Got milk? Why?

The precautionary principle is a fancy way of saying “better safe than sorry.” Often used in decisions that could affect public health or the environment, it asserts that strong evidence of harm — not definitive proof — should be enough to guide policy when big things are at stake.

The health of our nation’s children is one of those big things. Those of us involved in the debate about school lunch may not agree on much, but when it comes to our kids’ health, we’re all on board with “better safe than sorry.”

{mosads}At least we should be.

Last week, my colleagues and I published a report titled “Applying the Precautionary Principle to Nutrition and Cancer” in the Journal of the American College of Nutrition. The report warns about the strong association between cancer and milk, a school lunch staple.

We found that consuming 35 grams of dairy protein each day, the equivalent of one cup of low-fat mozzarella, increases the risk of prostate cancer by 32 percent. Drinking just two glasses of milk each day increases the risk by 60 percent.

The dairy-cancer connection isn’t new. Harvard researchers found that men who drink two or more glasses of milk daily are almost twice as likely to develop advanced or spreading prostate cancer as those who don’t drink milk. Another study published earlier this year found that diets high in meat and dairy products were linked to a fourfold increase in risk of death from cancer — which means eating a lot of animal-based foods can be just as dangerous as smoking.

We aren’t 100 percent sure why dairy is so harmful, but its high fat content is at least partially to blame. A study of more than 90,000 women found that those whose diets were high in animal fat had a 40 to 50 percent higher risk of breast cancer compared with women who ate the least animal fat.

Admittedly, we can’t say with absolute certainty that dairy products cause cancer. Proving this beyond all doubt would require a randomized controlled trial: the gold standard of research. But when the likelihood of harm is high, such studies are unethical. That’s why we’ve never done one to prove that tobacco causes lung cancer.

Instead, we say “better safe than sorry” and rely on common sense — and the strong scientific evidence we do have.

Why, then, are we taking the opposite approach by exposing children to harmful foods? Pumping carcinogenic dairy products through the lunch line is like enrolling our kids in one giant, unethical experiment, the results of which are already grim.

The answer is that in today’s politics, profit trumps precaution. Despite the more-than-likely risk, the U.S. Department of Agriculture openly admits that “the Federal Government encourages dairy consumption.” Since the mid-1990s, the dairy industry has received more than billion in federal subsidies and has earned billions more through the National School Lunch Program.

The USDA also manages a dairy “checkoff” program to promote everything from McDonald’s burgers to Domino’s pizza. The program helped McDonald’s sell 6 million extra pounds of cheese in 2009 alone and brought Domino’s pizza to more than 2,000 schools in 2011. It continues to market other unhealthful dairy products, including sweetened milk and yogurt, to children through school breakfast and lunch.

Not only are they quite obviously corporate welfare schemes, these programs are in direct conflict with the USDA’s own Dietary Guidelines for Americans. Meant to help Americans “maintain a healthy weight, promote health, and prevent disease,” the guidelines urge consumers to limit their intake of saturated fat, sodium and sugar.

As it turns out, dairy products are the largest source of this artery-clogging fat in Americans’ diets and one of the top sources of sugar and sodium. Thanks in large part to milk and cheese, one in five school-aged children now has high cholesterol — a precursor to heart disease. A third of children are obese or overweight, and one in three will have diabetes in his or her lifetime.

In the face of these epidemics, I challenge Congress and my fellow advocates for healthful school lunches to think beyond the current regulations. It’s time to open up a larger debate about what should and should not be on our children’s plates — and to let precaution be our guide.

Levin, M.S., R.D., is the director of nutrition education for the nonprofit Physicians Committee for Responsible Medicine.