Monday May 19 2014

What is it about food that causes cancer?


By Sandra Janet Birungi

For a long time, cancer was one of those diseases associated with people living in developed countries, but this trend is fast changing as many people in the so-called third world countries are fast becoming victims.

According to Timothy R. Rebbeck, of African Organization for Research and Training in Cancer (AORTIC), cancer is increasingly becoming a problem in Africa due to change, in among other things, diet and lifestyle.

“Increases in life expectancy, changes in diet and lifestyle, and lower burden of communicable diseases promise to increase the cancer burden in Africa over the coming years,” he writes in the foreword of Cancer in Africa.

The World Health Organisation recently announced that cancer will overtake heart disease as the number killer of human beings. Scientists believe that around 80 per cent of cancer is determined by our lifestyle choices.

One interesting question remains unaswered, how has the average diet around the world deteriorated to bring about this higher cancer rate? Read on to find out how.

Anything can cause cancer or can be carcinogenic. These range from drugs to toxins and foods although for them to cause cancer, it is over a long period of time, Dr Fred Okuku, an oncologist at Mulago Cancer Institute says: “Some cancers are slow in developing.

For example cervical cancer can take up to 10 years before symptoms begin manifesting,” he explains. This means if consumed, these carcinogens can take a long time before causing the cancer.


Dietician, Mr Jamiru Mpiima explaining food related carcinogens said one of the major causes of cancer in foods is artificial fertilisation of the foods, right from the garden to the time of consumption. “All foods are cancer free. However, how these foods are treated for example in the garden when they are growing and storage after harvesting can cause them to be carcinogenic,” he says.

Food in storage
Afflatoxins B1: These are produced by fungus formed by stored grains for example maize, nuts, peanut butter, sorghum, millet and ground nuts.

Dr Okuku says for the fungus to develop, there has to be a wet or moist environment and it is caused when cereals are not well-dried. “Afflatoxins are sometimes referred to as mould and form due to poor storage,” Mpiima adds.

Ugandans are exposed to afflatoxins mostly and people should be on the lookout according to Dr Okuku. “You see in some shops where they make groundnut paste, they remove the small groundnuts which people cannot buy and squash them for the paste and groundnut sauce.

These are usually not well kept and increase chances of taking in these toxins unknowingly. But, if you eat groundnuts which already have the fungus, you will have a bitter taste.”

Pesticides: These are commonly used to eradicate pests both in the gardens and during storage after harvesting. According to Fredrick Kizito, a nutritionist, when used, foods end up storing these pesticides which in turn end up being carcinogenic to the consumer after a certain period of time.

During preparation
Acryclamide: This component is formed in fried or over heated carbohydrate foods for example potato chips and also found in over re-used cooking oil. “Re-used oil can end up being carcinogenic depending on how many times it has been re-used. Whereas re-using oil three times is okay, exceeding that could cause it to change colour and become darker, a sign that it is dangerous” Mpiima cautions.

Kizito agrees but adds, “In Uganda, our levels of being exposed to acrylamide are high because of the way we cook. In case of cooking oil, the more you heat it, the higher the risk of it getting acrylamide.”

Biphenol: It is found in plastics used to make containers for packed or canned foods. It is also found in microwave ovens and baby bottles. “The more you heat the bottle, the more you release biphenol which in turn increases the baby’s exposure to the carcinogen,” Kizito explained.

Preservatives: A lot of these can prove to be cancerous and the common type is sodium dioxide. Explaining their danger, Mpiima noted that whereas a total of 0.05 million grams of sodium dioxide is acceptable for products, eating different products with the same amount of preservatives will lead to an increase in the component in the body, which can in the end become carcinogenic.

Preservatives are common in juice, tomato sauce, ketchup and some milk products. Kizito agreed that preservatives get more dangerous as they are linked with biphenol especially in canned foods and baby formulas.


Although food has the higher risk of causing cancer, there are other things that are carcinogenic.

Asbestos: These toxins are found mainly in building construction materials for insulation and can be found in roofings and pipework. In Uganda, old buildings still have roofs made out of asbestos. “A cement company manufactured these roofs in the past and many buildings today have them,” Dr Okuku said.

When rain falls, asbestos mixes with the water and people end up consuming it because people in Uganda today use rain water. Asbestos is linked to lung cancer.

Arsenic: This comes naturally and is found in compounds used in chemical manufacturing.

For people working in industries dealing in wood preservation, glass production, nonferrous metal alloys, and electronic semiconductor manufacturing, their exposure to the raw arsenic increases their chances of being exposed to the toxin and getting cancer in the long run.

Despite its negative effect on people, after extensive research, it is now being used to treat cancer. “In small amounts, however, arsenic is being used to treat leukemia,” Dr Okuku clarifies.

Radio therapy/radiation: This is used to treat cancer patients; radiotherapy can become carcinogenic when used over a period of time. Citing the Hiroshima, Japan incident in 1945, Dr Okuku said radiation is also a carcinogen.

Cancer drugs: These too are carcinogenic. Dr Okuku is, however, quick to state that people should not be scared when using cancer drugs because of their ability to be carcinogenic. “These drugs affect each patient differently and as a doctor, you cannot know what effect it will have on a particular patient.”

Alluding to ‘Poison used correctly can be medicine but medicine used wrongly can be poison,’ Dr Okuku gave an example of alcohol and cocaine which are taken as poisonous but when used correctly, they can be medicine. However, it is not safe to self prescribe them.


There are foods which also have components which can aid in preventing cancer or reducing on the chances of acquiring cancer.
Antioxidants: According to Kizito, antioxidants are chemicals that block the activity of other chemicals and are anti-carcinogenic.

Some of these are phenolic components and caratenoids. Caratenoids have the highest capability of preventing cancer and can be found in vitamin C from fruits and vegetables. “Vitamin C tablets do not apply in this case,” Kizito warned.

Vitamin E: Known for its role in reducing colon, liver and lung cancer, Vitamin E is a good anti-carcinogen. It can be found in peanut butter, peanuts and sunflower seeds.

Beta-carotene: This is commonly found in yellow, green and orange vegetables and fruits like bananas, carrots, oranges, to mention but a few. “According to research, including vegetables in every meal is known to cut down on the toxins in the body and flush them out so people should be able to eat them with every meal,” recommends Mpiima.

Vitamin D: This is found in milk and its products. Low Vitamin D is usually linked to colon and breast cancer. Although it is advisable to take milk to acquire Vitamin D, it should be well prepared to prevent other diseases like brucella.

“When boiling milk, let it boil up to four times, that is when it shops forming as though it is going to pour. Usually, when the milk heats for the first time, it forms and swells and sometimes, it spills; that is when people think it is ready but that is not true. Do this four times, the fourth time, it will just boil, it will not form, a sign that it is ready for consuming,” Kizito explained.

Omega 3 fatty acids: This can be got from fatty fish and cell fish. “Whenever we talk about these things, people think of taking dietary supplements but these are not in their natural forms. For these anti-carcinogens to work, you have to take them in their natural forms so, eat fish,” says Kizito.

Turmeric: This is a spice, yellow in colour and it is usually found in curry powder. “Not all curry powders have this spice so it is safe to consume powder from trusted or good manufacturers,” Kizito explains.

Catechins: This is found in green tea and it is known to stop the growth of cancer. “Research is still on-going about this. China is the largest consumer of green tea and its cancer rate is the lowest so there has to be some connection between tea and cancer although it is not conclusive,” Kizito says.


To prevent some of these carcinogens, there are a few things that people can do. Storing grains in dry places can be of a great help. “Let the cereals have enough sun,” Dr Okuku advises. For peanut butter, Kizito advises refrigeration to prevent the growth of this fungus.

Natural pest prevention methods: “Our grandparents also encountered pests but they did not have pesticides, they had natural ways of preventing pests. Ordinary and regular ways should be used to remove pests. The European market is now going organic which means that if you are interested in exporting foods to the European market, your food has to be grown naturally,” Kizito explained. He gave an example of mixing ash with the soil to prevent pests from attacking the crops.

For reused oil, Kizito advises that it should be well cleaned and kept well. However, Mpiima advises that it should only be re-used thrice. “It is healthier to use cooking oil once but since it is not economical, oil should only be re-used at most thrice. After this, the oil usually turns dark and once it does, it should be discarded,” he advised.

Another option that is being explored is lifestyle change. This is in the form of a good diet, physical activity and lifestyle change (DPL) method of reducing cancer. “When people watch what they eat, do physicals and change their lifestyle, they will be able to fight against the increasing cases of cancer in the country,” Kizito says.


•Dr Okuku says different individuals react differently to toxins, foods and other things, therefore, for one to get cancer, it has to be over a long period of time.
•Tattoos do not have any effect on individuals and cannot cause cancer or be carcinogenic. “For something to be termed as carcinogenic, it has to have the capability to make a cell develop abnormally through mutation, later on becoming a cancer. If there has been no mutation in the cell, there is no cancer. If a tattoo leaves a wound that won’t heal, then it can be cancerous,” Dr Okuku explains.
•Most common cancers in Uganda in children are Burkitt lymphoma (cancer which starts in immune cells called B-cells) and Kaposi’s sarcoma (cancer of the skin), in women it is cervical and breast cancer and in men it is prostate cancer and Kaposi’s sarcoma. Dr Okuku says most of them are caused by untreated or recurring infections.
•Cancer is not contagious although the infections that cause it can be.
•To cure cancer faster, it has to be detected early through screening for example the pap smear for women going for cervical cancer screening.