40 - Plant-Based Diets and Selenium Intake and Status

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Selenium (Se) is an essential trace element for mammals but not for plants. This fundamental difference is of high importance for a plant-based diet, as it is very difficult to predict the Se content of plant-derived nutrients. Depending on the area of residency, soil Se content, and the individual food choice, a purely vegetarian diet may lead to Se deficiency. Accordingly, a relatively low Se status in ovolactovegetarians and vegans as compared to omnivores was determined in a number of epidemiological studies. As Se is essential to animals, a minimum level is required and maintained. However, as Se can also become toxic at higher doses, a maximum level is not surpassed. An optimal range is favored by molecular mechanisms regulating body Se concentrations. Consequently, animal products have a relatively predictable Se content. In contrast, plants can differ dramatically in their Se content. Unfortunately, Se concentrations are rarely declared on food labels. This lack of information argues in favor of selecting presumably Se-rich food items or supplementing the diet in case an insufficient Se intake can be assumed for reasons of place of residency, to avoid Se deficiency. To this end, a daily intake of at least 1μg Se/kg of body weight should be aimed for to reduce health risks from tumor, autoimmune, or degenerative diseases. In how far Se supplementation may reduce disease symptoms and positively affect therapeutic interventions in patients is a matter of ongoing debate, as large-scale intervention trials are either missing or have yielded ambiguous results. In this respect, several trials with different Se supplements were initiated, and the results are eagerly awaited to better judge the therapeutic potential of Se and the importance of the basal Se status as risk factor for disease incidence and poor course. But besides potential treatment effects, a sufficiently high Se intake appears necessary for avoiding disease and maintaining a healthy life.