How the Body Naturally Filters and Excretes Toxic Substances
Although plant-based diets might increase exposure to potentially toxic substances like heavy metals (e.g. cadmium, arsenic), the health benefits of plant-based diets (which have been increasingly advocated by health professionals and backed by scientific studies) far outweigh any consequences. In fact, most plant-based foods which are the basis of exposure are commonly equipped with the nutrients needed to help bodies eliminate or reduce the absorption of the offending metals.
A healthy individual will rarely get near toxic levels, despite being commonly exposed heavy metals. Nonetheless, ALL metals (including zinc, copper, nickel, etc.) can cause toxicity if consumed in extremely high amounts. It is important to remember that various factors affect the absorption and retention of heavy metals, wherein the content of heavy metals in a food item, will not necessarily be the amount retained in your body. For example, the World Health Organization states that the body only absorbs about 2-6% of ingested cadmium and only 20% of ingested lead.
Through proper diet, the body has natural ways of eliminating and/or reducing the toxic effects of heavy metals during their consumption or after their absorption, if any. Nutrients commonly found in food with antioxidant activity like vitamin A, C, E, alpha-lipoic acid (commonly found in meat), glutathione, lactoferrin (iron from milk protein) will increase protection from oxidative stress attributed to the presence of any metals in the body. Even the trace minerals zinc and selenium have antioxidant properties to aid in this capacity. The amino acids (found in dietary protein) cysteine, glycine and glutamine are also important detoxifying agents as they help to form glutathione in the presence of magnesium. Glutathione combines with many toxic substances and converts them into harmless forms that are then excreted from the body. Also, metallothionein is a cysteine rich, metal-binding protein produced in the body that works closely with zinc and has been shown to protect against cadmium toxicity (1). Certain plants, most notably in the micro-algae family have been studied as heavy-metal “scavengers” though most research has shown these properties to occur within the plant itself, in test-tubes, or in animal studies. Chlorella and spirulina are popular micro-algae purported and sold by many natural product companies for their metal-binding capabilities, though studies on the effects in humans remain limited.
Supplying the body with proper nutrients from a balanced diet (rich in a variety of fruits, vegetables, whole grains and lean protein) will help the body equip itself against the burden of heavy metals. Needless to say, immediate medical attention should be sought should an actual toxicity exist.
- Klaassen CD, Liu J, Chouhuri S. Metallothionein: An intracellular protein to protect against cadmium toxicity. Annu Rev Pharmacol Toxicol. 1999. 39: 267–94.