In this series of articles on coronary heart disease (CHD) I have emphasised that diet can make a significant contribution to preventing the degenerative changes that occur in blood vessels. Some of the most crucial weapons we have in our fight against this killer disease are antioxidants and other protective nutrients.
What are antioxidants?
Antioxidants are nutrients such as vitamins and minerals that combat the damaging effects of "free radicals". Free radicals are harmful chemical compounds, which are formed when our bodies are exposed to cigarette smoke and pollutants that occur in air, water, and the food we eat.
Unfortunately our bodies also produce free radicals during basic metabolic processes involving oxygen. The antioxidant defence system of our body is , however, equipped to neutralise free radicals with and it is only when the protective capacity of this defence system is exceeded by excessive exposure to free radicals that we develop a condition known as "oxidative stress" which can lead to damage of biological molecules and degenerative diseases such as CHD.
Certain compounds and nutrients are our "first line of defence" in the battle against free radicals. Our bodies are capable of producing some antioxidants, but most of these chemical weapons are obtained from the food we eat.
The following nutrients are powerful antioxidants which can protect us against degenerative diseases, including CHD:
Vitamins C and E and beta-carotene, are the most effective antioxidant vitamins known to mankind.
Other dietary antioxidants
Flavonoids, and polyphenols which occur in plants and foods made from plants are becoming more and more important in our fight against heart disease.
Zinc and selenium have also been identified as antioxidants which can combat free radicals.
Food sources of antioxidants
Vitamin C - the best sources of vitamin C are fruits and vegetables, i.e. citrus fruit such as oranges, lemons, grapefruit, limes and naartjies, strawberries, spanspek, pawpaw, guavas, Kiwi fruit, green peppers, the cabbage family (broccoli, green, red and Chinese cabbage, Brussels sprouts, cauliflower), tomatoes, spinach and of course potatoes (most of the vitamin C is found under the skin).
Vitamin E - the best sources of vitamin E are vegetables oils, especially cold-pressed oils (wheat germ, sunflower, canola, etc), nuts, avocado, green leafy vegetables and whole grain cereals.
Beta-carotene - is mainly found in dark green or dark yellow fruits and vegetables such as carrots, sweet potatoes, pumpkin, butternut, spinach, green beans, broccoli, apricots, pawpaw spanspek, and yellow peaches (fresh and dried).
Flavonoids are found in fruit and vegetables, tea, soy beans and products made with textured vegetable protein.
Polyphenols occur in grains (sorghum, Maltabella), fruit especially in grapes if you eat the skins, wine, tea, chocolate and cacao.
Zinc is mainly found in lean meat, fish, dry beans, peas and lentils, and unprocessed grains and cereals.
Selenium occurs in vegetables and grains, provided that the soil and water in the area where these foods are cultivated contain selenium.
Basic dietary advice
It is evident that fresh fruits and vegetables and unprocessed grains and cereals are the main dietary sources of antioxidants such as vitamins C and E, beta-carotene, flavonoids, polyphenols and selenium.
To prevent CHD it is essential to eat at least 5 portions of fresh fruit and vegetables every day, making sure that at least one of these foods is a source of vitamin C and one is rich in beta-carotene, e.g. have a glass of freshly squeezed orange juice at breakfast and a carrot salad at dinner and you will have topped up on vitamin C and beta-carotene for the day.
To obtain your requirement for zinc you need to eat some meat or fish, but keep in mind what we said last week about eating only lean meat and not adding large amounts of fat during preparation.
What about supplements?
Research has indicated that humans need more vitamin E on a daily basis than is provided by most western diets, so it is a good idea to take a vitamin E supplement of about 100 IU a day. Selenium is also a tricky nutrient to get enough of because it may be deficient in locally produced foods if the soil and water in your region lack selenium, which may make it necessary to take selenium supplements. Nowadays you can buy ‘heart-friendly’ supplements at pharmacies and health-shops that contain combinations of vitamins C and E, beta-carotene, zinc and selenium. - (Dr I.V. van Heerden, DietDoc, February 2007)
Any questions? Ask DietDoc