by Jennifer Novakovich
Lycopene, the major carotenoid in tomatoes, is an up-and-coming power house nutrient with an impressive spectrum of health benefits. Evidence is accumulating on lycopene’s protective effects on many chronic diseases, including heart disease and cancer; it is currently a hot area for modern nutritional research. Want to know more about why tomatoes and tomato products are such a great addition to your diet?
Lycopene is a fat-soluble red pigment carotenoid that is found in many plants, primarily tomatoes but also (to a lesser degree) in guava, pink grapefruit, watermelon, and papaya. Lycopene is the most predominant carotenoid in human blood among the other most common carotenoids, including zeaxanthin, lutein, b-cryptoxanthin, and b-carotene. Like other carotenoids, lycopene is a polyunsaturated hydrocarbon but without the vitamin A activity that other carotenoids have. The small structural variations in lycopene compared to other carotenoids give it both its incredible antioxidant activity (higher than other carotenoids) and its associated deep red color. Lycopene is well absorbed and is transported throughout the body by lipoproteins, accumulating in our adrenals, testes, and liver, with a half-life of 12–33 days.
Strong evidence suggests that fruit and vegetable consumption significantly reduces risks for many chronic diseases. Carotenoids have been implicated to be the major bioactive ingredient in plants due to the high concentrations they are found in the foods we eat. Of carotenoids, beta-carotene is the most well studied, but lycopene is growing in popularity. High concentrations of blood lycopene levels have been linked with lower risks for age-related macular degeneration, lower cancer risks, lower risks for heart disease, and reduced inflammation. The consumption of 30 mg of lycopene per day, through processed tomato products like juice or spaghetti sauce, has been demonstrated to significantly enhance blood lycopene levels and total antioxidant capacities as well as diminish oxidative stress.
The most exciting research on lycopene surrounds its cancer fighting actions. Lycopene has been demonstrated to prevent cancer cell growth in a dose-dependent manner for a number of tissue locations including the mammary gland, endometrium, lungs, and blood. It seems to be particularly strong at preventing sex hormone-dependent cancers, perhaps due to the accumulation of lycopene in sex related tissues. In rat models, lycopene significantly improved the outcome of prostate cancers and has been shown to block cell proliferation by acting on a number of signalling pathways. Lycopene has also been demonstrated to reduce the aggressiveness of tumour development in cancer patients in a number of cancer types. This all sounds amazing but how can a single tomato carotenoid have such incredible health impacts? Why is lycopene such a great cancer preventative?
The cancer fighting potential of lycopene can be partially explained by its antioxidant capacity which exceeds other carotenoids and may be based on its chemical structure. Antioxidants effectively quench free radicals that may otherwise cause oxidative damage by reacting with other molecules. Free radicals are important components of the development of chronic diseases, inflammation, and cancer. Research has also demonstrated that lycopene may promote the regeneration of other non-enzymatic dietary antioxidants (vitamin E and C) as well as boost our internal detoxification systems (phase 2 metabolism enzymes).
How can we get the most from tomatoes in terms of lycopene? Like other carotenoids, the ones in tomatoes (lycopene, phytoene, and phytofluene) are located in the food matrix and are more efficiently absorbed after processing and cooking, which breaks down the food matrix. Since lycopene is lipophilic, it is also best absorbed when it is consumed with fat (e.g. olive oil). Take home point: cook or blend your tomatoes with an oil to get the most bang for your buck in terms of lycopene.
Since lycopene has such great health benefits, should you consider supplementing? Unlike other carotenoids, lycopene at supplemental doses has not been associated with a pro-oxidant effect at an increased oxidative stress level (e.g. from smoking or drinking). Therefore it would likely be a safe option for a supplement. There is convincing evidence that lycopene alone, in either a synthetic or natural form, can prevent cancer. However, when consumed in a food complex with other phytonutrients, lycopene has significantly improved health benefits, likely through a synergistic modulation of transcription. Benefits can therefore be gained by simply adding more tomato or tomato products to your diet, but particularly by cooking tomatoes with oil. If you still want to supplement, make sure that the tomato extract is in an oil suspension.
Tomatoes are not only a nutritious addition to your diet, but they are also delicious! What gets better than sides of salsa, tomato sauce, or one of my favorites, bruschetta? Tomatoes are easy to incorporate into the foods you eat; there is really no reason for you to miss out on this power house food!
Kelkel M, Schumacher M, Dicato M, Dederich M. (2011) Antioxidant and anti-proliferative properties of lycopene. Free Rad Research 45(8): 925–940
Sharoni Y, Linnewiel-Hermoni K, Zango G, Khanin M, Salman H, Veprik A, Danilenko M, Levy J. (2012) The role of lycopene and its derivatives in the regulation of transcription systems: implications for cancer prevention. Am J Clin Nutr 96(suppl):1173S–8S.
Wang X. (2012) Lycopene metabolism and its biological significance. Am J Clin Nutr 96(suppl):1214S–22S.
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