Matters culinary

I occasionally worry about eating too much sugar. If you spend time reading about cancer, you'll inevitably read something arguing that eating sugar "feeds tumors" and thus should be avoided to the extent possible.

Tumors, after all, are on metabolic hyperdrive compared to normal cells; and glucose, indeed, is the fuel of cellular metabolism. This is why PET scans work; malignant cells suck up and process the radioactive sugar faster than normal ones. But it does not necessarily follow that dietary sugar is like premium unleaded for cancers, in the same way that it doesn't follow that eating fat deposits fat on our bodies. (As they say: It's the calories, stupid.) Cells have elaborate mechanisms for producing their own glucose, which they would do even if one achieved the miserable (and probably impossible) end of eating a diet without sugar. I'm no expert, and this is not the definitive word on the matter, but I found this, and particularly this convincing:

The idea that sugar feeds cancer, if it was true, would understandably terrify anyone. It is this belief, though, that has helped to feed fears of refined sugars and flours and other ‘bad’ carbohydrates.

Recent stories circulating the internet and media have led many people to think that concerns over sugars are real and that they come from upstanding doctors at prestigious institutions. No one can blame them for believing sugar is linked to cancer. There are more than one million websites (a stunning 1,080,000 by last count) capitalizing on this fear and virtually none offering the science.

But it is nothing more than an urban legend, the result of misunderstood and distorted science.
...
But there is no truth to the rumor that sugar causes cancer, or that people with cancer shouldn’t eat sugar because it causes cancer to grow faster, said Dr. Timothy Moynihan, M.D., a cancer specialist at Mayo Clinic, in Rochester, Minnesota. He debunked this popular misconception in a recent article, explaining:

Sugar doesn't make cancer grow faster. All cells, including cancer cells, depend on blood sugar (glucose) for energy. But giving more sugar to cancer cells doesn't speed their growth. Likewise, depriving cancer cells of sugar doesn't slow their growth.

This misconception may be based in part on a misunderstanding of positron emission tomography (PET) scans. Doctors use PET scans to help determine the location of a tumor and see if it has spread. During a PET scan, your doctor injects a small amount of radioactive tracer — typically a form of glucose — into your body. All tissues in your body absorb some of this tracer. But tissues that are using more energy — exhibiting increased metabolic activity — absorb greater amounts.

Tumors are often more metabolically active than healthy tissues. As a result, they may absorb greater amounts of the tracer. For this reason, some people have concluded that cancer cells grow faster on sugar. But this isn't true.

This isn't completely dispositive, and I'm not arguing in favor of eating tons of sugar -- just of not worrying overmuch about enjoying dessert. There may be good reasons to moderate the Ben & Jerry's, but depriving tumors of "fuel" is not one of them.