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Gene & Protein in Disease Natural carotenoids prevent prostate cancer

bottom quantile. An analysis of more recent data from In contrast, the existing evidence regarding the role of
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the Cancer Prevention Study II Nutrition Cohort also carotenoids in preventing colorectal cancer, the third most
showed an inverse association between breast cancer risk common cancer globally, is less promising. A pooled
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and plasma α-carotene levels in postmenopausal women, analysis of 11 cohort studies published in 2007 found no
which became even stronger after adjusting for multiple association between the risk of colorectal cancer and the
covariates (OR = 0.50, 95% CI = 0.29 – 0.85). Finally, dietary intake of individual carotenoids. This finding is
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updated results from the Nurses’ Health Study, which in agreement with the results of a recent meta-analysis
included 2188 breast cancer cases and 2188 controls, published in 2017, which included both cohort (n = 4) and
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indicated that higher plasma concentrations of β-carotene case–control studies (n = 11). However, it is important
and total carotenoids were associated with a decreased to note that the authors reported significant heterogeneity
risk, both for measurements taken greater and less than among the studies. In addition, a meta-analysis of 15
10 years before diagnosis (β-carotene: RR = 0.77, 95% observational studies focusing on lycopene consumption
CI = 0.62 – 0.96 and RR = 0.70, 95% CI = 0.51 – 0.97; total revealed that although no protective effect against overall
carotenoids: RR = 0.79, 95% CI = 0.64 – 0.98 and RR = 0.69, colorectal cancer risk was observed, there was an inverse
95% CI = 0.50 – 0.95). 59 association between lycopene consumption and colon
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Moreover, carotenoids have demonstrated a beneficial cancer (RR = 0.88, 95% CI = 0.81 – 0.96). However, a
role in reducing the risk of lung cancer, a disease associated key limitation across these studies is that the assessment
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with the highest mortality rates. A systematic review and of dietary intake of carotenoids relied primarily on food
meta-analysis comprising 24 cohort studies investigated frequency questionnaires, which are susceptible to recall
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the association between lung cancer risk and both dietary bias and do not account for variability in bioavailability.
intake and serum concentrations of total and individual Head-and-neck cancer ranks sixth among the most
carotenoids. Results regarding dietary intake revealed common cancers, and carotenoids have been suggested
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an inverse association for total and specific carotenoids, to have a protective effect against its development.
except for lutein. Specifically, when comparing the highest A meta-analysis of one cohort and 15 case–control studies
with the lowest intake, the pooled RR for total carotenoids (5,482 cases and 14,130 controls), published in 2015,
was 0.79 (95% CI = 0.71 – 0.87). Similarly, the RRs for investigated the association between carotenoid intake
β-carotene, β-cryptoxanthin, lycopene, and lutein- and head-and-neck cancer at several sites. The analysis
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zeaxanthin were 0.89 (0.79 – 1.00), 0.80 (0.72 – 0.89), revealed an inverse association between cancer of the
0.86 (0.77 – 0.97), and 0.89 (0.79 – 1.00), respectively. oral cavity and pharynx and the intake of α-carotene
Furthermore, the dose-response analysis revealed a 1% (OR = 0.57, 95% CI = 0.41 – 0.79), β-cryptoxanthin
and 2% decreased risk of lung cancer for every 0.5 and (OR = 0.46, 95% CI = 0.29 – 0.74), and lycopene (OR = 0.74,
1 mg increase in daily consumption of β-carotene and 95% CI = 0.56 – 0.98). Similarly, a protective role of
total carotenoids, respectively. However, for studies β-carotene equivalents (OR = 0.43, 95% CI = 0.24 –0.77),
involving serum carotenoid concentration measurements β-cryptoxanthin (OR = 0.41, 95% CI = 0.33 – 0.51), and
and adjusting for smoking status, a statistically significant lycopene (OR = 0.50, 95% CI = 0.28 – 0.89) was observed
inverse association with lung cancer risk was observed for laryngeal cancer. Furthermore, a pooled analysis
only for lycopene (RR = 0.71, 95% CI = 0.51 – 0.98). In conducted by the International Head and Neck Cancer
an updated systematic review with a meta-analysis of Epidemiology Consortium, which included 10 case–
prospective studies by the World Cancer Research Fund control studies involving a total of 5959 cases and 12,248
and American Institute for Cancer Research published controls, corroborated these findings. Individuals with
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in 2016, 17 studies were included, comprising 3,603 cases the highest intake of total carotenoids exhibited a 39%
and 458,434 participants. The results indicated that reduced risk of developing either oral and pharyngeal
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increased blood levels of total carotenoids, β-carotene, cancer (OR = 0.61, 95% CI = 0.53 – 0.71) or laryngeal
and lycopene were associated with a reduced risk of lung cancer (OR = 0.61, 95% CI = 0.50 – 0.76) compared
cancer by 36% (RR = 0.64, 95% CI = 0.44 – 0.93), 29% to those with the lowest intake. Moreover, increased
(RR = 0.71, 95% CI = 0.56 – 0.91), and 32% (RR = 0.68, consumption of β-carotene equivalents (OR = 0.52, 95%
95% CI = 0.54 – 0.87), respectively. The results of the dose- CI = 0.40 – 0.67 and OR = 0.55, 95% CI = 0.43 – 0.71),
response analysis confirmed the findings for the above β-cryptoxanthin (OR = 0.62, 95% CI = 0.52 – 0.74 and
carotenoids and in addition α-carotene. Nevertheless, it OR = 0.73, 95% CI = 0.59 – 0.89), and combined lutein
is important to note that the results were not adjusted for and zeaxanthin (OR = 0.79, 95% CI = 0.67 – 0.93 and
smoking status, which is the most important confounding OR = 0.73, 95% CI = 0.59 – 0.90) was associated with a
factor in this type of cancer. 61 reduced risk of oral, pharygeal, and laryngeal cancers.

Volume 3 Issue 1 (2024) 6 https://doi.org/10.36922/gpd.2827