Few things affect your health as much as what you eat. That means changing your diet can reduce your risk of chronic health problems, writes Sylvia Thompson.
We dig our graves with our teeth, according to one Irish professor who tries to impress on his students the huge contribution made to our health - or, more precisely, our ill-health - by what we eat.
Diet's role as a key cause of heart disease and other chronic health problems is the spur for an increasing number of research projects.
One seminal US study, which looked at the diets of 100,000 men and women, provides further evidence of the role healthy diets play in preventing disease. Researchers at Harvard University adapted US Department of Agriculture dietary guidelines to include more specific advice on choosing certain foods.
So instead of simply stressing the usual diet - low in fat, high in carbohydrates, with more fruit and vegetables and moderate amounts of dairy products and foods from the "meat" group (meat, chicken, fish and beans) - the researchers emphasised white meat (fish and chicken) over red meat, whole grains over refined grains and unsaturated over saturated fats. Then they compared the results.
They found that men following the original departmental guidelines were 11 per cent less likely to develop chronic disease and that women were 3 per cent less likely. When following the alternative guidelines, however, men were 20 per cent less likely to develop chronic disease overall and 39 per cent less likely to develop cardiovascular disease. The figures for women were 11 per cent and 28 per cent.
The Irish Heart Foundation is about to revise its dietary guidelines to place more emphasis on many of the foods found to be significant in the Harvard study.
Janis Morrissey, a dietician with the foundation, says: "The British Dietetics Association also recently issued guidelines on secondary prevention of heart disease [for those who have already had one heart attack\], which suggest replacing saturated fats with polyunsaturated fats and monounsaturated fats, increasing the intake of fruit and vegetables and eating oily fish two to three times a week.
Prof Ian Graham, a consultant cardiologist at the Adelaide & Meath Hospital, in Tallaght, says: "Every population in the world which has a high consumption of saturated fats has a moderate to high death rate from cardiovascular disease.
"However, there is no magic bullet in nutritional terms. A balanced, varied diet with more emphasis on carbohydrates and fruit and vegetables will automatically displace fat in the diet."
Graham says dietary changes alone can prevent further problems developing for patients with marginally raised cholesterol levels.
"An optimum diet will reduce cholesterol levels by between 5 and 7 per cent, while cholesterol-lowering drugs will do so by about 30 per cent."
Few mainstream health professionals regard food supplements, which are increasingly popular, to be helpful in preventing disease. Graham points out that eating fruit and vegetables has more beneficial effects than taking supplements.
"The trials looking at the value of anti- oxidants in supplement form are disappointing," he says.
Morrissey, however, says the value of omega-3 fatty acids is such that if someone cannot or will not eat them in their everyday food - they are found in oily fish and rapeseed, for example - then omega-3 supplements are better than nothing.
She also points to common food myths that often have negative impacts on people who are trying to improve their diets.
"Many people believe that bread and potatoes are fattening, but they are high- carbohydrate, low-fat foods," she says. "It's what we do with them that affects the fat content - making chips and rich, creamy pasta sauces.
"People also believe that eggs are bad for them, but even those with high cholesterol can eat between four and six eggs per week. And then sea salt is often considered to be a good substitute for table salt, but sea salt, onion salt and garlic salt all contain more or less the same salt as table salt." Herbs, lemon juice, spices, black pepper and garlic can be used as salt alternatives, she says, especially by people who are at risk of high blood pressure.
The value of food in protecting people from cancer is less clear-cut. The Harvard study found that the risk of cancer was not significantly reduced in either those following the standard dietary guidelines or those following the alternative guidelines.
But a new French study has concluded that an appropriate intake of antioxidant vitamins and minerals may reduce the incidence of cancer in men. The study looked at more than 13,000 participants, who for seven and a half years were given daily nutritional supplements: six milligrams of beta-carotene, 120 milligrams of vitamin C, 30 milligrams of vitamin E, 100 milligrams of selenium and 200 milligrams of zinc.
It found that they cut their cancer risk by 31 per cent but showed no reduced risk for heart disease. No benefits were found for women. French women already had healthy levels of antioxidants through eating more fruit and vegetables, according to the researchers.
"There is some evidence from epidemiological studies that people who eat lots of fruit and vegetables don't show the same incidence of colon and breast cancer," says Liz Barnes, a Dublin-based dietitian with a special interest in oncology. She says there isn't enough scientific evidence to support the many alternative diets that claim to cure or prevent cancer, however.
"There is an increasing number of people looking at alternative diets, some of which promote a very low body weight or are nutritionally imbalanced, which can reduce their ability to fight infection, particularly if they are on chemotherapy and are immunosuppressed from that," says Barnes.
Some studies of breast cancer have suggested that lower levels of fat might be associated with lower recurrence and better survival rates. And the American Cancer Society suggests that breast- cancer survivors may want to limit fat intake to 20 per cent of their total calories (fat should make up about 35 per cent of the average person's diet).
Overall, there is increased knowledge of a link between obesity and some forms of cancer, and the inclusion of fibre in the diet has been found to significantly reduce the risk of colorectal cancers.
The Irish Cancer Society doesn't promote any one diet in the effort to prevent cancer. Instead it follows Europe-wide guidelines on cancer prevention. These recommend that if you drink alcohol, for example, you should cut down on the amount you drink and maintain a healthy diet by increasing your daily intake of fresh fruit and vegetables and by eating a range of foods low in fat and high in fibre.
Series concluded
A new exercise programme set in motion by the Irish Rugby Football Union and VHI Healthcare will target children in more than 700 primary schools.
A fitness routine developed to encourage children to be more active, the programme concentrates on developing skills with a number of fun exercises.
Significantly, the children's level of fitness will be tested at the beginning and end of a six-week period by external trainers who will visit the schools.
"Young children have many distractions in their lives, which sometimes means that physical exercise comes last in the priorities. This programme aims to reverse this process and ensure that regular exercise is also part of their daily routine," says Andy Crawford, vice-president of the IRFU.
Food and your child:
More than 100 children were recently being treated at one Dublin hospital for disorders caused by poor diet and lack of exercise.
Childhood obesity is becoming a major healthcare issue, not only because of associated medical disorders, such as kidney problems and joint fractures, but also because of the long-term consequences of being overweight.
"It is a huge problem, and we have to realise that adult chronic diseases such as hypertension, heart disease and diabetes all start in childhood," says Prof Denis Gill, professor of paediatrics at the Royal College of Surgeons.
British child-health experts recently called for annual weight checks for children as young as five. In parts of the US weight and fitness checks are included in school reports, and children found to be at serious risk are encouraged to enrol in exercise programmes and advised to follow diets. In Ireland, obesity clubs for children have met with limited success.
"The worst aspect of it all is the effect it has on the child or teenager. They are demoralised. They don't like themselves. They can't exercise because they are carrying so much extra weight. They can't get any clothes to fit them so they get more depressed and they eat more," says Gill.
Recent proposals to tax fatty foods, fizzy drinks and salt are considered a waste of time by healthcare professionals.
"The excessive intake of sugar, fat and salt - we eat about 20 times more salt than we need - is the chief culprit, but prevention is the only answer
and nutritional education is the key," says Gill. "People don't realise the calorie content of food. For instance,
a bag of crisps and a soft drink is 400 calories."
He reiterates the importance of better food labelling, to provide clear information on calorie, fat, salt and sugar content. "I believe the food industry is being deceitful. For instance, no added sugar just means no additional sugar added. Light drinks contain sugar and even sporty drinks have more sugar in them."
Dieticians also point to poor eating habits as contributors to childhood obesity - not eating together as families, for example, and offering children too wide a choice of food rather than concentrating on fresh produce. The prevalence of treats is another significant factor. Once a weekly event, "treats" are now often a daily feature in many households.
Health-promotion units admit they can't compete with the food industry's advertising budgets, so rather than taxing foods high in fat, salt or sugar, perhaps the Government should consider calls to ban food advertising targeted at children.
Food for thought:
Eat more: Fruit, whether fresh, tinned, cooked or as juice; vegetables, whether raw or cooked; oily fish such as mackerel, trout or salmon, whether fresh or tinned; wholegrain cereals and breads, baked potatoes, rice and pasta; fat derived from plants, such as olive and rapeseed oil, in place of some of your intake of saturated fat, which comes mainly from animal sources.
Eat fewer:
Fried foods; convenience foods; salty snacks; biscuits, cakes, sweets and chocolate products; fatty cuts of meat and meat products.
Source:Irish Heart Foundation
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