There's been a quiet revolution taking place in the food-manufacturing industry since the 1980s, and it's one that could be damaging our health and making us over-weight. Indeed, the new evidence suggests that it may even be responsible for the learning and behavioural problems so often seen in our children nowadays.
Over the past 30 years, food manufacturers have slowly been replacing sucrose as a food and drink sweetener with high-fructose corn syrup (HFCS)-or 'glucose corn syrup' as it's known in the UK.
In 1970, more than 83 per cent of the sweetener consumed in the US was sucrose. However, according to OU (Orthodox Union) Kosher-a non-profit communal organization based in New York City-by 1997, sucrose-containing food and drink had dropped to just 43 per cent, with 57 per cent using HFCS instead.
OU Kosher has a logo-a U in a circle-that, when seen on a label or packaging, means that the food has been officially certified as kosher (see www.oukosher.org for more information) and, in order to obtain this certification, the food company must submit a complete list of the food's ingredients.
In the UK, the Institute of Food Research, based in Norwich, has described HFCS as "a brilliant technological invention", as it has many advantages over traditional sweeteners.
In addition to its ability to lengthen the shelf life of products, it blends more easily into liquids and keeps its sweetness better than sugar. For this reason, it was quickly adopted by Coca-Cola, Pepsi and other soft-drink manufacturers. Also, it helps to stop food 'freezer-burn' as it prevents icy crystalliza-tion and so is used in frozen products such as ice cream. What's more, it helps to turn baked goods brown, and so is used in cakes, pastries, bread rolls, crackers and breakfast cereals. Most important of all, it's far cheaper to produce than other sweeteners.
Nowadays, it is found in virtually every processed food and drink-from Coca-Cola, Pepsi, Kellogg's Cornflakes and its other breakfast cereals to some Ben & Jerry's ice creams, Campbell's Vegetable Soup, processed breads and cakes, Ribena, Ocean Spray Cranberry Juice-and many other products as well.
Best of all, claim its advocates, it's both natural and safe, a view that is supported by America's foods regulator, the Food and Drug Administration (FDA). Indeed, most scientists and commentators apparently agree. Nevertheless, there are a few who believe that HFCS-enriched foods and drinks are a direct cause of obesity and diabetes (see box, page 7).
However, while the experts continue to debate whether or not HFCS is contributing to the growing obesity and diabetes pandemic, a recent report has now discovered a much more serious health concern: the sweetener evidently contains mercury, and may be a richer source of the toxic heavy metal than even fish.
Corn syrup and mercury
While the FDA continues to maintain that HFCS is a safe food additive, other investigators have been uncovering evidence that clearly suggests otherwise.
One such investigator was Renee Dufault who, in 2005, found mercury levels in nine of the 20 HFCS samples that she had collected from processing plants. However, the FDA did nothing in response to her findings, leaving her no choice but to go public with the information after she retired last year.
Dufault had discovered levels of mercury ranging from 0.005 to 0.570 micrograms (mcg)/g of HFCS and, as the average daily consump-tion of the sweetener is around 50 g in the US, consumers are very likely-and unwittingly-ingesting every day up to 28.5 mcg of mercury, the most toxic metal known to man.
As the standard 20-oz bottle of Coca-Cola contains around 17 tea-spoons' worth of HFCS, it's easy to see why processed snack foods and soft drinks are easily a far higher source of mercury than are fish (Environmental Health, 2009; 8: 2; doi: 10. 1186/1476-069X-8-2).
But how did the mercury get into the HFCS samples in the first place? Although its advocates describe HFCS as 'natural' and even 'organic', it's nothing of the sort. While other sweeteners are based on cane and beet sugar, HFCS is a derivative of corn starch-and it comes about only as a result of various industrial processes.
In 1957, scientists discovered an enzyme that could convert the glucose in corn syrup into fructose, a process that was finally perfected only in the 1970s, thereby paving the way towards mass production of HFCS.
The process involves several steps and three different enzymes, and the result is a syrup with a 90-per-cent fructose content. This is then blended down with untreated, glucose-only syrup into a mix thatis either 42-per-cent or 55-per-cent fructose.
Around 50 processing plants around the world, including eight in the US and three in the UK, are currently producing HFCS. And some of these plants-more correctly known as 'industrial chlorine' or 'chlor-alkali' plants-still use caustic soda (sodium hydroxide) in the manufacture of HFCS, although it's an outmoded form of manufacturing and some plants have replaced it with safer technology. Other food ingredients, such as citric acid, are also manu-factured at these plants.
The caustic soda is referred to as 'mercury-grade' or 'rayon-grade', which indicates that these plants are reliant on mercury for part of the process. Astonishingly, the plants regularly report that some of the mercury mysteriously disap-pears. In the year 2000, for example, the four plants in the US that still use caustic soda each reported an unaccountable loss amounting to around seven tons of mercury.
What's more, the three UK plants report a similar story, although the environmental lobby group Oceana believes that the mercury loss isn't so mysterious, and that it's pumped out into the air and into the general water supply.
In fact, according to the group's report Poison Plants, published in January 2005, these three plants are responsible for a third of all mercury emissions in the air and nearly half of all emissions in the water supply of the UK.
Nevertheless, the release of mercury into the environment accounts for only a mere fraction of the total mercury 'lost'. In 2003, nine of the mercury-using plants around the world reported that eight tons of the stuff had been emitted into the air and water supply. Neverthess, they still could not explain the disappearance of a further 30 tons to the US Environ-mental Protection Agency for its 2003 report [68 FR (Federal Register) 70904].
In light of these facts, it's not an enormous leap of imagination or judgement to suspect-given such cavalier safety procedures-that some of the so-called missing mercury may well be getting into the HFCS itself, as Dufault and her colleagues discovered.
Snacking on mercury
Alerted by Dufault and her colleagues' findings, Dr David Wallinga and other researchers at the Institute for Agriculture and Trade Policy (IATP), an independent lobby group based in Minneapolis, MN, went out and bought a range of commonly consumed soft drinks and snack foods sweetened with HFCS, and tested them for mercury (see lower box, page 9).
Of the 55 products they pur-chased from the local supermarket, the researchers found that one-third contained mercury, including prod-ucts made by Quaker, Kraft and Nutri-Grain-all international and well-known brands.
The levels of mercury varied enormously, with the highest level being twice the amount of the lowest. The highest amounts were found in barbecue sauces, whereas the colas and soft drinks contained no mercury.
Nevertheless, Wallinga and the other IATP researchers strongly emphasize in their report-Not So Sweet: Missing Mercury and High Fructose Corn Syrup, published in January 2009-that their findings are only a snapshot based on just a one-off purchase.
More important, they believe that the food and drink manufacturers are probably unaware that their products contain mercury, and they may not even be aware that mercury-grade caustic soda is being used in the processing of the sweetener. And judging by the website of the UK's HFCS industry group, the IATP may have a point.
Indeed, on its website (www. highfructosecornsyrup.co.uk), the group reiterates that the FDA regards HFCS as a "natural product as the only two elements present in HFCS are fructose and glucose. Both fructose and glucose are naturally occurring sugars, and they also happen to be the sugars which form the disaccharide sucrose, which is commonly known as sugar".
While this is true as far as it goes, the HFCS advocacy site fails to mention that the sweetener is derived from corn syrup, a glucose-heavy product that would never contain fructose in its original form. In other words, the "natural" claim is being used out of context: fructose is indeed natural, but not in association with corn syrup.
In addition, there's no mention of the industrial processes involved in getting fructose into the product.
The industry response
American corn producers have been one of the chief beneficiaries of the explosion in HFCS usage, so it's not very surprising that its industry group, the Corn Refiners Asso-ciation (CRA), was quick to refute Dufault's findings. It did not, however, respond to the IATP study and its discovery of mercury in a substantial number of snacks sweetened by HFCS.
CRA's president, Audrae Erickson, says the Dufault study is based on "outdated information of dubious significance". She claims that the industry has used mercury-free processing plants for several years-and yet, according to the IATP, four of the eight plants in the US still use mercury-based technology-and there may be many more plants around the world that are still reliant on mercury.
Erickson also reports that the FDA deemed HFCS safe in 1983 and again in 1996, although it was not made aware of Dufault's findings until 2005-since which time it has not issued any new statements on the safety of HFCS.
Erickson concludes by repeating the claim that HFCS is "natural" as it contains no artificial or synthetic ingredients or additives. However, it appears to be somewhat of a stretch to claim that any product is natural when it has passed through three industrial processes and used enzymes to create its final form.
As Michael Jacobson, director of the Center for Science in the Public Interest, a US nutrition advocacy group, has said: "You're causing a change in the molecular structure and that shouldn't be considered natural." Instead, he believes that HFCS should be reclassified as an artificial sweetener.
The mercury load
While we the general public are generally aware of the amount of mercury we are exposed to from the fish we eat and the amalgam in our dental fillings, no one so far has taken into account the additional mercury load we may be unwittingly ingesting from our snacking and drinking habits. If Dufault and her co-workers are correct in their analyses, the average person is swallowing an additional 28.5 mcg/ day of mercury-and this figure may be even higher among teenagers, as they tend to eat more snack foods, and drink more colas and sodas.
Nevertheless, some critics accuse Dufault and the IATP of being alarmist. Toxicologist Carl Winter, of the FoodSafe Program at the University of California at Davis, says that the most toxic form of mercury is methylmercury, the type found in the fish we eat, as this form is more easily absorbed into the body.
It's possible, he says, that Dufault and Wallinga have been measuring elemental mercury, which is not so dangerous.
Even so, there's no such thing as 'safe mercury' in any form, and high doses can cause damage to the heart, kidneys, lungs and immune system (see box, page 8).
Furthermore, this unsuspected additional mercury load from snacks and soft drinks might also be a contributory factor to the alarming rise we've seen in recent years of cases of attention-deficit/hyper-active disorder (ADHD), autism and behavioural problems among our youngsters.
As Wallinga says, "For me, the take-home message is really that this [HFCS] is a totally avoidable, unnecessary exposure to mercury."
HFCS and obesity
There are a number of researchers who firmly believe that the introduction of HFCS (high-fructose corn syrup) has played a considerable role in the obesity epidemic that is very much in evidence in many countries. Yet, frustratingly for them, they have not been able to provide evidence of a direct causal connection, although they can point to national statistics of population and health that appear to support their argument.
Human consumption of HFCS increased by 1000 per cent between 1970 and 1990 while, over that same period of time, obesity levels in the general US population climbed from 23 per cent to 30 per cent.
As HFCS was the only significant dietary change seen during that time period, it's reasonable to assume, they argue, that it has played a major part in the obesity crisis.
In a study of 1400 schoolchildren, around one-third of their caloric intake was from added sugars, instead of the sugars found naturally in fruit and vegetables (Nutr Rev, 2005; 5: 133-57). In addition, that same year, the Corn Refiners Association stated that the average American had consumed more than 42 lb (19 kg) of HFCS.
Dr George Bray, a diabetes specialist at the Pennington Research Center at Louisiana State University, has been a leading advocate of the obesity connection (Am J Clin Nutr, 2004; 79: 537-43), and has come up with a novel explanation as to why HFCS can make us fat.
He says that the fructose in HFCS is metabolized differently from table sugar. "Table sugar gives the body 'satiety' signals, whereas fructose and HFCS do not," he says. In other words, you don't get sick of consuming HFCS whereas you soon feel you've had enough of table sugar.
It's a view that has been supported by the research of Peter Havel at the University of California at Davis. He has discovered that the body metabolizes fructose in a way that promotes weight gain. It does not trigger the release of insulin and leptin, hormones that help to suppress appetite, nor does it slow the body's production of the hormones that increase hunger (Am J Clin Nutr, 2008; 87: 1194-203; J Clin Endocrinol Metab, 2004; 89: 2963-72).
Nevertheless, others have, so far, been unable to establish that HFCSis indeed the main culprit behind obesity. The Center for Food, Nutrition and Agriculture Policy at the University of Maryland created an expert panel to look into the claims, and reported that the evidence was either unreliable or inconclusive, while research into HFCS and general sucrose consumption has never been carried out (Crit Rev Food Sci Nutr, 2007; 47: 561-82).
Researchers at the University of Rhode Island were also unable to provide compelling evidence of the harmful effects of HFCS over and above those that come with any other form of refined sugar. Also, they found no differences in the body's metabolic responses to HFCS and sucrose in lean women (Nutrition, 2007; 23: 103-12).
And that seems to be the real point: all refined sugars-whether fructose, sucrose or HFCS-are bad for you, and should be avoided by everyone. Of course, the latest findings by Dufault and the IATP (see main story) that HFCS is contaminated by mercury gives a further reason to avoid the additive.
Some physicians have advocated the use of fructose for diabetics, believing it to be a safer form of sugar than sucrose as it doesn't adversely affect blood-glucose regulation.
But nutritionist Dr Alan Gaby warns that this is bad advice. Fructosecan badly affect other aspects of metabolism, and plays a key role in the ageing process, he says. Worse, it can exacerbate the visual, vascular and renal problems that are already major health concerns in diabetic people.
Furthermore, fructose can cause bowel problems such as diarrhoea and, paradoxically, may be responsible for the current increases in diabetes, obesity and non-alcoholic fatty-liver disease (Altern Med Rev, 2005; 10: 294-306).
Mercury - deadly in any form
Throughout history, mercury-in all of its various forms-has often been the centre of health alarms. However, in recent times, the focus has been on the methylmercury found in fish swimming in contaminated waters and in amalgam dental fillings, and used as a preservative in vaccines.
Mercury in all of its forms is toxic, although its effects depend on the way we absorb it. Mercury poisoning can result from vapour inhalation, ingestion, injection or absorption through the skin, and the most commonly affected organs are the brain, kidneys and stomach.
- Organic mercury is most commonly found in antiseptics, fungicides, laundry products and wood preservatives. Out of all types of mercury, this is the most devastating to the central nervous system. It comes in three forms: amyl; short-chain (more commonly known as 'methylmercury'); and long-chain. This form is more easily absorbed by the body, and crosses the blood-brain barrier and placenta. As it's the form found in industrial waste, this may be the type of mercury found in HFCS-containing products, despite the claims of critics that it is most likely 'elemental' mercury.
- Elemental mercury (Hg) comes in liquid form, and its most common usages are in thermometers, barom-eters, dental amalgam fillings, paints and lamps. It can be very damaging if it's breathed in, as it can then penetrate into the central nervous system and cause long-lasting neurological damage. It's only mildly toxic, however, when ingested.
- Inorganic mercury is commonly found in car batteries, cosmetics, perfume, antisyphilitic agents, perfumes, spermicidal jellies and wood preservatives. This form is highly toxic, and can be absorbed orally and through the skin. It can cause life-threatening kidney damage, and affect the central nervous system.
Until the Dufault and IATP reports, it was thought that the most common exposure to mercury was through eating contaminated fish. The unborn child in the womb is especially at risk, leading America's Environmental Protection Agency (EPA) to advise pregnant women, breastfeeding mothers and young children to avoid eating fish with high mercury contents such as shark, swordfish, mackerel and tuna. (Tinned tuna is not on the list.) HealthCanada advises that these fish should not be consumed more than once a week or, if you are a woman of childbearing age or a young child, no more than once a month.
Thimerosal, the mercury-containing preservative used in vaccines since the 1930s, has been suspected of causing autism and other neurological problems in children. In 1999, the Public Health Service and the American Academy of Pediatrics concluded that thimerosal should be reduced or eliminated from all vaccines. The result is that, nowadays, no vaccines contain the preservative.
Amalgam dental fillings have also been suspected of causing neurological problems, and several European countries have banned the use of such fillings in pregnant women and breastfeeding mothers.
What you can do
The simplest answer to the HFCS problem is to stop consuming any snack or drink that mentions 'high-fructose corn syrup', 'HFCS' or 'glucose corn syrup' on the label. Not only does this mean that it contains a sweetener that may be contaminated by mercury, but it is also an indication that the snack is highly processed and also high in added carbs that can contribute to weight issues.
If you have young children and so have more control over what they eat, try introducing more whole and unprocessed foods into their diet. Indeed, the best sources of natural sugar is from fruit and vegetables.
If you have teenagers, show them this article and then get them to show it to their friends. It's easier for a group to stop a bad eating habit than it is for one person on his own.
Aside from the threat to their health and weight, HFCS may also be adding to their mercury exposure. For this reason, it's important to reduce their overall exposure in other ways, too, such as avoiding fish that may be contaminated by mercury. Check out the IATP website for its Smart Fish Guide at www.healthobservatory.org.
Also, if you have a mouthful of amalgam fillings, you may want to have them removed. It can be an expensive procedure, however, and it is also imperative that it be performed by a dentist who has experience in carrying out the procedure. Often, in inexperienced hands, excessive mercury fumes can be released into the body as the fillings are removed, and this may be more dangerous than leaving them in the teeth in the first place.