Flexitarian diets and heart health

Aim

This cross-sectional study aimed to evaluate the association between a flexitarian diet comparative to a vegan and omnivorous diet on cardiovascular disease (CVD) risk factors.

The study population was young to middle aged, healthy German people. The research was conducted as part of a wider interdisciplinary research project ‘NES’ (Nachhaltige Ernahrungsstile).

It aimed to elucidate if an elimination of all animal products from the diet was required or if reducing red and processed meat is sufficient.

Method

The study was conducted between March and August 2020.

Participants were included if they had followed their diet for over a year and were classified as follows:

• Flexitarians: <50g/day meat and processed meat consumption

• Vegans: exclusion of all food of animal origin

• Omnivores : meat and processed meat >170g/day

The study aimed to have a homogenous cohort and included a narrow age, BMI (20-28kg/m2) and non-smokers. The participants were matched on these variables.

Dietary habits were validated by a validated food frequency questionnaire and diet quality was based on the Healthy Eating Index-Flex score.

CVD was based on arterial stiffness measurements and blood biomarkers.

Key findings

Anthropometric composition

Flexitarian women had significantly lower body fat percentages than the omnivorous women (p=0.003). Vegan women also had lower body fat than the omnivorous women.

Food group intake and diet quality

• There were no significant differences in median consumption of beverages, soft drinks, and bread/rice/noodles/potatoes between the three diet groups.

• Omnivores consumed the least vegetables, flexitarians twice as much and vegans three times as much (p=<0.001).

• Fruit consumption was twice as high in flexitarians and vegans (p=0.018) with only a slight difference between flexitarians and vegans.

The HEI-Flex score results differed significantly between all diet groups (p < 0.001) with Vs showing the most favourable diet quality, followed by FXs and then by OMNs.

Comparison of CVD risk profile parameters

• Blood glucose markers: Vegans had the lowest fasting insulin concentrations with statistical significance from the omnivorous diet

• Blood lipid markers: Flexitarian and vegan diets had significantly lower LDL cholesterol and fasting triglycerides than omnivorous diets

• Metabolic syndrome: Flexitarian diets had the most favourable scores based on BMI and waist circumference

• Vascular health parameters: Significantly better values for pulse wave velocity (PWV) were seen in the flexitarian group

Association between CVD risk factors and food groups intake

Total cholesterol: an inverse relationship was seen with fruit, plant-based dairy alternatives, legumes and HEI-flex scores.

LDL-cholesterol had a positive association with soft drinks, sweets and meat. The converse was found with intake of vegetables, fruit, dairy alternatives, legumes and HEI-Flex scores.

Processed meat consumption was associated with increased BMI and waist circumference, used as a proxy measure for metabolic risk.

Regression analyses showed that animal-based foods may have an adverse association with CVD risk factors.

Conclusion

In conclusion, plant-based diets, including a flexitarian diet are associated with improved blood lipid profiles. The data showed that those following flexitarian and vegan diets had more beneficial levels of insulin, triglycerides, total cholesterol and LDL cholesterol compared to those having an omnivore diet. 

Flexitarians and vegans reported higher intake rates of vegetables, fruit, nuts/seeds and plant-based milk alternatives.

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