A friend of mine recently asked me “Is regular soda or diet soda better for you?”

I tried to probe for details.  “Are you talking about calories?  Obviously, if you’re watching your weight or restricting carbohydrates, you should have the diet soda.”

“No, I don’t mean the calories.”

“Oh, you mean the concern that the citric acid might leach calcium out of your body?”

“No.  I just mean overall, are they good or bad for you?”

This precipitated an important revelation that had been percolating in my head for years but that never actually crystallized until now.  People think of things we ingest as generally “good for you” or “bad for you”.  But nothing is globally good or bad.  Everything has specific effects, some positive and some negative.

Amoxicillin is great for Strep throat.  It’s not very useful for lupus or seizures.  Beta blockers are terrific to prevent heart attacks, but make for lousy asthma medicine.  Even water, which is essential for life, is life-threatening if inhaled.  The most universally positive health intervention I can think of is cardiovascular exercise, and even that has some risks, like muscle sprains.

With that in mind I found an interesting study in this week’s New England Journal of Medicine.  The study attempted to prevent a serious potential complication of pregnancy – eclampsia – which is dangerous to both the mother and the baby.  It was thought that antioxidants, like vitamins C and E, could prevent the chemical abnormalities that lead to eclampsia.  And besides, aren’t antioxidants good for you?

The study randomized about 10,000 pregnant women in their first pregnancy.  Half received a daily vitamin E and vitamin C supplement, and half received placebo.  The women and their babies were followed for any signs of eclampsia or pre-eclampsia.  The outcome was disappointing.  The women on the vitamin supplements did no better than the women on placebo.

So vitamin C and E don’t help prevent eclampsia.  Does that mean they’re “not good for you”?  No.  Vitamin C is essential in preventing or treating scurvy.  So if you have scurvy, I strongly recommend it.

Oh, and to answer my friend’s question about sodas, artificial sweeteners are safe as far as we know.  So I would prefer diet sodas to avoid the calories of non-diet sodas.  The only health benefit of sodas is that they contain water, which can be obtained from other sources.

Learn more:

New England Journal of Medicine article:  Vitamins C and E to Prevent Complications of Pregnancy-Associated Hypertension