Cocoa—For Your Heart’s Content

Should We Eat More Chocolate?
Man and woman cannot live by chocolate alone,
but the “food of the gods” can be very good for us
By Hyla Cass, M.D.

n 2005, an editorial in the American Journal of Clinical Nutrition that discussed some of the health benefits of cocoa flavonoids bore the tantalizing title, “Cocoa, diabetes, and hypertension: should we eat more chocolate?”1 OK, let’s resist the impulse to say “Duh” while reaching for the nearest 5-pound box of candy. Instead, let’s have a look at some of the scientific evidence that chocolate is good for us. Because it really is—with two catches, and you know what they are: fat and sugar. Just as the health and longevity benefits of red wine (especially from its resveratrol content) are easily overridden by too much alcohol, the fat and sugar in conventional chocolate work against the health benefits of those wonderful flavonoids it contains.

You caught the word “conventional,” didn’t you? It suggests that there are ways around the fat/sugar problem. The trick is to find unconventional chocolate products—more specifically, cocoa-powder products, such as chocolate pudding—that are largely free of fat and sugar but still loaded with rich, chocolatey goodness, so that you can indulge your cravings for the divine flavor to your heart’s content. (Hint: such a product does exist and can easily be found. Good luck, though, in trying to find a nonalcoholic wine that you would actually want to drink.)

Take Cocoa Flavonoids to Heart

Your heart’s content—it’s a charming phrase, and here it has a double meaning because, of all the health benefits chocolate has to offer, heart health is number one. Your heart, therefore, should be made physiologically as well as emotionally happy whenever you partake of a truly healthful chocolate product. The essence of all such products, of course, is the cocoa solids that give chocolate both its flavor and its flavonoids.* The higher the cocoa content, the higher the flavonoid content, which is why dark chocolate is much more healthful than milk chocolate. (Don’t even think about “white chocolate,” which is not really chocolate at all, because it has no cocoa solids, just cocoa butter, a sweet-tasting fat.)

The American authors of a recent review of the effects of cocoa on cardiovascular health stated,2

Several in vivo studies have provided strong support for the hypothesis that the consumption of flavanol-rich foods, such as certain cocoas and chocolates, may be associated with reduced risk for vascular disease. Significantly, in vitro studies with highly purified flavanols and procyanidins [sic] support the hypothesis that many of the biological effects observed with flavonoid-rich foods can be directly attributed to the flavonoids.


*No, flavonoids are not called that because they taste good (they don’t). The word is derived from the Latin flāvus, yellow, because many of these brightly colored plant pigments are yellow; others are red, orange, blue, or purple. Flavonoids (aka bioflavonoids, a synonym—all flavonoids are biological in origin) give most fruits, vegetables, and flowers their characteristic colors. All flavonoids belong to the larger class of compounds called polyphenols, which are known for their strong antioxidant properties.


Flavanols and proanthocyanidins (the correct term in this context) are the types of flavonoid that predominate in cocoa, as well as in tea, apples, and apricots. The authors discuss the well-known antioxidant properties of these compounds in vitro (“in glass,” i.e., in laboratory experiments) while acknowledging that in vivo (“in life,” i.e., in living organisms), other mechanisms of action may predominate. These mechanisms fall into three major categories: (1) modulation of certain cell signaling pathways; (2) regulation of gene expression for certain types of genes; and (3) modification of cell membrane properties and receptor function. (For a surprising revelation about the antioxidant properties of flavonoids, see the sidebar.)

Antioxidants: A Story of Blueberries and Red Herrings

As a rule, the more colorful a fruit or vegetable, the more likely it is to be high in beneficial flavonoids. Berries are particularly rich in these compounds, and blueberries are the berry best of all, being loaded with potent anthocyanins and proanthocyanidins, two types of flavonoids. (On the other hand, blueberries have virtually no flavanols, a kind of flavonoid found abundantly in cocoa and tea.)

Based on a great body of epidemiological research, medical scientists believe that a diet rich in fruits and veggies is vital for good health and antiaging, owing in part to their diverse content of flavonoids and other polyphenols—and the greater the variety of these compounds, the better.1 There is little doubt that they can help prevent some of the major diseases of aging, such as cancer, heart disease, and certain neurodegenerative diseases.

How they accomplish this is an intriguing question, however. It was long believed that the biological activity of polyphenols (including flavonoids) occurred via their antioxidant properties, because experiments with cell cultures have consistently shown that they are, in fact, strong antioxidants—in cell cultures. There’s the rub.

Much evidence obtained over the past decade has suggested that these laboratory results are red herrings. In March 2007, scientists at the Linus Pauling Institute announced that flavonoids actually have little or no value as antioxidants and that their health benefits are likely the result of entirely different biochemical mechanisms.2 It has been proved, they said, that flavonoids are poorly absorbed (usually less than 5%) and that what small amounts do get through to the circulation are rapidly metabolized to derivative compounds and excreted.

In a media release, Dr. Balz Frei, professor of biochemistry and biophysics and director of the institute, was quoted as saying,2

What we now know is that flavonoids are highly metabolized, which alters their chemical structure and diminishes their ability to function as an antioxidant. . . . If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants. . . . But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body. . . .We can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them. But this process of gearing up to get rid of unwanted compounds is inducing so-called Phase II enzymes that also help eliminate mutagens and carcinogens, and therefore may be of value in cancer prevention. Flavonoids could also induce mechanisms that help kill cancer cells and inhibit tumor invasion.

Dr. Frei also stated that the flavonoids (or their bioactive metabolites) strongly influence cell signaling pathways and gene expression, with relevance to cancer, heart disease, and neurodegenerative disease. He believes that the large increase in total antioxidant capacity of blood observed after the consumption of flavonoid-rich foods is not caused by the flavonoids themselves, but is most likely the result of increased uric acid levels.

© iStockphoto.com/
Eva Serrabassa
The above is a classic example of the way science works: an attractive theory, no matter how long in existence, no matter how widely believed or even cherished by its partisans, must be modified or discarded if new and convincing evidence refutes it. There are dogmas in science, but they are written in sand, not stone—they are always subject to change.

Unchanged by all of this, however, is the fact that flavonoids, and the fruits and veggies that provide them, are highly beneficial. Which brings us back to blueberries—we should eat more of them. For a delicious blueberry treat, see the sidebar “A Glycemic Control Recipe” with the interview “Durk Pearson & Sandy Shaw’s 21st Century Weight Loss Program, Part II” (page 14 in the January 2007 issue). A convenient cake mix for this recipe can be obtained.

Reference

  1. Lau FC, Shukitt-Hale B, Joseph JA. The beneficial effects of fruit polyphenols on brain aging. Neurobiol Aging 2005;26S:S128-32.
  2. Anon. Studies force new view on biology, nutritional action of flavonoids. Linus Pauling Institute, media release, March 5, 2007.

The Big Three Cardiovascular Benefits

Whatever the mechanism, the various study results described in the review mentioned above, as well as in a similar review by German authors,3 indicate that cocoa flavonoids improve vascular function and provide protection against cardiovascular disease in three major areas:

  • Inflammation – Cocoa flavonoids suppress the release of various proinflammatory enzymes that are associated with atherosclerosis, congestive heart failure, hypertension, and high cholesterol. These enzymes not only cause or exacerbate tissue inflammation but also produce reactive oxygen species, including free radicals, which damage tissues by attacking their constituent molecules. Cocoa flavonoids also suppress the release of various proinflammatory cytokines, which are small proteins that are involved in immune and allergic responses, among other things.
  • Platelets – Cocoa flavonoids suppress the tendency for blood platelets to aggregate, the process by which thrombi (clots) are formed. Although sometimes necessary for our health or even survival, as in wound healing, blood clots are implicated in heart attack, stroke, and venous thromboembolism. That’s why anticoagulants are important for people at high risk for such potentially fatal events.
  • Vascular endothelium – This is the layer of smooth, flat cells that line the inner walls of our blood vessels; it plays a key role in vascular function, in part by regulating the contraction and dilation of arteries as needed so as to regulate blood pressure. Its condition plays a critical role in the development of, or resistance to, disorders such as hypertension and atherosclerosis. Cocoa flavonoids help maintain healthy endothelial function in various ways, notably by enhancing the production of nitric oxide (NO) and preventing its inactivation by oxidative processes.

NO is the chief mediator of vasorelaxation (reduction in tension in the walls of the blood vessels), which helps to lower blood pressure through vasodilation (dilation of the blood vessels), allowing blood to flow more freely. It thus combats hypertension, which is strongly associated with cardiovascular disease and type 2 diabetes. NO also, however, plays a key role in facilitating the insulin-mediated uptake of glucose by our cells. It thus helps to maintain insulin sensitivity, i.e., it combats insulin resistance, which is the precursor condition to diabetes. Its importance to our health cannot be overestimated.

Dark Chocolate Benefits Hypertensives . . .

Not included in either of the reviews cited above was a recent human clinical trial in Italy comparing the effects of flavanol-rich dark chocolate and flavanol-free white chocolate on various measures of cardiovascular health.4 The subjects were 20 middle-aged, never-treated patients with essential hypertension (hypertension of no known cause, i.e., not attributable to some disease or disorder). For 15 days, two groups of patients ate a 3½-oz chocolate bar of one kind or the other, while abstaining from other flavonoid-rich foods, such as tea and wine; then, after a 7-day washout period, each group switched to the other kind of chocolate for an additional 15 days.

The results showed that dark chocolate produced significant reductions in daytime and nighttime blood pressure as well as in LDL-cholesterol (the bad cholesterol), and it produced significant increases in NO-dependent vasorelaxation and insulin sensitivity. White chocolate, not surprisingly, produced no such effects.

. . . And Healthy People Too

The results described echoed those of a similar study done previously by the same research group, that time using healthy people as subjects.5 As with the hypertensives, their blood pressure and insulin sensitivity were improved by dark chocolate but not by white chocolate. The authors stated, “. . . our study is the first one to show that cocoa may have favorable metabolic effects and thereby further protect against cardiovascular diseases.”

It was that study that prompted the editorial cited at the beginning of this article.1 Its author noted that “Other studies with other flavanol-containing foods, such as tea and wine, have shown similar effects on vascular and blood pressure regulation.” He never did get around to answering the question he raised in the title, but the implication was clear—with the understanding, of course, that we go easy on the fat-and-sugar aspect of chocolate. Which brings us back to cocoa powder.

Things to Know About Cocoa

Commercial cocoa powders are largely fat-free, having only about 10–22% residual cocoa butter. In any case, cocoa must be sweetened to make it palatable, and here it’s important to look for nonsugar sweeteners, preferably natural ones. One compound that fills the bill is erythritol, a sugar alcohol that has about 70% of sugar’s sweetness but only one-tenth the calories. Erythritol does not promote tooth decay (and may even help inhibit it), and it’s well tolerated by the digestive tract—unlike most other sugar alcohols, which have a laxative effect. Erythritol is safe for diabetics, having no effect on blood sugar or insulin levels.

An important thing to know about commercial cocoa products is that many are “Dutched,” meaning that they’ve been alkali-treated to mellow the inherent bitterness of cocoa. The trouble with this process is that it destroys most of the beneficial flavonoids. Thus, consumers who want the health benefits of cocoa should look for products that have not been Dutched. Either way, the initial flavonoid content of cocoa depends on the variety of cacao tree (Theobroma cacao) from which it came, and the final content depends on a variety of factors in the production methods used.*


*For more about cocoa and chocolate, and about cocoa’s possible cardiovascular benefits and tendency to reduce mortality risk, see “Chocolate for Longer and Happier Life” in the May 2007 issue.


Live a Lot!

By the way, did you think we were recommending that you never eat conventional chocolate again, because of the fat and sugar? Of course not! Life without genuine chocolate—are you kidding? What kind of life is that? So go ahead and eat some chocolate, and drink some wine. Live a little! But because you also want to live a lot, i.e., for a good long time, you do have to be careful about things like chocolate and wine (moderation is the key). Fortunately, you can obtain their health benefits in other ways, and in the case of chocolate, it’s a delightfully tasty way. Enjoy!

References

  1. Fraga CG. Cocoa, diabetes, and hypertension: should we eat more chocolate? Am J Clin Nutr 2005;81:541-2.
  2. Keen CL, Holt RR, Oteiza PI, Fraga CG, Schmitz HH. Cocoa antioxidants and cardiovascular health. Am J Clin Nutr 2005;81(Suppl):298S-303S.
  3. Sies H, Schewe T, Heiss C, Kelm M. Cocoa polyphenols and inflammatory mediators. Am J Clin Nutr 2005;81(Suppl):304S-12S.
  4. Grassi D, Necozione S, Lippi C, Croce G, Valeri L, Pasqualetti P, Desideri G, Blumberg JB, Ferri C. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. Hypertension 2005;46:398-405.
  5. Grassi D, Lippi C, Necozione S, Desideri G, Ferri C. Short-term administration of dark chocolate is followed by a significant increase in insulin sensitivity and a decrease in blood pressure in healthy persons. Am J Clin Nutr 2005;81:611-4.


Dr. Hyla Cass is a nationally recognized expert in integrative medicine, an assistant clinical professor of psychiatry at the UCLA School of Medicine, and the author or coauthor of several popular books, including Natural Highs: Supplements, Nutrition, and Mind-Body Techniques to Help You Feel Good All the Time and 8 Weeks to Vibrant Health: A Woman’s Take-Charge Program to Correct Imbalances, Reclaim Energy, and Restore Well-Being.

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