If you’re like me, you often find yourself confused by scientific advice on what to eat for good health. For every study that finds some miracle benefit to some food, another study always seems to come along and contradict the results of the first. This meeting is no exception. One study released yesterday claimed to have found a chemical reason why soy prevents cancer. But another study presented today claims the opposite, reporting that soy doesn’t prevent colon cancer. So should you blend up that delicious tofu shake, or not?

Part of the problem here is that studies on diet and health often use different methods. So the study presented yesterday only examined cells in a culture dish, while the study presented today examined how tofu influenced cancer spread in live rats. Their results aren’t really comparable. So which one is right?

Honestly, they’re both pretty meaningless. We human beings aren’t rats, and we’re not single cells plated across a plastic dish in a lab refrigerator. Until a study finds that something has a large effect on cancer risk in a lot of people, over many years, it doesn’t really mean that much.

Unfortunately, a lot of the news we read on diet and exercise online and in the newspapers every day doesn’t pass that test. But that doesn’t stop researchers and reporters from claiming that maybe the diet intervention du jour will save you from cancer – be it pomegranate juice, broccoli or green tea.

But none of these things on their own will save you from cancer. What might? Eating lots of fruits and veggies, and staying trim. Obesity has consistently been linked to many different types of cancers in large studies in thousands of patients. And people who eat diets high in fruits and vegetables generally – not single ingredients, like apples or broccoli – also seem to be at lower risk for cancer.

So eating right and exercising isn’t as easy as guzzling down a soy shake every day, but it’ll probably do you a lot more good.