Examining nutrition strategies to influence DNA methylation and epigenetic clocks: a systematic review of clinical trials.

Nutrition has powerful impacts on our health and longevity. One of the mechanisms by which nutrition might influence our health is by inducing epigenetic modifications, modulating the molecular mechanisms that regulate aging. Observational studies have provided evidence of a relationship between nutrition and differences in DNA methylation. However, these studies are limited in that they might not provide an accurate control of the interactions between different nutrients, or between nutrition and other lifestyle behaviors. Here we systematically reviewed clinical studies examining the impact of nutrition strategies on DNA methylation. We examined clinical studies in community-dwelling adults testing the effects of nutrition interventions on i) global DNA methylation and its proxies, and ii) epigenetic clocks. We included 21 intervention studies that focused on the effects of healthy nutrition patterns, specific foods or nutrients, as well as the effect of multivitamin or multimineral supplements. In four studies on the methylation effects of healthy dietary patterns, as defined by being rich in vegetables, fruits, whole-grains, and nuts and reduced in the intake of added sugars, saturated fat, and alcohol, two of them suggested that a healthy diet, is associated with lower epigenetic age acceleration, one of them reported increases in global DNA methylation, while another one found no diet effects. Studies examining epigenetic effects of specific foods, nutrients, or mixtures of nutrients were scarce. For both folic acid and polyunsaturated fatty acids, the available independent studies produced conflicting findings. Although more evidence is still needed to draw firm conclusions, results begin to suggest that healthy dietary patterns have positive effects on DNA methylation. Additional evidence from large randomized-controlled clinical trials is needed to support the effects of healthy nutrition on the DNA methylome.

Gene-diet interactions and cardiovascular diseases: a systematic review of observational and clinical trials.

BACKGROUND: Both genetic background and diet are important determinants of cardiovascular diseases (CVD). Understanding gene-diet interactions could help improve CVD prevention and prognosis. We aimed to summarise the evidence on gene-diet interactions and CVD outcomes systematically. METHODS: We searched MEDLINE® via Ovid, Embase, PubMed®, and The Cochrane Library for relevant studies published until June 6th 2022. We considered for inclusion cross-sectional, case-control, prospective cohort, nested case-control, and case-cohort studies as well as randomised controlled trials that evaluated the interaction between genetic variants and/or genetic risk scores and food or diet intake on the risk of related outcomes, including myocardial infarction, coronary heart disease (CHD), stroke and CVD as a composite outcome. The PROSPERO protocol registration code is CRD42019147031. RESULTS AND DISCUSSION: We included 59 articles based on data from 29 studies; six articles involved multiple studies, and seven did not report details of their source population. The median sample size of the articles was 2562 participants. Of the 59 articles, 21 (35.6%) were qualified as high quality, while the rest were intermediate or poor. Eleven (18.6%) articles adjusted for multiple comparisons, four (7.0%) attempted to replicate the findings, 18 (30.5%) were based on Han-Chinese ethnicity, and 29 (49.2%) did not present Minor Allele Frequency. Fifty different dietary exposures and 52 different genetic factors were investigated, with alcohol intake and ADH1C variants being the most examined. Of 266 investigated diet-gene interaction tests, 50 (18.8%) were statistically significant, including CETP-TaqIB and ADH1C variants, which interacted with alcohol intake on CHD risk. However, interactions effects were significant only in some articles and did not agree on the direction of effects. Moreover, most of the studies that reported significant interactions lacked replication. Overall, the evidence on gene-diet interactions on CVD is limited, and lack correction for multiple testing, replication and sample size consideration.

Association of plant-based diet and early onset of natural menopause.

OBJECTIVE: To evaluate the association of plant-based diet index (PDI) with early onset of natural menopause in the Nurses' Health Study (NHS) and Nurses' Health Study II (NHSII). METHODS: We conducted a prospective study with a mean follow-up time of 20 years among premenopausal women living across the US. Participants of the NHS (n = 121,701) and NHSII (n = 116,429) were included from 1984 (age mean [standard deviation]; 44.9 [4.3]) and 1991 (age mean [standard deviation]; 36.4 [4.6]), respectively. Early menopause was self-reported and defined as natural menopause before age 45 years. PDI was derived from semiquantitative food frequency questionnaires administered every 4 years. Cox proportional hazards models were used to assess the association between PDI in quintiles and early menopause in NHS and NHSII separately, and fixed-effect models to pool the results from both cohorts. RESULTS: During follow-up, 715 and 2,185 women experienced early natural menopause in NHS and NHSII, respectively. After adjustment for potential confounders, no association was observed between PDI and incidence of early natural menopause in either cohort, or when pooling the results from both cohorts, with an exception for unhealthy plant-based diet index which was associated with higher risk of early menopause with increasing levels of consumption (P trend = 0.04). CONCLUSION: Adherence to PDI was not associated with timing of menopause while unhealthy plant-based diet might be associated with higher risk of experiencing early menopause.

Dietary factors and onset of natural menopause: A systematic review and meta-analysis.

BACKGROUND: Diet has been suggested to play a role in determining the age at natural menopause; however, the evidence is inconsistent. OBJECTIVE: We systematically reviewed and evaluated published research about associations between diet and onset of natural menopause (ONM). METHODS: We searched 6 databases (Medline, Embase, Cochrane, PubMed, Web of Science and Google Scholar) through January 21,2021 to identify prospective studies assessing the association between diet and ONM. Two independent reviewers extracted data using a predesigned data-collection form. Pooled hazard risks (HRs) were calculated using random effect models. RESULTS: Of the 6,137 eligible references we reviewed, we included 15 articles in our final analysis. Those 15 articles included 91,554 women out of 298,413 who experienced natural menopause during follow-up. Overall, there were 89 food groups investigated, 38 macronutrients and micronutrients, and 6 dietary patterns. Among the food groups, higher intake of green and yellow vegetables was associated with earlier age of ONM, while high intakes of some dairy products, such as low-fat, skimmed milk, and low intake of alcohol were associated with a later onset. We observed no consistent association between macronutrient and micronutrient intake and ONM. Our results suggests that a vegetarian diet could be associated with early ONM; we did not observe any other consistent effect from other dietary patterns. Limitations included the number of studies, lack of replication studies and the research being of an observational nature; most studies (11/15) were at medium risk of bias. CONCLUSION: Although some food items were associated with ONM, the overall evidence about associations between diet and ONM remains controversial. Prospero id: CRD42021232087.

What Influences the Sustainable Food Consumption Behaviours of University Students? A Systematic Review.

Objectives: Global environmental challenges demand sustainable behaviours and policies to protect human and planetary health. We aimed to summarize the evidence about the factors related to Sustainable Food Consumption (SFC) behaviours of university students, and to propose an operational categorization of SFC behaviours. Methods: Seven databases were searched for observational studies evaluating Sustainable Food Consumption (SFC) among university students and that reported at least one behavioural outcome measure. Qualitative synthesis was conducted, and PRISMA guidelines for reporting were followed. Results: Out of 4,479 unique references identified, 40 studies were selected. All studies examined personal factors, while 11 out of 40 also measured social or situational factors. Except for food waste, females had higher levels of SFC behaviours, but situational factors moderated this association. Knowledge and attitudes showed mixed results. Overall, sustainable food consumers reported healthier lifestyles. Conclusions: Healthy lifestyle of sustainable food consumers suggests possible synergies between human health and sustainability in terms of motivations for food choice. Moderation effects of social and situational factors on personal factors reveal opportunities to design and examine the effects of choice architecture interventions.

Menopausal Transition Is Not Associated with Dietary Change in Swiss Women.

BACKGROUND: Adherence to a healthy diet could contribute to maintaining adequate health throughout the menopausal transition, but data are scarce. OBJECTIVE: We evaluated the association between menopausal status and changes in dietary intake in Swiss adult women. METHODS: Cross-sectional (n = 2439) and prospective analyses (n = 1656) were conducted between 2009 and 2012 (first follow-up) among women (mean age ± SD, 58.2 ± 10.5 y) living in Lausanne, Switzerland. In both visits, dietary intake was assessed using a validated FFQ, and menopausal status was classified based on the presence or absence of menstruations. Multivariable linear and logistic regression models were used to investigate the cross-sectional association of menopausal status (postmenopausal compared with premenopausal) at the first follow-up with food intake and dietary recommendations. To examine whether menopausal status (premenopausal as reference group, menopausal transition, and postmenopausal) during 5 y of follow-up was associated with longitudinal changes in diet, including adherence to dietary Swiss recommendations, we applied multivariable linear and logistic mixed models adjusted for several covariates. RESULTS: At the first follow-up, postmenopausal women consumed less (P < 0.002) meat [median (IQR) 57.2 (35-86.2) compared with 62.5 (41.2-95.2) g/d], pasta [61.8 (37.5-89.2) compared with 85 (57.8-128) g/d], and added sugar [0.1 (0-4) compared with 0.7 (0-8) g/d] and more dairy products [126 (65.4-214) compared with 109 (64.5-182) g/d] and fruit [217 (115-390) compared with 174 (83.2-319) g/d] than premenopausal women. However, linear regression analysis adjusted for potential confounding factors showed no independent (cross-sectional) associations of menopausal status with total energy intake (TEI) and individual macro- or micronutrient intakes. In the prospective analysis, compared with women who remained premenopausal during follow-up (n = 244), no differences were found in changes in TEI, dietary intakes, or adherence to the Swiss dietary recommendations in women transitioning from premenopausal to postmenopausal (n = 229) and who remained postmenopausal (n = 1168). CONCLUSION: The menopausal transition is not associated with changes in dietary habits among Swiss women.

Knowledge and beliefs about dietary inorganic nitrate among UK-based nutrition professionals: Development and application of the KINDS online questionnaire

OBJECTIVES: To examine knowledge and beliefs about the biological roles of dietary inorganic nitrate in UK-based nutrition professionals, and to explore potential differences by participants' education level. SETTING: An online questionnaire was administered to UK-based nutrition professionals, exploring knowledge and/or beliefs across five areas: (1) health and performance effects of nitrate; (2) current and recommended intake values for nitrate; (3) dietary sources of nitrate; (4) methods of evaluating nitrate intake and (5) nitrate metabolism. PARTICIPANTS: One hundred and twenty-five nutrition professionals. PRIMARY OUTCOME: Knowledge and beliefs about inorganic nitrate. RESULTS: Most nutrition professionals taking part in the survey had previously heard of inorganic nitrate (71%) and perceived it to be primarily beneficial (51%). The majority believed that nitrate consumption can improve sports performance (59%) and reduce blood pressure (54%), but were unsure about effects on cognitive function (71%), kidney function (80%) and cancer risk (70%). Knowledge of dietary sources of nitrate and factors affecting its content in food were generally good (41%-79% of participants providing correct answers). However, most participants were unsure of the average population intake (65%) and the acceptable daily intake (64%) of nitrate. Most participants (65%) recognised at least one compound (ie, nitric oxide or nitrosamines) that is derived from dietary nitrate in the body. Knowledge of nitrate, quantified by a 23-point index created by summing correct responses, was greater in individuals with a PhD (p=0.01; median (IQR)=13 (9-17)) and tended to be better in respondents with a masters degree (p=0.054; 13 (8-15)) compared with undergraduate-level qualifications (10 (2-14)). CONCLUSIONS: UK-based nutrition professionals demonstrated mixed knowledge about the physiology of dietary nitrate, which was better in participants with higher education. More efficient dissemination of current knowledge about inorganic nitrate and its effects on health to nutrition professionals will support them to make more informed recommendations about consumption of this compound.