Diet change cured my cancer

It's a miserable business, having cancer. I can remember those years clearly, and they were dreadful. I had no family history of cancer, but I knew what it was when I found the lump in my breast in 1987. I tried to convince myself it wasn't real, but when I was diagnosed with cancer, I wasn't that surprised. It was a real strain on my family. I was 42 and my sons, Mark and Tom, were 16 and six then, but it was hardest for my daughter, Emma, who was 13 - all her teenage years were blighted by my cancer.

And then one day, it all made sense - and what I discovered that day was to change my life for ever. It was six years after I was first diagnosed, and my family and I had been to hell and back. I'd had so many gruelling operations - a mastectomy, 12 sessions of chemotherapy and 35 radiotherapy treatments, and despite everything, I was still left with a lump the size of half a boiled egg sticking out of my neck. It was a secondary cancer, since the disease had reached my lymph system, and I was absolutely fed up. I'd just had a session of chemotherapy which had had no effect on this latest large lump - I was measuring it with callipers, so I knew.

It's hard to explain to a non-scientist the mental and emotional buzz you get when you know that you have just had an important insight. It's as if you have had a lot of jigsaw pieces in your mind and suddenly the whole picture becomes clear.

My husband Peter is also a scientist - he's a mineralogist and gemologist - and he had recently come back from a trip to China. We were musing on why so few Chinese women get breast cancer - their incidence of the disease is one in 100,000 - and what was different about their way of life, and it suddenly struck me that they just didn't have any dairy products in their diet. I eliminated all dairy produce from my diet immediately - I had been eating organic yoghurt to help my digestive tract recover from the chemotherapy, but I also threw out anything containing milk products, from biscuits to soups and even some forms of margarine. Within days, the lump began to itch, then to soften and shrink, until, after six weeks, it had vanished altogether.

What I believe I've done is to go back and establish the root cause of breast and prostate cancer. That's what I've been trained to do throughout my career as a scientist - to find the fundamental cause. Conventional therapy deals with the symptoms of cancer - the tumours - but my regime goes further. I don't believe dairy produce initiates cancer, rather that it promotes it - if the body weren't constantly taking in growth factors from milk, it would be able to clean up its damaged cells by itself.

When my tumour disappeared, I couldn't just pronounce that the one thing had led to the other. I have been trained throughout my working life to give data for the statements I am makingor to give sources, so I began researching the whole subject. Friends who had been wonderfully supportive during the years I been struggling with breast cancer would send me clippings from papers and magazines, which often produced new lines of enquiry, and gradually I formed my views about diet and its relation to cancer. It is not an extreme regime - if people want to follow diets that are extremely unconventional, that's fine, but it's not what I'd recommend. Barry Sheene did so and, in the end, the regime failed and he died. I would never recommend that people avoid conventional treatment.

Cancer is such a clever disease that you have to use everything at your disposal to tackle it. I recommend that people use my diet and lifestyle factors to help them through procedures such as chemotherapy, and to give them some awareness of the factors that you can control in your diet and lifestyle. On the other hand, I try not to preach. Just because this worked for me, I don't presume it will work for everyone else. But I present, scientifically, the evidence that I have uncovered as a scientist, and leave it for people to decide for themselves.

The fact is that dairy milk contains a number of substances called growth factors; breast and prostate tissue both have receptors for growth factors, which cause cells to divide and reproduce. It seems that if you have a damaged cell, these growth factors will select these damaged cells, and cause them to grow out of all control.

I now believe that the link between dairy produce and breast cancer is similar to the link between smoking and lung cancer. It was difficult to accept that a substance as " natural" as milk might have such ominous health implications, but I am living proof that it worked.

Cutting out dairy produce is one of the main dietary points, but there are other very important ones. You should eat masses of vege- tables and fruit (with more emph- asis on vegetables) - not only are they full of vitamins, minerals and antioxidants, but many contain chemicals which have anticancer properties, such as allicin in garlic, or lycopene in tomatoes. You should limit your intake of saturated fats, and eat a diet rich in monounsaturates (such as olive oil), and omega 3 and 6 oils (oily fish, flax seeds and nuts). Eating adequate amounts of protein is important for your body - though I suggest that as much as possible should be from vegetable sources (eg, lentils); salt and sugar should be kept to a minimum, in favour of seasonings which have anti-cancer action, such as the curcumin in turmeric.

Wholegrain cereals are good for the body, because they contain detoxing enzymes and substances which help suppress the growth of tumours, and it is vital to drink lots - I prefer filtered boiled water to what comes out of the tap, though I don't recommend bottled water - I don't like anything in plastic bottles, because of the harmful plasticising chemicals that can migrate into the water.

I'm still working - I'm professor of geochemistry [the study of the Earth's crust] at Imperial College, London - and have updated my book to take account of the latest scientific research (everything I said in the first book has now been confirmed by other literatures) - but I still spend time telling people about my discoveries. People write to me and say: "Why has no one told me this before?"

I'm trying to redress that - I give talks about once a week on the subject, and my work is featured in various magazines. The strange thing is that scientists have made the connection before, but all the papers were published in scientific journals, in scientific language. What my books are about is translating this knowledge-into a language that is accessible-and readable.

I have followed this regime for the past 10 years, and have remained free from cancer. My specialist at Charing Cross Hospital was sceptical about my ideas at first, but now I have heard that he uses maps showing cancer mortality in China when he is lecturing, and recommends a non-dairy diet to his cancer patients.

When I go to hospital for checkups, if he is not around, other doctors who read my notes often can't believe that I had cancer as extensively and seriously as I did, given that I now look so healthy.

I'm so relieved I made my discovery, because it has given me 10 years with my family - and, I hope, many more - which the doctors thought I'd never have. And my message is for everyone who has had a diagnosis of breast cancer - don't be afraid. I got better - and so can you.

Your Life in Your Hands (Virgin Books, £9.99) and The Plant Programme (Virgin Books, £10.99).