Prepackaged, processed foods are typically high in fat, salt, and sugar. If that's not enough to make you put down a cookie or resist a frozen dinner, consider an observational study published online Feb. 14, 2018, by The BMJ. It analyzed dietary questionnaire answers of 105,000 middle-aged men and women in France for five years. Foods were grouped according to degree of processing — that is, the amount of change the ingredients go through as food makers improve flavor, coloring, and shelf life. For example, dehydrated soups, baked goods, sugary cereals, processed meats, biscuits, and sauces were considered ultra-processed foods. Less processed foods included canned vegetables, cheeses, and freshly made unpackaged bread. Every 10% increase in consumption of ultra-processed foods was associated with a 12% higher risk for cancer in general and an 11% increased risk for breast cancer. No significant link was found to prostate or colorectal cancer. The study doesn't prove that ultra-processed foods cause cancer, but researchers say the cumulative effects of food additives remain largely unknown.