A trip to almost any bookstore or a cruise around the Internet might leave the impression that avoiding cancer is mostly a matter of watching what you eat.But there is a huge gap between this folklore and science.
During the last two decades the connection between the foods we eat and cancer has been broken bit by bit. Recently, at the annual meeting of the American Association for Cancer Research, that drew more than 18,500 professionals in the field, the latest results about diet and cancer were relegated to a single poster session and a few scattered presentations. There were new hints that coffee may lower the risk of some cancers and more about the possible benefits of vitamin D. Beyond that there wasn’t much to say.
In the opening plenary session, Dr. Walter C. Willett, a Harvard epidemiologist who has spent many years studying cancer and nutrition, gave a status report. Whatever is true for other diseases, when it comes to cancer there was little evidence that fruits and vegetables are protective or that fatty foods are bad, he said.
The situation seemed different in 1997, when the World Cancer Research Fund and the American Institute for Cancer Research published a report, concluding that diets loaded with fruits and vegetables might reduce the overall incidence of cancer by more than 20 percent.
After reviewing more than 4,000 studies, the authors were persuaded that green vegetables helped ward off lung and stomach cancer. Colon and thyroid cancer might be avoided with broccoli, cabbage and brussels sprouts. Onions, tomatoes, garlic, carrots and citrus fruits all seemed to play important roles.
A decade later, a major follow-up reversed the findings. While some kinds of produce might have subtle benefits, the authors concluded, “in no case now is the evidence of protection judged to be convincing.”
The reason for the change was more thorough epidemiology, according to NYT. The earlier studies tended to be “retrospective,” relying on people to remember dietary details from the distant past. These results were often upended by “prospective” protocols, in which the health of large populations was followed in real time.
The hypothesis that fatty foods are a direct cause of cancer has also been crumbling, along with the case for eating more fiber. The idea that red meat causes colon cancer is shrouded in ambiguity. Two meta-analyses published in 2011 reached conflicting conclusions — one finding a small effect and the other no clear link at all.
One study suggests that a 50-year-old man eating about a third of a pound of red meat a day raises his chance of getting colorectal cancer to 1.71 percent during the next decade, from 1.28 percent. Spread over a population of millions, that would have an impact. From the point of view of an individual, it barely seems to matter, NYT says.
With even the most rigorous studies, it is hard to adjust for what epidemiologists call confounding factors: Assiduous eaters of fruits and vegetables probably weigh less, exercise more often and are vigilant about their health in other ways. Some of this can be sorted out with randomized controlled trials, with two large groups of people arbitrarily assigned different diets. But such studies are expensive, and the rules are hard to enforce in the short term — and probably impossible over the many years it can take for cancer to develop.
The emphasis at the meeting was on other things: new immunotherapies, the role of chronic inflammation and the endlessly intricate subterfuges of cancer cells. With his focus on nutrition, Dr. Willett seemed like the odd man out.
“Diet and cancer has turned out to be more complex and challenging than any of us expected,” he said. There were some reasons for optimism. A study last year suggested that while eating lots of produce had no effect on most breast cancers, vegetables might reduce the occurrence of a type called estrogen-negative. Cutting back on milk and other dairy products might possibly lower the risk of prostate cancer. As epidemiologists began to follow the health of younger populations, Dr. Willett hoped that more dietary influences would yet emerge.
And what about other myths – do superfoods prevent cancer? Is there a miracle cure? Can sugar make it worse?
And to make matters worse there are millions of web pages misinforming people about the preventions, cures and causes. In fact, if you google “cancer” you will be inundated with incorrect information.
Express.co uk has teamed up with Cancer Research UK to distinguish fact from fiction.
1. Cancer is a manmade modern disease
Cancer has existed as long as humans have. It was described thousands of years ago by Egyptian and Greek physicians, and researchers have discovered tell-tale signs of cancer in a 3,000-year-old skeleton.
The only reason people think it is a modern disease is because it is more prominent in the public consciousness and we know more about it, the newspaper writes.
2. Cancer is on the rise
There is some truth in the fact that lifestyle related diseases like cancer are on the rise. The biggest risk factor for cancer is age and because people are living longer they are more likely to develop the disease.
3. Superfoods prevent cancer
Foods such as blueberries, beetroot, broccoli, garlic and green tea have been labelled as “superfoods” but there is actually no such thing. It is a marketing ploy to help sell products.
However watching what you eat is important and some foods are healthier than others.
4. Acidic diets cause cancer
One myth is that eating a diet high in acid can increase your risk of cancer.
There’s no good evidence to prove that diet can manipulate whole body pH, or that it has an impact on cancer.
5. Sugar makes cancer worse
Some people believe that sugar feeds cancer cells and so should be banned from a patient’s diet. However this is a massive oversimplification of a highly complex topic.All cells use sugar, not just cancer cells. All sugars are carbohydrates and get broken down in our digestive system to release glucose and fructose. These get absorbed into the bloodstream to provide energy for us. All our cells, cancerous or not, use glucose for energy.
Because cancer cells are usually growing very fast compared with healthy cells, they have a particularly high demand for this fuel. There’s also evidence that they use glucose and produce energy in a different way from healthy cells, but researchers are working to understand the differences.
While it’s very sensible to limit sugary foods as part of an overall healthy diet and to avoid putting on weight, there is no proof that sugary foods specifically feed cancer cells.
6. Cancer is a fungus – and sodium bicarbonate is the cure
This theory comes from the observation that “cancer is always white”.
Firstly cancer cells are not fungal in origin, and secondly cancer isn’t always white.
Proponents of this theory say that cancer is caused by infection by the fungus candida, and that tumours are actually the body’s attempt at protecting itself from this infection. But there is no evidence to show that this is true.
These theorists think the simple solution is to inject tumours with baking soda.
Not only have there been no published clinical trials of sodium bicarbonate as a treatment for cancer, but there’s actually evidence that high doses of sodium bicarbonate can lead to serious, and even fatal consequences.
7. There is a miracle cancer cure
Internet is awash with videos and personal anecdotes about natural, miracle cures for cancer.
Unfortunately there is no evidence to back up these theories.
8. There is a cure for cancer but it is being hidden from the public
Some people believe that governments, the pharmaceutical industry and even charities are hiding the cure for cancer because they make so much money out of existing treatments.
But it simply doesn’t make sense that pharmaceutical companies would want to suppress a potential cure. Finding a highly effective therapy would guarantee huge worldwide sales so why wouldn’t they want to sell it?
9. We’ve made no progress in fighting cancer
This simply isn’t true. Thanks to advances in research, survival from cancer has doubled in the UK over the past 40 years, and death rates have fallen by 10 per cent over the past decade alone.
Thus, the only evident conclusion seems to be that our bodies are complex and cancer is too, so it’s gross over-simplification to say that any one food, on its own, could have a major influence over your chance of developing cancer.
The best way of reducing risk of cancer is by a series of long-term healthy behaviours such as not smoking, keeping active, keeping a healthy body weight and cutting back on alcohol.