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The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis.
Crit Rev Food Sci Nutr 2018; 58(8):1359-1374CR

Abstract

BACKGROUND

Vegetarian diets exclude meat, seafood, and products containing these foods. Although the vegetarian lifestyle could lead to a better health status in adults, it may also bear risks for certain nutritional deficiencies. Cross-sectional studies and narrative reviews have shown that the iron status of vegetarians is compromised by the absence of highly bioavailable haem-iron in meatless diets and the inhibiting effect of certain components present in plant foods on non-haem iron bioavailability.

METHODS

The databases Pubmed, Scopus, Embase, and Cochrane CentralRegister of Controlled Trials were searched for studies comparing serum ferritin, as the major laboratory parameter for iron status of adult vegetarians with non-vegetarian control groups. A qualitative review was conducted as well as an inverse-variance random-effects meta-analysis to pool available data. In addition the effect of vegetarian diets according to gender was investigated with a subgroup analysis. The results were validated using a sensitivity analysis.

RESULTS

A total of 27 cross-sectional studies and three interventional studies were selected for the systematic review. The meta-analysis which combined data of 24 cross-sectional studies showed that adult vegetarians have significantly lower serum ferritin levels than their non-vegetarian controls (-29.71 µg/L, 95% CI [-39.69, -19.73], p < 0.01). Inclusion of semi-vegetarian diets did not change the results considerably (-23.27 µg/L, 95% CI [-29.77, -16.76], p < 0.01). The effects were more pronounced in men (-61.88 µg/L, 95% CI [-85.59, -38.17], p < 0.01) than in both premenopausal women (-17.70 μg/L, 95% CI [-29.80, -5.60], p < 0.01) and all women (-13.50 μg/L, 95% CI [-22.96, -4.04], p < 0.01), respectively.

CONCLUSIONS

In conclusion our results showed that vegetarians are more likely to have lower iron stores compared with non-vegetarians. However, since high iron stores are also a risk factor for certain non-communicable diseases, such as type 2 diabetes, it is recommended that not only vegetarians but also non-vegetarians should regularly control their iron status and improve their diet regarding the content and bioavailability of iron by consuming more plants and less meat.

Authors+Show Affiliations

a Department of Environmental Health , Center for Public Health, Medical University of Vienna , Vienna , Austria.b Department of Epidemiology , German Institute of Human Nutrition , Nuthetal , Germany.c Department of Nutritional Sciences , University of Vienna , Vienna , Austria.a Department of Environmental Health , Center for Public Health, Medical University of Vienna , Vienna , Austria.

Pub Type(s)

Journal Article
Meta-Analysis
Review
Systematic Review

Language

eng

PubMed ID

27880062

Citation

Haider, Lisa M., et al. "The Effect of Vegetarian Diets On Iron Status in Adults: a Systematic Review and Meta-analysis." Critical Reviews in Food Science and Nutrition, vol. 58, no. 8, 2018, pp. 1359-1374.
Haider LM, Schwingshackl L, Hoffmann G, et al. The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis. Crit Rev Food Sci Nutr. 2018;58(8):1359-1374.
Haider, L. M., Schwingshackl, L., Hoffmann, G., & Ekmekcioglu, C. (2018). The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis. Critical Reviews in Food Science and Nutrition, 58(8), pp. 1359-1374. doi:10.1080/10408398.2016.1259210.
Haider LM, et al. The Effect of Vegetarian Diets On Iron Status in Adults: a Systematic Review and Meta-analysis. Crit Rev Food Sci Nutr. 2018 May 24;58(8):1359-1374. PubMed PMID: 27880062.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis. AU - Haider,Lisa M, AU - Schwingshackl,Lukas, AU - Hoffmann,Georg, AU - Ekmekcioglu,Cem, Y1 - 2017/07/05/ PY - 2016/11/24/pubmed PY - 2018/10/3/medline PY - 2016/11/24/entrez KW - Vegetarian diets KW - ferritin KW - iron KW - iron status KW - meta-analysis KW - systematic review KW - vegan diet KW - vegetarians SP - 1359 EP - 1374 JF - Critical reviews in food science and nutrition JO - Crit Rev Food Sci Nutr VL - 58 IS - 8 N2 - BACKGROUND: Vegetarian diets exclude meat, seafood, and products containing these foods. Although the vegetarian lifestyle could lead to a better health status in adults, it may also bear risks for certain nutritional deficiencies. Cross-sectional studies and narrative reviews have shown that the iron status of vegetarians is compromised by the absence of highly bioavailable haem-iron in meatless diets and the inhibiting effect of certain components present in plant foods on non-haem iron bioavailability. METHODS: The databases Pubmed, Scopus, Embase, and Cochrane CentralRegister of Controlled Trials were searched for studies comparing serum ferritin, as the major laboratory parameter for iron status of adult vegetarians with non-vegetarian control groups. A qualitative review was conducted as well as an inverse-variance random-effects meta-analysis to pool available data. In addition the effect of vegetarian diets according to gender was investigated with a subgroup analysis. The results were validated using a sensitivity analysis. RESULTS: A total of 27 cross-sectional studies and three interventional studies were selected for the systematic review. The meta-analysis which combined data of 24 cross-sectional studies showed that adult vegetarians have significantly lower serum ferritin levels than their non-vegetarian controls (-29.71 µg/L, 95% CI [-39.69, -19.73], p < 0.01). Inclusion of semi-vegetarian diets did not change the results considerably (-23.27 µg/L, 95% CI [-29.77, -16.76], p < 0.01). The effects were more pronounced in men (-61.88 µg/L, 95% CI [-85.59, -38.17], p < 0.01) than in both premenopausal women (-17.70 μg/L, 95% CI [-29.80, -5.60], p < 0.01) and all women (-13.50 μg/L, 95% CI [-22.96, -4.04], p < 0.01), respectively. CONCLUSIONS: In conclusion our results showed that vegetarians are more likely to have lower iron stores compared with non-vegetarians. However, since high iron stores are also a risk factor for certain non-communicable diseases, such as type 2 diabetes, it is recommended that not only vegetarians but also non-vegetarians should regularly control their iron status and improve their diet regarding the content and bioavailability of iron by consuming more plants and less meat. SN - 1549-7852 UR - https://www.unboundmedicine.com/medline/citation/27880062/The_effect_of_vegetarian_diets_on_iron_status_in_adults:_A_systematic_review_and_meta_analysis_ L2 - http://www.tandfonline.com/doi/full/10.1080/10408398.2016.1259210 DB - PRIME DP - Unbound Medicine ER -