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Effect of a Hop Extract Standardized in 8-Prenylnaringenin on Bone Health and Gut Microbiome in Postmenopausal Women with Osteopenia: A One-Year Randomized, Double-Blind, Placebo-Controlled Trial.
Lecomte, M, Tomassi, D, Rizzoli, R, Tenon, M, Berton, T, Harney, S, Fança-Berthon, P
Nutrients. 2023;15(12)
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Osteoporosis is a bone condition characterized by weakened and brittle bones, leading to an increased risk of fractures. Oestrogens play a vital role in maintaining bone health, whereby oestrogen deficiency elevates the risk of osteoporosis and fractures, particularly in menopausal women due to the decline in oestrogen levels. Phytoestrogens, plant-derived compounds capable of interacting with human oestrogen receptors, have presented an intriguing non-pharmaceutical avenue for preventing bone loss. Other phytoestrogens have received some attention in the field, however, limited human research exists on prenylflavonoids, a phytoestrogens found in hops (Humulus lupulus). This randomized, double-blinded, placebo-controlled trial aimed to investigate the effects of a year-long supplementation of standardised hop extract (8-PN) Lifenol® on bone mineral density in postmenopausal women. Additionally, the study explored potential mechanisms, particularly focusing on changes in gut bacteria. Notably, gut bacteria play a role in bone metabolism and the pathogenesis of osteoporosis. They are also, along with the liver, responsible for converting hops phenols into active phytoestrogenic compounds. The trial was completed by 95 postmenopausal, women with Osteopenia aged 50 to 85. They all received calcium and vitamin D3 tablets in addition either a hop extract (100mcg) or a placebo for 48 weeks. Changes were monitored using DXA scans for bone mineral density (BMD) and bone metabolism, blood samples for markers for bone health, a quality of life questionnaire, gut microbiome testing, and tests for short-chain fatty acid (SCFA) levels. In conclusion, the intake of hop extract confirmed a previously observed trend of a slight increase in total bone mineral density (BMD), in addition to the benefits linked to calcium and vitamin D supplementation. Although there were no significant changes in the composition of gut bacteria and SCFA levels, the hop extract candidates had a higher abundance of specific genera associated with total body BMD, suggesting a potential positive impact. Larger studies are required to validate these findings.
Abstract
Estrogen deficiency increases the risk of osteoporosis and fracture. The aim of this study was to investigate whether a hop extract standardized in 8-prenylnaringenin (8-PN), a potent phytoestrogen, could improve bone status of osteopenic women and to explore the gut microbiome roles in this effect. In this double-blind, placebo-controlled, randomized trial, 100 postmenopausal, osteopenic women were supplemented with calcium and vitamin D3 (CaD) tablets and either a hop extract (HE) standardized in 8-PN (n = 50) or a placebo (n = 50) for 48 weeks. Bone mineral density (BMD) and bone metabolism were assessed by DXA measurements and plasma bone biomarkers, respectively. Participant's quality of life (SF-36), gut microbiome composition, and short-chain fatty acid (SCFA) levels were also investigated. In addition to the CaD supplements, 48 weeks of HE supplementation increased total body BMD (1.8 ± 0.4% vs. baseline, p < 0.0001; 1.0 ± 0.6% vs. placebo, p = 0.08), with a higher proportion of women experiencing an increase ≥1% compared to placebo (odds ratio: 2.41 ± 1.07, p < 0.05). An increase in the SF-36 physical functioning score was observed with HE versus placebo (p = 0.05). Gut microbiome α-diversity and SCFA levels did not differ between groups. However, a higher abundance of genera Turicibacter and Shigella was observed in the HE group; both genera have been previously identified as associated with total body BMD. These results suggest that an 8-PN standardized hop extract could beneficially impact bone health of postmenopausal women with osteopenia.
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Effects of whey and soy protein supplementation on inflammatory cytokines in older adults: a systematic review and meta-analysis.
Prokopidis, K, Mazidi, M, Sankaranarayanan, R, Tajik, B, McArdle, A, Isanejad, M
The British journal of nutrition. 2023;129(5):759-770
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Reduced muscle mass and reduction in physical activity may lead to sarcopenia in older people. Age-related sarcopenia is associated with increased systemic low-grade inflammation and obesity. Protein supplementation is found to be beneficial in reducing circulating pro-inflammatory cytokines in old people. Previous research has shown that supplementation with isolated whey and soy protein reduces the levels of inflammatory cytokines in older adults. However, there is limited research on intact whey and soy protein supplementation in reducing age-related inflammation. This systematic review and meta-analysis investigated the effect of intact whey and soy protein on serum inflammatory markers such as C-reactive protein (CRP), Interleukin-6 (IL6) and TNF-α in older adults. The results of this meta-analysis show a significant reduction in circulating IL-6 and TNF-α levels after the supplementation with whey and soy protein. The addition of soy isoflavones resulted in a further decline in serum CRP levels. Subgroup analysis showed that the whey protein supplementation significantly improved sarcopenia and pre-frailty. Healthcare professionals can use the result of this systematic review and meta-analysis to understand the anti-inflammatory properties of intact whey and soy protein and soy isoflavones. However, further robust studies are required to assess the anti-inflammatory properties of whey and soy protein due to the high heterogeneity of included studies in this review.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Nutritional strategies such as whey and soy protein supplementation may be regarded as safe and effective to attenuate adverse changes in muscle mass with ageing, however need to be considered alongside individual dietary intake and health status.
- Consider optimising protein intake and quality of protein through diet as an alternative or first line strategy.
Evidence Category:
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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:
Introduction
- A decline in muscle mass and physical capacity, known as sarcopenia, may start in the fourth decade with accumulation of adiposity, resulting in elevated circulating proinflammatory cytokines.
- Systematic and local elevation of oxidative stress and reactive oxygen species accumulation may accelerate age-related muscle wasting, however may be mitigated with antioxidant nutrients.
- This SR and MA evaluated whey and soy proteins effects on interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α) and C-reactive protein (CRP) in older adults.
Methods
SR followed PRISMA guidelines, was registered on PROSPERO and included 31 RCT studies published in English between 2004-21. Intervention group received soy/whey supplements and comparator group received a placebo; circulating levels of CRP, IL-6 and/or TNF-α were assessed. MA used random-effects to calculate the pooled effects. Overall quality of evidence was rated as moderate.
Results
Males and females with a mean age 50 - 80 years were included.
Whey protein:
- IL-6 levels were reduced significantly (Number of studies (k) = 12, Mean Difference (MD): −0·79, 95 % Confidence Interval (CI): −1·15, −0·42, p< 0.01), however, high heterogeneity was observed (I2 = 96 %).
- Treatment duration ≤ 8 weeks showed a significant reduction in serum CRP (k = 4, MD: –0·30, 95 % CI: –0·39, –0·21, I2 = 0 %) compared with > 8 weeks (k = 6, MD: 0·13, 95 % CI: –0·13, 0·40, I2 = 9 %), whereas TNF-α and IL-6 remained unaltered.
- Individuals with sarcopenia and pre-frailty displayed a significant reduction of IL-6 (k = 3, MD: –0·98, 95 % CI: –1·56, –0·39, I2 = 0 %) but no benefits were observed for CRP or TNF.
Soy protein:
- There was a significant reduction in TNF-α (k = 6, MD: −0·16, 95 % CI: −0·26, p<0·05).
- The addition of isoflavones demonstrated a significant decrease in TNF-α (k = 5, MD: –0·20, 95 % CI: –0·31, –0·08, I2 = 34 %) but an increase in CRP (k = 7, MD: 0·53, 95 % CI: 0·12, 0·94), however high heterogeneity was observed in the latter (I2 = 91 %).
Conclusion
- The study found a significant reduction in IL-6 following whey protein with effects augmented in those with frailty and sarcopenia and a significant reduction in TNF-α following soy protein with effects augmented by additional soy isoflavones, possibly due to antioxidant effects.
Clinical practice applications:
- Consider whey and/or soy protein supplementation in older adults particularly those reported with pre-frailty and sarcopenia as an effective and safe strategy to attenuate low-grade inflammation and associated risks.
- Soy isoflavones may have additional antioxidant benefits for older adults although further research is needed to confirm this due to high heterogeneity found.
Considerations for future research:
Future research could:
- Evaluate other factors which influence the inflammatory profile such as nutrient density, vitamins and minerals supplementation and exercise.
- Include those with co-morbidities and healthy populations with placebo comparator groups.
- Evaluate dose and type of soy isoflavones on circulating inflammatory markers and the effect of combined whey and soy protein.
Abstract
BACKGROUND AND AIMS Low-grade inflammation is a mediator of muscle proteostasis. This study aimed to investigate the effects of isolated whey and soy proteins on inflammatory markers. METHODS We conducted a systematic literature search of randomised controlled trials (RCT) through MEDLINE, Web of Science, Scopus and Cochrane Library databases from inception until September 2021. To determine the effectiveness of isolated proteins on circulating levels of C-reactive protein (CRP), IL-6 and TNF-α, a meta-analysis using a random-effects model was used to calculate the pooled effects (CRD42021252603). RESULTS Thirty-one RCT met the inclusion criteria and were included in the systematic review and meta-analysis. A significant reduction of circulating IL-6 levels following whey protein [Mean Difference (MD): -0·79, 95 % CI: -1·15, -0·42, I2 = 96 %] and TNF-α levels following soy protein supplementation (MD: -0·16, 95 % CI: -0·26, -0·05, I2 = 68 %) was observed. The addition of soy isoflavones exerted a further decline in circulating TNF-α levels (MD: -0·20, 95 % CI: -0·31, -0·08, I2 = 34 %). According to subgroup analysis, whey protein led to a statistically significant decrease in circulating IL-6 levels in individuals with sarcopenia and pre-frailty (MD: -0·98, 95 % CI: -1·56, -0·39, I2 = 0 %). These findings may be dependent on participant characteristics and treatment duration. CONCLUSIONS These data support that whey and soy protein supplementation elicit anti-inflammatory effects by reducing circulating IL-6 and TNF-α levels, respectively. This effect may be enhanced by soy isoflavones and may be more prominent in individuals with sarcopenia.
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Neither soy nor isoflavone intake affects male reproductive hormones: An expanded and updated meta-analysis of clinical studies.
Reed, KE, Camargo, J, Hamilton-Reeves, J, Kurzer, M, Messina, M
Reproductive toxicology (Elmsford, N.Y.). 2021;100:60-67
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Much of the soy-related health research published over the past 3 decades has taken place because among commonly consumed foods, the soybean is a uniquely rich source of isoflavone. Isoflavones have a chemical structure similar to the hormone oestrogen. The aim of this meta-analysis was to update and expand the 2010 meta-analysis in order to determine whether soy or isoflavone intake affects total testosterone, free testosterone, estradiol, estrone, and sex hormone binding globulin. The study included a total of 41 studies in the analyses of which 20 utilized a parallel design (controlled), eight a crossover design and 15 single arm or parallel arms designs. Results confirm the findings of a meta-analysis published in 2010 that found neither soy nor isoflavone intake affects total or bioavailable circulating testosterone concentrations in men. Authors conclude that in men, neither soy nor isoflavone intake, even when exposure occurs for an extended period of time and exceeds typical Japanese intake, affects levels of total testosterone, free testosterone, estradiol or estrone.
Abstract
Concerns that the phytoestrogens (isoflavones) in soy may feminize men continue to be raised. Several studies and case-reports describing feminizing effects including lowering testosterone levels and raising estrogen levels in men have been published. For this reason, the clinical data were meta-analyzed to determine whether soy or isoflavone intake affects total testosterone (TT), free testosterone (FT), estradiol (E2), estrone (E1), and sex hormone binding globulin (SHBG). PubMed and CAB Abstracts databases were searched between 2010 and April 2020, with use of controlled vocabulary specific to the databases. Peer-reviewed studies published in English were selected if (1) adult men consumed soyfoods, soy protein, or isoflavone extracts (from soy or red clover) and [2] circulating TT, FT, SHBG, E2 or E1 was assessed. Data were extracted by two independent reviewers. With one exception, studies included in a 2010 meta-analysis were included in the current analysis. A total of 41 studies were included in the analyses. TT and FT levels were measured in 1753 and 752 men, respectively; E2 and E1 levels were measured in 1000 and 239 men, respectively and SHBG was measured in 967 men. Regardless of the statistical model, no significant effects of soy protein or isoflavone intake on any of the outcomes measured were found. Sub-analysis of the data according to isoflavone dose and study duration also showed no effect. This updated and expanded meta-analysis indicates that regardless of dose and study duration, neither soy protein nor isoflavone exposure affects TT, FT, E2 or E1 levels in men.
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Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review.
Domínguez-López, I, Yago-Aragón, M, Salas-Huetos, A, Tresserra-Rimbau, A, Hurtado-Barroso, S
Nutrients. 2020;12(8)
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Phytoestrogens are polyphenolic molecules with a structural similarity to endogenous human hormones. The main dietary source of these plant secondary metabolites is legumes (particularly soy), and to a lesser extent fruits, vegetables, and cereals. The aim of this study was to synthesize the results obtained by human studies and assess the potential hormone-related health effects of dietary phytoestrogens throughout the human lifespan. Literature shows that: - the impact of phytoestrogens can vary according to the life stage. - soy isoflavones appear not to have any influence on sex and thyroid hormones, bone remodelling and insulin-like growth factor. - although phytoestrogens transfer from maternal blood to the foetus, no effects have been observed in early life. - in later stages of childhood, an increase of androgens and decrease of oestrogens associated with dietary phytoestrogens have been observed in girls and boys, respectively. - in adulthood, endocrine changes arising from phytoestrogen consumption are unclear, although goitrogenic [compounds that interfere with the normal function of the thyroid gland] activity has been observed in men. - in premenopausal women results regarding sex hormones, breast cancer protection and bone remodelling are uncertain. Authors conclude that intake of phytoestrogens does have some physiological effects in humans related to hormone regulation, but like hormones, the benefits depend on the stage of life.
Abstract
Dietary phytoestrogens are bioactive compounds with estrogenic activity. With the growing popularity of plant-based diets, the intake of phytoestrogen-rich legumes (especially soy) and legume-derived foods has increased. Evidence from preclinical studies suggests these compounds may have an effect on hormones and health, although the results of human trials are unclear. The effects of dietary phytoestrogens depend on the exposure (phytoestrogen type, matrix, concentration, and bioavailability), ethnicity, hormone levels (related to age, sex, and physiological condition), and health status of the consumer. In this review, we have summarized the results of human studies on dietary phytoestrogens with the aim of assessing the possible hormone-dependent outcomes and health effects of their consumption throughout a lifespan, focusing on pregnancy, childhood, adulthood, and the premenopausal and postmenopausal stages. In pregnant women, an improvement of insulin metabolism has been reported in only one study. Sex hormone alterations have been found in the late stages of childhood, and goitrogenic effects in children with hypothyroidism. In premenopausal and postmenopausal women, the reported impacts on hormones are inconsistent, although beneficial goitrogenic effects and improved glycemic control and cardiovascular risk markers have been described in postmenopausal individuals. In adult men, different authors report goitrogenic effects and a reduction of insulin in non-alcoholic fatty liver patients. Further carefully designed studies are warranted to better elucidate the impact of phytoestrogen consumption on the endocrine system at different life stages.
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Effects of Soy Foods in Postmenopausal Women: A Focus on Osteosarcopenia and Obesity.
Tang, S, Du, Y, Oh, C, No, J
Journal of obesity & metabolic syndrome. 2020;29(3):180-187
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The body composition of postmenopausal women changes rapidly due to hormonal changes, including the loss of bone (osteoporosis) and muscle (sarcopenia), usually in the presence of increased adiposity and fat redistribution towards central-type obesity. The aim of this study was to summarise the efficacy of soy foods and their impact on body composition. Research shows that soy products: - may improve the body composition of menopausal and premenopausal women. - delay the physical disabilities of menopausal women with osteosarcopenia and obesity. - may improve muscle mass and bone strength to prevent the development of osteosarcopenia in post-menopausal women. Authors conclude that further research is required since some studies have questioned the mechanism of the protective effect of soybean ingredients on certain metabolic diseases.
Abstract
Chronic diseases in postmenopausal women are caused by rapid changes in hormones and are accompanied by rapid changes in body composition (muscle, bone, and fat). In an aging society, the health of postmenopausal women is a social issue, and people's interest in ingesting high-quality protein is increasing in order to maintain a healthy body composition. This review aims to summarize the efficacy of soy foods and their impact on body composition. The soy protein and isoflavones contained in soy foods can improve muscle and bone density quality and reduce body weight. It is considered a breakthrough in preventing osteosarcopenia and obesity that may occur after menopause.
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Nutritional Interventions to Improve Asthma-Related Outcomes through Immunomodulation: A Systematic Review.
van Brakel, L, Mensink, RP, Wesseling, G, Plat, J
Nutrients. 2020;12(12)
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Asthma is a chronic inflammatory disease of the airways, with the infiltration of immune cells into the airways leading to localized inflammation and asthmatic symptoms. This review sought to establish whether nutritional interventions can help improve asthma and if this happens via regulation of the immune system. 28 studies were included that investigated the impact on both asthma and immunological parameters. The interventions include herbs (Nigella sativa, Crocus sativa, Boswellia serrata gum, Aegle marmelos), supplements (Vitamin E, soy isoflavones, tomato extract), weight loss and reduced-calorie diets, Vitamin D3, omega-3 fatty acids and whole-food approaches such as the Mediterranean diet. Half of the studies reported improvements in either asthma symptoms or immunological parameters. Two studies showed worsening. The herbal mixtures had the most consistent impact in both areas, followed by omega-3 fatty acids. Of interest here was that low to moderate dosages seemingly obtained wider-ranging improvements than higher dosages. The least evidence was found for vitamin D in the studies included. Overall only a couple of studies showed clinically relevant improvements and the authors insist that more research is needed before further nutritional interventions can be included in guidelines for asthma management. According to this review, the evidence for nutritional evidence for asthma management is still limited, in particular for those interventions where symptoms improvements correlate with beneficial immunological changes.
Abstract
Asthma is a chronic inflammatory disease of the airways, characterized by T-helper (Th) 2 inflammation. Current lifestyle recommendations for asthma patients are to consume a diet high in fruits and vegetables and to maintain a healthy weight. This raises the question of whether other nutritional interventions may also improve asthma-related outcomes and whether these changes occur via immunomodulation. Therefore, we systematically reviewed studies that reported both asthma-related outcomes as well as immunological parameters and searched for relations between these two domains. A systematic search identified 808 studies, of which 28 studies met the inclusion criteria. These studies were divided over six nutritional clusters: herbs, herbal mixtures and extracts (N = 6); supplements (N = 4); weight loss (N = 3); vitamin D3 (N = 5); omega-3 long-chain polyunsaturated fatty acids (LCPUFAs) (N = 5); and whole-food approaches (N = 5). Fifteen studies reported improvements in either asthma-related outcomes or immunological parameters, of which eight studies reported simultaneous improvements in both domains. Two studies reported worsening in either asthma-related outcomes or immunological parameters, of which one study reported a worsening in both domains. Promising interventions used herbs, herbal mixtures or extracts, and omega-3 LCPUFAs, although limited interventions resulted in clinically relevant results. Future studies should focus on further optimizing the beneficial effects of nutritional interventions in asthma patients, e.g., by considering the phenotypes and endotypes of asthma.
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Soy Products Ameliorate Obesity-Related Anthropometric Indicators in Overweight or Obese Asian and Non-Menopausal Women: A Meta-Analysis of Randomized Controlled Trials.
Mu, Y, Kou, T, Wei, B, Lu, X, Liu, J, Tian, H, Zhang, W, Liu, B, Li, H, Cui, W, et al
Nutrients. 2019;11(11)
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With obesity on the rise this analysis of 22 trials and a total of 870 overweight or obese adults looks at whether soy products are effective food for weight loss. Sixteen trials examined soy products and Body Mass Index (BMI) and concluded that soy products significantly reduced body mass compared to the control groups. The remaining studies examined the effects of soy on fat mass, fat percentage, and waist and hip circumference and showed declines in fat mass but not significant reductions in waist and hip measurements. The amalgamated results showed a total reduction of 0.34 kg body weight. Various types of soy products were included such as soy protein, isoflavones, soy milk, soy shakes and some other soy products. Further sub-group analysis showed differences in people from developed countries (typically a BMI higher than 25.0) versus developing countries (average BMI lower than 25.0). They also highlighted differences between cultures with meat-based and plant-based diets and the wide acceptance of soy in Asia. Significant effects were observed in non-menopausal women with reduced body weight, BMI and waist circumference, while no results were observed in postmenopausal women. The study concludes that soy protein, isoflavones and fibre all contribute to fullness and signalling pathways which may be helpful in reducing body weight.
Abstract
BACKGROUND The effect of soy products on the weight of overweight or obese people is controversial, so we aimed to conduct a systematic review and a meta-analysis of published randomized controlled trials to analyze whether supplementation with soy products can help them to lose weight. METHODS The relevant data before January 2019 in PubMed, Embase and Cochrane Library were searched. A random-effect model was adopted to calculate the weighted average difference of net changes of body weight, body mass index (BMI), body fat percentage, fat mass, waist circumference, etc. Results: A total of 22 trials (870 overweight or obese participants) were reflected in the present meta-analysis. Analysis showed that soy products significantly reduced body weight, BMI, body fat percent and waist circumference in overweight or obese Asian populations (-0.37 kg, P = 0.010; -0.27 kg/m2, P = 0.042; -0.36%, P = 0.032; -0.35 cm, P = 0.049) and more significant effects were observed in non-menopausal women reduced body weight (-0.59 kg, P = 0.041), BMI (-0.59, P = 0.041) and waist circumference (-0.59 cm, P = 0.041) in overweight or obese populations. CONCLUSION This meta-analysis showed that soy products have weight loss effects, mainly due to soy protein, isoflavone and soy fiber.
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Efficacy and Safety of Lactobacillus Plantarum C29-Fermented Soybean (DW2009) in Individuals with Mild Cognitive Impairment: A 12-Week, Multi-Center, Randomized, Double-Blind, Placebo-Controlled Clinical Trial.
Hwang, YH, Park, S, Paik, JW, Chae, SW, Kim, DH, Jeong, DG, Ha, E, Kim, M, Hong, G, Park, SH, et al
Nutrients. 2019;11(2)
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Mild cognitive impairment (MCI) describes a range of symptoms that impact on cognition and memory, but not to such an extent that it seriously affects a person's day to day life. People with MCI are at higher risk of going on to develop dementia. Consumption of both probiotics and soy beans have been shown to enhance memory function in previous studies on animals and humans. In this Korean study, a randomised, double-blind, placebo-controlled trial, researchers used soybeans that had been fermented with a bacterium called Lactobacillus plantarum C29, a type of bacteria which is found in the traditional Korean food kimchi. One hundred men and women diagnosed with MCI were given capsules containing either 800 mg of dried fermented soybeans or a placebo for 12 weeks. Participants underwent a series of memory and attention tests to measure cognitive function. Researchers also looked at levels of a protein that supports nerve cells, called brain-derived neurotropic factor (BDNF) in the blood, as well as the composition of bacteria in the stool samples of the participants. The group that consumed the fermented soybeans showed greater improvements in the overall cognitive function, especially attention, compared to those who took the placebo. BDNF levels increased in the soybean group but declined in the placebo group. Increases in BDNF were associated with improvements in cognitive function. The results of this clinical trial suggest that fermented soybeans can be safely consumed by people with MCI to enhance cognitive function. The authors suggested that the increase in blood BDNF levels may be partly responsible for the improved cognitive function, and this in turn points to the importance of the so-called gut-brain axis in improving symptoms of MCI.
Abstract
Early intervention using dietary supplements may be effective in alleviating cognitive impairment among individuals with mild cognitive impairment (MCI). This study investigated the efficacy and safety of Lactobacillus plantarum C29-fermented soybean (DW2009) as a nutritional supplement for cognitive enhancement. One hundred individuals with MCI were randomly assigned to take DW2009 (800 mg/day, n = 50) or placebo (800 mg/day, n = 50) for 12 weeks. The primary outcome measure was change in the composite score of cognitive functions related to memory and attention, measured by computerized neurocognitive function tests. Associations between changes in serum brain-derived neurotrophic factor (BDNF) levels and cognitive performance for each treatment group were evaluated. Compared to the placebo group, the DW2009 group showed greater improvements in the combined cognitive functions (z = 2.36, p for interaction = 0.02), especially in the attention domain (z = 2.34, p for interaction = 0.02). Cognitive improvement was associated with increased serum BDNF levels after consumption of DW2009 (t = 2.83, p = 0.007). The results of this clinical trial suggest that DW2009 can be safely administered to enhance cognitive function in individuals with MCI. Increased serum BDNF levels after administering DW2009 may provide preliminary insight into the underlying effects of cognitive improvement, which suggests the importance of the gut-brain axis in ameliorating cognitive deficits in MCI.
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Bioactivity of soy-based fermented foods: A review.
Cao, ZH, Green-Johnson, JM, Buckley, ND, Lin, QY
Biotechnology advances. 2019;37(1):223-238
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Fermented foods are growing in popularity in the West due to their unique flavour and nutritional value. This review investigates the fermentation processes, health-associated bioactive components and underlying mechanisms of the popular fermented soy products Natto, fermented soy milk, Tempeh and soy sauce. Each fermented soy product is summarised based on functional activities. The existing literature points to an overall positive effect on bone health and immune activities. Interestingly, each fermented soy food exhibits different profiles of bioactive components and therefore different mechanisms of action. Based on this review, the authors conclude there is a need for further in-depth human studies with large sample sizes and long-term follow up to better understand these foods benefits and potential toxicity.
Abstract
For centuries, fermented soy foods have been dietary staples in Asia and, now, in response to consumer demand, they are available throughout the world. Fermentation bestows unique flavors, boosts nutritional values and increases or adds new functional properties. In this review, we describe the functional properties and underlying action mechanisms of soy-based fermented foods such as Natto, fermented soy milk, Tempeh and soy sauce. When possible, the contribution of specific bioactive components is highlighted. While numerous studies with in vitro and animal models have hinted at the functionality of fermented soy foods, ascribing health benefits requires well-designed, often complex human studies with analysis of diet, lifestyle, family and medical history combined with long-term follow-ups for each subject. In addition, the contribution of the microbiome to the bioactivities of fermented soy foods, possibly mediated through direct action or bioactive metabolites, needs to be studied. Potential synergy or other interactions among the microorganisms carrying out the fermentation and the host's microbial community may also contribute to food functionality, but the details still require elucidation. Finally, safety evaluation of fermented soy foods has been limited, but is essential in order to provide guidelines for consumption and confirm lack of toxicity.
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Effects of a 2-year randomized soy intervention on sex hormone levels in premenopausal women.
Maskarinec, G, Franke, AA, Williams, AE, Hebshi, S, Oshiro, C, Murphy, S, Stanczyk, FZ
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2004;13(11 Pt 1):1736-44
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Countries that have a high consumption of soy, such as Japan and China, tend to have lower breast cancer rates. Soy contains isoflavones, phytoestrogens which may have oestrogenic and antieostrogenic effects. The aim of this trial was to examine the effect of soy foods on menstrual cycle length and circulating sex hormone levels. 189 healthy premenopausal women completed the 2-year study, during which the treatment group consumed two daily servings of soy foods (tofu, soy milk, roasted soy nuts, soy protein powder or soy protein bars) containing a total of 50 mg of isoflavones. The control group maintained their regular diet. Blood samples were taken 5 days after ovulation in months 0, 3, 6, 12 and 24. Soy did not have any significant effects on the levels of circulating sex hormones or length of menstrual cycle. The authors concluded that any preventative effects of soy on breast cancer risk may be mediated by mechanisms other than its effect on circulating sex hormone levels.
Abstract
OBJECTIVE Several epidemiologic studies have described protective effects of soy consumption against breast cancer. The goal of this trial among premenopausal women was to examine the effect of soy foods on menstrual cycle length and circulating sex hormone levels. METHODS This 2-year dietary intervention randomized 220 healthy premenopausal women. The intervention group consumed two daily servings of soy foods containing approximately 50 mg of isoflavones; the control group maintained their regular diet. Five blood samples (obtained in months 0, 3, 6, 12, and 24) were taken 5 days after ovulation as determined by an ovulation kit. The serum samples were analyzed for estrone, estradiol, sex hormone binding globulin, androstenedione, and progesterone by immunoassay. RESULTS At baseline, both groups had similar demographic, anthropometric, and nutritional characteristics. The dropout rates of 15.6% (17 of 109) in the intervention group and 12.6% (14 of 111) in the control group did not differ significantly. According to soy intake logs, 24-hour recalls, and urinary isoflavone excretion, the women closely adhered to the study regimen. Menstrual cycles became slightly shorter in both groups but did not differ by group. Mixed general linear models indicated no significant intervention effect on any of the serum hormones. However, androstenedione and progesterone decreased significantly over time in both groups. CONCLUSIONS The results of this study suggest that the preventive effects of soy on breast cancer risk in premenopausal women may not be mediated by circulating sex hormone levels. Different mechanisms of actions or effects of exposure earlier in life are alternate hypotheses that require further investigation.