How to stop bad eating habits

People often ask me for a list foods to avoid and foods to include in order to prevent disease. If only it were that easy!

When we look at dietary intervention in terms of health it is important to remember that you are a whole person, and we need to take into account you eating habits, dislikes, as well as social and physiological factors. We “inherit” our eating habits from our parents to a large extent and we know that children learn more from what we do than what we say. A lot of adult patients we see in the practice have incorrect ideas regarding diet due to the way they were raised and the beliefs of their family. In terms of genes and food, it is often habits more than genetics that lead to bad dietary choices.

When it comes to cancer prevention, certain foods seem to play a role. Please keep in mind that there is no such thing as good or bad food. We get good and bad diets, and if we stick to better options most of the time, we can relax every now and again.

Fibre is the skeleton of plants. It is the part of food that you cannot digest. Fibre adds bulk to your digestive system, shortening the amount of time that waste products travel through the colon. Fibre is the major fuel source for the colon cells and helps prevent colon cancer.  When you become constipated the waste products stay in the colon for a longer duration. The waste often contains carcinogens and it is best if they are removed as quickly as possible from the colon. Fibre is found in a large range of foods such as cereals, wholemeal and granary bread, fruit, vegetables, legumes and pulses, grains and seeds.

Protein is important for growth and repair. Certain proteins present in meat, cooked at high temperatures, especially grilling and frying, have been found to produce compounds called heterocyclic amines that damage DNA cells and can cause cancer, especially breast and colon cancer.

Nitrates and nitrites have received attention because of their relationship with nitrosamines, which are potent carcinogens. Sodium and potassium nitrates are used in the processes of salting, pickling and curing foods e.g. hams, salami, pickled onions, etc. Nitrosamines are also found in tobacco smoke. An association has been found between an increased risk of esophageal cancer and the frequent intake of smoked foods.

Tips on what to avoid:

  • Do not eat charred (burnt) food.
  • Limit your intake of “braaivleis” to once a week.
  • Avoid cured and smoked meats including smoked snoek/chicken/salmon.
  • Avoid pickled foods like gherkins and onions.
  • Limit your intake of salt.
  • Always include a source of vitamin C at mealtimes as this helps reduce the carcinogenic effect of nitrates in food.

Research has shown that the daily intake of Omega 3 fats may decrease the incidence of bowel cancers such as colon cancer. The best source is oily fish, such as salmon, sardines, herring, mackerel and trout, or fresh tuna. Flaxseeds are a good source of Omega-3 fats for vegetarians and vegans.

Fruit and vegetables are important sources of vitamins, minerals and fibre in the diet. They also contain vitamins that help protect against cancer. Vitamin A, C, E, Carotenoids (e.g. lycopene), selenium, and phytochemicals (usually related to the colour) are all anti-oxidants with strong cancer-fighting properties.  Anti-oxidants protect cells from free radicals, substances that work to destroy cell membranes and DNA.

To benefit from this protection you should aim for at least five helpings of fruit and vegetables each day. One portion is equal to one tennis ball sized fruit, half a cup of cooked veggies, or a cup of raw veggies.

The following fruit and vegetables are good sources of:

For many people, drinking alcohol is a pleasant social activity. In small amounts alcohol can be beneficial to one’s health but excessive drinking can be very harmful. The regular intake of large amounts of alcohol has been linked with a variety of cancers, including breast, oesophagus, liver, head, neck and pancreatic cancers.

Let us always remember that food is meant to be enjoyed in moderation!


Berna Harmse is a private practicing dietitian in Cape Town, she holds a MSc in Dietetics and has a special interest in oncology nutrition. She is also an external lecturer at Stellenbosch University Division of Human Nutrition.

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