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Intake and adequacy of the vegan diet. A systematic review of the evidence.

Dimitra Rafailia Bakaloudi, Afton Halloran, Holly L Rippin, Artemis Christina Oikonomidou, Theodoros I Dardavesis, Julianne Williams, Kremlin Wickramasinghe, Joao Breda, Michail Chourdakis

Journal: Clinical nutrition (Edinburgh, Scotland) 2021;40(5):3503-3521

PMID: 33341313

Free Full Text on Elsevier Science View on PubMed

Plain Language Summary

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This systematic review investigated vegan diets in the European populations and their adequacy of macro-and micronutrient intake, compared to the recommendations of the World Health Organization. Included were 48 studies and their outcomes regarding protein, carbohydrates, fats and micronutrients summarized. The overall results and their impact on health are discussed in the later sections of the paper. Adequate intake amongst vegans was seen with carbohydrates, fats, Vitamin A, B1, В6, C, E, iron, phosphorus, magnesium, copper and folate. Sodium exceeded recommended intake, whilst protein, Vitamin B2, B3, B12, D, iodine, zinc, calcium, potassium, selenium was of low consumption in a vegan diet. The bioavailability of some nutrients was also acknowledged. In summary, following a vegan diet appears to have positive and negative aspects. A vegan diet profile can contribute to disease prevention with lower incidence rates of obesity, Type 2 diabetes, and cardiovascular disease. Yet veganism appears to increase the risk for mental health conditions, bone fractures, immune system impairments, anaemias and deficiencies from low nutrient intake. This review yields a comprehensive overview of the positive and negative health consequences of a vegan diet. It may be a useful reference for those looking to support vegans or individuals considering adopting a vegan diet pattern.

Expert Review

Reviewer: Caroline Farrell
6th Apr 2022
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Conflict of interest

None

Take home message

  • Vegan diets in European populations tend to be lower in protein intake, particularly amino acids lysine, methionine and tryptophan.
  • Other micronutrients that tend to lower in vegan diets are Vitamin B12, zinc, calcium and selenium.
  • Healthcare practitioners should be aware of these potential deficiencies when working with vegan clients.

Evidence category

B: Systematic reviews including RCTs of limited number

Summary review

Vegan diets have become increasingly popular in the last ten years. This systematic review of 48 studies investigated the adequacy of vegan diets in European populations. It compared their macro- and micronutrient intakes compared to World Health Organization recommendations. It found that vegan diets tend to be lower in protein and in essential amino acids (lysine, methionine and tryptophan). They can also be lower in micronutrients especially vitamin B12, zinc, calcium and selenium. However, the lower intakes are not always associated with health impairments.

Clinical practice applications

Practitioners should be aware of the potential deficiencies in a vegan diet.

Considerations for future research

More research is needed to determine whether lower nutrient intakes in vegans correlated with poor health outcomes.

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Expert reviews are written by nutrition professionals and academics with advanced qualifications to provide a critical appraisal of the article and implications for practice. Each review is peer-reviewed by a member of the NED Editorial Board. Find out more about our NED Expert Reviewers here.

Abstract

BACKGROUND

Vegan diets, where animal- and all their by-products are excluded from the diet, have gained popularity, especially in the last decade. However, the evaluation of this type of diet has not been well addressed in the scientific literature. This study aimed to investigate the adequacy of vegan diets in European populations and of their macro- and micronutrient intakes compared to World Health Organization recommendations.

METHODS

A systematic search in PubMed, Web of Science, IBSS, Cochrane library and Google Scholar was conducted and 48 studies (12 cohorts and 36 cross-sectional) were included.

RESULTS

Regarding macronutrients, vegan diets are lower in protein intake compared with all other diet types. Veganism is also associated with low intake of vitamins B, Niacin (B), B, D, iodine, zinc, calcium, potassium, selenium. Vitamin B intake among vegans is significantly lower (0.24-0.49 μg, recommendations are 2.4 μg) and calcium intake in the majority of vegans was below recommendations (750 mg/d). No significant differences in fat intake were observed. Vegan diets are not related to deficiencies in vitamins A, B, Β, C, E, iron, phosphorus, magnesium, copper and folate and have a low glycemic load.

CONCLUSIONS

Following a vegan diet may result in deficiencies in micronutrients (vitamin B, zinc, calcium and selenium) which should not be disregarded. However, low micro- and macronutrient intakes are not always associated with health impairments. Individuals who consume a vegan diet should be aware of the risk of potential dietary deficiencies.

Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.

Address: Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Electronic address: [email protected].; WHO European Office for the Prevention and Control of NCDs, WHO Regional Office for Europe, Moscow, Russian Federation; Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark. Electronic address: [email protected].; WHO European Office for the Prevention and Control of NCDs, WHO Regional Office for Europe, Moscow, Russian Federation. Electronic address: [email protected].; Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Electronic address: [email protected].; Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Electronic address: [email protected].; WHO European Office for the Prevention and Control of NCDs, WHO Regional Office for Europe, Moscow, Russian Federation. Electronic address: [email protected].; WHO European Office for the Prevention and Control of NCDs, WHO Regional Office for Europe, Moscow, Russian Federation. Electronic address: [email protected].; WHO European Office for the Prevention and Control of NCDs, WHO Regional Office for Europe, Moscow, Russian Federation. Electronic address: [email protected].; Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Electronic address: [email protected].
DOI: 10.1016/j.clnu.2020.11.035

Patient Centred Factor

Mediators: Macro- & Micronutrients

Clinical Imbalances

Gastro-intestinal

Modifiable Lifestyle Factors

Diet

Nutrition Evidence Keywords

Obesity Iron Calcium Folate Vitamin D Metabolic disease Type 2 diabetes Mental health Cardiovascular disease Bone fractures Zinc Copper Magnesium Sodium Potassium Phosphorus Vitamin E Vitamin C Protein Vitamin A Iodine Carbohydrates Vitamin B3 Selenium Vitamin B12 Veganism Aneamia Fats Vitamin B1 Vitamin В6 Vitamin B2

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MeSH Terms: Adolescent, Adult, Aged, Diet, Vegan, Europe, Female, Humans, Male, Middle Aged, Nutrients, Nutritive Value, Vitamins, Young Adult
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