Systematic review of lycopene studies

The Anti-Cancer Activity of Lycopene: A Systematic Review of Human and Animal Studies (2022, Full Text)

A major review of lycopene studies with 130 references.

"Abstract

Lycopene is a nutraceutical with health-promoting and anti-cancer activities, but due to a lack of evidence, there are no recommendations regarding its use and dosage. This review aimed to evaluate the benefits of lycopene supplementation in cancer prevention and treatment based on the results of in vivo studies. We identified 72 human and animal studies that were then analysed for endpoints such as cancer incidence, improvement in treatment outcomes, and the mechanisms of lycopene action. We concluded that the results of most of the reviewed in vivo studies confirmed the anti-cancer activities of lycopene. Most of the studies concerned prostate cancer, reflecting the number of in vitro studies. The reported mechanisms of lycopene action in vivo included regulation of oxidative and inflammatory processes, induction of apoptosis, and inhibition of cell division, angiogenesis, and metastasis formation. The predominance of particular mechanisms seemed to depend on tumour organ localisation and the local storage capacity of lycopene. Finally, there is a need to look for predictive factors to identify a population that may benefit from lycopene supplementation. The potential candidates appear to be race, single nucleotide polymorphisms in carotene-cleaving enzymes, some genetic abbreviations, and insulin-like growth factor-dependent and inflammatory diseases."

From the Full Text:

"Conclusions

Most in vivo studies have confirmed the anti-cancer activities of lycopene, particularly in prostate cancer. Human and animal studies have confirmed the influence of lycopene on some hallmarks of cancer, but the contributions of particular mechanisms seem to depend on the tumour organ localisation. The heterogeneity of the analysed interventions shows the need for systematised prospective studies to determine the appropriate recommended dose of lycopene in the daily diet and to search for predictive factors for the use of lycopene, particularly for oncological indications."

I did a fair amount of research on phytochemicals with benefit for PCa the first few years after my PCa diagnosis and treatment and took several daily, but after 4-5 years I cut down to just tumeric curcumin and lycopene (50 mg daily).

From the Full Text:

"A European Food Safety Authority panel recommends a lycopene intake of 0.5 mg/kg body weight per day, at most 75 mg per day, but some reviews have shown that a dietary or formulated lycopene consumption of even up to 3 g per day is safe [96,128,129]. The lack of toxicity of high doses of lycopene may be due to the fact that lycopene absorption has an upper limit of saturated concentration and is not absorbed when the dose exceeds 60 mg [129]"

Without getting into a lengthy discussion of the pros and cons of phytochemical (plant-derived) supplements, the major problem with those that do have proven in vitro anti-PCa properties is one of bioavailability: taking these orally is no guarantee that effective amounts reach the target cells in amounts beneficial for prevention and treatment. The other problem is that of commercial hype: many phytochemicals are worthless, may be harmful in high doses, or may benefit only some men (e.g., pomegranate extract, according to one major study, showed no overall statistical benefit, but did benefit about 25% of men who had a specific genetic phenotype, if memory serves me correctly). As the Abstract states: "Finally, there is a need to look for predictive factors to identify a population that may benefit from lycopene supplementation.".

On the other hand, I didn't want to avoid the more promising phytochemical entirely, only to read in 10-15 years that some indeed proved beneficial as dietary supplements and that I missed out. Keep in mind that a supplement can be beneficial even it does not prevent a recurrence, but does slow progression and PSA doubling rate. I'm not personally advising anyone take these supplements. Rather, if you are interested, do your own research and, if you decide in favor, don't go overboard or you'll just waste money.

How to develop some of these phytochemical into medications is an active area of research.

Djin