Dark chocolate contains healthy fats.
Cocoa butter, which is extracted from the cacao bean and incorporated into most reputable dark chocolate bars, is mostly monounsaturated and saturated fat, with very little polyunsaturated fat. And because most of that saturated fat is stearic acid, widely known for having neutral effects on LDL, even avowed lipophobes can happily and heartily gobble up cacao fat.
Dark chocolate contains lots of polyphenols, particularly flavanols.
When it comes to polyphenol content and antioxidant capacity, cacao trounces the “superfruits” acai, pomegranate, cranberry, blueberry and whatever else your annoying friend who always falls for multilevel marketing schemes is hawking this week. The most studied polyphenol in cacao is epicatechin, a flavanol. Although last week’s post on the benefits of polyphenol consumption centered on pigment-derived antioxidants, cacao’s polyphenols are also quite potent and potentially healthful.
What happens when the rubber hits the road, though? Or, somewhat more literally, what happens when the square of polyphenol-rich dark chocolate melts on the tongue, is swallowed, digested, and incorporated into the body? What are the actual health benefits of consuming high-cacao content dark chocolate?
Dark chocolate and blood pressure.
Epidemiological studies pretty consistently show that dark chocolate consumption is related to lower blood pressure readings. In Jordan, among Kuna Indians living in Panama, among pregnant women, and among elderly Dutch, this holds true. That’s all well and good, but it’s just an association. We need controlled studies:
One found that fifteen days of eating dark chocolate, but not white chocolate, lowered blood pressure (and improved insulin sensitivity) in healthy subjects. The main difference between white and dark chocolate is the polyphenol content; both types contain cocoa fat. Cocoa consumption also improved arterial flow in smokers.
Some studies suggest that the flavonoids are key. In one, flavanol-rich dark chocolate consumption improved endothelial function while increasing plasma levels of flavanols (which indicates the flavanols had something to do with it). Another study used flavanol-rich cocoa to increase nitric oxide production in healthy humans, thus inducing vasodilation and improving endothelial function. In another, the highest dose of cacao flavanoids caused the biggest drop in blood pressure. Still another found that while dark chocolate did not reduce blood pressure, improve lipids, nor reduce oxidative stress, it did improve coronary circulation.
Or maybe it’s the soluble fiber. In “spontaneously hypertensive” rats, cacao-derived soluble fiber lowered blood pressure, perhaps by reducing weight gain.
It’s probably both, in my opinion, although the polyphenols undoubtedly contribute more to the cause than the five grams or so of soluble fiber you’ll get in the average serving of dark chocolate.
Dark chocolate and cardiovascular disease.
You’ve heard of the cholesterol-fed rabbit; how about the cocoa-fed rabbit? If the former is an effective vehicle to study the negative effects of poor lipid clearance, the latter is a testament to the inhibitory effects of cocoa polyphenols on lipid peroxidation. We also have similar findings in rodents. Feeding hypercholesterolemic and normocholesterolemic rats polyphenol-rich “cocoa fiber” (defatted, sugar-free chocolate, basically) reduced markers of lipid peroxidation in both groups (PDF). It also seems to work quite well in test tubes.
In humans, both with normal and elevated cholesterol levels, eating cocoa powder mixed with hot water lowered oxidized LDL and ApoB (LDL particle number, which, if you remember my post on lipid panels, you want to lower) counts while increasing HDL. All three doses of high-flavanol cocoa powder – 13, 19.5, and 26 g/day – proved beneficial. If you’re wondering, 26 grams of powder is about a quarter cup. It also works if you drink it with milk (and no, Hershey’s syrup doesn’t work the same).
Given the effects of chocolate on lipid peroxidation, we can probably surmise that it will also lower the risk of cardiovascular disease. And indeed, epidemiological studies suggest that this is the case. In a sample of over 2200 patients (PDF), chocolate consumption was inversely associated with progression of atherosclerotic plaque (determined by calcium scoring). What’s incredible is that the association held for chocolate in general, and I don’t think it’s likely that everyone was consuming 100% raw cacao powder brimming with polyphenols. A study from this year from the same group got similar results: chocolate consumption was inversely associated with prevalent cardiovascular disease.
While most cacao research focuses on vascular function and heart disease risk, there are other, less intensively-studied benefits. Here are a few of them:
Dark chocolate and insulin resistance.
For fifteen days, hypertensive, glucose-intolerant patients received either 100 daily grams of high-polyphenol dark chocolate or 100 daily grams of zero-polyphenol white chocolate. Diets were isocaloric, and nothing differed between the groups besides the type of chocolate. Dark chocolate improved beta cell function, lowered blood pressure, increased insulin sensitivity, and improved endothelial function, while white chocolate did none of those things.
Dark chocolate and fatty liver.
Rats with fatty liver evince higher levels of oxidative stress and inflammation, but cocoa supplementation partially attenuated these pathological changes – even in choline-deficient rats. While cocoa wasn’t enough to fully resolve fatty liver, the researchers concluded that cocoa may be of therapeutic benefit in “less severe” forms of fatty liver.
Dark chocolate and UV damage.
Resistance to UV damage is commonly measured by MED – minimal erythema dose. A higher MED means greater resistance to UV rays, while a lower MED indicates lower resistance. High MED, good. Low MED, bad. One study found that feeding high levels of dark chocolate to healthy people over twelve weeks doubled their MED; feeding low levels of dark chocolate had no effect on the MED.
Similarly, another study found that a high-flavanol-from-cacao group had greater resistance to a given UV dosage than a low-flavanol-from-cacao group (who actually saw no benefit at all) over a six and twelve-week period.
