Needing to worry about food additives seems so very 'last century'. It appeared certain that the food industry had finally acknowledged the dangers of food colourings, preservatives and trans fatty acids, given that thousands of products now proudly proclaim "no additives or preservatives", "no artificial colours" and "no hydrogenated fats".
But the shocking fact is that there is hardly a single food or drink that is 100 per cent additive-free, unless it's raw organic produce or glass-bottled water.
In Europe, there are a staggering 1,521 additives "permitted" under the official regulations; some are vitamins and minerals (vitamin C is considered a preservative, for example), and some colours are derived from vegetables, but fully two-thirds of them have been concocted by industrial chemists.
By definition, most additives are compounds that mankind had never encountered before the early 1900s. So, unlike natural substances, which our digestive and immune systems have learned to cope with over the course of our evolution, man-made additives in our diet are like invaders from outer space.
And that's the problem, according to the latest research. It's not just that additives are potential toxins, it's that they also fool the body into thinking it's getting food energy and nutrients when it's not.
Western nations are in the midst of an obesity epidemic, which we are told is caused by people eating too much fat and sugar. The endlessly repeated advice from health authorities has been to switch to low-fat foods and to replace sugar with sugar substitutes. Take this statement from one of Britain's top nutritionists: "Sugar provides around 10 per cent of total calories. If this were entirely replaced by a non-nutritive, non-caloric sweetener such as aspartame, then obesity could be vanquished," said Dr Michael Lean, Chair of Human Nutrition at the University of Glasgow, as little as 10 years ago.1
Artificial sweeteners are by far the largest sector of the additives market, worth $1.5 billion a year worldwide. Many people buy sweeteners for their own tea and coffee, but the biggest users are food and drink manufacturers. Any sweet-tasting processed food product you buy will contain artificial sweeteners-including toothpaste. This makes sweeteners almost impossible to avoid.
Saccharin was the first sweetener to be discovered-over a century ago-but there are now a staggering 19 others. This huge choice is partly a response to concerns about their effects on health. Although manufacturers (and health authorities) have always insisted that every new sweetener is 100 per cent safe, there have been persistent fears about toxicity.
Aspartame is the most controversial with a long history of adverse health findings-all of which have been rebutted by both manufacturers and health authorities (see box, page 49). That's why aspartame is still licensed for use, and found in a wide variety of manufactured foods.
Partly in response to aspartame's bad press, other sweeteners have been developed, all claiming to be ultrasafe. However, many of these have also been linked to health problems (see box, page 49). Because of these concerns, maximum limits have been set on the amounts permitted in foods. But food manufacturers have managed-and indeed are encouraged-to sidestep the spirit of these regulations by using a cocktail of sweeteners in foods and drinks.1
Two obvious problems with this are: first, although a single sweetener might not exceed legal limits, the ensemble could; and second, combinations of chemicals can interact with each other and become toxic, yet few of these potential interactions have ever been safety-tested.
But whichever the manufacturer and whatever they're made of, almost all artificial sweeteners have the same problem: although they're 'low-' or 'zero-calorie' and so should help you shed pounds, in practice, they not only fail to do so,
but actually achieve the reverse.
Yes, artificial sweeteners make you fat. This startling discovery was first reported about seven years ago after a nine-year US study looked at people with heart disease.
The researchers were surprised to find that people who drank the most diet sodas had double the risk of being overweight. They found "a significant positive dose-response relationship", suggesting that the low-calorie drinks were directly responsible for the extra pounds.2
These findings raised the question of whether artificial sweeteners "might be fueling-rather than fighting-our escalating obesity epidemic," the University of Texas researchers concluded. And much to conventional dietitians' chagrin, hot on that study's heels came four more, involving a total of more than 100,000 adults and children, that also found the same weight-gain phenomenon.3
These surprising findings have gone some way towards explaining why, despite millions of Americans switching to low-calorie 'diet' drinks and sugar substitutes like Sweet'N Low, obesity rates have still soared. For nutritionists, none of this makes any sense: if people switch from a high-calorie/high-sugar diet to a low-calorie/fake-sugar one, the theory says they should inevitably lose weight.
But the studies show they don't . . . so why not?
Fooling the body
The discovery that artificial sweeteners (ASs) don't help you lose weight wouldn't be a surprise to anyone who kept up with the scientific evidence. As long ago as 1988, clinical trials showed that adding saccharin to rats' water supply made them eat up to 15 per cent more food than rats drinking plain water.4
That same year, a Leeds University study found the same thing in people. Tests comparing ASs with sugar as sweeteners showed that the artificial ones increased people's appetites, making them eat more food. Why? Probably because of "the uncoupling of the sensory and energetic components of sweet solutions", said the researchers.5
In other words, having tasted something sweet, the body expects, yet fails to receive, the promised energy boost, so it resorts to fulfilling the expectation by eating more food.
Since the 1980s, scores of studies have confirmed the paradoxical fact that ASs don't help people lose weight. One of today's leading researchers is Professor Susan Swithers at Purdue University. Her theory? That sweeteners upset "fundamental homoeostatic, physiological processes"6 [by] "interfering with learned relations between the sweet taste of food and the caloric or nutritive consequences of consuming those foods."7
Indeed, there's evidence that ASs have powerful effects on the brain. In 2008, scientists compared people's responses to ASs and ordinary sugar using functional magnetic resonance imaging (fMRI) brain scans-with intriguing results. Sugar activates totally different parts of the brain compared with ASs-in particular, the dopamine transmission system. This ties in with Swithers' theory, as dopamine is involved in the so-called reward signals in the brain.
"Brain response distinguished the caloric from the non-caloric sweetener, although the conscious mind could not," said the University of Colorado researchers. "This could have important implications on how effective artificial sweeteners are in their ability to substitute sugar intake."8
Of course, as with most biological research, there are disagreements: some human studies haven't found the sweetener paradox, but these tended to be funded by the sweetener industry itself.9
The most reliable findings have come from animal research. The downside (apart from ethical issues) is that rats and mice aren't people, but the upside is that precise measurements can be made of their physiological responses. And these have now revealed some bombshell discoveries about ASs.
In one landmark experiment in 2013, scientists in Brazil compared the effects of sugar and ASs on weight gain in rats. Once again, the rats that gained the most weight were the ones on sweeteners, but-and here's the kicker-their calorie intakes did not differ. The animals with ASs added to their feed ended up fatter than the ones given sucrose, regardless of the similar caloric intakes.10
If the calorie theory has any merit at all, there should have been no differences in weight between the two groups.
Other researchers have confirmed these unexpected findings.
"Consumption of sweeteners resulted in significantly increased body weight; however, the food intake did not change," reported a team of Hungarian nutritionists doing similar experiments in mice. "These results question the effect of non-caloric artificial sweeteners on weight-maintenance or body weight decrease."11
Why should ASs cause weight gain with the same amount of food consumption? Professor Swithers has found what she thinks may be the culprit: the glucose regulation system. She has shown that ASs cause a significant extra rise in blood glucose in the presence of carbohydrates in rats.7 That's a key discovery because high glucose levels tend to result in weight gain.
The second key discovery, and one that fully explains how ASs cause weight gain, was reported in Nature, the highly respected science journal. A large Israeli research team, mostly from the prestigious Weizmann Institute in Rehovot, announced that ASs have "deleterious effects" on beneficial gut bacteria in both animals and people, causing what's called "gut dysbiosis".
This major intestinal disturbance is a well-known cause of a huge range of health problems-from food intolerances to diabetes and the metabolic syndrome. Specifically, it "drives the development of glucose intolerance", say the Israelis.
Glucose intolerance is a close relative of insulin resistance, and both interfere with the body's natural way of neutralizing high glucose levels.
And that's the clincher that explains the weight-increase paradox with ASs. As Swithers found, ASs cause a rise in blood glucose. That's already serious enough, but now the Israelis have discovered that ASs also knock out the body's own glucose regulation system, so it can't handle the extra glucose the ASs have themselves created.
So the apparent paradox of zero-calorie sweeteners causing weight gain is solved. They deliver a sinister double whammy: first a rise in glucose, which is then followed by hobbling of the glucose 'antidote' mechanism-two huge hits that can only result in weight gain-because, as we now know, the major cause of fat storage is not excess calories, but excess glucose in the blood circulation.
But if ASs disrupt such a key body regulatory system, wouldn't other health problems show up-ones far more serious than the results of putting on a few extra pounds?
Well, in fact, they have.
In the last few years, population studies have investigated the health dangers of 'diet beverages' like colas and sodas. They've found worrying increases in a range of serious conditions, including preterm births,13 cardiovascular disease,14 non-Hodgkin's lymphoma, multiple myeloma and leukaemia,15 the metabolic syndrome and type 2 diabetes,16 and abdominal obesity.17
One 14-year survey of over 66,000 French women found that diet drinks more than doubled the risk of diabetes, a figure that's put into startling perspective by the fact that the women who drank ordinary sugary drinks had a far lower diabetes risk-specifically, a quarter of the AS drinkers' rates.18
Shocking, but it makes perfect sense. Glucose intolerance and insulin resistance are the primary causes of diabetes. Sugar has always been considered the main culprit, but laboratory evidence now suggests that sugar substitutes are even more powerful triggers of insulin resistance and so much more guilty of causing diabetes.
Western societies are currently in the grip of the twin epidemics of diabetes and obesity-even in countries where sugar consumption is actually falling.19 These new AS data explain why that's no longer a mystery.
To date, however, both the AS industry and academia have tended to soft-pedal the new findings, brushing them off with the standard 'more research needed' response.20
But hands-on experts think we already know enough, and they're urging the authorities to act. "The real concern with artificial sweeteners is what they are doing metabolically-negative outcomes like hyperglycaemia, insulin resistance, and increased abdominal adiposity, independent of changes in body weight. That's a huge concern," says Susan Swithers.
"Our findings suggest that non-caloric artificial sweeteners may have directly contributed to enhancing the exact epidemic that they themselves were intended to fight," says Weizmann Institute's Dr Eran Segal.
His colleague, Dr Eran Elinav, agrees: "Artificial sweeteners tend to develop the very disorders they were designed to prevent. This calls for a reassessment of today's massive, unsupervised consumption of these substances."
Reassessment? The silence is deafening.
The stevia stitch-up
If you must use a sweetener, stevia appears to be the best bet. Unlike saccharin and other artificial sweeteners, it doesn't increase appetite or weight;1 in fact, it increases insulin sensitivity.2 That's why it's considered a possible treatment for type 2 diabetes.3
Stevia's uniquely healthy properties is probably because it's not man-made, but is 100 per cent derived from the shrub Stevia rebaudiana.
Native to Paraguay, the plant has been used as a sweetener for centuries. Stevia has passed modern safety tests and is permitted for use in food products worldwide, except in the US, where it's been banned by the Food and Drug Administration (FDA).
Freedom of Information Act (FOIA) enquiries have revealed that the FDA was pressured by blacked-out (redacted) documents to declare stevia "an unsafe food additive", raising suspicions it was a stitch-up by the US sweetener industry, which was unhappy about the arrival of a cheap, non-patentable competitor.
Tellingly, once the FDA banned stevia, two major sweetener manufacturers quickly developed their own stevia-based compounds, making them patentable by adding extra ingredients.
Truvia (a Coca-Cola product) is a blend of stevia and erythritol, and PureVia (from PepsiCo) is stevia plus dextrose-yes, a sugar identical to glucose! Both rapidly received FDA approval.
Nevertheless, there's been a tsunami of complaints about Truvia; consumers describe a range of adverse effects like severe gastrointestinal problems, dizziness, headaches, kidney pain and urinary tract inflammation. Some of these effects have even resulted in visits to hospital emergency units.
Truvia's maker has dismissed these adverse reports as anecdotal, but an explanation came last year when American researchers tested Truvia on fruit flies and showed dramatic effects on the insects' lifespan.
Compared with flies fed ordinary sugar, which lived for about two months, Truvia killed them all off in under a week. So powerful was the effect that the scientists now recommend Truvia as an insecticide. It's clear that the toxic ingredient is not stevia, but erythritol, a 'sugar alcohol' approved as a food additive.4
Note: Stevia tends to have a bitter aftertaste, exacerbated by how it's grown and manufactured, so choose organic stevia that's been 'water-extracted'.
1 Appetite, 2010; 55: 37-43
2 Horm Metab Res, 2005; 37: 610-6
3 Rev Diabet Stud, 2006; 3: 189-99
4 PLoS One, 2014; 9: e98949
Lesser-known additives to watch out for
These chemicals are routinely added to margarine, mayonnaise, creamy sauces, ice cream, packaged processed foods and baked goods "to improve texture and extend shelf life", says the industry. Authorities have always claimed that emulsifiers are harmless, placing them in the GRAS ('generally regarded as safe') category.
But in a report from Georgia State University in Atlanta, when scientists fed emulsifiers to mice in their food and water, they found that the animals developed "low-grade intestinal inflammation" and metabolic disorders such as blood glucose abnormalities, increased body weight and abdominal fat.1
Emulsifiers apparently destroy the protective mucous lining of the intestines, "digesting" and then "infiltrating" it.
The mice had been given the same types and quantities of emulsifiers as used in processed foods for people. The scientists believe these findings explain the rise in inflammatory bowel disorders and the metabolic syndrome, both of which have soared in the last few decades.
"We were thinking there was some non-genetic factor out there, some environmental factor, that would be explaining the increase in these chronic inflammatory diseases," said Georgia State's Dr Andrew Gewirtz. "We thought emulsifiers were a good candidate because they are so ubiquitous and their use has roughly paralleled the increase in these diseases. But I guess we were surprised at how strong the effects were."
Last April, two scientists at Belgium's Louvain Drug Research Institute reported identical results in their own researches,2 and a pair of Israeli scientists have also warned that emulsifiers may be a "dietary clue to the pathogenesis of Crohn's disease", a condition characterized by gut inflammation.3
Since food manufacturers are now prohibited from using trans fatty acids (TFAs) because of the many confirmed health risks, they've been on the lookout for safer alternatives and hope interesterified fats (IEFs) are the answer.
IEFs are made by chemically combining solid and saturated fats with vegetable oils to create fats with the same function as TFAs-"extending shelf-life". But not surprisingly, trials with human volunteers have shown that IEFs are as hazardous as TFAs. One early study found they raise LDL cholesterol (the 'bad' one) and interfere with glucose metabolism.4
The most recent review of the evidence concluded that there were "negative biological effects on lipoproteins, blood glucose, insulin, immune function, and liver enzymes".
The Brandeis University researchers recommended that "more research is warranted to determine the appropriateness of IEF consumption, particularly before it becomes insidiously embedded in the food supply similar to TFA and intake levels are achieved that compromise long-term health".5
This damning review was published five years ago and, yet, not only are IEFs still permitted, but they're not even required to be listed on labels. So if you see a product boasting that it's "TFA-free" or contains "no hydrogenated fats", it's a safe bet that it's laced with IEFs.
Low-fat processed foods contain yet another class of fat substitute-added not to prolong shelf life, but to provide the yummy taste of fat without the weight gain supposedly caused by the real thing. Fat substitutes are made from chemically processed vegetable oils, carbohydrates or proteins; many are indeed low in calories, but mainly because they're not recognized by the body as food and so are expelled as undigested waste.
Of the products that have been developed, olestra is the brand leader in the US. But it's been banned in most other countries because it prevents nutrients in real food from being absorbed by the gut.6
As with artificial sweeteners, animal tests have shown that fat substitutes like olestra paradoxically lead to higher food intakes and greater weight gain.7
1 Nature, 2015; 519: 92-6
2 Trends Endocrinol Metab, 2015; pii: S1043-2760(15)00066-1
3 Dig Dis, 2014; 32: 389-94
4 Nutr Metabol, 2007; 4: 3; doi: 10.1186/1743-7075-4-3
5 J Am Coll Nutr, 2010; 29 [3 Suppl]: 253S-84S
6 J Nutr, 1997; 127 [8 Suppl]: 1699S-709S
7 Behav Neurosci, 2011; 125: 512-8