There are thousands of studies on the benefits or harms of various foods. Studies that show something (benefit or harm) tend to get media attention. Most of these have no scientific validity.
A recent study looked at scientific publications showing the association of various foods with cancer. They randomly picked 50 ingredients from a cookbook. Lo and behold, 40 out of the 50 ingredients (80%) had studies showing either risk of harm or protective benefit. But here’s the real kicker…. most ingredients had multiple contradictory studies – some showed harm and others found benefit (see here).
This isn’t to say that foods are irrelevant. But simple foods and spices don’t cause cancer. Nor do they prevent it. Studies that say otherwise should be viewed with a massive amount of skepticism.
Bottom line… it sells newspapers and gets attention to make claims that foods cause cancer, but they probably don’t. If it’s not a really large study (10,000 people or more) ignore the headline.
Kudos to Schoenfeld and Loannidis for a great article. The article is worth glancing at as part of a balanced diet of information. However, one should maintain a healthy skepticism when reading dubious headlines.
Sources: The American Journal of Clinical Nutrition “Is everything we eat associated with cancer? A systematic cookbook review”; National Cancer Institute “Colorectal Cancer Prevention”; Mayo Clinic “Cancer Causes: Popular myths about the causes of cancer”; Agency for Toxic Substances & Disease Registry “Cancer Fact Sheet”; CA: A Cancer Journal for Clinicians “American Cancer Society guidelines on nutrition and physical activity for cancer prevention”