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Antioxidants in Athletes - NED Infobite
BANT's scientific NED InfoBites are designed to provide key elements of the latest research using plain language. They provide quick overviews on particular health issues and nutrition topics for a speedy introduction to the science. Visually attractive and easily shareable with clients and social media followers.
2024
Abstract
Intense exercise that competitive sports athletes participate in can negatively affect their pro-oxidative-antioxidant status. This NED Infobite brings research on various antioxidant compounds with potential to prevent adverse changes.
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Association of Retinol and Carotenoids Content in Diet and Serum With Risk for Colorectal Cancer: A Meta-Analysis.
Han, X, Zhao, R, Zhang, G, Jiao, Y, Wang, Y, Wang, D, Cai, H
Frontiers in nutrition. 2022;9:918777
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The incident rate of malignant tumours has been increasing, and so has colo-rectal cancer (CRC), which is now the third most frequent cancer and the second most common cause of cancer death. CRC development is influenced by environmental and genetic factors. Diet, diabetes, obesity, lack of physical activity, age, family history and history of benign adenomatous polyps and inflammatory bowel disease are all known risk factors. Modulating diet is one way to modify cancer risk. Vitamin A (retinol) and carotenoids, which are precursors to Vitamin A, are indispensable in the human body and widely occur in a range of vegetables, fruits and animal-derived foods. In some studies high dietary intake of retinol and carotenoids had been linked to a decreased risk of CRC, however, this was not consistent in all findings. To get a better understanding of this matter, the authors of this meta-analysis analysed 22 clinical studies from the last 20 years. The authors found an inverse association with carotenoids in blood serum, so higher blood serum of carotenoids seemed to decrease CRC risk. In regards to dietary intake, total carotenoid intake did not increase CRC risk and in fact the carotenoids carotenes, lycopene, and β-cryptoxanthin reduced risk, which was particularly noticeable in men. In women, high dietary intake of retinol also showed to reduce CRC risk, but it appeared to increase the risk in men. This raised the idea of gender-specific differences. Of clinical relevance are that carotenoids can be an important dietary contributors in reducing CRC risk. However the protective role of retinol appears to be gender-specific and only seems to benefit women, with the opposite effect in men.
Expert Review
Conflicts of interest:
None
Take Home Message:
The results of this study were mixed:
- Total dietary intake of carotenoids was not associated with CRC risk.
- Case control studies found that high serum carotenoids may increase CRC risk.
- There were differences in findings between males and females.
- Larger, well-controlled studies over long time frames are needed to further explore the relationship between dietary intake and serum concentrations of carotenoids and retinol with CRC. These studies should include results by sex, race and dose response.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Colorectal cancer (CRC) is the third most common cancer worldwide, and second in terms of mortality. Diet and environmental factors may have a strong influence and causative effect. Research has linked dietary consumption and serum levels of carotenoids and retinol with CRC. However, results have been mixed.
The aim of this meta analysis was to identify a potential association between CRC and carotenoid and retinol intake. A total of 22 cohort and case control studies published between 2000-2019 from across Europe, North America and Asia were included. The number of CRC cases totalled 19,293 from a sample of more than 450,000 people.
Eligible studies reported data in either relative risk (RR) or odds ratios (OR) with 95% confidence intervals (95% CI). In the meta analysis, data were combined and expressed as OR with 95% CI.
Cases and control groups were based on high or low carotenoid intake as defined by the included studies and based on dietary intake or serum concentration. Sub-group analysis was undertaken by study type, sex and tumour type. A sensitivity analysis tested the robustness of the results.
Due to the heterogeneity between studies, adjustments were made for potential covariates and confounding factors including age, gender, a family history of CRC, smoking, alcohol consumption and levels of physical activity.
The quality of the studies was assessed against predefined inclusion and exclusion criteria and scored using the Newcastle-Ottawa Scale (NOS).
The nutrients studied included; beta-carotene, alpha-carotene, lycopene, lutein/zeaxanthin, beta-cryptoxanthin and retinol. These were assessed through dietary intake or serum concentrations.
Key Findings
- High dietary intake of beta-carotene was not associated with an increased risk of CRC in females (OR = 0.97; 95%CI 0.79-1.19), however, it may lower CRC risk in males (OR = 0.74; 95% CI 0.55-0.99).
- High dietary intake of retinol was not associated with CRC risk (OR = 0.99; 95% CI 0.89-1.10). However, the findings suggested that it may reduce CRC risk in females but increase CRC risk in males.
- There was a tendency towards a slightly decreased risk of CRC with high dietary intakes of alpha-carotene), lycopene, and beta-cryptoxanthin. The results were more pronounced in males.
- No association was found between high consumption of high lutein/zeaxanthin, retinol or total carotenoids and the risk of CRC
- Case control studies found a negative association between serum carotenoids and CRC risk. This relationship was not found in cohort studies and therefore remains uncertain.
Conclusions
This was a well-conducted meta-analysis that was not subject to any conflicts of interest. Larger, well controlled prospective studies adjusting for sex and with long-term follow-up are needed to confirm the relationship between dietary intake and serum levels of carotenoids and CRC.
Notes: The authors had no conflicts of interest to disclose.
Clinical practice applications:
- Healthcare practitioners working with people with a family history of CRC or those who may be at increased risk may like to consider increasing carotenoid intake modestly.
- A modest increase in dietary intake of beta-carotene for males may be beneficial.
- A modest increase in dietary retinol may be beneficial for females.
Considerations for future research:
- Further research is needed to explore the differences between sexes for dietary intake of carotenoids and retinol and CRC risk
- Further studies are needed to investigate the relationship between serum carotenoids and CRC
- Analysis of results by race and continent may be beneficial
- Further research is needed to define dose response
- Due to heterogeneity between studies, large, well controlled studies over long time frames are needed
Abstract
Background: Colorectal cancer (CRC) risk is linked to serum and dietary retinol and carotenoids, according to clinical and epidemiological research. However, the findings are not consistent. As a result, we did this meta-analysis to determine the link between them. Methods: From 2000 through 2022, the PubMed, Web of Science, and Embase databases, as well as pertinent article references, were searched and filtered based on inclusion and exclusion criteria and literature quality ratings. High and low intake were used as controls, and OR (odds ratio) or RR (relative risk) and 95% confidence interval were extracted. The extracted data were plotted and analyzed using Stata12.0 software. Results: A total of 22 relevant studies were included, including 18 studies related to diet and 4 studies related to serum. For high and low intake or concentration controls, the pooled OR was as follows: β-carotene (OR = 0.89, 95% CI: 0.78-1.03), α-carotene (OR = 0.87, 95% CI: 0.72-1.03), lycopene (OR = 0.93, 95% CI: 0.81-1.07), lutein/zeaxanthin (OR = 0.96, 95% CI: 0.87-1.07), β-cryptoxanthin (OR = 0.70, 95% CI: 0.48-1.01), total carotenoids (OR = 0.97, 95% CI: 0.81-1.15), retinol (OR = 0.99, 95% CI: 0.89-1.10), serum carotenoids (OR = 0.73, 95% CI: 0.58-0.93), serum retinol (OR = 0.62, 95% CI: 0.26-1.49). Subgroup analysis was performed according to tumor type, study type and sex. Conclusion: Total carotenoid intake and Lutein/Zeaxanthin intake were not associated with CRC risk. High β-carotene, α-carotene, lycopene, and β-cryptoxanthin all tended to reduce CRC risk. Serum carotenoid concentrations were significantly inversely associated with CRC risk.
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Plant-Based Foods and Their Bioactive Compounds on Fatty Liver Disease: Effects, Mechanisms, and Clinical Application.
Li, HY, Gan, RY, Shang, A, Mao, QQ, Sun, QC, Wu, DT, Geng, F, He, XQ, Li, HB
Oxidative medicine and cellular longevity. 2021;2021:6621644
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Fatty liver disease is the accumulation of fats and inflammation associated with poor dietary patterns. Plant-based foods have been recommended to manage this disease and this review aimed to highlight the most recent data on the mechanisms for this. Beyond their obvious capabilities of being low in fat, plant-based foods may contain naturally occurring compounds that can help alleviate fatty liver disease through improved inflammation, improved gut microbiota and cellular changes. In support of this, clinical benefits on fatty liver outcomes have been reported in the research. There may be safety issues with isolating certain natural compounds from plant-based foods, which requires more research, however plant-based foods is a promising therapy for fatty liver disease.
Abstract
Fatty liver disease (FLD), including nonalcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD), is a serious chronic metabolic disease that affects a wide range of people. Lipid accumulation accompanied by oxidative stress and inflammation in the liver is the most important pathogenesis of FLD. The plant-based, high-fiber, and low-fat diet has been recommended to manage FLD for a long time. This review discusses the current state of the art into the effects, mechanisms, and clinical application of plant-based foods in NAFLD and AFLD, with highlighting related molecular mechanisms. Epidemiological evidence revealed that the consumption of several plant-based foods was beneficial to alleviating FLD. Further experimental studies found out that fruits, spices, teas, coffee, and other plants, as well as their bioactive compounds, such as resveratrol, anthocyanin, curcumin, and tea polyphenols, could alleviate FLD by ameliorating hepatic steatosis, oxidative stress, inflammation, gut dysbiosis, and apoptosis, as well as regulating autophagy and ethanol metabolism. More importantly, clinical trials confirmed the beneficial effects of plant-based foods on patients with fatty liver. However, several issues need to be further studied especially the safety and effective doses of plant-based foods and their bioactive compounds. Overall, certain plant-based foods are promising natural sources of bioactive compounds to prevent and alleviate fatty liver disease.
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Effect of 12-Week Daily Intake of the High-Lycopene Tomato (Solanum Lycopersicum), A Variety Named "PR-7", on Lipid Metabolism: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study.
Nishimura, M, Tominaga, N, Ishikawa-Takano, Y, Maeda-Yamamoto, M, Nishihira, J
Nutrients. 2019;11(5)
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Tomatoes are a rich source of lycopene, a compound believed to have many health benefits. Researchers in Japan conducted a randomised, double-blind, placebo-controlled trial to investigate the effects of eating a type of tomato bred to be high in lycopene on 74 healthy volunteers with raised cholesterol levels. Participants were given 50g per day of either semi-dried high-lycopene tomato or lycopene-free tomato. Those eating the high-lycopene tomatoes significantly reduced their levels of LDL cholesterol over 12 weeks. The researchers concluded that their findings support the health benefits of eating tomatoes rich in lycopene.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Lycopene, a carotenoid, has antioxidant effects and exhibits the highest physical quenching rate constant for singlet oxygen.
- Lycopene has also been reported to inhibit the production of serum lipid peroxide and oxidize low-density lipoprotein (LDL)
- This study reported that the intake of 50g of high-lycopene (lycopene, 22.0-27.8mg) for 12 weeks significantly decreased LDL-C in subjects with LDL-C ranging from 120–139 mg/dL.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group study was conducted to investigate the effects of the regular and continuous intake of high-lycopene tomato, a variety named PR-7, for 12 weeks on 74 healthy Japanese subjects with low-density lipoprotein cholesterol (LDL-C) levels > 120 to <160mg/dL.
The subjects were randomly assigned to either the high-lycopene tomato or placebo (lycopene-free tomato) group. Each subject in the high-lycopene group ingested 50g of semi-dried PR-7 (lycopene, 22.0-27.8mg) per day. Medical interviews were conducted, vital signs were monitored, and blood and saliva samples were taken at 0 (baseline) and at 4, 8 and 12 weeks.
Primary clinical outcomes were:
- The intake of high-lycopene tomato improved LDL-C at week 12 when compared to the placebo group (Week 12: placebo, 4,1 +- 15.7mg/dL; high-lycopene tomato, -3.7 +- 13.8.mg/dL; p=0.027).
- Based on a subgroup analysis, the ingestion of high-lycopene tomato significantly decreased LDL-C in subjects with LDL-C ranging from 120–139 mg/dL at week 12 (Week 12: placebo, 4.3 15.1 mg/dL; high-lycopene tomato, +- 5.1 9.5 mg/dL; p = 0.030).
Secondary clinical outcomes were:
- There were no significant differences between the high-lycopene tomato and placebo groups in terms of lipid profiles comprising of total cholesterol (TC), HDL-C, triglycerides (TG), LDL-C/HDL-C ratio, and non-HDL, and adiponectin.
- The intake of high-lycopene tomato increased lycopene levels compared to the placebo group (Week 12: placebo,
+-24.2 49.3 g/dL; high-lycopene tomato, 22.7 47.9 g/dL; p < 0.001).
- In addition, beta-carotene levels increased in the high-lycopene tomato group compared to those in the placebo group at week 12 (Week 12: placebo, 0.9 13.6 g/dL; high-lycopene tomato, 12.0 24.5 g/dL; p = 0.009).
Clinical practice applications:
- A previous meta-analysis demonstrated that LDL-C decreases when more than 25 mg per day of lycopene is ingested. The biological mechanism was associated with a reduction in 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase activity in the liver, activation of LDL-receptors, and increased expression of the ABCA1 transporter gene, the key component of HDL-C production.
- This study also suggests that there is a decrease in LDL-C at 12 weeks in subjects with LDL-C ranging from 120–139 mg/dL.
- Based on these findings, a practitioner could therefore consider recommending 25mg of lycopene to help reduce LDL-C in patients with an LDL-C range of 120–139 mg/dL for at least 12 weeks.
Considerations for future research:
- Lycopene has been reported to possess the strongest singlet oxygen scavenging ability among the eight carotenoids, as measured by the singlet oxygen absorption capacity method, and some researchers have found that lycopene and tomato display antioxidant effects. However, other reports suggest that ingesting lycopene does not affect oxidative markers. These findings suggest that further investigation is needed to evaluate the effect of lycopene on oxidative markers.
- The LOX index is a biomarker for the early risk of arteriosclerosis, cerebral infarction, and myocardial infarction. Lycopene might be ineffective against LOX-1 which is a product of the peroxidation reaction. Additional studies with a longer intake period are required to investigate the effect of lycopene on the risk of arteriosclerosis.
- The subjects in this study were asked to avoid cooking the test food (semi-dried tomato). It is, therefore, necessary to investigate the differences in the effect of the high-lycopene tomato based on various cooking methods.
Abstract
Tomato (Solanum lycopersicum) is a rich source of lycopene, a carotenoid that confers various positive biological effects such as improved lipid metabolism. Here, we conducted a randomized, double-blind, placebo-controlled, parallel-group comparative study to investigate the effects of regular and continuous intake of a new high-lycopene tomato, a variety named PR-7, for 12 weeks, based on 74 healthy Japanese subjects with low-density lipoprotein cholesterol (LDL-C) levels ≥120 to <160 mg/dL. The subjects were randomly assigned to either the high-lycopene tomato or placebo (lycopene-free tomato) group. Each subject in the high-lycopene group ingested 50 g of semidried PR-7 (lycopene, 22.0-27.8 mg/day) each day for 12 weeks, while subjects in the placebo group ingested placebo semidried tomato. Medical interviews were conducted, vital signs were monitored, body composition was determined, and blood and saliva samples were taken at weeks 0 (baseline), 4, 8, and 12. The primary outcome assessed was LDL-C. The intake of high-lycopene tomato increased lycopene levels in this group compared to levels in the placebo group (p < 0.001). In addition, high-lycopene tomato intake improved LDL-C (p = 0.027). The intake of high-lycopene tomato, PR-7, reduced LDL-C and was confirmed to be safe.
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Lycopene and Risk of Prostate Cancer: A Systematic Review and Meta-Analysis.
Chen, P, Zhang, W, Wang, X, Zhao, K, Negi, DS, Zhuo, L, Qi, M, Wang, X, Zhang, X
Medicine. 2015;94(33):e1260
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Lycopene is an antioxidant agent derived from tomatoes, with possible anti-cancer properties including inhibiting growth factors, promoting cell apoptosis, and preventing carcinogenesis. This 2014 meta-analysis reviewed 26 studies and a total of 17,517 prostate patients to see if dose-dependent lycopene supplementation reduced the incidence of prostate cancer compared to 563,299 controls. Prostate cancer (PCa) is the second most common cancer, and a cause of mortality in men. General lycopene intake, via supplementation, showed a slight trend in reducing risk factors for prostate cancer but it was only significant when data from one study was removed to improve the data quality. However, dose-dependent analysis showed that each 5 mg/day increase in lycopene decreased the risk ratio. A higher lycopene consumption of 9 to 21 mg/d was inversely associated with a reduced risk of PCa. High circulating plasma levels of lycopene between 2.17 and 85mg/dL was linearly inversed with PCa risk. Interestingly sub-group analysis of important confounders such as age, family history, energy intake, BMI did not differ considerably between studies. The data was collected from food questionnaires so there may be slight limitations of reporting between the various studies. The study concludes that lycopene may reduce the risk of prostate cancer, but more studies are required to understand the mechanism.
Abstract
Prostate cancer (PCa) is a common illness for aging males. Lycopene has been identified as an antioxidant agent with potential anticancer properties. Studies investigating the relation between lycopene and PCa risk have produced inconsistent results. This study aims to determine dietary lycopene consumption/circulating concentration and any potential dose-response associations with the risk of PCa. Eligible studies published in English up to April 10, 2014, were searched and identified from Pubmed, Sciencedirect Online, Wiley online library databases and hand searching. The STATA (version 12.0) was applied to process the dose-response meta-analysis. Random effects models were used to calculate pooled relative risks (RRs) and 95% confidence intervals (CIs) and to incorporate variation between studies. The linear and nonlinear dose-response relations were evaluated with data from categories of lycopene consumption/circulating concentrations. Twenty-six studies were included with 17,517 cases of PCa reported from 563,299 participants. Although inverse association between lycopene consumption and PCa risk was not found in all studies, there was a trend that with higher lycopene intake, there was reduced incidence of PCa (P = 0.078). Removal of one Chinese study in sensitivity analysis, or recalculation using data from only high-quality studies for subgroup analysis, indicated that higher lycopene consumption significantly lowered PCa risk. Furthermore, our dose-response meta-analysis demonstrated that higher lycopene consumption was linearly associated with a reduced risk of PCa with a threshold between 9 and 21 mg/day. Consistently, higher circulating lycopene levels significantly reduced the risk of PCa. Interestingly, the concentration of circulating lycopene between 2.17 and 85 μg/dL was linearly inversed with PCa risk whereas there was no linear association >85 μg/dL. In addition, greater efficacy for the circulating lycopene concentration on preventing PCa was found for studies with high quality, follow-up >10 years and where results were adjusted by the age or the body mass index. In conclusion, our novel data demonstrates that higher lycopene consumption/circulating concentration is associated with a lower risk of PCa. However, further studies are required to determine the mechanism by which lycopene reduces the risk of PCa and if there are other factors in tomato products that might potentially decrease PCa risk and progression.