Plant-based diets offer heart benefits but may require supplementation

One study found that while unsupplemented vegan diets were associated with healthier body composition and cholesterol levels, they also carried a significantly higher risk of inadequate intake of essential vitamins and minerals, underscoring the importance of careful dietary planning.

Study: Healthier macronutrient profiles but higher risk of specific micronutrient deficiencies: A cross-sectional study of vegans, lacto-ovo-vegetarians and omnivores in Northeast China. Image credit: zi3000/Shutterstock.com

A new study published in the journal Nutrients reports significant micronutrient deficiencies among unsupplemented vegans and vegetarians in northeastern China.

Researchers compare plant-based diets in northeastern China

Plant foods are gaining enormous popularity in the daily diet due to their beneficial effects on both human and planet health. In China, the percentage of vegetarians is increasing rapidly. In line with this trend, the Chinese government has promoted plant-based dietary patterns through the updated Dietary Guidelines for Chinese Residents.

A large pool of studies has linked well-balanced vegetarian and vegan dietary patterns to a reduced risk of cardiometabolic disease and certain cancers. These benefits can be attributed to lower consumption of saturated fat and refined sugar and higher consumption of dietary fiber, unsaturated fat, vitamins and minerals.

Despite the significant health benefits, there is still concern about whether these dietary patterns can provide all essential micronutrients in adequate amounts, particularly when supplements or fortified foods are not included in the diet.

People living in the northeastern region of China have distinct dietary habits, characterized by high consumption of red meat, pickled vegetables, and fermented soy products, all of which are rich in many nutrients. However, vegans and vegetarians living in this area may experience a nutritional deficiency because plant-based diets can provide lower amounts of certain nutrients, with northeast China’s long winters limiting vitamin D synthesis and its naturally iodine- and selenium-poor soils potentially increasing this risk.

Given the lack of data on the nutritional status of vegans and vegetarians living in Northeast China, this study was designed to compare dietary intake, body composition, and dietary biomarkers in three dietary groups, including vegans (diet free of all animal products and by-products), lacto-ovo-vegetarians (diet including foods, and omnivores (diet including foods of plant and animal origin).

The study included 356 adults living in northeastern China, of whom 82 were vegans, 124 lacto-ovo-vegetarians and 150 omnivores. Importantly, all participants had followed their dietary pattern for at least two years and had not used dietary supplements in the previous six months, allowing the researchers to assess nutritional adequacy from diet alone. Participants’ dietary intake was assessed using a validated semiquantitative Food Frequency Questionnaire. In addition, participants’ body composition and serum nutritional biomarkers were assessed using validated methods.

Blood tests confirmed the benefits along with nutritional deficiencies

Dietary analysis showed that vegans generally consumed a healthier balance of macronutrients than omnivores. Their diets were lower in total fat and saturated fatty acids but higher in polyunsaturated fat and dietary fiber. Although protein intake was lower among vegans, all three dietary groups met China’s recommended protein intake.

This healthier macronutrient profile was accompanied by notable differences in micronutrient intake. Compared to omnivores, vegans consumed more vitamin C, vitamin E, folate, magnesium, potassium and copper, but less vitamin B12, vitamin D, calcium, zinc, iodine and selenium. Lacto-ovo-vegetarians usually fell between the vegan and omnivore groups.

When assessed against Chinese dietary recommendations, vegans were significantly more likely to have inadequate intakes of vitamin B12, vitamin D, iodine, selenium, calcium and zinc, while omnivores were more likely to exceed recommended intakes of sodium and saturated fat.

These dietary patterns were reflected in the participants’ physical health. Vegans had lower body weight, body mass index (BMI), waist circumference, fat mass, percent body fat and visceral adipose tissue than omnivores, while lacto-ovo-vegetarians showed a generally similar body composition to vegans.

The favorable body composition observed among vegans was also associated with a healthier cardiovascular risk profile. Compared to omnivores, they had lower levels of total cholesterol, low-density lipoprotein cholesterol and triglycerides, and higher levels of high-density lipoprotein cholesterol. However, blood tests also revealed significant nutritional differences, with vegans having lower serum concentrations of vitamin B12, vitamin D, ferritin, selenium and zinc and higher levels of homocysteine ​​than omnivores.

Plant-based diets offer benefits but require careful planning

This study provides one of the most comprehensive assessments to date of the nutritional status of unsupplemented vegans, lacto-ovo-vegetarians, and omnivores living in northeastern China. Overall, vegans and, to a lesser extent, lacto-ovo-vegetarians showed the most favorable body composition and cardiovascular risk profiles, suggesting that well-designed plant-based diets can provide significant health benefits.

The findings also challenge the common belief that plant-based diets cannot provide enough protein. All three dietary groups met Chinese recommendations for protein intake, while vegans consumed more dietary fiber than recommended and less saturated fat than omnivores. Along with a higher intake of polyunsaturated fat, these dietary patterns may contribute to improved cardiovascular and metabolic health. However, the researchers note that the quality and amino acid composition of plant proteins still require careful consideration.

Despite these advantages, the study also highlights important nutritional trade-offs. Vegans had a significantly higher omega-6/omega-3 ratio, which has been associated with increased inflammatory conditions and may indicate higher cardiovascular risk. The authors suggest that increasing your intake of foods rich in alpha-linolenic acid, such as flaxseed, chia seeds and walnuts, could help improve this balance.

Perhaps the most important finding of the study was the high prevalence of inadequate intake of several key micronutrients among vegans and vegetarians. The researchers suggest that these deficiencies may reflect not only the exclusion of animal foods but also environmental, social and behavioral factors unique to northeastern China. Vitamin B12 and vitamin D were the nutrients most commonly consumed at levels below the recommended range. However, because supplement users were excluded from the study, these findings should not be generalized to people who regularly consume vitamin supplements or fortified foods.

Local dietary habits may also have contributed to some of the observed nutrient gaps. Vegans often replace iodized salt with natural sea salt and avoid selenium-rich animal foods, which may explain their lower iodine and selenium intakes. Since deficiencies in both nutrients can impair thyroid function, the authors recommend careful dietary planning. They also caution that urinary iodine, the gold standard measure of iodine status, was not measured, so these findings should be interpreted with caution.

Another notable finding was that, despite consuming the highest amount of dietary iron, vegans had the lowest ferritin levels. This suggests that the lower bioavailability of plant-derived iron may reduce iron stores even when dietary iron intake appears adequate.

Balanced guidance can maximize the benefits of a plant-based diet

Overall, the findings suggest that well-designed plant-based diets can support favorable body composition and cardiovascular health, but may also increase the risk of inadequate intake of several essential micronutrients when supplements or fortified foods are not used. Therefore, the authors recommend that Chinese dietary guidelines place greater emphasis on food fortification and appropriate supplementation to help prevent subclinical micronutrient deficiencies among vegans and vegetarians, particularly in Northeast China.

The researchers also stress that the findings should be interpreted within the limitations of the study. Because this was a cross-sectional study that was partially based on food frequency questionnaires, it cannot establish cause-and-effect relationships, and the results may not be representative of all people following plant-based diets in China.

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