A microalgae docosahexaenoic acid supplement does not modify the influence of sex and diet on iron status in Spanish vegetarians or omnivores: A randomized placebo-controlled crossover study

Objective: Plant-based diets are accepted as healthy, provided that are well-planned and include supplements. In this context, iron deficiency is a threat, and data from Spanish vegetarians are scarce. The aim of this study was to determine if a microalgae ω-3 supplement rich in docosahexaenoic acid (DHA) affected iron status in this population.

Methods: Iron biomarkers and nutrient intake (72-h dietary records) were analyzed in 204 usual consumers of lacto-ovo vegetarian (LOV), vegan (VEG), or omnivorous (OMN) diets. A randomized double-blind, placebo-controlled crossover trial was performed in a subgroup (n = 98) to test if a microalgae DHA supplement (250 mg/d for 5 wk) changed iron status.

Results: Iron intake was higher in vegetarians than omnivores (P= 0.002), fiber intake was highest in vegans followed by lacto-ovo vegetarians and omnivores, whereas calcium intake was lower in vegans than both lacto-ovo vegetarians and omnivores (all P < 0.001). Women, regardless of diet type, showed lower iron status than men. Erythrocytes, hemoglobin, hematocrit, and serum ferritin were lower in lacto-ovo vegetarians and vegans than omnivores. The prevalence of iron deficiency anemia was low (<10%), but iron depletion (ferritin <15 ng/mL) was higher in lacto-ovo vegetarians than omnivores (P = 0.003). Iron biomarkers were similar in lacto-ovo vegetarians and vegans. The DHA supplementation did not change iron status compared with placebo.

Conclusions: Spanish vegetarians had lower iron status than omnivores. Consumption of eggs and dairy products increased the risk for iron deficiency, but a microalgae DHA supplement had no effect. Dietary strategies to increase iron bioavailability in vegetarians, particularly in lacto-ovo vegetarians and women, are recommended.