Studies reviewing lycopene and the incidence of heart disease

 

Cardiovascular diseases are one of the leading causes of death in North America. Scientific evidence indicates that oxidation of low-density lipoproteins, which carry cholesterol into the blood stream, plays an important role in the development of atherosclerosis – the underlying disorder leading to heart attacks and ischemic strokes (1). Antioxidants are believed to slow the progression of atherosclerosis because of their ability to inhibit cell-damaging oxidation (2). Recent studies indicate that consuming the antioxidant lycopene, contained in tomatoes and tomato products, can reduce the risk of heart diseases.

Scientists at Johns Hopkins University report that smokers with low levels of carotenoids are at an increased risk for heart disease (3). Lower blood lycopene levels are also associated with increased risk of coronary heart disease according to studies with Lithuanian and Swedish people (4). Another study of people from 10 different European countries, measured the relationship between antioxidant levels and acute heart disease (5). It was found that the consumption of lycopene in fruits and vegetables may reduce the likelihood of developing heart disease.

Lycopene is a lipid soluble antioxidant that is transported in the blood through lipoproteins. The absorption of lycopene and other carotenoids, including beta-carotene and vitamin E, has been shown to prevent the oxidation of LDL (or bad) cholesterol (6).

At the University of Toronto, a recent study investigated the effects of tomato lycopene on LDL oxidation. People consumed one-to-two servings per day of tomato juice, spaghetti sauce and concentrated lycopene for one week. Blood samples were collected and analyzed for lycopene, blood cholesterol and oxidized LDL. Lycopene levels were doubled by the consumption of tomato juice, spaghetti and concentrated lycopene. Although there was no change in cholesterol levels, the level of oxidized LDL was significantly lowered as a result of lycopene consumption through tomato products (7). The study results suggest that consumption of tomato products inhibits oxidative damage of LDL cholesterol, and thus may be helpful in reducing the risk of heart disease. The consumption levels from this study are consistent with current dietary guidelines for healthy eating. A glass of tomato juice, a serving of tomato soup or four tablespoons of ketchup can be part of the recommended daily consumption of fruits and vegetables.

References

  1. Steinberg D., Parthasarathy S., Care T.E., Khoo J.C., Witztum J.L. Beyond cholesterol: Modifications of low-density lipoprotein that increases its atherogenicity. N Engl J Med 1989: 320:915-924.
  2. Parthasarathy S. Mechanisms by which dietary antioxidants may prevent cardiovascular diseases. J Medicinal Food 1998; 1:45-51.
  3. Street D.A., Comstock G.W., Salkeld R.M., Schuep W., Klag M.J. Serum antioxidants and myocardial infarction. Are levels of carotenoids and alpha-tocopherol risk factors for myocardial infarction? Circulation 1994; 90:1154-1161.
  4. Kristenson M., Zieden B., Kucinaskiene Z., Elinder L.S., Bergdahl B., Elwing B., Abaravicius A., Razinkoviene L., Calkauskas H., Olsson A. Antioxidant State and Mortality from Coronary Heart Disease in Lithuanian and Swedish Men: Concomitant Cross Sectional Study of Men Aged 50. BMJ 1997; 314:629-633.
  5. Kohlmeir L., Kark J.D., Gomez-Garcia E., Martin B.C., Steck S.E., Kardinaal A.F.M., Ringstad J., Thamm M., Masaev V., Riemersma R., Martin-Moreno J.M., Huttunen J.K., Kok F.J. Lycopene and myocardial infarction risk in the EURAMIC study. Am J Epidemiol 1997; 146:618-626.
  6. Linseisen J., Hoffmann J., Riedl J., Wolfram G. Effect of a single dose of antioxidant mixture (vitamin E, carotenoids) on the formation of cholesterol oxidation products after ex vivo LDL oxidation in humans. Eur J Med Res 1998; 3:5-12.
  7. Agarwal S., Rao A.V. Tomato lycopene and low-density lipoprotein oxidation: a human dietary intervention study. Lipids 1998; 33:981-984.