Are you wary of dairy? HFG senior nutritionistRose Carrpours over the facts to bust the myths surrounding this staple food.
Most of us were brought up eating and drinking dairy products, such as milk, yoghurt and cheese. Some of us even have memories (fond or otherwise!) of the national free-school-milk program that ran from 1950 to 1973. But how do dairy foods affect our health? You may have heard the popular theory that most of us have a mild milk intolerance, and that this intolerance is the culprit behind many common conditions, from tummy bloat to teen acne. You may have also read that some scientific studies suggest that dairy foods cause cancer, whereas others claim they actually prevent it. A more common concern is that dairy foods promote weight gain, so when people decide to eat ‘healthily’ and slim down, they often ditch dairy foods — along with all their health benefits. To muddy the milk picture even more, the research on this topic can be confusing or conflicting, so let’s take a look at the current evidence to get a clearer idea.
myth #1: 75 per cent of people can’t digest dairy
Lactose is a natural milk sugar in dairy products. People who find it difficult to digest this sugar are lactose intolerant, which means they’re lacking in lactase, the enzyme the body needs to digest lactose. (Lactose intolerance can also follow a bout of gastrointestinal illness, but this usually passes as the gut bacteria recover.) Your ethnicity directly affects your chances of having lactose intolerance. In Australia, up to 5 per cent of Caucasians and 75 per cent of non-Caucasians can’t tolerate lactose. In Asia, Africa and South America, more than 50 per cent of people have lactose intolerance, and in some Asian countries, the rate is nearly 100 per cent. Most people with lactose intolerance still produce some lactase, which means they can consume small amounts of milk and other dairy products on a daily basis without experiencing any discomfort. In fact, many people can drink up to a cup of milk a day, but most lactose-intolerant individuals better tolerate foods such as cheese and yoghurt, as these contain less lactose.
myth #2: Cheese causes constipation
No — eating cheese won’t constipate you. When Finnish researchers put nursing-home residents on a high-cheese diet and a separate no-cheese diet (both of which ran for three weeks), they noted no changes in either digestion time or degree of constipation — and this was despite a tenfold increase in the cheese consumption of subjects following the high-cheese diet! Consequently, the researchers rejected the practice of avoiding cheese to prevent constipation. Still, it’s important to note that cheese has no fibre. If you eat so much cheese that you haven’t got room for fibre-rich foods, it’s time to find a better balance in your diet. You can also help keep your bowels healthy by drinking enough water and exercising regularly.
myth #3: Cheese triggers bad dreams
Many people think that English novelist Charles Dickens is the source of this particular cheese myth, because his character Scrooge blames his nocturnal visions on the crumb of cheese he eats before going to bed in A Christmas Carol. A more modern-day suspect upholding this particular myth is a midcentury antidepressant, the side effects of which can include nightmares. Before experts fully understood this drug, they implicated cheese as the culprit. (Today, people taking this drug are warned against eating cheese, as the combination can be fatal.) There’s been little research into the relationship between cheese and nightmares, possibly because most academics don’t believe any such relationship exists. The British Cheese Board is rumoured to have conducted a study on the subject, but it hasn’t appeared in any peer-reviewed journals, and therefore seems to be more of a marketing exercise.
myth #4: Milk contains harmful hormones
No, but cow’s milk contains various natural bioactive hormones, such as insulin-like growth factor 1 (IGF-1). Some experts say that milk’s IGF-1 content makes a negligible contribution to blood levels of IGF-1, but the hormone continues to interest researchers, especially in relation to prostate cancer. US manufacturers often use a synthetic bovine growth hormone (as well as naturally occurring hormones) to increase milk production. But this practice is banned in Australia, New Zealand and the European Union.
myth #5: Dairy products cause cancer
Some people think consuming large amounts of dairy protein may increase the risk of breast and prostate cancers. In 2007, the World Cancer Research Fund (WCRF), UK, undertook the most comprehensive review of all of the scientific evidence on diet, lifestyle and cancer prevention. Its report acknowledges that diet is a difficult area to study because of the variety of foods and the complexity of our meals. In addition, researchers found conflicting evidence surrounding any links between dairy foods and cancer, so they’re without guidelines for dairy consumption as regards cancer prevention. More recent reviews support recommendations that having three daily serves of milk and dairy products is safe and does not appear to increase overall cancer risk. In 2011, scientists at New Zealand’s University of Otago reported that schoolchildren who drank milk every day reduced their risk of bowel cancer in adulthood by 30 per cent. (Previous studies in adults have suggested that calcium consumption may reduce bowel-cancer risk.) As a result, the WCRF updated its findings the same year, noting a “probable”, as opposed to “convincing”, link between milk and calcium consumption and reduced colorectal-cancer risk.