TWO years ago Jenny Wilson, a lawyer from Fife, started having strange symptoms, including forgetfulness, problems concentrating and bouts of depression.
She put her troubles down to stress at work; she'd been spending long hours at the office and a lengthy commute didn't help.
Then her condition worsened. The once fit 42-year-old began having debilitating spasms in her back. Her speech became slurred and her skin broke out in rashes.
Unable to find a solution through traditional medicine, she turned to natural health instead.
Staff at Napiers in Edinburgh performed hair mineral analysis to investigate the possibility of heavy metal poisoning, which subsequently tested positive.
It would appear Jenny was being slowly but surely poisoned by the mercury fillings in her teeth, making her the latest in a growing number of people each year who believe they have fallen prey to heavy metal toxicity.
"I started treatment right away," says the mother of one, who later discovered several countries have outlawed the use of mercury in dental procedures. "But it wasn't until I had all my fillings removed that I really noticed the difference. It was like somebody had lifted a weight off my shoulders. Within a few months I was back to my old self."
Heavy metals can show up just about anywhere. There is arsenic in our rivers, lead in our air and mercury in our tuna sandwiches. The real issue, though, is how much of this potentially deadly stuff might be in our bodies. Heavy metal toxicity has been implicated in Alzheimer's, Parkinson's, obesity and diabetes, although research in this area has been limited.
Despite this, Dr Colin Ramsay, consultant epidemiologist at Health Protection Scotland, believes the risk is minimal.
"For most people to develop symptoms of poisoning they would need to build significant quantities of a heavy metal in their system. These metals exist in trace quantities, and there is no real scientific evidence that people who lead normal, healthy lives, with balanced diets, need to worry about being poisoned.
"Even those who are at risk - for example people who work with lead or pregnant women who may be more sensitive to mercury poisoning - are so carefully monitored now that it would be difficult for a problem to develop. The true phenomenon is not in those who have been poisoned but in the prevalence of testing."
Not so, according to Helen Gestwicki, a nutritional therapist at Napiers who, like many others in her field, believes the issue could be more widespread than previously realised. "Many metals are nutrients, and exposure at normal levels are not toxic, but heavy metals like lead, mercury, cadmium, arsenic and aluminium can be harmful even at relatively low concentrations."
In traditional medicine doctors rely on blood or urine tests. But at Napiers patients are asked to proffer one heaped tablespoon of hair, which is sent to an American company called ARL (Analytical Research Labs).
"It's a simple process in terms of collection, but the analysis can be life changing," says Gestwicki. "Thankfully treatment is fairly straightforward. As well as avoiding the source of the heavy metal poisoning we prescribe a course of supplements. For most people the detox takes from three to six months."
So what if you haven't experienced any symptoms, but would like to avoid the possibility of contamination in the first place?
"As well as taking positive steps like including plenty of green foods in your diet which help to break down heavy metals," says Gestwicki, "smoking should be cut out completely, as should working with old paint or wood when you are decorating. Fish with a high mercury count like tuna should only be eaten in moderation; opt for natural deodorants that don't contain aluminium and use a water distiller if you are drinking tap water to minimise lead.
"We can't say exactly how much of a risk heavy metal poisoning poses but while we are waiting for more research it can't hurt to be more aware of the potential risks."
Unexplained symptoms driving you round the bend? It's possible your fillings - or that tuna sandwich - is to blame
Source Dental amalgam fillings, tuna and swordfish, some medications
Toxicity symptoms Irritability, nervousness, impaired hearing, speech and walking, gingivitis, infertility, impairment of peripheral vision, muscle weakness, skin rashes, mood swings, memory loss, mental disturbance
Source Drinking water, paint, cosmetics, cigarette smoke, occupational exposure (eg plumbing, engineering), hair dyes
Toxicity symptoms Fatigue, constipation, abdominal pain, anaemia, kidney disease
Source Drinking water, paint pigments, table salt, pesticides, fungicides, treated wood
Toxicity symptoms Fatigue, abnormal heart rhythm, impaired nerve function, diarrhoea, skin inflammation, hair loss
Source Cigarette smoke, shellfish, tuna, liver and kidney, wheat, rice, tomatoes, potatoes, air pollution, fertilisers
Toxicity symptoms Chills, fever, muscle ache, headache, gastroenteritis, nausea, vomiting, abdominal pains, diarrhoea
Source Kitchen foil, food wrap, kitchen utensils, coated drink cans, processed cheese, baking powder, drugs, antiseptics, instant coffee
Toxicity symptoms Muscle aches, fatigue, poor memory, speech problems, anaemia, osteoporosis, impaired kidney function, depression
This article was first published in Scotland On Sunday, 31 October, 2010