Eating a healthy diet is probably one of the more challenging aspects of daily life, especially in North America. Faced with a growing number of people at risk for heart disease because of their diets, doctors and researchers are studying the foods we eat in an attempt to find out how we can counteract this trend. The American Heart Association (AHA) and the Mayo Clinic have issued statements on 2 very different types of food that have positive effects on our health - soy protein and chocolate.
As it turns out, both soy and chocolate contain substances that can help reduce or inhibit the effects of high cholesterol, and specifically low-density lipoprotein (LDL) blood cholesterol levels. LDL, known as the "bad" cholesterol, transports cholesterol from the liver to cells in the body. LDL can build up on the walls of the blood vessels, eventually blocking and damaging the arteries, which in turn causes stroke and heart disease.
The American Heart Association issued a nutritional advisory stating that people with total cholesterol levels of over 240 mg/dL could benefit substantially by eating 25 g to 50 g of soy protein daily. The advisory cited the conclusions of an earlier analysis of 38 controlled clinical studies, which said consuming that much soy protein every day is "both safe and effective in reducing LDL cholesterol by up to 8% in people who have elevated cholesterol levels." Moreover, soy protein actually increased levels of "good" high-density lipoprotein (HDL) by 2.4% or more.
For most adults, cholesterol levels over 200 mg/dL are considered high. Our daily intake of cholesterol should be less than 300 mg, which is roughly equivalent to one egg. However, the typical North American diet tends to be high in animal proteins, and contains a lot of saturated fat and cholesterol - up to 400 mg of cholesterol per day.
Dr. John Erdman, a professor at the University of Illinois who wrote the AHA advisory, explains that substituting soy, which has very low saturated fat and no cholesterol, would be a healthy thing to do. Soy protein, like animal protein, is complete - it contains all the essential amino acids in sufficient quantities to support human life. "I'm not suggesting that people become vegetarians, just that they consider using soy milks, soy nuts, tofu, or some of the new products on the market that you can make milk shakes out of, for example, as an alternative protein source."
The nutrition advisory also stressed the importance of eating intact soy protein - soy that has not been altered during processing. Dr. Mark Messina, an expert on soy protein, who wrote a book entitled The Simple Soy Bean and Your Health, says using soy isolates is a good way to get more intact soy into your diet: "There are many products, such as powders and energy bars, or beverages made with soy isolates that contain 15 or 20 grams of soy per serving."
What if your cholesterol isn't high? Eat soy anyway. Research shows that the positive effects of soy protein are not limited to its impact on cholesterol. It appears that soy protein may also cause the arteries to be more flexible.
Additionally, for men at risk of prostate cancer, data from some studies shows that those same soy-based phytoestrogens and isoflavones that help reduce cholesterol also inhibit the growth of prostate tumors - by as much as 70% in one study.
Another food - that some of us would consider essential to life itself - is also making news. Studies show that some types of chocolate products contain high levels of antioxidant flavonoid compounds. Antioxidant flavonoids are plant-based compounds that limit the harmful effects of LDL cholesterol, and are believed to neutralize free radicals - compounds that can damage the body's cells and cause disease.
Apparently, the type of chocolate we eat matters. Dark chocolate and bittersweet chocolate contain more flavonoids than milk chocolate. Sadly, white chocolate doesn't contain any flavonoids at all.
According to Dr. Donald Hensrud, a nutrition specialist at the Mayo Clinic, dark chocolate also contains a type of saturated fat that doesn't seem to raise cholesterol as much as other types of saturated fat. Cocoa butter, also found in dark chocolate, doesn't appear to have a negative effect either, because it is converted into an unsaturated fat in the liver.
"Milk chocolate will have milk and saturated fat added to it, which may counteract any benefit of flavonoid compounds from the chocolate," Dr. Hensrud says. He also cautions that chocolate contains small amounts of caffeine and other stimulants, which could, in susceptible people, have a very mild effect. "Whether chocolate really does exert an effect on cholesterol, whether we eat enough of it - and whether we should eat enough to see those effects are open questions."
Bottom line? "There may be some theoretic benefits in chocolate, but in terms of saying we should eat chocolate for health, we have to consider other potential drawbacks - such as the calorie content." Perhaps a compromise can be reached, by substituting that mid-afternoon chocolate bar with a chocolate-flavored soy shake 2 or 3 times a week.