Lycopene Benefits & Human Health
Despite decades of research, we are still learning about lycopene benefits and their role in human health. There are literally hundreds of research studies in progress around the world right now attempting to add to our understanding of:
- Does lycopene help prevent the onset of chronic diseases in humans?
- Does lycopene benefit those with established chronic diseases?
- How does it work? What are the mechanisms involved?
As you would expect, there is much debate within the scientific community. We describe below and elsewhere the current state of the science.
Where is the Best Evidence for Lycopene Health Benefits?
Lycopene is sometimes presented as a panacea, a miracle-substance that cures everything from prostate cancer and heart disease to asthma and baldness! For some conditions, those shown towards the top of the pyramid below, many studies and trials have suggested a beneficial effect of a lycopene-rich diet. However, as you move towards the base of the pyramid, the supporting evidence becomes steadily weaker.
There is a strong and growing research base to support the health benefits of a lycopene-rich diet in relation to some important conditions, most notably those relating to the prostate, the heart, the breast and the skin.
The evidence to support each of these claims is examined in detail elsewhere on this site but we implore you to read our comments on the nature of scientific advancement before moving on in order to put the state of the current research in context.
Possible Lycopene Health Mechanisms
Scientists have put forward many ideas to explain trial results that suggest health benefits associated with lycopene consumption. One theory is that carotenoids, including lycopene, help cells in our bodies to communicate with each other. We know that the lack of such inter-cell communication can contribute to the development of diseases such as cancer.
Another, more popular, theory is that lycopene (of all the carotenoids) is an excellent anti-oxidant which removes potentially damaging free radicals from the body. Indeed, this mechanism is proven beyond doubt in plants where excess sunlight would cause irreparable damage if it were not for the presence of carotenoids.
Our own research has shown that the presence of vitamin C reactivates “spent” lycopene, prolonging the anti-oxidising effects of the supplement. To see how this works, consider the dangerous nitrogen dioxide free radical found in exhaust fumes and cigarette smoke:
Phase 1: Antioxidant Effect
The damaging free radical is quenched by the lycopene antioxidant but in so doing, the lycopene becomes “spent”.
Phase 2: Reactivated Lycopene
The spent lycopene molecule is reactivated by the vitamin C such that it is ready to quench another poisonous free radical.
Another complication arises because lycopene occurs in many different “twisted” forms, called isomers. Some scientists claim special benefits for certain of these twisted versions of lycopene.
Some scientists have proposed reasons why lycopene might be more beneficial than other carotenoids in relation to prostate cancer and other diseases.
For example, Professor Stahl of the University of Dusseldorf has shown that lycopene is the most effective carotenoid anti-oxidant in removing one of the most important and damaging species of oxygen, known as singlet oxygen.
It has also been established that tomato lycopene accumulates better than any other carotenoid in the prostate gland.
The Need for More Extensive Trials
Whilst there have been some notable trials in this field, it is absolutely clear that more and larger studies are required. The sample sizes are too small and the variables too numerous to be able to attribute positive observed effects to lycopene and lycopene alone.
Indeed, our very own Professor Barber has published on how difficult it is to separate the health effects of tomatoes from those of vegetables in general. It is probably true that lycopene intake is a good marker of general vegetable and fruit intake, and that people who eat large amounts of fruit and vegetables tend to be those who are more health conscious and may well avoid high cancer risk behaviour. On the other hand, those same people are more likely to seek health screening services and to be diagnosed with chronic diseases when they are present.
“Evidence to date supports the beneficial role of lycopene in human health. Ongoing human intervention studies and other studies planned for the future will undoubtedly strengthen the existing scientific evidence. It will then be up to government agencies to allow appropriate health claims for lycopene and the food and related industries to use innovative strategies to promote the intake of lycopene that is consistent with maintaining good health”.
Dr A. V. Rao,
Editor and Professor Emeritus,
University of Toronto