‘Cancer diets’ to cut the fat?


Sarah Berry

“I pledge to go without sugar for 21 days to support those who are fighting cancer. Knowing that sugar intake contributes to cancer growth, I want to raise awareness for the role of nutrition in preventing and beating cancer.”

These are the words of someone who is searching for answers to explain a complicated epidemic that, it is estimated, will affect half of us by our 85th birthdays.

A common attempt to address this problem involves cutting out sugar and carbohydrates, which break down into glucose, because of the understanding that cancer cells are as addicted to sugar as we are and, if we remove the foods that feed it, we can “starve” cancer cells.

It is thinking that is well intentioned but misguided, according to experts, and confused further by new research from Harvard Medical School that has found that cancer cells find fat tasty too.

By the no-sugar logic, based on this research we should give up eating fat, too. But we would be misguided.

“Not all cancers are the same. Some like the fat, some like the sugar,” Kathy Chapman, director of programs and expert for nutrition and physical activity at Cancer Council NSW, says.

“When we talk about ‘they feed off the sugar’ – it’s sugar as the energy source. We’ve got to be careful that we don’t confuse this with the foods that we’re consuming. As we eat foods they get metabolised in the body so that they become our energy sources … we always have the fat cells and the sugar cells, which help us with all the bodily functions like our heart beating and breathing.”

This may be so, but it can be a confusing message when we consider that about 30 per cent of cancers are diet-related and up to 90 per cent are lifestyle-related. Nutrients affect our health, so tweaking them surely does too?

“We recommend people should minimise added sugars that they have, but carbohydrates and sugar comes in both natural forms and unnatural forms,” Steve Pratt, nutrition and physical activity manager for Cancer Council WA, says. “Cutting out fruit isn’t going to cure your cancer.”

The experts agree that there is good evidence that a healthy weight and diet along with regular exercise mitigates the risk of cancer and certainly leads to better outcomes for those with cancer as well as those in remission.

That is a far cry from thinking that complete avoidance of food groups, based on micronutrients – be it sugar or fat or carbohydrates alone – will make the difference.

“There are no foods that cure cancer,” says Pratt.

“If something is going to increase your risk of cancer, it’s more than likely going to increase your risk of recurrence … which is why we stick to the general healthy eating recommendation – lots of fruit and vegetables, whole grains, cutting down on the discretionary junk foods.

“There are very few people who eat a diet that is entirely consistent with the Australian dietary guide to eating.”

Pratt is right. Only about 4 per cent of Australians eat the recommended amount of vegetables, let alone meeting the guidelines on the other food groups.

Perhaps we need to think less about diet extremes, and more about balance and vegetables.

“What we know from population studies is that lifestyle factors – a healthy diet and how that impacts on our weight – are certainly really important risk factors for cancer and, after cigarette smoking, they’re the next most important,” says Chapman.

But, start cutting carbs or fat, and, as Pratt says “you’re running out of macronutrients to cut out”.

Besides, as Chapman says: “You find sometimes people can be quite zealous about what they’re eating and they’re hardly eating anything, so that restricting your diet can a much worse thing and lead to much worse weight loss, which is then making it harder to withstand the rigours of the treatment.”

Where does that leave us in terms of diet?

Cutting crap, for sure, benefits everyone’s health, ill or well. But, Pratt pleads: “Be skeptical of the hype.”



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