By Diane Fulton, PhD

Lycopene—the pigment in red fruits and vegetables like pink guava and tomatoes—is an important dietary tool researchers are touting for the prevention and suppression of neurodegenerative diseases. Past research has shown that it has potent antioxidant properties—effective in fighting chronic diseases such as cancer, heart disease, and bone loss.

Neurodegenerative Disease

According to a recent study published in Journal of Food Science, lycopene demonstrated antioxidant activity in protecting the neural system in vitro. Study authors concluded, “Our findings provide a novel preventive strategy against neurodegenerative diseases. Increased consumption of lycopene-based products and lycopene-rich fruits and vegetables may result in a lower risk for neurodegenerative diseases.”¹

In addition to suppressing oxidative stress and inflammation in the brain, lycopene restores changes associated with neurodegenerative disorders, epileptic conditions, aging, brain hemorrhages, spinal cord injury, and neuropathy. Moreover, studies have found that lycopene may prevent proteinopathies, neuroinflammation, apoptosis, cerebral edema, and synaptic dysfunction in the brain.²

In terms of cognitive health, lycopene was also found to ameliorate neuroinflammation, amyloid genesis, and memory loss through mediating cell signaling pathways related to inflammation. Thus, it could be effective in preventing Alzheimer’s disease.³

Similarly, in an in vitro study of mice, researchers found lycopene to be effective in reducing oxidative stress—a major cause of Alzheimer’s disease—by reducing cell apoptosis.⁴

Researchers at Seoul National University studied 6,958 subjects older than 50 years to assess the impact of carotenoids on mortality risk from Alzheimer’s. High levels of lycopene, lutein, and zeaxanthin were found to lower the risk of Alzheimer’s mortality.⁵ In an Alzheimer’s-induced mice study, oxidative stress biomarkers were measured with two treatments—lycopene and lycopene combined with vitamin E.

The synergistic combination significantly decreased memory impairment and improved three oxidative stress markers for Alzheimer’s. In an animal study, researchers demonstrated that lycopene lowered aluminum-induced hippocampal lesions by inhibiting oxidative stress-mediated inflammation and apoptosis in the brain.⁶

Finally, a mouse model found lycopene to be very effective in reversing age-associated neuronal damage and synaptic dysfunction in brain synapses by mitigating oxidative stress and inflammation markers.⁷

Cancer Risk

Twenty-six studies of 563,299 participants with 17,517 documented cases of prostate cancer were meta-analyzed, showing that higher lycopene intake (between 9 mg and 21?mg per day) reduced the incidence of prostate cancer. In a study of 404 participants, the prostate cancer risk declined 18 percent with increasing consumption of lycopene (tomatoes and watermelon).⁸

Additionally, researchers have found lycopene-rich foods like tomatoes to be positive for a variety of other cancers. In a meta-analysis including 15 studies of 644 animals, lycopene supplementation significantly reduced the incidence, number, and growth of liver cancer.⁹

In the comprehensive review of the literature, the scientists attested to tomato lycopene’s preventive action against the formation and development of lung cancer as well.¹⁰ Lycopene supplementation in lung and liver tumor-induced mice reduced experimental tumor metastasis in vivo by decreasing tumor invasion, proliferation, and angiogenesis.¹¹

In a pooled analysis of 21 studies, the group that consumed the most tomato products had the lowest risk for gastric cancer. In a study of US adults, tomato and lycopene intake was inversely related to all cancer deaths.¹³

Guava leaf extract has been shown to have a strong anticancer effect by preventing and stopping the growth of cancerous cells in in-vitro animal studies.¹⁴

Cardiovascular Disease Risk

In a meta-analysis of 14 studies, high dietary lycopene was significantly associated with low risk for cardiovascular disease, stroke, and coronary heart disease.¹⁵ Similarly, in a population-based cohort study of 23,935 patients, mortality from coronary heart and cerebrovascular disease was markedly lower for those who had high tomato and lycopene intake—illustrating the cardioprotective abilities.¹⁶

A systematic review and meta-analysis of 21 studies showed that increasing the intake of tomatoes and lycopene products has positive effects on blood lipids, blood pressure, and endothelial function—key nutritional strategies to fight cardiovascular diseases.

In a human study of 142 patients with cardiovascular disease, lycopene supplementation (7 mg per day) for four weeks increased serum lycopene levels more than four times, significantly improved tissue oxygenation and blood flow, and reduced inflammatory oxidative damage markers threefold.¹⁷ Tomato juice treatment (338 mg per day for 20 days) also reduced inflammation in a controlled trial of 106 overweight and obese females.¹⁸

Guava consumption was shown to have significant effects on heart health risk in 120 patients with high blood pressure. Specifically, the study found a 9.9 percent net decrease in total cholesterol, 7.7 percent decrease in triglycerides, and an 8 percent net increase in high-density lipoprotein after 12 weeks of guava fruit treatment.¹⁹

Bone Health

In a USDA-funded study, 370 men and 576 women (70 to 80 years of age) from the Framingham Osteoporosis Study completed a food frequency questionnaire and were followed for 17 years for bone fractures.

Results showed that subjects with higher lycopene intake had significantly lower risk of hip and nonvertebral fractures.²⁰ Tomato and tomato products, as rich sources of lycopene, have been shown to decrease bone loss, which significantly lowers risk for fractures in vivo and in vitro studies of postmenopausal women.²¹

In vitro and clinical studies of osteoblast cells found that intake of a lycopene-rich tomato sauce (5 mg and 10 mg) in 39 postmenopausal women resulted in no significant bone density loss with the treatment and better bone turnover results compared to those in the non-tomato sauce control group. Accordingly, study authors found that tomato sauce can be used to lower risk of bone loss and to prevent osteoporosis.²²

Top 12 Lycopene Food Sources

Boost your lycopene levels by increasing consumption of the following foods:

Top Fruits and Vegetables Highest in Lycopene
(By Milligrams Per Cup):

1. Tomato Puree (50)
2. Sun Dried Tomatoes (25) 
3. Guavas (8.6)
4. Fresh Tomato (7.3)
5. Watermelon (6.9)
6. Pink Grapefruit (3.3)
7. Papaya (2.7)
8. Red Bell Peppers (0.5)
9. Persimmon (0.3)
10. Asparagus (0.05)
11. Red Cabbage (0.02)
12. Mangos (0.01)

Although there is no daily minimum requirement for lycopene, current studies suggest consuming 8 mg to 21 mg per day may be optimal.²³

In summary, lycopene is a plant nutrient that gives fruits and vegetables (eg, tomatoes, guavas, watermelon, and red bell peppers) their distinguishing reddish hues. As a powerful antioxidant, lycopene packs a punch for its neuroprotective, anticancer, bone protective, and heart healthy properties.

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Diane Fulton, PhD, is Emeritus Professor at Clayton State University. During her 45-year career as administrator/professor teaching research and business, she authored 10 books, over 50 articles, and is now writing children’s books about the body, mindfulness, and cross-cultural awareness. Her passion is to share her knowledge to integrate a healthy body, mind, and soul.

Well Being Journal adapted this article from the previously published original article at Greenmedinfo.com titled “Guava and Tomato Lower Risks for Neurodegenerative Diseases,” December 23, 2020.

References available at the following web address:
https://www.wellbeingjournal.com/research-overview-lycopene-benefits-and-food-sources-wbj-summer-2022-references/