Talk:Lycopene

Research and health effects section

This edit was reverted because the research suggested was preliminary, inconclusive, out of date in most cases, and not published in medical journals as reviews, as indicated by WP:MEDRS. All of the sources used in the current Research section are valid reviews, which concluded there were no health effects demonstrated for lycopene. The Regulatory section, which is also based on comprehensive assessment of the literature by EFSA and the FDA, also concludes there are no proven effects of dietary lycopene. A 2021 meta-analysis concluded the research quality of studies reviewed was too low to enable clear interpretations of possible benefits from lycopene consumption, a common characteristic limitation of research on individual components in foods. Zefr (talk) 18:41, 19 January 2022 (UTC)

My understanding of this topic is that cancer charities and health agencies do recommend lycopene for reducing the risk of prostate cancer. For example, Cancer Research UK have concluded "Eating foods that contain lycopene reduces the risk of prostate cancer developing. But it's not thought that lycopene can slow the growth of cancer or stop the cancer coming back". [1]. The NHS in their lists of foods that "might lower my risk of prostate cancer" include lycopene from cooked tomatoes [2]. Similar statements have been made by the World Cancer Research Fund International [3], [4], Johns Hopkins School of Medicine [5], Prostate Cancer Foundation [6] and Prostate Cancer UK [7]. The MedlinePlus website which is operated by the National Institutes of Health says that "Taking lycopene by mouth might slightly reduce the risk of developing prostate cancer. It might also slightly reduce the risk of prostate cancer returning" [8]. I agree that the evidence is not conclusive, for example the Linus Pauling Institute [9] and the National Cancer Institute have said results from trials are inconclusive to draw any conclusion [10] but the dietary advice from cancer authorities have recommended lycopene consumption to reduce prostate cancer risk. Psychologist Guy (talk) 20:30, 20 July 2022 (UTC)

All those cancer agencies and MedlinePlus couch the language about how lycopene "might" have an effect, statements that are based on primary lab studies, not MEDRS reviews or clinical position statements. The 2021 meta-analysis above could not reach a positive conclusion, and the FDA qualified health claim from 2005 remains in effect in 2022, presumably because no convincing reviews have been published to change that position. The fate of lycopene in vivo remains unknown; it is only an in vitro antioxidant, but unlikely has that effect in vivo, as concluded by EFSA in 2011, with no updates since. It is not a defined nutrient, as it does not have a proven effect in people, does not have a defined effective dose as a nutrient does, and does not have sufficient evidence of being essential in diets for preventing a disease, as all nutrients do. Zefr (talk) 01:49, 21 July 2022 (UTC)

I am pretty much in agreement with you but I do think there is some evidence from epidemiology but I agree that it is not conclusive right now. When do you think EFSA will do an update? I have seen two dose–response meta-analyses (2015/2017) which reported a significant association for lycopene reducing prostate cancer risk [11], [12] but clinical trials are lacking. This 2022 review of six trials concluded no effect [13]. I guess because of the lack of clinical trials there won't be an update for a while. In regard to the 2021 umbrella review I have not been able to get full access but I suspect it was looking at observational studies and because these modern umbrella reviews use the GRADE system by default the evidence will be considered low or very low for observational studies. You might want to add this review to the article though [14] which looked at clinical trials. It concluded lycopene has not proven to have an effect on inflammatory markers. Psychologist Guy (talk) 03:19, 21 July 2022 (UTC)

Dietary studies of a whole food (tomatoes) or a specific phytochemical with unknown in vivo effects like lycopene on disease risk are fraught with design and analysis problems, which likely explain the absence of good clinical studies. A PubMed search shows no clinical studies of substance in recent years, about which EFSA and FDA reviewers must be aware. For balance to recognize a systematic review on prostate cancer risk, I made this edit. Zefr (talk) 05:27, 21 July 2022 (UTC)

Yes thanks for explaining this and your help with updating the article, I appreciate that. Psychologist Guy (talk) 12:48, 23 July 2022 (UTC)

'Structure and physical properties':

"Isomers distinct stabilities, with highest stability: 5-cis ≥ all-trans ≥ 9-cis ≥ 13-cis > 15-cis > 7-cis > 11-cis: lowest.[9][10]"

--A verb seems to be missing? 2A02:3035:1:33F2:1:1:245D:DEF9 (talk) 22:56, 14 January 2023 (UTC)

Dietary sources of lycopene

Isn’t it unlikely that tomatoes generally have “4.6” mg per cup of wet weight, to two significant figures? Won’t this depend on variety, growing conditions, ripeness, shelf life and other factors? Can an editor please find and evaluate sources and add a separate table for various and typical tomatoes, preferably with international and not just US data? In the meantime, a “+/-“ range would be helpful in that table entry. Also, a cup is a measure of volume not weight, and is a non-standardised one, so can an editor please add a note of the quantity of millilitres to the “cup” as used in the table? Given the dietary hype (IMHO) over lycopene, this article is likely to be widely read and cited, so its contents deserve to be of high quality. 92.10.175.26 (talk) 09:06, 4 October 2023 (UTC)

Lycopene is not an essential micronutrient and has no known roles in human physiology, so is not a definitive constituent in studies of human diets, diseases, or in tomato cultivars, and why any difference would matter. I don't think there is "hype" about lycopene among scientists, so it's questionable what WP:MEDRS-supported information can be added to the article..

Lycopene is a measurement in nearly 11,000 foods, as seen in a search on the USDA database, FoodData Central. Perhaps you can specify a revision for the article more clearly from this information.

This is a PubMed search for lycopene content in different tomato cultivars You can browse the abstracts to see if there are good sources to add to the article. Zefr (talk) 15:31, 4 October 2023 (UTC)