Topic 2.3 Concentration of phytohormones in food and feed and their impact on the human exposure*

Phytohormones, which naturally occur in plants, must be taken into consideration for their contribution to the total human exposure to potential endocrine active substances (EASs). Phytohormones are usually divided into two families: phytoestrogens that mainly occur from soybeans and soy derivatives and phytosterols that occur from vegetables and vegetable oils. The present paper compiles different sources of information about the concentration of phytohormones in foodstuffs in order to assess the current human exposure to those substances via food. Particular attention is given to most exposed groups of consumers, on the one hand, infants and young children fed with soy-based infant formulas for their exposure to phytoestrogens and on the other hand, consumers of fortified foods for their exposure to phytosterols. Available literature shows that the total dietary intake of isoflavones could reach 20 to 25 mg/day/person for the Japanese adult population. For infants and young children, the quantity of phytoestrogen ingested is likely to be 35–50 mg/day/person corresponding on a body weight basis to an exposure 7 to 11 times higher. Regarding phytosterols, an assessment of the exposure via food was done, considering both their natural occurrence and their potential concentration in fortified foods. Results shows that the “natural” exposure is estimated at 340 ± 440 mg/day/person at the mean and at 1040 mg/day/person at the 95th percentile. Considering the potential exposure via fortified foods, it is estimated at 2700 ± 1200 mg/day/person at the mean and at 4700 mg/day/person at the 95th percentile. After their ingestion, isoflavones are absorbed from the intestinal tract before being excreted in the urine and feces. The increasing use of phytohormones in human foodstuffs could increase locally their release into the environment. Nevertheless, considering the weak estrogenic potential of phytohormones in relation to synthetic or endogenous steroids, any introduction of these substances into aquatic ecosystems would probably have comparatively minor effects on aquatic organisms.