When 'bad' foods turn good
We may think we know what to avoid – but when it comes to diet, the rules are rarely that simple. By Roger Dobson
Tuesday 17 February 2009
Foods long considered to be tasty but taboo, may, it seems, have their healthy sides after all. Last week, we heard that new research has cleared eggs of serial involvement in disease. Where it was once thought that their high cholesterol content meant they should only be eaten in moderation, it is now thought that they have little effect on levels of cholesterol in our bodies. Meanwhile, red wine and chocolate, in moderation, have both been shown to have health benefits. Even dietary demons such as red meat, beer, butter and cheese, may have some health benefits.
Red wine and oily foods were among the first foods to undergo a makeover. The health benefits of wine, especially red, came to the fore when researchers were looking for explanations for the so-called French paradox – why the French have a much lower risk of heart disease, despite eating similar amounts of saturated fats. The answer, it was suggested, was that the wine the French drank with their meals had a protective effect on the heart. Resveratrol, a compound found in grapes, especially in the skins, is thought to be largely responsible for this, and has since been linked to a range of other health benefits, such as reducing the risk of cancer and dementia.
Oily food – much of it now considered to be healthy – were also once not recommended, but consumption of some, especially in oily fish, is now encouraged. More recently, there has also been a sea change in health attitudes to chocolate, with research showing that it can have beneficial effects for a wide range of problems, from depression to high blood pressure. One study suggests that eating 50g of dark chocolate a day may reduce the risk of heart disease and stroke by 10.5 per cent, while another finds that cocoa can reverse some of the ill health effects of smoking.
The debate over whether chocolate is healthy or not revolves around two key groups of ingredients. On the one hand it contains saturated fats, which have been linked to an increase risk of heart disease, but on the other it has significant amounts of antioxidants, which have an established protective effect. Until relatively recently it was the saturated fats that held the high ground in the debate, but the beneficial effects of antioxidants are now emerging as more important.
According to Dr Eric Ling and his colleagues at Harvard University, cocoa products contain a greater antioxidant capacity and larger amounts of flavonoids than tea and red wine. They calculate that a 100g bar of milk chocolate contains 170 mg of flavonoid antioxidants and flavanols. Dark chocolate contains more than twice the amount of flavonoids as milk chocolate. Dark chocolate is also healthier, perhaps because the milk may stop the body soaking up antioxidants.
Red meat may also have benefits, despite links with heart disease and cancer. "The saturated fat in red meat is the same as that in chocolate and is not as bad for you as people make out. It is not the saturated fat that we know is harmful. My personal view is that the fat in meat tends to get a bit of a bum rap," says Dr Alison Lennox, head of population nutrition at the Cambridge human nutrition unit of the Medical Research Council.
One of the problems is that research produces conflicting results. While one study may find an increased risk of disease, another will find none. Dr Lennox says that can be the result of the research being carried out in different countries and with different people. "Coffee is a case in point," she says. "Some research may say it causes heart disease, while another says it is OK. The thing about coffee is that we drink it in different ways. Some of the methods that we use to make coffee remove the nasty compounds while others do not. If you are doing a study in a country where they brew their coffee in ways which do not take out the nasties, you will find a risk of disease, but in a country where filters are used, there may be no risk found."
Herbert London, president of Hudson Institute, professor emeritus of New York University and author of a report on changing attitudes to foods, laments missing out on the foods he would have liked to eat. "There was a time not so long ago when most of the foods I enjoyed were bad for me. My physician said don't consume more than two eggs a week, stay away from chocolate and don't eat oily dishes," he says. "For years my doctor and parents deprived me of a restorative substance because they believed in the myth of chocolate's evil. Yet it turns out I was right and they were wrong."
Once regarded as universally bad, chocolate, at least the dark version, has undergone something of a makeover. Dark chocolate – with 70 per cent cocoa or more – reduces bad cholesterol, lowers risk of blood clots, increases blood flow in arteries, may lower high blood pressure, and may improve mood and pleasure by boosting serotonin and endorphin levels in the brain, according to the University of Michigan. Dr Chiaki Sanbongi at the St Marianna University School of Medicine in Japan has shown that the antioxidant cacao liquor polyphenol or CLP, a major ingredient of chocolate, has a beneficial effect on the immune system. At the University of Helsinki, Dr Katri Räikkönen found that expectant mothers who ate chocolate daily were more positive and less stressed about their babies' behaviour six months later.
Drinking coffee may protect younger women from breast cancer. Pre-menopausal women who drank more than four cups a day had a 40 per cent drop in their risk of the cancer, say researchers from the Roswell Park Cancer Institute, New York. The findings, which contradict some other studies, suggest that the protective effects of polyphenols, which work as strong antioxidants cleaning out toxic free radicals, may be greater than any damaging effect from caffeine. One study found that bladder cancer was about half as likely to occur in smokers who regularly drank coffee as in smokers who did not. Researchers also found that people who drink the most coffee have the lowest risk of contracting type two diabetes. Another study has shown that men who drink three cups of coffee a day have the smallest mental decline as they got older.
This can be better than calcium supplements for bone development in young girls, researchers say. They set 200 healthy girls to eat cheese; calcium; vitamin D plus calcium; or a placebo. After the trial, scans were taken. The researchers, from the Finland's University of Jyvaskyla, found the cheese group had bigger changes in the tibia bone than all the other girls, and had a higher whole-body bone mineral density than placebo. Research at Harvard University shows that cheese has high calcium levels, but it varies by type; an ounce of cream cheese has 23mg of calcium, but the same quantity of cheddar has 204mg. An ounce of Swiss cheese has 272mg, and half a cup of semi-skimmed ricotta has 337mg.
Despite its reputation, evidence is showing that beer can have health benefits. Moderate amounts have been linked to a protective effect in cancer, heart disease and osteoporosis, as well as increasing good cholesterol, boosting immune defences, and preventing blood-clotting. German researchers in Heidelberg say a key factor is that beer is high in antioxidants; about 80 per cent of its antioxidants are from barley and 20 per cent from hops, and they work individually and together against cancer to stop it developing and growing. Evidence has accumulated in the past decade pointing to the cancer-preventing potential of beer constituents, including the flavonoids xanthohumol and isoxanthohumol. The Council of Scientific Research in Madrid found that the level of a number of immune system cells increases significantly after 30 days, particularly in women. Researchers at Tufts University in the US say that silicate found in beer seems to reduce bone loss.
Health advice used to be to eat no more than three a week. There were theories that too many eggs raised the risk of heart disease, but research in the British Nutrition Foundation's Nutrition Bulletin shows that cholesterol in eggs has only a small and clinically insignificant effect on blood cholesterol. Other research has shown that eggs have positive effects on health. Michigan University researchers found that whole eggs offer almost every essential vitamin and mineral needed by humans, except vitamin C. The yolk contain vitamins A, D, E and K. Eggs have been linked to a lower risk of age-related macular degeneration. In a clinical trial at Rutgers University in America, women in the fourth or fifth month of pregnancy are being given a daily egg in the belief that it will boost foetal development. Eggs provide iodine and choline, and an iodine deficiency during pregnancy can cause miscarriage, stillbirth and mental impairment, while choline is important for the development of brain tissue. Eggs may also lower the risk of non-Hodgkin lymphoma.
The low-carb diet may have left the potato out in the cold, but it has significant health benefits. A medium-size potato, with skin, contains only 100 calories and is a good source of vitamin C, potassium and fibre. They also contain phytochemicals – nutrients that protect against cancer and heart disease.
Once regarded as a quick and cheap way to get happy, it is rapidly approaching health-food status. According to a Michigan University report, moderate consumption may lower the risk of coronary artery disease and heart attack, reduce the risk of stroke, stimulate appetite, promote regular bowel movement, and reduce the risk of gall bladder surgery in women. Moderate consumption may be associated with longevity, raised good cholesterol, more effective immune systems and a lower risk of cancer. Tannins and antioxidants are thought to be responsible for beneficial effects. Harvard University researchers found that women who drink red wine have lower risk of an early start to the perimenopause (the two to eight years leading up to the menopause itself). One theory is that it is a non-alcoholic compound in red wine – resveratrol, a phytoestrogen – that may effect the timing of menopause.
Red meat has long been linked to heart disease, cancer and other health problems, but some research suggests that leaner cuts can have health benefits. According to the American Dietetic Association, the world's largest organisation of food and nutrition professionals, lean meats are a key source of essential nutrients. "Red meats are great sources of iron, zinc, protein, vitamins B6 and B12 and niacin," it says.
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