Natural Substances in Supplements and Nutraceuticals as Endocrine Disruptors
Endocrine disrupting chemicals (EDCs) can be found in materials and products perceived as ‘safe’ by the public, including nutraceuticals. ‘Nutraceutical’ is a very broad term that designates any substance that may be considered as food or part of a food as well as providing health benefits. The term may include a range of products, known variously as dietary supplements, natural health products or food supplements: herbal products or'botanicals’ feature prominently. The intake of nutraceuticals is widespread and the range of substances and intended functions is broad; thus, adverse effects of nutraceuticals are definitely a challenge for risk assessors. In general, a more consistent international definition of what is a nutraceutical is required. Intended biological actions and target populations should be clearly defined in terms of age, gender and physiological status. Beyond biological action, the health-promoting scope should be clearly defined in humans. Some nutraceuticals may provide nutrients that, at excess intakes, induce adverse effects, such as algal supplements providing a high iodine intake with hyperstimulation of thyroid. Others provide plant bioactives and other non-nutrient functional substances with potential endocrine-disrupting effects, such as isoflavones from soy-based supplements. Dose–response relationships for the relevant endocrine effects, either beneficial or adverse, should be assessed, taking into account sex- and age-related differences; reporting of adverse effects of nutraceuticals should be strengthened. The approach toward nutraceuticals has to be that of evidence-based risk-to-benefit assessment.