Do acidic diets increase your risk of cancer?
No
We are told to stick to a diet of mostly alkaline foods, as acidic foods create a toxic environment within the body and encourage the development of cancer.
But this nutritional advice has no scientific backing. "There are many beliefs about the connection between body pH and cancer," says Dr Victor Hsue Chan-chee, president of the Hong Kong Association of Community Oncologists.
"One of these is that eating too many acidic foods can cause the blood to become acidic, raising your risk of cancer, and that the solution is to consume more alkaline foods like green vegetables and fruits, particularly lemons. But this is nonsense," he adds.
Dr Lynette Ngo, a specialist in medical oncology and consultant at Raffles Cancer Centre in Singapore, agrees. "The pH level measures how acid or alkaline a substance is. A pH of 0 is extremely acidic, while a pH of 14 is extremely alkaline," she says. "A pH of 7 is neutral. Human blood is slightly alkaline, with a pH of between 7.35 and 7.45. The stomach is very acidic, with a pH of 3.5 or below for the digestion of food to take place.
"It is thought that eating certain foods can make the body more alkaline or acidic, and there are some diets claiming that eating alkaline foods protects the body," Ngo says.
"Fortunately, our bodies are much smarter than we think. They naturally maintain their own pH level through the kidneys and lungs.
" Every day, excess acid in our bodies is constantly being metabolised, excreted through the kidneys or expired through the lungs."
What we eat will not affect the acid balance in our bodies.
"Perhaps the only case where 'acidic' foods - such as fatty foods, caffeine, carbonated beverages, spicy foods, peppermint and chocolate - are thought to be harmful is when they stimulate and increase gastric reflux," says Ngo.
Eating the right foods is important if you want to live healthily, but when it comes to reducing your risk of cancer, there is no "magic diet".
"While eating plenty of green vegetables is good, it has no effect on your body's pH," says Hsue.
"There is no evidence that diet can affect your body pH significantly and, even if your body pH is altered, the micro-environment within a tumour will remain unchanged."
Cancer cells cannot live in an overly alkaline environment, but then neither can any of the other cells in our body.
"There are no good quality studies that have consistently shown a link between certain foods and cancer risk," Ngo says. "A few studies have shown that red meat may increase the risk of colorectal cancer, while a high intake of tomatoes may decrease a man's prostate cancer risk.
"Vitamin D, calcium and folate may reduce the risk of colorectal cancer, while alcohol intake, even in moderate quantities, increases the risk for colon, breast, esophageal and oropharyngeal cancer," Ngo says.
Most doctors would advise you to live a healthy lifestyle if you want to ward off cancer.
This, says Ngo, includes not smoking, being physically active, maintaining a healthy weight, limiting your alcohol intake, avoiding excessive exposure to the sun, and getting regular screenings for breast, cervical and colorectal cancer.
