Tomatoes for Heart Health: More Evidence From Intervention Studies
TalkingNutrition has reported before on the health benefits of high intakes of tomatoes and tomato-based products over the past few years*. Tomatoes, like all fruits and vegetables, contain a complex and undefined mix of bio-active compounds. The precise mix in each fruit and vegetable depends on many factors including the cultivar used, growing conditions, soil type, degree of ripening, and method of food preparation. Nevertheless, lower rates of heart disease in people consuming higher levels of tomatoes and tomato products are likely to arise from both lycopene, the fat-soluble carotenoid that gives tomatoes their red color, and water-soluble components in the tomato. The effects of the water-soluble parts of the tomato have been shown to improve platelet function, which has been confirmed via an EFSA health claim. Lycopene is currently still being investigated, however it appears that it affects LDL (bad) cholesterol formation and breakdown (see review by Arab & Steck). There may be other effects, as lycopene is a strong antioxidant and affects gene expression.
Recently, a research group led by Gajendragadkar published the results of a clinical trial looking at the effects of lycopene on blood vessel function. They recruited two separate study populations: healthy volunteers with no cardiovascular disease or major risk factors, and people with stable cardiovascular disease who were being treated with statin medication. Healthy volunteers and cardiovascular disease patients were both randomized to either a 7 mg lycopene supplement, or placebo, for 8 weeks. This dose was equivalent to a serving of meatballs in tomato sauce, a cup of watermelon, or half a bowl of tomato soup, according to the USDA Food Database. The primary outcome measure was change in forearm blood flow: higher blood flow indicates a better blood vessel function. Better functioning blood vessels are an indication of a healthier cardiovascular system, and reduce risk of a heart attack.
After 8 weeks of treatment, there was an improvement in blood vessel function seen in the cardiovascular disease patients who were supplemented with lycopene, and a positive trend seen in the healthy volunteers. No changes were seen in the placebo groups. In addition, an increase in serum lycopene levels was also correlated with an improvement in blood vessel function. There was also a non-significant decrease in blood pressure of around 3 mmHg in the cardiovascular disease patients supplemented with lycopene.
This study showed that lycopene supplements could improve measures of blood vessel function in people with cardiovascular disease who are already receiving treatment. There was some evidence that people who have lower serum levels of lycopene (due at least in part to lower consumption of lycopene-rich products) had a better response to the treatment. The dose used in the study was about twice that of what is consumed in the average diet in the United States (see page 132 for lycopene values). People with low consumption of foods containing lycopene, especially tomato-based juices, soups and sauces, may benefit from increasing their intake.
*As Pubmed, my normal go-to for scientific research, appears to be on the blink today, please see a list below of our reports with links to original citations about tomatoes and health:
Bird, Julia. What Is It About Tomatoes That Makes Them Good For the Heart? May 21, 2013. http://www.dsm.com/campaigns/talkingnutrition/en_US/talkingnutrition-dsm-com/2013/05/20130521-lycopene-cardiovascular-disease-br-j-nutr-jacques-heart-healthy.html
Bird, Julia. What Do Quitting Smoking, Exercising More, and Eating More Pizza and Pasta Have in Common? Dec 10, 2012. http://www.dsm.com/campaigns/talkingnutrition/en_US/talkingnutrition-dsm-com/2012/12/20121211-lyc.html
McBurney, Michael. Did You Consume Enough Tomato Concentrate Today? Jan 20, 2012. http://www.dsm.com/campaigns/talkingnutrition/en_US/talkingnutrition-dsm-com/2012/01/20120120tomato.html
Parag R. Gajendragadkar, Annette Hubsch, Kaisa M. Mäki-Petäjä, Martin Serg, Ian B. Wilkinson, Joseph Cheriyan. Effects of Oral Lycopene Supplementation on Vascular Function in Patients with Cardiovascular Disease and Healthy Volunteers: A Randomised Controlled Trial. June 09, 2014 DOI: 10.1371/journal.pone.0099070
Arab L, Steck S. Lycopene and cardiovascular disease. The American Journal of Clinical Nutrition 2000;71(6):1691s-5s. http://ajcn.nutrition.org/content/71/6/1691s.abstract
Dutta-Roy AK, Crosbie L, Gordon MJ. Effects of tomato extract on human platelet aggregation in vitro. Platelets 2001;12(4):218-27. doi:10.1080/09537100120058757
European Food Safety Authority. Scientific Opinion of the Panel on Dietetic Products, Nutrition and Allergies. Water-soluble tomato concentrate (WSTC I and II) and platelet aggregation Scientific substantiation of a health claim related to water-soluble tomato concentrate (WSTC I and II) and platelet aggregation pursuant to Article 13(5) of Regulation (EC) No 1924/20061. The EFSA Journal (2009) 1101, 1-15. http://www.efsa.europa.eu/en/scdocs/doc/1101.pdf
O'Kennedy N, Crosbie L, Whelan S, Luther V, Horgan G, Broom JI, Webb DJ, Duttaroy AK. Effects of tomato extract on platelet function: a double-blinded crossover study in healthy humans. The American Journal of Clinical Nutrition 2006;84(3):561-9. http://ajcn.nutrition.org/content/84/3/561.abstract