Q and A

Q: I'm very interested in SAMe and DHEA, but I am concerned that their antidepressant effects could raise blood pressure in hypertensive people like myself. What would you advise? And, which one is most effective?

A: Thank you for your inquiry regarding SAMe and DHEA for depression. Neither product is contraindicated for those with hypertension. As far as which one works better, this will depend upon the individual. SAMe is specifically indicated for depression, whereas DHEA is a general hormone with many functions including relief from depression. When a person's DHEA levels are low they might suffer from low immunity, tiredness, depression, brain aging and so on. This hormone usually starts to drop in your early 30s. If you are not sure of your DHEA levels, they can be measured through a standard blood test. Many people use both SAMe and DHEA to help alleviate depression.

Q: I read for the first time in your carnosine articles about a pathological process called "carbonylation" which is formed by the accumulation of "carbonyl groups" in proteins. What are "carbonyls"?

A: A carbonyl group is a carbon atom attached to an oxygen atom by a double bond. Proteins are made up of amino acids. Carbonyl groups form in protein when certain amino acid constituents undergo oxidation, when amino acid side chains react with glycating agents or with aldehydes produced by lipid oxidation, and in other oxidative reactions. The resulting carbonyl groups can then react further to form protein cross-links that the body cannot break down. Carbonylation is thus a pathological step in the age-related degradation of the body's proteins. Carnosine appears to be the most effective anti-carbonylation agent yet discovered.

Q: What can you tell me about Gymnema Sylvestre?

A: Gymnema Sylvestre helps to lower blood sugar levels, primarily because it inhibits absorption of glucose. It has been shown that Gymnema can also regenerate insulin-producing beta cells of the pancreas, leading to an enhancement in the production of endogenous insulin, further controlling blood sugar.

Q: I enjoyed reading your article about heterocyclic amines (HCAs), but I'd like to point out that the reduction in HCAs caused by the marinades couldn't have been due to the action of the plant phenolics since those have to be metabolized in the body to work. In the research cited, the reduction in HCAs was detected directly after marinating and cooking. The researchers tested each component of the marinade separately and found that even salt dissolved in water inhibited some of the HCAs. Any idea what could account for it?

A: That's a good point. While substances in plants will help reduce the cancer potential of HCAs in a person's stomach, they can't account for the findings of Livermore researchers that even saltwater could reduce the formation of HCAs. We asked Dr. Jim Felton, one of the original researchers, if he had any new insight into this perplexing finding.

According to Felton, the various marinade ingredients caused some types of HCAs to increase at the same time others were decreasing. That points to a cooling effect, he says, rather than a chemical reaction between the meat and marinade. He's quick to add, however, that this is just conjecture at this point. Meanwhile we would like to point out that researchers in Japan have demonstrated that phenolic antioxidants (green tea, luteolin, caffeic acid and quercetin) suppress the formation of HCAs directly; no metabolism needed.

References

Oguri A, et al. 1998. Inhibitory effects of antioxidants on formation of heterocyclic amines. Mutat Res 402:237-45.

Salmon CP, et al. 1997. Effects of marinating on heterocyclic amine carcinogen formation in grilled chicken. Food Chem Toxicology 35:433-41.

Q: Recently I have read a great deal about vitamin K and how it works in the body. Yet, I am curious about possible toxicities. For optimal effects, what would be an adequate yet safe daily dose of vitamin K?

A: Vitamin K is not stored in the body, and is nontoxic in high amounts. In fact, in one osteoporosis study, up to 45 milligrams per day were used without ill effect. Based on the research, The Foundation recommends 10 milligrams a day-a safe and effective daily dose. The February 2000 issue featured vitamin K and included study references, should you wish to learn more.