Butter and Cancer

Health-related social media is all abuzz about some recent findings regarding increased cancer mortality rates associated with butter consumption. Since we’re rapidly approaching Thanksgiving, the day when many of us consume more butter in one meal than we do in a normal month, I thought it would be appropriate to look as this issue.

First of all, whenever studies come out talking about increased risks of dying from a particular disease from engaging in a particular behavior, I think it’s important to look at how meaningful the increased risk actually is. The large study I’m about to discuss found an increased risk of mortality from all types of cancer in those with the highest butter consumption of about 12%.

Now, that doesn’t mean that 12% more of the population will die from cancer from eating butter. That’s a 12% increase over the usual cancer death rate. The lifetime cancer mortality rate (the proportion of the population that will die from cancer, rather than something else) is about 20%, depending on what study you look at and gender. So, about 20 people out of 100 will die from some form of cancer. A 12% increase in that would raise the number to 22 to 23 people out of 100. And that increase is seen in the highest consumers of butter, so we’re not exactly talking about a butter-related cancer epidemic.

It’s important to note that what was studied was cancer mortality, not cancer development. There was no investigation into whether butter caused people to get cancer. It might simply be that it causes those with cancer from other causes to die at a higher rate for some reason. But again, a 12% increase is still not really as ominous as it sounds.

In addition, the study in question, although it was carried out over many years and had a lot of test subjects, had some limitations. One of the big ones is that it didn’t distinguish between butter and margarine. Back when the study was initiated in the early 1990’s, margarine still contained trans fats, which are now known to… increase cancer risk. Trans fats weren’t phased out until the study had been ongoing for over 10 years. Even so, when possible margarine “contamination” of the statistics is considered, there probably is still a slightly elevated risk in those with high butter consumption, although it’s likely even smaller than just discussed.

Another interesting point in this study is that the increased risk from butter consumption wasn’t seen when it was used in cooking and baking, just in those who used it mainly as a condiment, such as spreading it on bread or putting it on cooked vegetables. The researchers proposed that perhaps this was due to less frequent consumption of butter in cooked/baked foods or maybe the fact that not all of the butter used in cooking is always consumed (for example, butter left in the pan after frying with it), therefore leading to an overestimation of intake. In any case, the reason for the cooked versus uncooked consumption is a matter of conjecture.

Overall, while this study does raise a small red flag on butter consumption, the risk of increased cancer mortality is pretty small. If you are concerned about it, it’s not too difficult to simply use less. And given the study findings, the most important shift would be to not use as much in condiment form – perhaps dip bread in seasoned olive oil rather than slather it in butter, and/or use other seasonings in place of butter on cooked vegetables.

But given the relatively small risk seen in the highest butter consumers, as long as you use it in moderation (maybe give yourself a pass for Thanksgiving dinner), the contribution of butter to your eventual demise will probably be pretty insignificant.

Until next time…

George F. Best, D.C.