Lycopene Benefits & Heart Disease

More than 100,000 people die from coronary heart disease each year in the UK, making it the country’s number one health problem. Someone suffers a heart attack every 2 minutes and the death rate in the UK from this disease is one of the highest in the world.

Coronary heart disease results from atherosclerosis, a condition in which artery walls thicken as the result of a build-up of fatty materials such as cholesterol. As the coronary arteries narrow, patients will often experience chest pain or tightness, known as angina. In severe cases the blood supply can be cut off completely and a heart attack occurs. If an artery in the brain becomes blocked this can trigger a stroke to occur. 

By the time that heart problems are detected, the underlying cause is usually quite advanced, typically having progressed for decades. There is therefore an increased emphasis on preventing atherosclerosis by modifying risk factors such as healthy eating, exercise and avoidance of smoking.

Heart Disease Research

The causes, prevention and treatment of all forms of heart disease remain active fields of biomedical research, with thousands of scientific studies published. Since the early 2000s, numerous studies have shown a link between fast food and an increase in heart disease and researchers have also shown that the so-called "Mediterranean diet" reduces the risk of heart disease. One component of the Mediterranean diet is tomatoes and many researchers have claimed that the lycopene in tomatoes is one of the keys to the heart disease benefits of the Mediterranean diet.

Over 50 medical/biochemical studies have concerned the possible role of tomato lycopene, for example, as an anti-oxidant to reduce atherosclerosis via reduced oxidation of cholesterol. The majority show a benefit for lycopene but some show little or no correlation.

Cholesterol is an essential body fat (lipid), that is carried around the body in the blood. Cholesterol is required by the body to keep itself healthy, but too much cholesterol circulating in the blood is a health risk.

Cholesterol binds to special proteins to make lipoproteins, of which there are 2 main types:

• Low density lipoproteins (LDL) - too much LDL in the blood can build up on artery walls and may give you an increased risk of coronary heart disease;
• High density lipoproteins (HDL) - this is good for maintaining the health of the heart and preventing the narrowing of the arteries because it carries cholesterol away from the arteries and back to the liver for disposal;

It is well established that oxidation of the lipids in LDL ultimately lead to heart disease. One theory is that oxidising free radicals, arising for example from pollution or smoking, cause oxidation of LDL and this leads to atherosclerosis. Further, it is suggested that reduction of such oxidation by anti-oxidants may be a way to reduce heart disease. Lycopene is one of the best anti-oxidants known and, not surprisingly, studies of lycopene as a way to fight heart disease have been of significant interest for well over 10 years. Despite many such studies rather few ‘dietary intervention’ studies have been made.

Notable Trials

With so many trials perhaps it is not surprising a range of results are reported – almost all use different amounts of anti-oxidants, methods of assessment and, of course, risk factors may well be different depending on the country of origin of the people assessed.

Overall, it seems about two-thirds of the epidemiological trials show a benefit for dietary lycopene while one third do not. In some cases this ‘failure’ may well be due to low daily intakes of lycopene and the need for the lycopene level to be above some ‘threshold' level for effective protection. Most of these trials have been compared by Dr Rissanen from the School of Public Health and Clinical Nutrition at the University of Kuopia, Finland (several well-respected trials have come from scientists in Finland). Quoting from her conclusions:

"The findings from epidemiological studies support the claim that higher blood or tissue levels of lycopene or higher intake of lycopene from dietary sources are beneficial in the prevention of atherosclerosis and CVD [cardio vascular disease]. However, there are still many questions concerning the role of lycopene and tomato products in cardiovascular health and more studies will be needed to clarify this association. In addition a large intervention study would help to evaluate the relation between the intake of lycopene (or tomatoes and tomato products) and the risk of CVD."

Another important report comes from the so-called EURAMIC study. This multi-centre, multi-national trial examined the lycopene level in fat tissue against the incidence of heart attack. This study reported, for example, that men with the highest concentration of lycopene had a 48% reduction in developing heart disease compared to those with the lowest lycopene concentration.

An intervention study (i.e. supplementation of the diet with lycopene capsules) on blood pressure (called hypertension) has been reported by Dr. Paran, from Ben Gurion University. She only studied people with slightly raised blood pressure and the trial used 15 mg lycopene per day from lyc-o-mato capsules.

Of course, raised blood pressure is a most common risk factor for heart disease and Dr Paran measured the effect of the added lycopene for 2 months on both the systolic and diastolic blood pressure. This was a ‘double-blind’ pilot study but showed promising results. Typically, the trial showed a drop in the systolic blood pressure from 144 to 134 and in the diastolic from 87 to 83. While these results are encouraging it must be emphasised that it was a small trial and a short trial on patients with low grade hypertension. Clearly a longer and much larger trial is needed. However, the results given are claimed to be ‘clinically significant’.

Possible Mechanisms

In the fight against heart disease, it seems likely that more than one mechanism is at work. Certainly the value of lycopene as an antioxidant in the prevention of cholesterol (LDL) oxidation is likely to be important. However, evidence for other possible mechanisms is accumulating.

One suggestion concerns a decrease in cholesterol synthesis. Another proposed mechanism concerns an improvement in communications between cells in our body. In diseased cells this inter cell communication is less efficient, but carotenoids in general, including lycopene, seem to improve this communication mechanism via a ‘gap junction’ gene called connexion 43.

Clearly more research is needed to decide for certain if lycopene can help the fight against heart problems and how it may work in such protection.

References

• Kohlmeier, L., Kark, J. Gomez-Gracia, E., Martin, B.C. et al. (1997) Lycopene and myocardial infarction risk in the EURAMIC study Am. J. Epidemiol, vol 146, pages 618-626
• Paran, E. (2006) Reducing Hypertension with Tomato Lycopene In A. V. Rao (Ed) Tomatoes, Lycopene & Human Health. Caledonian Science Press, pages 169-181 
• Palozza, P., Parrone, N., Simone, R.E., Catalano, A. (2010) Lycopene in atherosclerosis prevention: An integrated scheme of the potential mechanism of action from cell culture studies. Arch. Biochem. Biophys., vol 504, pages 26-33

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