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From The July 2000 Issue of Nutrition Science News
Nutrition Q&A
with Dan Lukaczer, N.D.
Stevia, the Natural Sweetener
Q: Customers of mine look for natural sweeteners. I like honey but find it inconvenient. Any suggestions?
A: My best suggestion for an easy-to-carry sweetener is stevia, generally available at health food stores in small squeeze bottles. This extract, sold as a dietary supplement, comes from the leaves of a South American shrub, Stevia rebaudiana. The leaves contain a small amount of stevioside, a carbohydrate reported to be approximately 300 times sweeter than sucrose (table sugar). It is widely used in Brazil and Japan as a non-caloric sweetening agent. Other fractions in the leaf may actually have some positive effects on glucose tolerance.1 The data on this health benefit are not all in, but it does appear to be an excellent, easy-to-use sweetener.
The Antioxidant Spice
Q: A customer tells me a spice she uses frequently, rosemary, may do more than just improve the taste of food. Is that true?
Indeed it does. Rosemary (Rosmarinus officinalis) has been used in medicine and cosmetics as well as cooking for thousands of years. Rosemary has been utilized in food not just for flavor, but also as a food preservative because of its ability to prevent the oxidation of fats and oils. It is this oxidation that results in foods becoming rancid.
Rosemary's ability to prevent oxidation in foods led to research on its antioxidant effects. It was found that rosemary contains compounds that act as natural antioxidants to deactivate free radicals.2
Rosemary appears unique, however, in that there is a multilevel cascade to the deactivation of these free radicals. A specific molecule found in rosemary, identified as carnosic acid, starts this cascade. After carnosic acid finds and neutralizes a free radical, it is transformed into another molecule, called carnosol, which in turn neutralizes another free radical. This cascade continues on down through metabolites rosmanol and galdosol in the same way, ultimately neutralizing a whole host of free radicals.
The cascade is probably why rosemary has a significantly higher antioxidant capability than vitamin E, which must be recycled after quenching a free radical before it can quench another. Interestingly, there is some evidence that rosemary, along with its own antioxidant activity, actually recycles vitamin E to do just that.3
Rosemary is therefore a great way to spice up your food and live the adage to let food be your medicine. If you are going to take a rosemary supplement, it would be wise to choose one that is standardized to carnosic acid and carnosol to ensure you are getting that free radical-quenching activity.
Green Tea Cuts Cancer
Q: I have a family history of colon cancer, and a colleague told me I should drink green tea. Is this true?
It is. The good news on green tea (Camellia sinensis) keeps getting better. Tea is one of the oldest beverages in terms of human consumption; next to water, it is the most widely consumed beverage in the world. Epidemiological studies suggest a protective effect of green tea against a variety of cancers, including colon cancer. The way this works is not exactly clear, but there is some evidence to suggest some components in tea have a direct effect on the digestive tract.
Green tea contains polyphenols and a specific family called catechins. Individual catechins have names like epicatechin and epigallocatechin gallate. It appears that most of the benefits of tea can be attributed to these catechins. A study on human volunteers suggested that these catechins increase lactic acid bacteria and decrease putrefactive bacteria in the gut while lowering the intestinal pH.4
A similar effect has been found in animal studies.5 Lactic acid-producing bacteria include lactobacillus and bifidobacterium, gut dwellers with many beneficial effects. Putrefactive bacteria, such as clostridia and enterobacteriaceae, generally appear to have some negative effects. Changing the balance of these bacteria is probably at least one reason green tea appears protective against colon cancer. When you stop drinking tea, not surprisingly the positive effects also stop, so it should probably become part of your daily routine. It is a habit more health-promoting than drinking coffee.
There is some caffeine in green tea—far less than in coffee. Supplementing specifically with green tea catechins in capsule form is likely to have the same positive effects, and there is only a residual amount of caffeine in purified catechins (about 10 percent of catechin content).
Dan Lukaczer, N.D., is director of clinical services at the Functional Medicine Research Center, a division of HealthComm International Inc., in Gig Harbor, Wash.
References
1. Curi R, et al. Effect of Stevia rebaudiana on glucose tolerance in normal adult humans. Brazilian J Med Biol Res 1986;19:771-4.
2. Aruoma O, et al. Antioxidant and pro-oxidant properties of active rosemary constituents: carnosol and carnosic acid. Xenobiotica 1992;22(2):257-68.
3. Fang X, Wada S. Enhancing the antioxidant effect of alpha tocopherol with rosemary in inhibiting catalyzed oxidation caused by Fe2+ and hemoprotein. Food Res Intl 1993;26:405-11.
4. Hara Y. Influence of tea catechins on the digestive tract. J Cell Biochem Suppl 1997;27:52-8.
5. Terada A, et al. Effect of supplements of tea polyphenols on the caecal flora and caecal metabolites of chicks. Microbial Ecol Health Dis 1993;6:3-9.
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