The goal of this study was to review published data on iron status among vegetarian adults. Thirteen original articles met the inclusion criteria. Among female vegetarians, the percentage of the sample with ferritin <12 µg/L or <12 ng/mL ranged from 12% to 79%. An inadequate hemoglobin concentration ranged from 6% to 30.3%. Among males, the range of ferritin <12 µg/L across studies was from 1.7% to 29%. The prevalence of hemoglobin below deficiency cutoff ranged from 0% to 15.3%. A higher percentage of vegetarian females, compared to nonvegetarian participants, had ferritin below deficiency cutoff in all but one study (34% vs 0%, 47% vs 42%, 18% vs 13%, 27.8% vs 6.5% among Catholic nuns and 19.4% among college students, 79% Indian, and 56% Caucasian vegetarian vs 27% of nonvegetarian). Serum ferritin was lower in male vegetarians than male nonvegetarians in each study (11% among vegans and 21% among vegetarians compared to 6% and 7% among high and moderate meat consumers, 3% of vegetarians, and 25% vegans vs 0% of nonvegetarians, 29% vs 7%, 9% vs 0%). Vegetarians have a high prevalence of depleted iron stores. A higher proportion of vegetarians, compared to nonvegetarians, had iron deficiency anemia. This is especially true for premenopausal vegetarian women.

IN BRIEF Epidemiological studies have found a lower prevalence of type 2 diabetes among vegetarians compared to nonvegetarians. This reduced risk is likely a function of improved weight status, higher intake of dietary fiber, and the absence of animal protein and heme iron in the diet. Interventional studies have shown that vegetarian diets, especially a vegan diet, are effective tools in glycemic control and that these diets control plasma glucose to a greater level than do control diets, including diets traditionally recommended for patients with diabetes (e.g., diets based on carbohydrate counting). Vegetarian diets are associated with improvement in secondary outcomes such as weight reduction, serum lipid profile, and blood pressure. Studies indicate that vegetarian diets can be universally used in type 2 diabetes prevention and as tools to improve blood glucose management.

Pawlak R, et al. Nutr Res Pract. 2009 Spring;3(1):56-63. http://dx.doi.org/10.4162/nrp.2009.3.1.56

Diet significantly influences the risk of developing cardiovascular disease (CVD), the leading cause of death in the United States. As vegetarian dietary patterns are increasingly being included within clinical practice guidelines, there is a need to review the most recent evidence regarding if and how these dietary patterns mitigate CVD risk. This umbrella review of systematic reviews compared the relationships between vegetarian, vegan and non-vegetarian dietary patterns and CVD health outcomes and risk factors among presumably healthy adults (≥18 years) in the general population. MEDLINE, CINAHL, Cochrane Databases of Systematic Reviews, Food Science Source and SportsDiscus databases were searched for systematic reviews (SRs) published from 2018 until March 2024. Eligible SRs and meta-analyses examined relationships between vegetarian or vegan diets and CVD risk factors and disease outcomes compared to non-vegetarian diets. SRs were screened in duplicate, and SR quality was assessed with AMSTAR2. The overall certainty of evidence (COE) was evaluated using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) method. There were 758 articles identified in the databases’ search and 21 SRs met inclusion criteria. SRs targeting the general population had primarily observational evidence. Vegetarian, including vegan, dietary patterns were associated with reduced risk for CVD incidence [Relative Risk: 0.85 (0.79, 0.92)] and CVD mortality [Hazard Ratio: 0.92 (0.85, 0.99)] compared to non-vegetarian diets. Vegan dietary patterns were associated with reductions in CVD risk factors including blood pressure [systolic mean difference (95 % CI): -2.56 mmHg (-4.66, -0.445)], low-density lipoprotein cholesterol [-0.49 mmol/l (-0.62, -0.36)], and body mass index [-1.72 kg/m² (-2.30, -1.16)] compared to non-vegetarian dietary patterns, as well as c-reactive protein concentrations in a novel meta-analysis [-0.55 mg/l (-1.07, -0.03)]. Practitioners can consider recommending vegetarian dietary patterns to reduce cardiometabolic risk factors and risk of CVD incidence and mortality.