Increasing dietary fibre intake in healthy adults using personalised dietary advice compared with general advice: a single-blind randomised controlled trial

Assessing the impact of dietary choices on fiber deficiency: insights from the 2017-2020 Polish national adult nutrition survey

Introduction

Dietary fiber is a key component of a healthy diet, associated with a reduced risk of cardiovascular disease, obesity, type 2 diabetes, certain cancers, chronic inflammation, or depression. The aim of the study was to perform an in-depth analysis of dietary fiber intake in the Polish population, taking account of the consumption of groups of products that are fiber sources and identify any age-related differences in the dietary fiber intake of the subjects.

Methods

We analyzed data obtained from two representative cross-sectional studies on the diet and nutritional status of adult Polish residents including the total of 4,000 individuals aged 19 years and more. Two 24-h recalls were used per individual to assess the diet using the computer-assisted personal interview (CAPI) technique. Total fiber content and fiber contained in cereal products, vegetables, fruits, legumes, nuts and seeds were calculated. Fiber intake was compared to the recommendations: 25 g/d for adults up to 65 years of age and 20 g/d for those aged 66 years and older. All statistical analyses, including the Pearson's chi-squared test, the Student's t-test, and the Analysis of Variance (ANOVA), were conducted using STATISTICA™ version 13.3, with the results being adjusted for demographic distribution biases to enhance the representativeness.

Results

The average daily fiber intake was 17.83 ± 0.14 g/day (78% of the recommended intake), with 20.5% of respondents meeting the requirement. More men than women (27.05% vs. 14.3%;) met the requirement and men were characterized by a higher average intake (19.34 ± 0.20 g/day) than women (16.43 ± 0.19 g/day). The main fiber sources were cereals (44.1%), vegetables (23.6%), and fruits (16.0%). As regards men, the sources included refined bread (25.8%), vegetables (23.1%), and fruits (10.2%) and for women, they were vegetables (24.0%), fruits (17.2%), and refined bread (16.3%). Although refined bread is not recommended as a primary fiber source due to its lower fiber content compared to whole grain bread, its high consumption significantly contributed to the total fiber intake.

Conclusion

The prevalence of widespread dietary fiber deficiency calls for the intensification of educational efforts that address the health advantages and sources of dietary fiber, as well as methods for its inclusion in daily meals.

Rationale and design of a randomized placebo-controlled nutritional trial embracing a citizen science approach

Modulation of the gut microbiota through specific dietary interventions shows potential for maintenance and optimization of health. A dietary fiber diet and fermented foods diet appear to alter the gut microbiota, but evidence is limited. Therefore, we designed the Gut Health Enhancement by Eating Favorable Food study, a 21-week randomized controlled trial studying effects of dietary fibers and fermented foods on gut microbiota diversity and composition, while also stimulating dietary behavior changes through a citizen science (CS) approach. We hypothesized that a high-fermented food diet would increase microbial diversity, whereas a high-dietary fiber diet would stimulate the growth of specific fiber-degrading bacteria. The following elements of CS were adopted: education on the gut microbiota, tailored dietary intervention, remote data collection by participants, sharing of personal gut microbiota outcomes with participants, and vlogs by participants for dissemination of results. Here we describe the study protocol and report the flow of participants, baseline characteristics, and compliance rates. Completed in March 2024, the trial included 147 healthy adults randomized to a high-dietary fiber intervention, high-fermented food intervention, or control group. Each group received an additional study product after 2 weeks: dried chicory root, a fermented beverage, or maltodextrin (placebo). A 3-month follow-up assessed the participants' ability to sustain dietary changes. The recruitment of participants was successful, reflected by 1448 applications. The compliance with the dietary guidelines and study products was >90%. This study shows that including elements of CS in an randomized controlled trial is feasible and may help recruitment and compliance.

Technology-delivered personalized nutrition intervention on dietary outcomes among adults with overweight and obesity: A systematic review, meta-analysis, and meta-regression

The prevalence of overweight and obesity has continued to increase globally, and one-size-fits-all dietary recommendations may not be suitable for different individual characteristics. A personalized nutrition intervention may be a potential solution. This review aims to evaluate the effects of the technology-delivered personalized nutrition intervention on energy, fat, vegetable, and fruit intakes among adults with overweight and obesity. A three-step comprehensive search strategy was performed from 10 databases and seven clinical registries in published and unpublished trials. A total of 46 randomized controlled trials (RCTs) involving 19,670 adults with overweight and obesity from 14 countries are included. Subgroup and meta-regression analyses were conducted. Meta-analyses showed a reduction of energy intake (-128.05, 95% CI: -197.08, -59.01) and fat intake (-1.81% energy/days, 95% CI: -3.38, -0.24, and -0.19 scores, 95% CI: -0.40, 0.02) in the intervention compared with the comparator. Significant improvements in vegetable and fruit intakes with 0.12-0.15 servings/day were observed in the intervention. Combined one- and two-way interactions had a greater effect on energy intake reduction compared with their counterparts. Meta-regression analyses revealed that no significant covariates were found. Given that the certainty of the evidence was rated as low or very low, further well-designed RCTs with long-term follow-up are warranted.

Components, prospects and challenges of personalized prevention

Effective preventive strategies are urgently needed to address the rising burden of non-communicable diseases such as cardiovascular disease and cancer. To date, most prevention efforts to reduce disease incidence have primarily targeted populations using "one size fits all" public health recommendations and strategies. However, the risk for complex heterogeneous diseases is based on a multitude of clinical, genetic, and environmental factors, which translate into individual sets of component causes for every person. Recent advances in genetics and multi-omics enable the use of new technologies to stratify disease risks at an individual level fostering personalized prevention. In this article, we review the main components of personalized prevention, provide examples, and discuss both emerging opportunities and remaining challenges for its implementation. We encourage physicians, health policy makers, and public health professionals to consider and apply the key elements and examples of personalized prevention laid out in this article while overcoming challenges and potential barriers to their implementation.

A high-fibre personalised dietary advice given via a web tool reduces constipation complaints in adults

Constipation can greatly impact the quality of life (QoL), which can be relieved by dietary fibres; however, preserving a higher fibre intake remains a challenge. We investigated the effects of a personalised dietary advice (PDA) on fibre intake and mild constipation complaints. A total number of twenty-five adults with mild constipation complaints were included in a 4-week observation period followed by a 4-week personalised intervention. The PDA provided high-fibre alternatives via a web tool. In weeks 1, 4 and 8, dietary intake, constipation complaints and QoL were assessed. Furthermore, participants collected a faecal sample at weeks 1, 4 and 8 to determine microbiota diversity and composition, and short-chain fatty acids (SCFA). Participants completed questions daily for 8 weeks regarding abdominal complaints, stool frequency and stool consistency. Fibre intake in week 8 was significantly higher compared to week 1 (Δ = 5·7 ± 6·7 g, P < 0·001) and week 4 (Δ = 5·2 ± 6·4 g, P < 0·001). Constipation severity and QoL significantly improved at week 8 compared to the observation period (P < 0·001). A higher fibre intake significantly reduced constipation severity (β = -0·031 (-0·05; -0·01), P = 0·001) and the QoL (β = -0·022 (-0·04; -0·01), P = 0·009). Stool consistency (P = 0·040) and abdominal pain (P = 0·030) improved significantly during the intervention period (P = 0·040), but stool frequency did not. Average microbial alpha diversity and composition and SCFA concentrations did not change over time, but indicated individual-specific dynamics. Several SCFAs were associated with constipation complaints. To conclude, a PDA effectively increased fibre intake and subsequently reduced constipation complaints, indicating that guided dietary adjustments are important and feasible in the treatment of mild constipation complaints.

A Systematic Review and Meta-Analysis of the Impact of Different Intensity of Dietary Counselling on Cardiometabolic Health in Middle-Aged and Older Adults

Dietary counselling has been identified as one of the nutritional strategies to alleviate cardiometabolic health conditions. Its effectiveness however may vary due to factors such as intensity level and provider while this has not been comprehensively studied. This systematic review and meta-analysis aimed to assess the effects of dietary counselling on the cardiometabolic health in middle-aged and older adults and the sub-group analyses with dietary counselling intensity and the provider were also assessed. Four databases including PubMed, CINAHL Plus with Full Text, Cochrane Library and EMBASE were systematically searched. Data from 22 randomised controlled trials (RCTs) were compiled and those from 9 RCTs were utilised for meta-analysis. Dietary counselling lowered total cholesterol (TC) and fasting blood sugar (FBS) but had no impact on triglycerides (TG) and low-density lipoprotein (LDL). Sub-group analysis revealed significant lowering effect of high intensity dietary counselling for TG (weighted mean difference (WMD): −0.24 mmol/L, 95% confidence intervals (CIs): −0.40 to −0.09), TC (WMD: −0.31 mmol/L, 95% CIs: −0.49 to −0.13), LDL (WMD: −0.39 mmol/L, 95% CIs: −0.61 to −0.16) and FBS (WMD: −0.69 mmol/L, 95% CIs: −0.99 to −0.40) while medium or low intensity dietary counselling did not show favouring effects. Counselling provider showed differential responses on cardiometabolic health between dietitian and all other groups. The findings from this systematic review and meta-analysis suggest that dietary counselling is a beneficial dietary strategy to improve cardiometabolic health in middle-aged and older adults with the emphasis on the counselling intensity.

Exploring the Potential of Personalized Dietary Advice for Health Improvement in Motivated Individuals With Premetabolic Syndrome: Pretest-Posttest Study

Background

Dietary quality plays an essential role in the prevention and management of metabolic syndrome (MetS).

Objective

The aim of this pilot study is to organize personalized dietary advice in a real-life setting and to explore the effects on dietary intake, metabolic health, and perceived health.

Methods

We followed a one-group pretest-posttest design and included 37 individuals at risk of MetS, who indicated motivation to change dietary behavior. For a period of 16 weeks, participants received personalized advice (t=0 and t=8) and feedback (t=0, t=4, t=8, t=12 and t=16) on dietary quality and metabolic health (ie, waist circumference, BMI, blood pressure, lipid profile, fasting glucose levels, and C-peptide). Personalized advice was generated in a two-stage process. In stage 1, an automated algorithm generated advice per food group, integrating data on individual dietary quality (Dutch Healthy Diet Index; total score 8-80) and metabolic health parameters. Stage 2 included a telephone consultation with a trained dietitian to define a personal dietary behavior change strategy and to discuss individual preferences. Dietary quality and metabolic health markers were assessed at t=0, t=8, and t=16. Self-perceived health was evaluated on 7-point Likert scales at t=0 and t=16.

Results

At the end of the study period, dietary quality was significantly improved compared with the baseline (Dutch Healthy Diet Index +4.3; P<.001). In addition, lipid profile (triglycerides, P=.02; total cholesterol, P=.01; high-density lipoprotein, P<.001; and low-density lipoprotein, P<.001), BMI (P<.001), waist circumference (P=.01), and C-peptide (P=.01) were all significantly improved, whereas plasma glucose increased by 0.23 nmol/L (P=.04). In line with these results, self-perceived health scores were higher at t=16 weeks than at baseline (+0.67; P=.005).

Conclusions

This exploratory study showed that personalized dietary advice resulted in positive effects on dietary behavior, metabolic health, and self-perceived health in motivated pre-MetS adults. The study was performed in a do-it-yourself setting, highlighting the potential of at-home health improvement through dietary changes.

Trial Registration

ClinicalTrials.gov NCT04595669; https://clinicaltrials.gov/ct2/show/NCT04595669