We are living longer, but the 60-80 year olds who are living longer ate different food, probably from better soils. And we are living longer because of an unsustainable thing. To put in a pacemaker in a 70-80 year old costs the Australian government $30,000. To do a coronary artery bypass is much higher. We can't continue to carry those costs.

The costs are going up and up, and Joe Public doesn't want to pay for it all out of his taxes. We cannot sustain it as a cost thing - but that's why we have been living longer.

The book is also is the standard textbook for a course at the Australian College of Nutritional and Environmental Medicine (www.acnem.org), which was designed by doctors for doctors.

If you are concerned about your health, I suggest you find a well-trained naturopath, or a doctor from www.acnem.org - there is a list of practitioners on the site.

For your vege garden, I could only suggest that you use well balanced organic mineral supplements. If the soil is fully mineralised, you might get enough minerals that way.

Also, magnesium deficiency is increasingly being recognised as an unsung cause of many health disorders related to the heart, pre-eclampsia (a common cause of urgent Caesarian section), asthma, anxiety and depression.

In one study in a neurological journal, Cephalalgia, it was found by giving magnesium supplements to people with migraine headaches, they halved the frequency and severity of the headaches. That was in 1996. All of the neurology clinics in Australia are aware of that study, but very few put it into practice. I use it all the time, and have a very high success rate.

The medical profession's response to nutrition in general:

- the profession talks about me condescendingly as that "alternative" doctor, but it's surprising how many medical doctors come to me or send their family to me to deal with issues that they can't correct themselves.

- Max Planck's comment was that "Old theories do not die because they are disproven, they die because those who cling to them die, and a new generation grows up that is familiar with the new idea".

There is a general perception that farmers are more prone to lymphoma and leukemia than other parts of the population, and this is sheeted home to agricultural chemicals. I can't back that up with figures, but I have often heard rural doctors say, "Not another farmer with lymphoma/leukemia".

Furthermore, I was interested to note that the NSW Health Department chose Dubbo as an area for researching Parkinson's disease. Although Dubbo is urban, we know that there is an increased risk of Parkinson's in people handling agricultural chemicals or even garden chemicals.

The problem with all of this is that in some ways, farmers are living a healthier life - less pollution, lots of sunshine - but on the other hand they are often in contact with toxic chemicals. You're really not comparing like to like with other areas of the population. However, as a general statement, I see quite a few sick farmers.

I don't know anything about zeolite on soils. In humans it works in the gut to absorb heavy metals, but does not get absorbed into the bloodstream. The extent to which it helps the body relieve any heavy metal burden is thought to be limited. In cases of serious body toxicity, chelation therapy may be necessary, although a safe alternative is the use of supplements like selenium and zinc which get absorbed into the bloodstream and shift heavy metals out of the body.

Selenium shifts mercury and zinc shifts lead.

First of all, I would attempt a serious attack on the junk food industry. On television this week there was a forum talking about involving the industry in tackling obesity, which to my mind is like putting the lunatics in charge of the asylum. Politicians show no evidence of making a serious effort on this issue.

Secondly, I'd support farmers to really implement best practice according to the Thames Valley report on food, farming and health.

Thirdly, I'd invest in the medical profession so that our reliance on the pharmaceutical industry for research and health care treatment is diminished.