For people with type 2 diabetes, tomato juice may help stave off the heart troubles that often complicate the disease. Researchers have found that drinking tomato juice for three weeks had a blood-thinning effect in people with the disease. The juice reduced "platelet aggregation" — the blood’s ability to clot.
If corroborated by larger studies, the finding may one day also help "individuals with increased clotting tendency such as smokers, long-distance air travelers (deep vein thrombosis), etcetera," said Manohar L. Garg, one of the authors of the letter detailing the results. Garg is an associate professor of nutrition and dietetics at the University of Newcastle in Australia.
"When platelets aggregate, they form the plug that clots the vessels," explained Dr. Stuart Weiss, a clinical assistant professor of medicine at New York University School of Medicine. "In diabetes patients, platelets are more sticky." Platelets are responsible for the blood’s ability to clot which, in the case of an injury, is a good thing. Clotting can go too far, however, and cause strokes, heart attacks and other life-threatening problems.
As a result of this excessive "stickiness," for instance, people with type 2 diabetes have an increased risk of atherosclerosis and cardiovascular problems, such as heart attack and stroke. Anti-clotting medications have been shown to reduce this risk.
"In diabetes, there are a lot of pro-inflammatory markers that contribute to increasing platelet aggregation, so if there’s something we can do that can reverse or limit that, that would be a very positive thing," Weiss added.
Consumption of tomato products has been shown to reduce the incidence of various heart ailments, so the researchers behind the research letter decided to test the hypothesis in people with type 2 diabetes.
For the study, they recruited 14 men and six women aged 43 to 82 years old with type 2 diabetes but no prior history of clotting problems. None was taking aspirin, nonsteroidal anti-inflammatory drugs or other medications that might influence clotting. The participants were randomly assigned to drink 250 milliliters of tomato juice or a placebo — a tomato-flavored beverage — every day for three weeks. All were instructed to maintain their normal diet.
Blood samples were collected at the beginning and at the end of the study, then analyzed. Platelet aggregation turned out to be significantly lower at the end of the trial for the group drinking tomato juice. There was no significant difference in platelet aggregation in the placebo group.
It’s not clear why the juice had this effect, Garg said. Knowing why could be instrumental in helping to decide if tomato juice needs to be part of a dietary plan for those with type 2 diabetes.
"Mechanisms of how tomato juice inhibits platelet aggregation need to be delineated prior to issuing practical recommendations," said Garg. "A substance named P3 has been isolated from the yellow, jelly-like fluid around the seeds of the tomato… P3 has been shown to possess anti-aggregatory effects."
For now, a little tomato juice may be a fine thing for diabetics, but don’t overdo it.
"There’s some sugar in tomato juice but it’s not particularly large," Weiss said. "Depending on your blood glucose control, you don’t necessarily want to have a lot. It’s also acidic so your stomach can get a little unhappy with large amounts."
In time, Weiss predicted, "we’ll find that more and more vegetables and more and more foods have things in them that keep us healthy."
The finding appears in a research letter in the Aug. 18 issue of the Journal of the American Medical Association.