Positive association of unhealthy plant-based diets with the incidence of abdominal obesity in Korea: a comparison of baseline, most recent, and cumulative average diets

Plant-based and sustainable diet: A systematic review of its impact on obesity

The food system significantly affects the environment through land use, emissions from livestock, deforestation, and food waste. Diet sustainability considers the environmental effects of food production, distribution, and consumption. Animal products emit more greenhouse gases than plant-based foods, prompting a shift towards plant-focused diets for reduced emissions. Sustainable diets, like the EAT-Lancet model, prioritize plant-based foods, adjusting for regional eating habits. These diets aim to be both environmentally friendly and conducive to human health, addressing concerns like obesity and chronic diseases. Obesity is a major global health challenge, and its complex relationship with food production and consumption patterns calls for sustainable solutions to reduce pressure on ecosystems and promote healthier lifestyles. Tackling obesity requires holistic strategies that address not only individual health but also the broader environmental impacts of food systems. A systematic review examined the link between plant-based diets and obesity focusing on studies assessing Body Mass Index (BMI) and body fat assessment. Despite limited research, evidence suggests that adherence to a plant-based diet, particularly a healthy one, is associated with lower obesity rates. More longitudinal and intervention studies are necessary for a stronger consensus on the matter.

Association between plant-based diets and risk of metabolic dysfunction-associated steatotic liver disease in Korean adults: A prospective cohort study

OBJECTIVES

Few studies have investigated the correlation between plant-based diet indices (PDIs) and the risk of metabolic dysfunction-associated steatotic liver disease (MASLD) in the Korean population. Therefore, this study aimed to investigate the association between PDIs and the risk of MASLD in Korean adults.

METHODS

This cohort study utilized data from the Health Examinees Study conducted in the South Korean population. Dietary and nutrient intake were assessed at baseline and follow-up using a food frequency questionnaire and the Korean Food Consumption Table. Food items were categorized into overall PDI, healthy PDI (hPDI), and unhealthy PDI (uPDI), with MASLD defined using the fatty liver index. Baseline characteristics and food intake groups were evaluated based on PDI quintiles and stratified by sex. Further analyses involved stratification by age, body mass index, alcohol intake, and physical activity in men and women.

RESULTS

Over a median follow-up period of 4.2 y, MASLD occurred in 1532 participants. Both men and women in the highest hPDI quintile had a reduced risk of MASLD (men: HR: 0.71, 95% CI: 0.55-0.91, p = 0.0031; women: HR: 0.61, 95% CI: 0.48-0.78, p < 0.0001). Conversely, the highest uPDI quintile was associated with a higher risk of MASLD.

CONCLUSIONS

This cohort study revealed an association of the overall PDI and hPDI with a lower risk of MASLD, highlighting the importance of adhering to these types of plant-based diets to prevent MASLD among Korean adults.

Adherence to the nutritional recommendations according to diabetes status in Korean adults: a cross-sectional study

BACKGROUND

Nutritional therapy plays a crucial role in diabetes management. Assessing adherence to nutritional recommendations is critical for evaluating whether the current status of nutrition education is appropriate. This study aimed to evaluate adherence to nutritional recommendations according to diabetes status using data from the Korean National Health and Nutrition Examination Survey from 2016 to 2019.

METHODS

A total of 2,793 participants (55.4% male) were evaluated regarding their adherence to nutritional recommendations. The "aware" group comprised people who had been clinically diagnosed by a physician. The "treated" group comprised people receiving anti-diabetic medications. The "control" group comprised people who achieved an HbA1c level < 6.5%. The "educated" group comprised people who had received nutrition education or counseling at various locations.

RESULTS

Among the 1,918 individuals in the "aware" group, only 243 (8.7%) had received nutrition education. Adherence to nutritional recommendations was generally low, with people with diabetes showing slightly higher adherence to total energy intake (59.6% vs. 55.3%) and total sugar intake (88.0% vs. 84.5%) than people without diabetes. However, adherence to total carbohydrate intake was poor in both the treated and educated groups (34.3% and 26.0%, respectively) compared to the untreated and non-educated groups (44.4% and 36.0%, respectively).

CONCLUSIONS

These findings indicate inadequate nutritional management for people with diabetes in Korea. Nutrition education should be effectively strengthened to achieve nutritional goals.

Plant-based diets and the gut microbiome: findings from the Baltimore Longitudinal Study of Aging

BACKGROUND

Mounting evidence indicates that although some plant-based diets are healthful, others are not. Changes in the gut microbiome and microbiome-dependent metabolites, such as trimethylamine N-oxide (TMAO), may explain differential health effects of plant-based diets. However, human data are sparse on whether qualitatively distinct types of plant-based diets differentially affect gut microbiome diversity, composition, particularly at the species level, and/or metabolites.

OBJECTIVES

We aimed to examine cross-sectional associations of different plant-based indices with adult gut microbiome diversity, composition, and the metabolite TMAO.

METHODS

We studied 705 adults in the Baltimore Longitudinal Study of Aging with data for diet, fecal microbiome (shotgun metagenomic sequencing), and key covariates. We derived healthful plant-based diet index (hPDI) and unhealthful plant-based diet index (uPDI) using data from food frequency questionnaires. We examined plant-based diet indices with microbiome α-diversity (richness and evenness measures), β-diversity (Bray-Curtis and UniFrac measures), composition (species level), and plasma TMAO. We used regression models to determine associations before and after adjustment for age, sex, education, physical activity, smoking status, body mass index, and total energy intake.

RESULTS

The analytic sample (mean age, 71.0 years, SD = 12.8 years) comprised 55.6% female and 67.5% non-Hispanic White participants. hPDI was positively and uPDI negatively associated with microbiome α-diversity, driven by microbial evenness (Pielou P < 0.05). hPDI was also positively associated with relative abundance of 3 polysaccharide-degrading bacterial species (Faecalibacterium prausnitzii, Eubacterium eligens, and Bacteroides thetaiotaomicron) and inversely associated with 6 species (Blautia hydrogenotrophica, Doreasp CAG 317, Eisenbergiella massiliensis, Sellimonas intestinalis, Blautia wexlerae, and Alistipes shahii). Furthermore, hPDI was inversely associated with TMAO. Associations did not differ by age, sex, or race.

CONCLUSIONS

Greater adherence to a healthful plant-based diet is associated with microbiome features that have been linked to positive health; adherence to an unhealthful plant-based diet has opposing or null associations with these features.

Scoping review of the association of plant-based diet quality with health outcomes

Introduction

The association of plant-based dietary patterns with health outcomes has traditionally been assessed without considering nutritional value. The plant-based dietary index (PDI), first published in 2016, overcomes this limitation with both a healthful PDI (hPDI) and an unhealthful PDI (uPDI), based on the quality of plant foods consumed plus the frequency of animal foods. We sought to summarize the breadth of research using the hPDI and uPDI to gain insight into how the quality of plant-based dietary patterns might be associated with health outcomes.

Methods

Scoping review of studies that used the PDI, hPDI, or uPDI to report associations with health outcomes. Multiple databases were searched from 2010 through April 2023 with 2 authors independently assessing eligibility and extracting data. In addition to assessing the association of the indices to health outcomes, we determined the frequency of concordant or discordant findings for hPDI versus PDI and for hPDI versus uPDI.

Results

We included 95 articles (54% longitudinal, 37% cross-sectional, and 9% case-control) with a median sample size of 3,646. Higher hPDI levels were associated with favorable health outcomes in 36% of comparisons (most often for obesity, mortality, diabetes, cardiovascular disease, and psychiatric disorders), compared to 25% for the PDI and only 2% for the uPDI. Conversely, higher levels of the uPDI were associated with unfavorable health outcomes in 33% of comparisons, in contrast to under 1% for the hPDI and 2% for the PDI. When the hPDI association to an outcome was discordant with the uPDI or PDI, the significance and directionality always favored the hPDI over the uPDI, and nearly always favored the hPDI over the PDI.

Discussion

Dietary indices that account for the quality of plant foods can show health benefits that might be missed by a generic plant-based index. A greater focus on the quality of plant foods could improve nutrition guidelines, raise awareness about the benefits of adding unrefined plant foods to the diet, and empower consumers to make incremental additions of such foods to displace unhealthy foods. We anticipate increasing use of indices that address food quality in future research.