast cancer and cardiovascular disease are, at best, premature.
Links
www.milk.co.uk
The Dairy Council
www.vegansociety.com
Offering (milk-free) food for thought