Chocolate: The New Health Food?
Chester J. Zelasko, Ph.D. | December 1, 2006

In the spirit of the holiday season, and in light of some interesting research, I thought it appropriate to talk about one of our favorite foods--chocolate. For years, chocoholics have claimed that chocolate must be a health food because they feel better when they eat it. It turns out they may be right!

Here’s a brief review of the latest research--but before you reach for that chocolate candy, be sure to read the entire Newsletter.

Cardiovascular Health
In the first study of the possible benefits of chocolate that caught my attention, researchers examined the effects of dark chocolate and white chocolate on patients recently diagnosed with hypertension who had not started a treatment plan (1). In a cross-over study, subjects either received 100 grams of dark chocolate or 90 grams of white chocolate for 15 days. Those who ate dark chocolate had an average decrease in systolic blood pressure of 12 mm Hg and a decrease in diastolic blood pressure of 8 mm Hg. In addition, LDL-cholesterol decreased 3.4 mg/dl. One of the key factors in the study is that the subjects remained isocaloric. The calories in the amounts of chocolate used in the study equals about 500 calories. The subjects had to remove 500 calories from fat and sugar in their diets to be replaced by the white or dark chocolate.

In another study, subjects were given dark-chocolate food bars containing plant sterols (2). Sterols are sort of the plant equivalent of cholesterol in animals and have been shown to lower serum cholesterol when used in margarines. In a double-blind, placebo-controlled study, subjects with elevated cholesterol levels who received the dark chocolate food bars with sterols for six weeks lowered their total cholesterol almost 5% and the LDL-cholesterol (the lethal cholesterol) 6%. That’s very significant because for every 1% you lower your cholesterol, you lower your risk of heart disease 2%. While this study included a factor other than dark chocolate, researchers demonstrated that a good-tasting, snack-food bar can have a positive effect on cardiovascular risk factors.

Researchers studied the effects of a single dose of dark chocolate on young volunteers (3). They found that dark chocolate caused a vasodilation of the brachial artery, with the peak dilation occurring about an hour after eating the chocolate. The dilation of blood vessels could explain the decrease in blood pressure found in other studies.

What’s Special About Dark Chocolate?
In a word, phytonutrients. Specifically, this class of phytonutrients is called polyphenols. While the exact mechanism of action is not known, it seems that polyphenols have a beneficial effect on the cells that line arteries known as endothelial cells. In addition, this class of polyphenols also acts as antioxidants and has been shown to prevent oxidation of LDL-cholesterol in test-tube studies (4). That’s important because while LDL-cholesterol is bad, oxidized LDL-cholesterol is very, very bad.

Certainly more research is warranted but this is important, because of all the money spent on foods that contain antioxidants, chocolate ranks third behind fruits and vegetables (4). The key is that most money is spent on milk chocolate, which does not contain as many polyphenols but has more sugar and saturated fat. Education will be a key component of getting people to switch to the right type of chocolate.

Which types of chocolate are those? In a recently published paper, researchers examined the antioxidant, polyphenol, and procyanidin content of various forms of chocolate (5). Natural cocoa powder, baking chocolate, and dark chocolate ranked best in terms of highest levels of antioxidant activity, total polyphenols, and procyanidins, another type of phytonutrient.

Since the holiday season is fast approaching, and the cold weather to go with it, looks like it’s time for home-made hot chocolate made with cocoa powder!

What This Means for You
With each media announcement of studies on the potential benefits of dark chocolate, health experts express their concern because even dark chocolate contains fat and sugar. As mentioned earlier, education must be part of the process so we make the right choices. And there’s still much more research to go. For example, most studies use 100 grams (3.3 ounces) of dark chocolate. We don’t know if 50 or even 25 grams would get the same positive effect, a smaller effect, or no effect at all. We also don’t know how often you should eat chocolate to get the positive effects: every day, three times a week--who knows?

What should you do? Other than making hot chocolate with cocoa powder, it seems reasonable to eat one ounce of dark chocolate per day. There are two qualifications. First, you must cut out about 150 calories from carbohydrates and fat elsewhere in your diet. The other is that you have to like chocolate. I know chocoholics are saying, “Duh!” but I know that some people will try anything they think will help their health, whether they enjoy it or not. There are many other foods that can lower the risk of heart disease, so try one of those if you don’t like chocolate. But if you love chocolate, an ounce a day together with that apple might just keep the doctor away.

References:
  1. Grassi, D. et al. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. Hypertension. 2005;46(2):398-405.

  2. Polagruto, JA et al. Cocoa flavanol-enriched snack bars containing phytosterols effectively lower total and low-density lipoprotein cholesterol levels. J Am Diet Assoc. 2006;106(11):1804-1813.

  3. Vlachopoulos C, et al. Effect of dark chocolate on arterial function in healthy individuals. Am J Hypertens. 2005;18(6):785-91.

  4. Vinson, JA et al. Chocolate is a powerful ex vivo and in vivo antioxidant, an antiatherosclerotic agent in an animal model, and a significant contributor to antioxidants in the European and American diets. J Agric Food Chem. 2006; 54(21):8071-6.

  5. Miller, KB et al. Antioxidant activity and polyphenol and procyanidin contents of selected commercially available cocoa-containing and chocolate products in the United States. J Agric Food Chem. 2006;54(11):4062-8.
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