Foods Reducing the Risk of Prostate Cancer: Tomatoes

Last Updated on March 30, 2024 by Max

Introduction

Lycopene, a member of the carotenoid family, is generously found in tomatoes and tomato-based products, pink grapefruit, and watermelon. Interestingly, despite their lack of red or orange color, asparagus, and parsley are also substantial sources of lycopene.

As a potent antioxidant, lycopene is vital in neutralizing reactive oxygen species. The human body, however, cannot synthesize lycopene alone; it must be supplied through our daily diet. Once absorbed, lycopene is primarily stored in the testes, liver, adrenal glands, and prostate. Its concentration in the testes is up to ten times higher than in other tissues, suggesting a unique biological role in these areas.

Lycopene content in different foods.

Tomato and tomato-based products account for approximately 80% of lycopene consumption.

The Role of Lycopene in Reducing Prostate Cancer Risk

Lycopene is recognized for its effectiveness in combating various types of cancer, particularly those affecting the prostate, lung, stomach, breast, and ovaries.

A study by Giovannucci E et al. (1995) examined the association of various carotenoids with the risk of prostate cancer. The results showed no significant correlation between the intake of beta-carotene, alpha-carotene, lutein, beta-cryptoxanthin, or dietary retinol and prostate cancer risk. Conversely, lycopene intake was associated with a reduced risk (age- and energy-adjusted RR = 0.79; P = .04). Remarkably, among 46 vegetables and fruits or related products, they identified three lycopene-rich sources that significantly lowered prostate cancer risk: tomato sauce (P= .001), tomatoes (P = .03), and pizza (P = .05).

A meta-analysis of twenty-six high-quality studies, which included 17,517 cases of prostate cancer, demonstrated that a higher lycopene consumption significantly reduced prostate cancer risk. A key finding of the study was that blood lycopene levels between 2.17 and 85 μg/dL were linearly associated with a reduced risk of prostate cancer, with a threshold between 9 and 21 mg/day.

Other Health Benefits of Lycopene

Lycopene’s advantageous properties also address diabetes, cardiovascular diseases, inflammatory conditions, and disorders affecting the skin, bone, liver, neural, and reproductive systems.

In relation to reproductive disorders, lycopene has shown promise in reducing sperm DNA fragmentation and lipid peroxidation, improving sperm motility and mitochondrial enzymatic activity, and increasing sperm count. Human trials have reported increased pregnancy rates with daily 4–8 mg of lycopene supplementation for 3–12 months. Treatment of men with infertility due to poor sperm quality resulted in six pregnancies among 26 patients (23%) (Gupta NP, Kumar R. 2002). These trials suggest that a daily dose of 4–8 mg of lycopene, equivalent to approximately 100 g of tomato sauce or 100 g of watermelon for 3-12 months, can effectively treat male infertility.

Other studies indicate this carotenoid supports mental longevity (Crowe-White KM et al. 2019).

Lycopene primarily confers health benefits through its anti-oxidative, free-radical scavenging, and antiapoptotic activities. This powerful plant pigment also safeguards the human body against toxins from bacteria, mycotoxins, fluoride, metals, and pesticides. It’s worth noting that factors like age and chronic diseases such as cardiovascular diseases can lower the bioavailability of lycopene. Therefore, it is beneficial to supplement it through various sources like grapefruit, watermelon juices, or tomato sauce.

Bioavailability of Lycopene

Not all lycopene present in foods can be absorbed by humans; only about 10%–30% is utilized, with the rest being excreted.

The factors helping in the absorption of lycopene are: 

• Heating and processing food (particularly tomatoes) leads to the breakdown of the food matrix, which increases lycopene bioavailability.
• The cis-isomers of lycopene are more readily absorbed than trans-isomers. Heating and processing convert trans-isomers to cis-isomers, enhancing lycopene absorption by up to 2.5 times.
• Due to its lipophilic nature, lycopene’s absorption improves when consumed with dietary fats or cooked in an oil medium.

Recommended Doses of Lycopene

There is no universally recommended daily dose of lycopene, as it largely depends on a person’s age and health status. However, according to research in this field, the suggested daily lycopene intake ranges from 2 to 20 mg (Saini RK. et al. 2020). A lycopene intake as low as 6.5 mg/day has been found effective against prostate cancer (Giovannucci E et al. 1995), but this should be increased to 10 mg/day for advanced cases.

Lycopene Toxicity

Normal doses of lycopene have not been found to cause any adverse effects in humans, even at levels as high as 3 g per day per kg of body weight – far exceeding the recommended intake. Due to lycopene’s potent antioxidant effects, caution should be exercised for patients undergoing chemotherapy and radiation therapy, as it may interfere with these treatments.

Conclusions

An unusual case of liver lycopenemia was documented in a woman who consumed two liters of tomato juice daily for several years. Interestingly, this excessive intake did not impair her liver function but only led to unusual skin discoloration. Once she stopped drinking the tomato juice, her skin color returned to normal after three weeks.

Though this case represents an extreme scenario, it does suggest that individuals at risk for prostate cancer could benefit from incorporating lycopene-rich foods into their daily diets, specifically tomatoes, tomato sauces, and especially tomato ketchup. It’s important to remember that tomatoes available in stores are often harvested green and ripen in the dark without exposure to sunlight. As such, they may not contain optimal levels of lycopene. To maximize the benefits, consider consuming tomatoes in the form of heat-treated products like ketchup or sauces, which can enhance the bioavailability of lycopene.

References

• M. Imran et al. Lycopene as a Natural Antioxidant Used to Prevent Human Health disorders. Antioxidants (Basel). 2020 Aug 4;9(8):706.
• Giovannucci E, et al. Intake of carotenoids and retinol in relation to risk of prostate cancer. J Natl Cancer Inst. 1995 Dec 6; 87(23):1767-76.
• P. Chen et al,2015. Lycopene and Risk of Prostate Cancer. A Systematic Review and Meta-Analysis. Medicine (Baltimore). 2015 Aug; 94(33): e1260.
• Mozos I, et al. Lycopene and Vascular Health. Front Pharmacol. 2018; 9():521.
• Crowe-White KM, Phillips TA, Ellis AC. Lycopene and cognitive function. J Nutr Sci. 2019; 8():e20.
• Corridan B., O’Donohue M., Morrissey P. Proceedings of Proceedings-Nutrition Society of London. Cambridge University Press; Cambridge, UK: 1998. Carotenoids and immune response in elderly people; p. 4A.
• Saini RK. et al. Protective effects of lycopene in cancer, cardiovascular, and neurodegenerative diseases: An update on epidemiological and mechanistic perspectives. Pharmacol Res. 2020 May; 155():104730.
• Gupta NP, Kumar R. Lycopene therapy in idiopathic male infertility–a preliminary report. Int Urol Nephrol. 2002; 34(3):369-72.