1.
Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease.
Dimidi, E, Cox, SR, Rossi, M, Whelan, K
Nutrients. 2019;11(8)
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Fermented foods have grown in popularity due to their proposed health benefits but there is limited clinical evidence for the effectiveness of most fermented foods in gastrointestinal health. This review paper looks at non-dairy fermented foods which have been studied in at least one RCT: kefir, sauerkraut, natto, and sourdough bread. The health benefits are attributed to the high ratio of probiotic microorganisms, metabolites, or ability to convert compounds into active metabolites, as well as prebiotics and vitamins contained in these foods. Kimchi has the greatest evidence from epidemiological and case control studies investigating risk of gastric cancers. Different food composition of kimchi is shown to both increase and decrease risks, whilst it had no impact on H. pylori levels. There were no studies on kefir in functional bowel disorders however, it was shown to help lactose malabsorption and reduce H. pylori levels. A small RCT on Sauerkraut showed it reduced IBS severity in patients and increased in vitro activity of key liver and kidney detoxifying enzymes. There are small pockets of data that show that tempeh may influence gut microbiota in humans, and that natto may increase bifidobacterial and short-chain fatty acids in healthy volunteers. There are numerous limited cohort studies on miso and cancer risk but no studies on gastrointestinal conditions. Finally, sourdough was shown to reduce FODMAPS and be better tolerated in IBS patients, reducing bloating, nausea and discomfort. Overall, all the studies provide insufficient evidence on fermented foods and gastrointestinal health.
Abstract
Fermented foods are defined as foods or beverages produced through controlled microbial growth, and the conversion of food components through enzymatic action. In recent years, fermented foods have undergone a surge in popularity, mainly due to their proposed health benefits. The aim of this review is to define and characterise common fermented foods (kefir, kombucha, sauerkraut, tempeh, natto, miso, kimchi, sourdough bread), their mechanisms of action (including impact on the microbiota), and the evidence for effects on gastrointestinal health and disease in humans. Putative mechanisms for the impact of fermented foods on health include the potential probiotic effect of their constituent microorganisms, the fermentation-derived production of bioactive peptides, biogenic amines, and conversion of phenolic compounds to biologically active compounds, as well as the reduction of anti-nutrients. Fermented foods that have been tested in at least one randomised controlled trial (RCT) for their gastrointestinal effects were kefir, sauerkraut, natto, and sourdough bread. Despite extensive in vitro studies, there are no RCTs investigating the impact of kombucha, miso, kimchi or tempeh in gastrointestinal health. The most widely investigated fermented food is kefir, with evidence from at least one RCT suggesting beneficial effects in both lactose malabsorption and Helicobacter pylori eradication. In summary, there is very limited clinical evidence for the effectiveness of most fermented foods in gastrointestinal health and disease. Given the convincing in vitro findings, clinical high-quality trials investigating the health benefits of fermented foods are warranted.
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Dietary Inflammatory Index, Dietary Non-Enzymatic Antioxidant Capacity, and Colorectal and Breast Cancer Risk (MCC-Spain Study).
Obón-Santacana, M, Romaguera, D, Gracia-Lavedan, E, Molinuevo, A, Molina-Montes, E, Shivappa, N, Hebert, JR, Tardón, A, Castaño-Vinyals, G, Moratalla, F, et al
Nutrients. 2019;11(6)
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This study aims to correlate the risk factors of inflammation and antioxidant capacity in cases of colon and breast cancer, using data from a large Spanish case-controlled study (1852 colon cancer subjects, 1567 breast cancer subjects and a total 4933 controls). The role of diet in colon cancer is widely accepted, however it is more controversial with breast cancer where genetic mutations and other lifestyle factors are cited as primary risk factors. What unites these cancers is the inter-related presence of both inflammation and oxidative stress. The dietary inflammatory index (DII®) and non-enzymatic antioxidant capacity (NEAC) were used to evaluate inflammation and oxidative stress using 30 nutrient parameters and 6 inflammatory blood markers. The results showed that colon cancer subjects typically ate a more pro-inflammatory diet compared to controls, with a higher odds ratio of men to women, and tended to be older, heavier and less physically active. The breast cancer subjects also had higher inflammatory scores versus controls but demographically were younger, premenopausal, frequently with a first-degree family link to breast cancer, and including a higher percentage of smokers. For both cancers, inflammation significantly and statistically increased risk factors. Adding in oxidative stress results showed a statistically higher risk of developing colon cancer whilst in breast cancer subjects the risk was increased but non-statistically valid. They did report that meat-eaters had a relative 9% increased risk of Breast cancer. Overall the study concluded that dietary components of inflammation and oxidative stress increased risk of colon cancer but were not statistically valid for breast cancer.
Abstract
Inflammation and antioxidant capacity have been associated with colorectal and breast cancer. We computed the dietary inflammatory index (DII®), and the total dietary non-enzymatic antioxidant capacity (NEAC) and associated them with colorectal and breast cancer risk in the population-based multi case-control study in Spain (MCC-Spain). We included 1852 colorectal cancer and 1567 breast cancer cases, and 3447 and 1486 population controls, respectively. DII score and NEAC were derived using data from a semi-quantitative validated food frequency questionnaire. Unconditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95%CI) for energy-adjusted DII (E-DII), and a score combining E-DII and NEAC. E-DII was associated with colorectal cancer risk (OR = 1.93, highest quartile versus lowest, 95%CI:1.60-2.32; p-trend: <0.001); this increase was observed for both colon and rectal cancer. Less pronounced increased risks were observed for breast cancer (OR = 1.22, highest quartile versus lowest, 95%CI:0.99-1.52, p-trend: >0.10). The combined score of high E-DII scores and low antioxidant values were associated with colorectal cancer risk (OR = 1.48, highest quartile versus lowest, 95%CI: 1.26-1.74; p-trend: <0.001), but not breast cancer. This study provides evidence that a pro-inflammatory diet is associated with increased colorectal cancer risk while findings for breast cancer were less consistent.