Our bodies are continuously exposed to poisonous substances - both natural and man made. Although we have biochemical mechanisms to cope with most them, when our bodies are subject to overwhelming quantities of toxins, severe health problems occur.

The human body deals with poisonous substances in various ways. Enzymes and components of the immune system in the intestines are the first line of defense in this regard. They either convert the toxins into harmless substances or prevent their absorption into the blood stream by binding to them. In addition food-derived compounds help to neutralize harmful agents before they are absorbed through the bowel wall. Interestingly, and somewhat paradoxically, metals like iron, zinc and copper (that are potential toxins themselves) can also help prevent the absorption of poisonous heavy metals like lead.

If a toxin manages to evade the defense systems in the intestines and gains access to the blood stream it may then be rendered safe by enzymatic action or other processes in the liver ? the most important detoxifying organ. If the liver fails to deal with a toxin it may then be excreted by the kidneys. However, some the most problematic toxins are those that the body cannot neutralize or get rid of.

The most important examples of these are the metals ? especially arsenic, copper, iron, zinc and the heavy metals like lead and mercury. As the body has difficulty excreting these poisons it tries to sequestrate them in tissues like fat and bone where they will not cause as much harm as they would in other organs or tissues. Unfortunately when the stores of these toxic substances reach a certain threshold they inevitably begin to cause damage. Lead and mercury are particularly damaging to the brain and other nervous tissue and this is especially so in children.

The treatment of choice for metal poisoning is chelation therapy; a therapy whereby a chelating agent is used to 'grab' or bind to the toxin; either rendering it harmless or allowing the body to excrete it more easily. Examples of chelating agents that are used to treat metal poisoning are: DMSA, DMPS, ALA, EDTA.

There are also many naturally occurring compounds that have chelating properties. The spice, coriander (cilantro) has been shown to chelate lead while turmeric binds to both copper and iron. Other studies have shown how vitamins B1, E, C and zinc can help prevent the absorption of lead and enhance the capacity of chelating drugs.

As well as acting as chelating agents plant derived compounds play a vital role in countering the damaging effects of heavy metals and other toxic substances. Many toxins are free radicals and as such cause oxidative damage to cells and tissues. Spices, fruits, nuts and vegetables all provide large numbers of important antioxidant and other compounds that play a vital role in helping to contain free radical damage.

If we want to minimize the effect of heavy metals and other environmental pollutants on our bodies we need to ensure that we have an adequate daily intake of spices, fruit and vegetables. It is these foods that provide us with the best means to deal with this inexorable threat to our health.