The food you eat doesn’t just provide you with energy it can have a powerful impact on your body’s ability to fight off heart disease, cancer, diabetes, high blood pressure, stroke, and weak bones. Study after study has shown that a diet high in plant-based foods — fruits, vegetables, beans and grains — is the body’s best form of defence against poor health. Here’s a round up of what research has to tell us about the disease-fighting power of food.

The cancer fighters

Study after study has consistently shown that approximately 30 to 40 percent of all cancers could be avoided if people ate more fruits, vegetables, and plant-based foods and minimized high-fat, high-calorie foods with little or no nutritional value. Although researchers are still not completely sure they’re beginning to focus their attention in particular on two components –antioxidants and phytochemicals.

The antioxidants (carotenoids, such as beta carotene and lycopene, and vitamins C and E) found in fruits, vegetables, and other plant-based foods fight free radicals, which are compounds in the body that attack and destroy cell membranes. The uncontrolled activity of free radicals is believed to cause many cancers. The carotenoids, in particular, which give fruits and vegetables their bright yellow, orange, and red colours, are now gaining recognition as cancer fighting super stars and numerous studies have also extolled the virtues of lycopene (the carotenoid that makes tomatoes red and also found in such foods as watermelon and red grapefruit) in preventing cancer.

The phytochemicals present in fruits and vegetables protect the body by stunting the growth of malignant cells. Phytochemicals, naturally occurring substances, include indoles in cabbage or cauliflower, saponins in peas and beans, and isoflavones in soy milk and tofu. Investigators aren’t really sure how phytochemicals work but they do believe that you can get enough anti-cancer nutrients by eating at least five servings a day of fruits and vegetables with seven or more starchy or protein-rich plant foods such as grains, peas and beans.

Note: Supplements can help you get some of the benefits of these substances, but they are no replacement for real food. This is because when you take a supplement, you’re getting specific vitamins and minerals, but not the thousands of potentially life saving phytochemicals that might be present in fruits and vegetables.

Heart savers

What you eat, and choose not to eat, can have a dramatic effect on your risk for high cholesterol, high blood pressure, heart disease and stroke. Saturated fat, found mostly in meat and full-fat dairy products, is the major culprit in raising blood cholesterol, the main ingredient of artery-clogging plaque. Overindulging in these foods raises the risk of developing heart disease. But you can lower this risk by shifting the emphasis so that nutrient- and fibre rich foods such as fruits, vegetables, and grains make up approximately two-thirds of what you eat each day.

Plant-based foods contain very little fat and provide complex carbohydrates as well as vitamins and minerals. Because they’re rich in indigestible fibre, they take up space in the intestines, which can help you control your appetite, your weight and, most important of all, your risk of heart disease.

Fibre comes in two forms, soluble and insoluble. Soluble fibre, found in fruits, vegetables, brown rice, oats, and barley, lowers blood cholesterol levels (and your risk of heart disease) and slows the entry of glucose into the bloodstream, an important factor in preventing or controlling diabetes.

Insoluble fibre, found mainly in whole grains, fruit and vegetable peels, keeps your digestive tract in order by soaking up water and adding the bulk that pushes possible cancer-causing substances (carcinogens) out of the intestine.

Studies show that simply adding two servings a day of oats or other cereals high in soluble fibre can reduce cholesterol levels by almost 3 to 4 percent. Although the reasons aren’t entirely clear, it may be that soluble fibre combines with intestinal fluids to form a gel that binds to fat or prevents it from being absorbed into the bloodstream.

The bone builders

Research has shown that a diet low in calcium can increase the risk of osteoporosis. Leafy green vegetables and seeds like sesame are excellent sources of calcium, the mineral that keeps your bones strong. Your body uses calcium for more than keeping your bones strong. Calcium permits cells to divide, regulates muscle contraction and relaxation, and plays an important role in the movement of protein and nutrients inside cells.

If you have a more acidic diet, your body’s demand for calcium will be high as your body will have to take calcium from your bones to neutralise the acid. So by eating a more alkaline diet with fruit and vegetables and less animal protein, especially red meat and cheese, you are not only giving yourself more antioxidants but also protecting your bones. (For more information on acid/alkaline balance for bone health see my book ‘Osteoporosis – the silent epidemic’).

‘An apple a day keeps the doctor away’ is an old adage that seems to be proving true, as study after study shows that apples confer a huge range of health benefits. A meta-analysis in 2003 of 7 studies involving over 100,000 people highlighted apples as significantly reducing the risk of heart disease, by an astonishing 20%; while the following year a meta-analysis of 85 studies found that eating apples was also linked to reduced risks cancer, type 2 diabetes and asthma.

Apples are rich in vitamins, minerals and fibre. A medium-sized (138g) apple provides around 6.3mg – 16% – of your daily immune system-boosting vitamin C requirement and a useful amount of your vitamin K intake, which helps your blood to clot normally. It is also packed with antioxidants, to the extent that 100g of apple and peel has the same antioxidant effect as 1500 mg of vitamin C. Apples’ low glycaemic index rating means snacking on them helps to keep blood sugar levels stable, which can ward off weight gain and, in the long-term, lifestyle diseases such as type 2 diabetes.

The high fibre content (around 2.4g/100g – 13% of your daily recommended intake), particularly the soluble fibre, pectin, found in the peel, helps to reduce both ‘bad’ LDL cholesterol levels and the risk of bowel cancer. It can also reduce the risk of dying of heart disease by up to 30%

Apple peel is also rich in antioxidant procyanidins, which have been shown to reduce the number of pre-cancerous colon cancer cells and could be used for future cancer treatments. Lab studies have shown that quercetin, a type of flavonoid found most abundantly in apples, can prevent the growth of human prostate cancer cells, while the National Cancer Institute in the States has reported that apple flavonoids could halve the risk of lung cancer. As it is good to eat the peel, make sure you buy organic apples so that the it has not been sprayed with pesticides.

Quantity is important, too: according to British epidemiological researchers, eating two apples a week reduces the risk of developing asthma by 22-32%, while a 28-year study in Finland found that people who ate the most apples had the lowest risk factors for thrombotic strokes.

And if you’re worried this is a lot of information to take on board in one go, don’t forget that US researchers have found that apples could improve your memory, cognitive function and ability to learn – and might even protect against Alzheimer’s disease.

When cloves are chewed, crushed or cut, they release a sulphur-bearing compound called allicin – the chemical that gives garlic its pungent taste and smell. And it’s the allicin that scientists have discovered is the magic ingredient thought to be responsible for garlic’s therapeutic qualities.

Most of the modern research on garlic has concentrated on its ability to lower cholesterol and blood pressure as well as offering protection against strokes and heart disease. For example, when the Journal of the Royal College of Physicians reviewed data on cholesterol in 1993, it found that after just four weeks there was a 12 per cent reduction in cholesterol levels in the research groups that had taken garlic.

Scientists have also looked at the role garlic plays in helping prevent the formation of blood clots. A review of recent clinical trials, published in the Journal of Hypertension, showed that taking garlic tablets cut volunteers’ blood pressure by between one and five per cent. These results led the report’s authors to conclude that taking supplements could cut the incidence of stroke by anything from 30-40 per cent, while heart disease could be reduced by 20-25 percent.

While garlic is gathering a reputation for helping to maintain a healthy heart, regular amounts of garlic seems to also help the body fight off infections. A recently published study found that a daily garlic supplement reduced the risk of the volunteers catching a cold by half. The researchers also discovered that even when those taking the supplement did develop a cold they were more likely to make a speedier recovery than the non-garlic taking volunteers. And if that’s not enough, just one clove a day will top up your body’s supplies of vitamins A, B and C, as well as a vast array of minerals including selenium, iodine, potassium, iron, calcium, zinc and magnesium.

Research into the benefits of garlic are continuing all the time and some scientists have been reviewing evidence that suggests it may even help to protect against stomach cancer. The thinking behind this is that the allicin compounds, contained in garlic, may help prevent cancerous changes in the stomach wall. While more research is clearly needed there is little doubt that a little garlic, every day, can go a long way in helping to protect, as well as boost, your health.

For some, garlic can be the cause of heartburn as well as flatulence. And then, of course, there is the smell that eating garlic leaves behind! For those who prefer not to eat the garlic, it is available in supplement form. If you’d prefer to stick to the real thing, a clove a day can help improve your overall health and two or three cloves a day can help to stem a cold. Chew parsley after eating garlic to help neutralise your breath. When used in cooking, crush or cut the garlic finely, then leave for 10 minutes to allow the allicin to fully develop before adding to recipes. Add the garlic about five minutes before the end of cooking – this way you apply just enough heat to convert the allicin into medically active compounds.

Note: Garlic can interact with anticoagulants, such as Warfarin and aspirin, so if you take blood thinning medication, talk to you doctor before taking garlic supplements. It is also recommended that no garlic supplement is taken for two weeks before surgery, as they may interfere with blood clotting and increase risk of bleeding.