Research Review: Dark Chocolate And Lycopene
Chester J. Zelasko, Ph.D. | January 10, 2006

One of the things that frustrates me is to read something in the newspaper, a magazine, or on the web that goes something like this:

Researchers reported that rubbing whipped cream on your thighs will decrease body fat.

I’d like to know more, but too often they don’t report the names of the researchers, don’t say when the study was published, and sometimes don’t even give the journal name. How can we verify the information?

This is the beginning of the sixth year of the Better Life Newsletter. In that time, we’ve explained controversies in science and medicine, examined wild claims for miracle products and identified urban health myths. We will continue to do that, but I also want to add some perspective on recent research--not just an unsubstantiated statement that sounds provocative but what the research behind the statement really says. This Newsletter starts with two such pieces of research. By the way, I made up the whipped cream thing--I just figured it would get your attention.

Dark Chocolate May Reduce Blood Pressure
This is the headline we all wish were true--and it appears that it is, with couple of important qualifications.

First, the research. Scientists in Italy recruited 20 subjects with essential hypertension who were never treated for the condition to participate in the study. Essential hypertension means the person has high blood pressure, but there’s no known cause; that includes over 90% of those with hypertension. Subjects were kept chocolate-free for seven days, then given either dark chocolate or white chocolate for 15 days. Then after another seven-day chocolate-free phase, the subjects reversed groups and were tested again for another 15 days. The results demonstrated that subjects who ate the dark chocolate significantly lowered their systolic blood pressure--12 mm Hg--while those who ate the white chocolate did not receive the benefit. Researchers attributed the benefits to specific phytonutrients found in cocoa called flavonals, which are absent from white chocolate.

What You Need to Know: Before you run to the store and buy dark chocolate, there are three important points about this study.
  • The subjects were kept isocaloric; 100 grams of dark chocolate or 90 grams of white chocolate contain almost 500 calories, and the chocolate wasn’t just added to their diet. Researchers took out other foods (not fruits and vegetables) to keep the calorie level the same.

  • The study was only 15 days long. Longer studies should be conducted with varying amounts of dark chocolate to determine what minimal dose of dark chocolate will give the maximum effect.

  • This study does not mean that anyone is relieved from doing those things that should be done for hypertension. Exercise, eating a better diet with more fruits and vegetables, and losing weight if necessary all still come first.
Bottom Line: Instead of your typical dessert, eating a piece of dark chocolate instead might just prove to be healthy for you.

Whole Tomato Concentrate Is Better Than Lycopene Alone
Prior research has shown that men who eat a significant amount of foods containing lycopene have a reduced rate of prostate cancer. Lycopene is a phytonutrient that’s found in red foods, especially tomatoes. But some researchers wanted to see if there was a difference between whole tomatoes and the lycopene extracted from tomatoes.

The science: If you regularly read the Newsletter, you know that I’m very critical of animal studies when generalized to humans, but that doesn’t mean I don’t believe in the value of animal research as a way to begin to test a hypothesis. In this case, researchers induced prostate cancer in several groups of rats: a placebo group, a group receiving the phytonutrient lycopene, and a group receiving a concentrate made from whole tomatoes. The rats that received the whole-plant concentrate had a lower death rate from prostate cancer than both the lycopene and placebo groups; the rats that received lycopene had a lower death rate from prostate cancer than the ones getting a placebo.

What You Need to Know: What this study demonstrates is that there may be something in the whole plant that exceeds the benefit of a single extract alone--even one as beneficial as lycopene. It doesn’t mean that lycopene is ineffective; studies have shown that lycopene is effective in reducing the risk of prostate cancer and heart disease. But rather than focusing on a single phytonutrient, it may be better to eat the entire food that contains the phytonutrient.

Bottom Line: Until we know more, eat your vegetables and fruits and complement your diet with a food supplement that contains whole-plant concentrates.

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

  2. Boileau, TW et al. Prostate Carcinogenesis in N-methyl-N-nitrosourea (NMU)–Testosterone-Treated Rats Fed Tomato Powder, Lycopene, or Energy-Restricted Diets. J Natl Cancer Inst 2003; 95:1578–86.
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