Lycopene Is a Rising Star of Health BenefitsLycopene Protects Skin, Heart, and More
f you plan to spend much time outdoors this summer, you might want to make sure that tomatoes figure prominently in your diet. So look forward to eating plenty of tomatoes and dishes made with tomato sauce, drinking some tomato juice, having a bowl of steaming hot tomato soup (better for you than the delicious cold tomato soup gazpacho), and topping it all off with a big wedge of watermelon. Why should you eat these specific foods? Well, for starters, they are loaded with lycopene. You already knew that lycopene is good for prostate health, but now there's a new and unexpected angle: according to a recent report by European researchers, lycopene protects your skin from damage caused by solar ultraviolet radiation.
LYCOPENE IS A POWERFUL ANTIOXIDANT
Lycopene is a natural carotenoid that has received much attention lately because of its potent antioxidant activity. Carotenoids are common in the plant world and are responsible for giving many vegetables and fruits, such as carrots and tomatoes, their characteristic colors. (You knew that a carrot is a vegetable, but did you know that a tomato is technically a fruit?) These plant compounds are important for much more than just pretty colors, however. Antioxidants such as lycopene (as well as vitamin E, vitamin C, and beta-carotene, a precursor to vitamin A) help to neutralize rogue molecules called free radicals.
Free radicals can greatly damage our bodies' tissues and have been implicated in cancer, cardiovascular disease, diabetes, cataracts, Alzheimer's disease, and others. They also figure prominently in the aging process. These pesky little molecules are hard to escape, as they are all around us and are especially prominent in cigarette smoke and air pollution. To make matters worse, we produce them in our own bodies as natural metabolic byproducts. In addition, the UV rays in sunlight can induce the formation of free radicals in the cells of our skin to generate further oxidative stress.
For many years now, we have understood the dangers of excessive sun exposure. And while it looks nice to have a good tan, exposure to solar UV that results in sunburn dramatically increases the risk of skin cancer. Fortunately, many people now routinely use sunscreen to protect themselves from the sun's harmful rays. Over your lifetime, however, much of the UV exposure you experience is likely to occur when your skin is not protected on the outside.1 For this reason, you should take proactive measures to ensure that your skin is protected from the inside. A good way to do that, it seems, is with lycopene.
TOMATOES PROTECT SKIN FROM UV DAMAGE
German and Dutch researchers have found that diets rich in tomato paste dramatically reduce UV-induced skin damage.1 In a study recently published in the Journal of Nutrition, nine volunteers consumed a diet supplemented with 40 grams (about 1.4 oz, or 3 tablespoons) of tomato paste mixed with olive oil, while ten control subjects received just olive oil (in addition to their normal diet) for ten weeks. The amount of lycopene in the tomato paste was about 16 mg. At the beginning of the study, and again four weeks and ten weeks later, all the subjects were exposed to UV radiation to induce mild erythema (or sunburn, if you prefer a less clinical term) on their shoulders. The participants, aged 26-67 years, were homogeneous in their coloring. They all had lightly pigmented skin, light-colored hair, and blue eyes, and had experienced minimal tanning.
The degree of skin damage (called the a-value) caused by the repeated UV exposures was measured in both groups at the three stages of the study. After the first exposure, both groups had similar a-values (6.0 for controls and 5.6 for those consuming tomato paste), as would be expected for a random sample of individuals. Four weeks later, the a-values caused by UV exposure were slightly lower (5.4 for controls, 5.1 for the test group) but were still not significantly different. At the tenth week, however, UV exposure caused a much lower a-value (3.8) in the tomato-paste eaters than in the controls (6.3). To put this another way, those who ate 3 tablespoons of tomato paste daily for ten weeks had 40% less UV-induced skin damage than those who did not.
LYCOPENE IS THE PROTECTIVE AGENT
One way to explain the results of the erythema study is to look at the level of lycopene in the two groups. By the tenth week, the control group showed an 8% decrease in lycopene levels in their blood, and a whopping 51% decrease in total carotenoids in their skin. Conversely, those who consumed the tomato paste increased their blood lycopene levels by 95% and their skin carotenoid content by 15%. It is likely that the increased levels of lycopene and other carotenoids in their skin cells offered a protective benefit against the UV radiation to minimize skin damage.
Additional experiments support this idea. A separate study at Tufts University revealed that lycopene levels are depleted much more than those of other carotenoids (beta-carotene, for example) in UV-damaged skin when compared to adjacent undamaged skin.2 The researchers concluded from this that lycopene is preferentially sacrificed to protect the skin when UV radiation creates free radicals in the skin cells.
DO I HAVE TO EAT MY TOMATOES?
Just about everyone loves tomatoes, but they were regarded with great suspicion in Europe when Spanish explorers first brought them back from their native South America. They were thought to be poisonous, in fact, because they were recognized as belonging to the Nightshade family of plants, many of which are deadly. But fear soon gave way to enthusiasm for the delectable red fruit, which came to be known as the "love apple" because of its supposed aphrodisiac properties. It was the Italians, God bless 'em, who took the tomato to its greatest culinary heights, without even knowing about the benefits of lycopene. Mangia!
Lycopene intake is most strongly
associated with reducing the
risk of prostate, stomach,
breast, and lung cancer.
Based on a 1999 Canadian study of dietary habits, the average daily intake of lycopene is 25 mg, an amount that falls well short of the recommended intake of 35 mg/day.3 Individuals with a tomato-poor diet are especially susceptible to lycopene deficiency, as 80-85% of dietary lycopene is typically supplied by tomatoes. We could all eat a lot more tomatoes, but not everyone wants to do that, especially not every day. An easier and more reliable way to make up the deficit is through supplementation.
But we'll still eat some tomatoes, of course, and Table 1 demonstrates that cooked, processed tomatoes are the best source of lycopene, because they have significantly higher levels than raw tomatoes. In addition, oils or fatty foods, such as cheese, eaten together with tomato products increase the amount of lycopene released into your bloodstream, making that much more of it available to the cells that need it most. Pizza, it turns out,is especially good in this regard - but don't use that as an excuse to become a pizza pig, or you'll probably die young.
LYCOPENE MAY ALSO PROTECT AGAINST CANCER AND HEART DISEASE
We've already seen that lycopene is a potent antioxidant. Thus it is surprising to find that the amount of lycopene in a particular food does not directly correlate to the antioxidizing power of that food. When the foods listed in Table 1 were analyzed for total antioxidant capacity, it was found, e.g., that tomato soup has at least twice as much antioxidant capacity as any of the other foods.4 This can be explained by considering that tomatoes contain multiple antioxidants in addition to lycopene, such as vitamin C, lutein, beta-cryptoxanthin, alpha-carotene, and beta-carotene (and possibly many more).7 These antioxidants likely tolerate the processing procedures differently, and consequently the foods in Table 1 have different antioxidant capacities than would be predicted based solely on lycopene content.
While it is true that lycopene is an important antioxidant, it may have a host of other beneficial effects on the body as well. For example, it has been proposed that lycopene may participate in improving hormonal, immune, and metabolic processes in our bodies to improve our health and reduce the risk of certain diseases.8
Several studies indicate that tomato-enriched diets promote improved health by reducing the risk of various cancers and heart disease. For example, when the dietary habits of 1271 elderly individuals in Massachusetts were examined, it was found that a tomato-rich diet reduced the cancer death rate by 50%, whereas a diet rich in carrots or beta-carotene had no protective effect.9 Additional studies support these results and indicate that lycopene intake is most strongly associated with reducing the risk of prostate, stomach, breast, and lung cancer.10
Men with the highest
concentrations of lycopene had a
48% lower risk for heart attack
than those with the lowest
There are also numerous studies indicating that a high intake of tomatoes reduces the risk of certain types of cardiovascular disease.11 But is it tomatoes in general, or lycopene in particular, that reduces the risk of cancer and cardiovascular disease?
STUDIES LARGE AND SMALL POINT TO LYCOPENE
A number of studies have recently been initiated in an effort to ascertain whether lycopene, and not some other compound in tomatoes, is responsible for improved health benefits in people who consume a tomato-rich diet. Many of these studies have not yet been completed, because it takes a long time, especially with diseases such as cancer and heart disease, to establish a link between a specific compound and a reduced risk of disease. However, the results of a few studies indicate that lycopene is the specific ingredient in tomatoes that provides improved health benefits.
One study showed that high lycopene intake reduced the risk of prostate cancer by 21%, whereas other antioxidants found in tomatoes, including beta-carotene, alpha-carotene, lutein, and beta-cryptoxanthin, had no beneficial effect with respect to this cancer.12 Importantly, this study involved 47,894 male health professionals and is the largest study of its kind completed to date.
Separate studies have been conducted to investigate the role of lycopene in cardiovascular diseases. One important study examined a group of men under the age of 70, recruited from ten European countries, who had experienced an acute myocardial infarction (death of heart cells due to lack of oxygen in the heart tissue) and compared them to an appropriate control group.13 The results indicated that men with the highest concentrations of lycopene in their adipose (fat) tissue had a 48% lower risk for myocardial infarction than those with the lowest lycopene concentrations.
A small pilot study (employing only 19 healthy adults) showed that dietary supplementation with lycopene (40-75 mg/day) at least doubled the amount of lycopene in the blood and decreased the amount of lipid peroxidation, a damaging oxidative degradation of fatty molecules or molecular complexes, such as LDL.14 Reducing lipid peroxidation is important because oxidized LDL leads to the formation of artery-clogging plaque and increases the risk of heart disease. It turns out that lycopene is carried in the blood by LDL and may help to protect it from oxidation. Thus, lycopene may help reduce the risk of heart disease. It sounds like lycopene is a good deal all around.
Whatever route you take, make sure you arm yourself with the natural substances that will ensure your general good health during your active, sun-drenched summer.
- Stahl W, Heinrich U, Wiseman, et al. Dietary tomato past protects against ultraviolet light-induced erythema in humans. J Nutr 2001;131:1449-51.
- Ribaya-Mercado JD, Garmyn M, Gilchrest BA, Russell RM. Skin lycopene is destroyed preferentially over beta-carotene during ultraviolet irradiation in humans. J Nutr 1995;125:1854-9.
- Rao AV, Waseem Z, Agarwal S. Lycopene contents of tomatoes and tomato products and their contribution to dietary lycopene. Food Res Intl 1999;31:737-41.
- Djuric Z, Powell LC. Antioxidant capacity of lycopene-containing foods. Intl J Food Sci Nutr 2001;52:143-9.
- Agricultural Research Service. USDA-NCC Carotenoid Database for US Foods - 1998. Beltsville Human Nutrition Research Center, Beltsville, MD, 1998.
- Clinton SK. Lycopene: chemistry, biology and implications for human health and disease. Nutr Rev 1998;56:35-51.
- Duke JA. Handbook of Phytochemical Constituents of GRAS Herbs and Other Economic Plants. CRC Press, Boca Raton, FL, 1992, pp 345-9.
- Rao AV, Agarwal S. Role of antioxidant lycopene in cancer and heart disease. J Am Coll Nutr 2000;19:563-9.
- Colditz GA, Branch LG, Lipnic RJ. Increased green and yellow vegetable intake and lowered cancer death in an elderly population. Am J Clin Nutr 1985;41:32-6.
- Giovannucci E. Tomatoes, tomato-based products, lycopene, and cancer: review of the epidemiologic literature. J Natl Can Inst 1999;91:317-31.
- Arab L, Steck S. Lycopene and cardiovascular disease. Am J Clin Nutr 2000;71(Suppl):1691-5S.
- Giovanucci EL, Ascherio A, Rimm EB, Stampfer MG, Colditz GA, Willett WC. Intake of carotenoids and retinol in relationship to risk of prostate cancer. J Natl Cancer Inst 1995;87:1767-76.
- Kohlmeier L, Kark JD, Gomez-Garcia E, et al. Lycopene and myocardial infarction risk in the EURAMIC study. Am J Epidemiol 1997;146:618-26.
- Agarwal S, Rao V. Tomato lycopene and low-density lipoprotein oxidation: a human dietary intervention study. Lipids 1998;33:981-4.