According to Diabetes UK's 2013 State of the Nation report, more than three million people in England alone are living with the disease-90 per cent of whom have type 2-and more are being diagnosed every day at a rate of one person every
The not-so-usual suspects in question are a group of pervasive chemicals in the environment that are finding their way into our food and water-namely, persistent organic pollutants (POPs), heavy metals and bisphenol A (BPA). Here's a look at the compelling evidence implicating these toxic contaminants in diabetes and what you can do to avoid them.
A groundbreaking 2006 study of more than 2,000 American adults led by preventative medicine professor Dr Duk-Hee Lee discovered "striking" connections between blood levels of POPs and diabetes. POPs, a group of chemicals that persist in the environment and accumulate in the fat-tissue stores of animals and humans, include some of the most toxic environmental pollutants known to man, including polychlorinated biphenyls (PCBs) and dioxin.
Dr Lee, of Kyungpook University in Daegu, South Korea, specifically looked at six POPs-PCB153, HpCDD, OCDD, DDE, oxychlordane and trans-nonachlor-as these had been found in at least 80 per cent of the study participants, a representative sample of the general US population. She and her team found that the higher the levels of these POPs in the bloodstream, the greater the chances of having diabetes.
Although the study didn't distinguish between the different types of diabetes, the researchers noted that most of the diabetic participants probably had type 2, as nearly all were aged over 40 (whereas type 1 is usually diagnosed in children and young adults).
Alarmingly, those in the highest category of POP exposure were nearly 40 times more likely to be diabetic. But just as shocking is what the study didn't find. Among those with no detectable levels of POPs, there was no association between diabetes and obesity-one of the factors usually associated with type 2 diabetes.
Obesity was a risk factor for diabetes only in the presence of POP concentrations above a certain level. This suggests that, as an editorial in The Lancet put it, "virtually all the risk of diabetes conferred by obesity is attributable to persistent organic pollutants, and that obesity is only a vehicle for such chemicals".
In other words, it could be that it's not obesity itself that's causing diabetes, but the toxic chemicals stored in fat.
Since the publication of Dr Lee's study, there's been a flurry of research into the connection between POPs and type 2 diabetes, with a recent review of 72 epidemiological studies finding a clear, positive association between certain POPs and the disorder.
Exposure to heavy metals in the environment, particularly arsenic, has also been linked to diabetes. Studies carried out in Taiwan, Bangladesh and Mexico show that people living in areas with extremely high levels of arsenic in the drinking water are up to 10 times more likely to have diabetes than those who are not exposed.
But even low levels of exposure can boost the risk it seems. In a study carried out in the US, where arsenic levels in drinking water are generally low, there was a significant link between arsenic and type 2 diabetes. Those with the highest levels of arsenic in their urine were nearly four times more likely to have diabetes than those with the lowest levels. Mercury and cadmium have also been linked to diabetes, but the evidence is less consistent.
One large US study found that people with high mercury exposures as young adults may have an elevated risk of diabetes later in life, whereas other studies could find no link between diabetes and usual levels of mercury exposure. Similarly, studies of cadmium exposure and diabetes have come to conflicting conclusions, although one of the latest reports suggests this may be because the risk varies according to age.
In the large-scale study of adults aged 40 and over, only the over-60s showed a significantly increased risk of prediabetes (described as the 'grey area' between normal blood sugar and diabetic levels) with increasing levels of urinary cadmium.
The hormone-disruptor bisphenol A (BPA), a chemical used in the production of plastic consumer products and in the epoxy resins that line food and drink cans, is another possible culprit in type 2 diabetes. The chemical is widespread in the environment and in people too-mainly because it leaches from containers into our food and water. US studies have found detectable levels of BPA in more than 90 per cent of the general population.
Most studies of the health effects of BPA have focused on its well-known oestrogenic activity. BPA and other hormone disruptors diminish sperm production, accelerate the onset of puberty and damage sexual organs. But newer reports have revealed that BPA can disrupt glucose metabolism too, and so may play a role in the development of diabetes.
One animal study found that BPA-given at a dose well below the 'lowest observed adverse-effect level' accepted by the US Environmental Protection Agency (EPA)-interfered with the function of pancreatic beta cells (responsible for the storage and release of insulin, the main hormone involved in blood glucose metabolism), thereby inducing the insulin resistance that heralds type 2 diabetes.
Another study found that just four days of low-dose BPA injections led to insulin resistance in mice. Although these animal findings may not necessarily apply to humans, a US study of nearly 1,500 adults found that those with higher levels of urinary BPA had a 39 per cent higher risk of diabetes than those with lower levels.
The researchers also found that participants with a body mass index (BMI) score of 35 kg/m2 or above had almost twice the levels of BPA as those with a BMI of 18.5-24.9 kg/m2, again suggesting that it might not be obesity per se that's responsible for diabetes, but consuming more toxic chemicals like BPA-or retaining more of them in body fat stores.
What is diabetes?
Diabetes is a lifelong metabolic disorder caused by too much glucose (sugar) in the blood. This happens when the body fails to produce enough, or doesn't properly use, insulin, a hormone made by the pancreas necessary for converting sugar, starches and other foods into energy.
There are two main forms of diabetes. Type 1, often called 'early-onset diabetes' because it typically develops in adolescence, results from the loss of function of the insulin-producing cells (beta cells) in the pancreas. Type 1 diabetics must take artificial insulin or they will enter a glucose-induced coma and die.
But the majority of people with diabetes (90 per cent) don't have this extreme, physiological form. Any dysfunction of the insulin-glucose system-such as the body not producing enough insulin, or not responding to insulin properly, or producing too much insulin-can cause insulin resistance and eventually lead to type 2 diabetes.
According to the World Health Organization (WHO), there's an emerging global epidemic of diabetes-around 382 million people worldwide now have the disorder-which can be traced back to the ever-increasing prevalence of overweight/obesity and physical inactivity.
Yet, as the latest research into environmental pollutants shows, these factors may not be the whole story.
How to minimize your risk
An estimated 9.6 million people in England alone-one in four of the adult population-are at high risk of developing type 2 diabetes, according to Diabetes UK. Besides eating healthily and getting enough exercise, cutting down on toxic chemical exposures could help slash your risk of getting the disease. Here's what you can do about the main chemicals of concern.
- Consume fresh, unprocessed foods and avoid canned goods as much as possible.
- Avoid polycarbonate plastic food containers (marked with the number '7' in the recycling logo), as these usually contain BPA. They tend to be rigid, transparent plastic containers. Plastics that are numbered 1, 2 and 4 are safer.
- Choose glass instead of plastic for water bottles, or choose bottles labelled BPA-free. Avoid metal water bottles as they may be lined with BPA-containing plastic.
- Avoid using plastic containers in the microwave. Ceramic, glass and other microwaveable dishware are safer alternatives.
- Avoid storing food and drink in plastic containers. Glass and stainless steel are better, safer choices.
- Invest in a countertop water filter or, better yet, a mains water filter to reduce the amount of heavy metals you're exposed to on a daily basis via your water supply.
- If you eat fish, limit consumption to twice a week, and choose varieties less likely to be polluted with high levels of mercury (generally, the smaller the better). Anchovies, sardines, trout and wild salmon are good options.
- Don't smoke, and avoid second-hand smoke too, as you'll be inhaling cadmium and arsenic as well as other toxic substances.
As this includes such a wide range of chemicals, pinpointing routes of exposure can be difficult. But according to environmental researcher David Carpenter, most exposures to POPs are through eating animal fat, so limiting the amount of such fats in your diet could reduce the risk of diabetes. Eating organic produce whenever possible may also help.
Another approach is to undertake regular detox to help the body get rid of any harmful environmental chemicals that may be clogging up your system. Some proven ways to do this include:
- Saunas. They increase sweating and so encourage the elimination of all kinds of toxic chemicals-from heavy metals to pesticides and drugs. Make sure you shower immediately afterwards.
- Exercise. Physical activity can help you sweat out harmful chemicals too; it also boosts your levels of detox enzymes.
- Herbs and supplements. Milk thistle, vitamin C, selenium, alpha-lipoic acid and N-acetylcysteine (NAC) can all increase body levels of glutathione, an enzyme essential for detoxification. HMDTM, a supplement containing homeopathic Chlorella and its growth factor plus coriander (Coriandrum sativum) leaf tincture (available from www.drhmd.com) can help clear arsenic, cadmium, mercury and other heavy metals from the body-without removing essential minerals.
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Published in the February 2015 Issue