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Chocolate. It's the food we love to hate. We alternately cast aspersions and praise on the rich, sweet stuff. It contains saturated fat and caffeine, as well as ample amounts of sugar. But it has also been hailed for its ability to boost mood, and some say it contains compounds that can increase immunity and protect against heart disease. So what's the real truth about our favorite legal drug?
Let’s start with cocoa butter, the fatty part of pure dark chocolate. The good news: chocolate’s main fat, stearic acid, doesn’t seem to raise LDL, the really bad cholesterol that makes heart surgeons both over-worked and rich. In a study reported in American Journal of Clinical Nutrition (1), researchers checked the blood lipids (total cholesterol, LDL, etc.) in 42 healthy men, then gave them either a milk chocolate bar or a low-fat snack. The theory was that stearic acid and a few associated antioxidants would reduce cholesterol enough to make up for the fat in the added milk. After seven weeks, researchers rechecked the subject's blood lipids, and found their cholesterol and LDL stayed the same.
Sounds great, but we have to look at some details. The first hint that all was not completely smurfy in chocolate-land comes in the research’s location and funding: Pennsylvania State University and the American Cocoa Research Institute. (Does Hershey, Pennsylvania ring a bell?) Then there’s the size of the experimental group: more people than you’d want to share your chocolate with, but not enough to generate much in the way of statistical "power"--that elusive ability to say that a study hasn’t simply missed an important difference. All of that leads us to a more recent, larger and happily non-industry-funded piece of research: Dietary Saturated Fats and their Food Sources in Relation to the Risk of Coronary Heart Disease in Women(2).
No shortage of bodies for this one: 80,082 nurses filled out dietary surveys, from which researchers could figure out how much of this or that fatty acid was being consumed. The nurses were then followed for more than 14 years for "outcome measures"--not effete laboratory values like LDL, but down-and-dirty stats like heart attacks and deaths. And there were, unfortunately, plenty. Even more unfortunately for chocolate fans, they happened more often in the high stearic-acid-eating group. Perhaps these poor stats resulted from the nasty company our apparently benign fatty acid keeps: beef tallow.
Turns out beef fat contains nearly as much stearic acid as cocoa butter. But a close reading reveals chocolate was only fifth on the list of the study subject’s dietary stearic acid sources, steaks being A-1. Beef consumption, then, was what researchers used to generate their numbers, which raises the question: Do we trust the scientists’ ability to tease out stearic acid’s effect from all the other bad fats in red meat?
A greasy conundrum, indeed. On one hand we have a study showing chocolate probably won’t raise your cholesterol, an experiment that was weak and biased, but at least used the foodstuff in question. On the other we have a long-term population study--the bottom line to showing how preventive and dietary issues actually effect life spans--which reveals that cocoa butter’s main fatty component paves the way to the ICU, but doesn’t really look at cocoa butter itself. Add to that a couple of studies which report that compounds called polyphenols in chocolate can boost immunity and reduce the risk of heart disease by preventing LDL cholesterol from oxidizing and clogging the arteries (3, 4).
The studies have markedly conflicting results, so let’s call it a draw: chocolate is unlikely to increase your cardiac risk by much, but don’t be going Swiss and doing three ounces a day of the stuff.
What about caffeine? I’m always hearing patients--thin, vibrating ones like yours truly, who avoid coffee like the plague--tell me how chocolate makes them even jumpier. No studies to review here; this is the stuff of biochemistry. Hot cocoa, for instance, contains just 4 mg. per serving, similar to instant decaf and way short of the 80-plus mg. in a cup of full leaded. But caffeine is a member of the methylxanthine family, which also includes theobromine, cocoa powder’s main stimulant. Theobromine can certainly wake you up, though it doesn't have caffeine's palpitating cardiac effects.
And then there’s chocolate as a love drug--or at least a drug we love. The active ingredients in cocoa powder are said to release endorphin, the brain’s pleasure-chemical, a neurotransmitter also released by opium, love and other addictive things. And it has been shown that a chocolate bar does, in fact, raise endorphin levels. But not because it's chocolate, as we see in our third study, Pharmacological Versus Sensory factors in the Satiation of Chocolate Craving (5). Thirty-four chocolate-obsessed women and men were given either a chocolate bar (cocoa powder, cocoa butter, sugar, etc.), white chocolate (fat and sugar without cocoa products), six capsules of cocoa powder alone or six capsules of a pure placebo.
Guess what? The first two fatty, sugary compounds soothed the savage beast almost equally; the third and fourth did zip. It wasn’t perfect research--a few subjects couldn’t keep away from their personal stashes for even the necessary 90-minute fast before each trial; another gave chocolate up, mid-test, for Lent. Still, it was enough to say that chocolate is no more a drug than any other fatty, sugary substance.
So let's summarize a bit, starting with cocoa butter’s stearic acid. For all its theoretic innocence, at least one major study puts it next to beef and dairy fat in the things-to-avoid category, and it should be consumed with a measure of restraint. On to the caffeine issue: yes, cocoa powder has only a little, but it does contain theobromine, a stimulating cousin to caffeine. Finally, if you love the confection to excess, you’re not addicted--it’s just because it’s lovable.
1.Chris-Etherton, et.al., American Journal of Clinical Nutrition,1994, Vol. 60:1037S-1042S
2. Hu, et.al., American Journal of Clinical Nutrition, 1999, Vol. 70:1001-1008
3. Letter to the Editor. 1996 Sep 21;348(9030):3-5.
4. Sanbongi C, Suzuki N, Sakane T. Cell Immunol 1997 May 1;177(2):129-36.
5. Michener, et.al., Physiol. Behav., 1994, Vol.56:419-422
Barry Burnett, MD, MPH, practices family and preventive medicine in Boulder, Colorado.
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