Plant-based diets offer heart benefits but may require supplements

A study found that while unsupplemented vegan diets were linked to healthier body composition and cholesterol levels, they also carried a substantially higher risk of inadequate intakes of key vitamins and minerals, highlighting 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 substantial micronutrient deficiencies among unsupplemented vegans and vegetarians in Northeast China.

Researchers compare plant-based diets in Northeast China

Plant-based foods are gaining immense popularity in everyday diets because of their beneficial impact on both human and planetary health. In China, the proportion of vegetarian people 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 reduced risk of cardiometabolic diseases and certain cancers. These benefits can be attributed to lower consumption of saturated fat and refined sugar and higher consumption of dietary fibers, unsaturated fats, vitamins, and minerals.

Despite significant health benefits, there remains a concern whether these dietary patterns can provide all essential micronutrients in sufficient 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 several nutrients. However, vegans and vegetarians living in this region may experience nutritional inadequacy because plant-based diets can provide lower amounts of some 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 scarcity of evidence on nutritional status of vegans and vegetarians living in Northeast China, this study was designed to compare dietary intake, body composition, and nutritional biomarkers across three dietary groups, including vegans (diet excluding all animal products and by-products), lacto-ovo-vegetarians (diet including plant-based foods and excluding meat, poultry, and seafood), and omnivores (diet including both plant-based and animal-based foods).

The study included 356 adults living in northeastern China, comprising 82 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 during the previous six months, allowing the researchers to assess nutritional adequacy from diet alone. Participants’ dietary intake was assessed using a validated semi-quantitative Food Frequency Questionnaire. In addition, participants’ body composition and serum nutritional biomarkers were assessed using validated methods.

Blood tests confirmed benefits alongside nutritional shortfalls

The 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 fats and dietary fiber. Although protein intake was lower among vegans, all three dietary groups met the Chinese-recommended protein intake.

This healthier macronutrient profile was accompanied by notable differences in micronutrient intake. Compared with 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 typically fell between the vegan and omnivorous groups.

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

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

The favorable body composition observed among vegans was also associated with a healthier cardiovascular risk profile. Compared with omnivores, they had lower total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels, and higher high-density lipoprotein cholesterol levels. However, blood tests also revealed important nutritional differences, with vegans showing lower serum concentrations of vitamin B12, vitamin D, ferritin, selenium, and zinc, and higher homocysteine levels 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 Northeast China. Overall, vegans and, to a lesser extent, lacto-ovo-vegetarians showed the most favorable body composition and cardiovascular risk profiles, suggesting that well-planned plant-based diets can offer important health benefits.

The findings also challenge the common perception that plant-based diets cannot provide enough protein. All three dietary groups met the Chinese recommendations for protein intake, while vegans consumed more dietary fiber than recommended and less saturated fat than omnivores. Together with their higher intake of polyunsaturated fats, 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 states and may indicate higher cardiovascular risk. The authors suggest that increasing intake of alpha-linolenic acid-rich foods, such as flaxseed, chia seeds, and walnuts, could help improve this balance.

Perhaps the study’s most important finding was the high prevalence of inadequate intakes of several key micronutrients among vegans and vegetarians. The researchers suggest these shortfalls may reflect not only the exclusion of animal-derived foods but also environmental, social, and behavioral factors unique to Northeast 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.

Regional 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 help 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 plant-based diet benefits

Overall, the findings suggest that well-planned 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. The authors therefore 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 emphasize that the findings should be interpreted within the study’s limitations. Because this was a cross-sectional study that relied partly 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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