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What do those unpronounceable chemicals listed on the back of tins and packages of processed foods actually do to your health? Linia Patel investigates.


What’s in a can of tomatoes? Most people expect to see just one ingredient – tomatoes. Maybe some water, salt or oil at the very most. But pick up an actual can and you are likely to find other ingredients like citric acid or potassium bisulphate on the label as well. However, that said, this is nothing in comparison to the long list of complex names on the back of a ready meal or a tub of ice cream. Ascorbic acid, guar gum and carrageenan to name but a few. What are these food additives? Are they safe?

What are food additives?

Additives are ingredients used in the preparation of processed foods. Some of these may be extracted from naturally occurring materials; others are manufactured by the chemical industry. Additives are described by the European legislation as chemical substances deliberately added to foods, directly or indirectly, in known and regulated quantities for the following purposes(1):

  • To maintain product quality and freshness by significantly delaying the deterioration of fresh foods caused by oxidation and the growth of microorganisms, bacteria and yeast
  • To enhance the appeal of foods and food products by maintaining or improving the consistency, texture and other sensory properties, such as taste and colour
  • To maintain the nutritional quality of a food (e.g., by avoiding degradation of vitamins, essential amino acids and unsaturated fats)
  • To provide ingredients for consumers with specific nutritional requirements (e.g., sweeteners or bulking agents for those seeking to reduce calorie intake)

History of food additives

Food additives are not a new invention. Preserving food is an age-old necessity. The practice probably started when mankind first discovered that fire would cook and thereby preserve meat. Later early people realised that the addition of salt preserved food without cooking. The ancient Egyptians used colouring, flavourings and dye for preservation and to improve the appearance of foods. The Romans used vinegar (acetic acid) and saltpeter (nitrite) as a preservative (both permitted food additives to date)(2).

In recent times, our way of life has changed dramatically. With the busier lives we lead, the trend is for people to spend less and less time in the kitchen preparing food. As consumers, we are also demanding more variety and choice alongside convenience at affordable prices. Meeting these demands has resulted in developments of food technology, as well as an increased use of food additives over the last few decades. Without additives, bread would become stale very quickly, fatty foods would turn rancid and most tinned fruits and vegetables would lose their firmness and colour.

The food industry plays on this and, in turn, markets convenience products as indispensible. Today, there are 2,300 food additives currently approved for use.(3)

Regulation of food additives

All food additives must have a demonstrated useful purpose and undergo a rigorous scientific safety evaluation before they can be approved for use. Most additives are only permitted to be used in certain foods and are subject to specific quantitative limits. Safety tests include animals being given the additive mixed with their diet at much higher concentrations than will occur in human food. The tests are designed to give information on any possible effects from short-term or long-term exposure to the proposed additive, including whether it may have any potential to cause cancer or affect reproductive processes or the development of the embryo or foetus if consumed by a pregnant woman. Tests are also carried out to assess its ability to interfere with genetic material in the body, which could lead to the development of cancer or adverse effects in future generations.

The results of the safety tests are assessed by the European Food Safety Authority (EFSA) and used to calculate the maximum level of additive that has no demonstrable toxic effect (NOAEL). This is then used to calculate the Acceptable Daily Intake (ADI) for each food additive. The ADI is the amount of a food additive that can be consumed daily over a lifetime without any adverse effect on health(1,3,4).

Are food additives safe?

According to the EFSA and the Food Standards Agency (FSA), food additives are safe, as any additives used in food have been scientifically tested to ensure that they are not harmful to your health in the quantities consumed. In fact, the FSA advises that, rather than being sinister about these ingredients, if an additive has an E number then it means it’s passed safety tests and has been approved for use in the UK and the rest of the EU.

However, it is important to remember that, at the moment, additives are tested for safety individually, but in real life they aren’t found in isolation – they are normally combined with other additives. There is now emerging evidence that the effect of combined additives is far worse than the individual effects. A recent study that looked at the combined and individual effect of a group of four common food additives on the development of nerves found that the mixture stunted nerve cell growth up to seven times more than the individual additives in rats(5).

Another issue is that, although food labels have to list additives, they don’t have to say exactly how much is in the product. It is therefore very difficult to calculate whether you are exceeding the ADI or not. We rely on the FSA, which says it monitors the average diet to ensure we don’t regularly exceed the ADI for any additive.

Seven common food additives under the microscope

1. Ascorbic acid

Where is it found? Cured meats, canned vegetables, bottled juices, jams and other preserved fruit

What does it do? Ascorbic acid is a water-soluble vitamin with antioxidant properties. It neutralises oxygen when it comes into contact with it. Ascorbic acid slows down the decay process by creating an acidic environment, which makes it hard for enzymes that accelerate oxidation and, therefore, encourage decay. Ascorbic acid also preserves flavour.

Is it safe? Yes, it is just vitamin C. In fact, it’s even beneficial because it helps inhibit the conversion of nitrates to nitrosamines in cured meat. Epidemiological studies have shown a link between processed meats and cancer. Recent studies suggest that nitrosamines are carcinogenic(6).

What to look for on a label: Ascorbic acid

2. Carrageenan

Where is it found? Dairy products, as well as dairy alternatives (such as soy milk, rice milk, almond milk or coconut milk) and processed lunch meats.

What does it do? It is a thickening agent and therefore used to replace fat. It is also used as a stabiliser in beverages whose contents are known to separate, such as chocolate milk or nutritional supplements.

Is it safe? Carrageenan may be the most controversial food additive that many people have never heard of. Although it has been used for decades as a thickening agent in a wide variety of foods, a growing body of evidence is raising questions about its safety. However, many professional health bodies such as the FSA and EFSA still don’t believe the available evidence makes a strong enough case to ban it, the reason being that the majority of studies are done on animals and use very high doses of carrageenan, which doesn’t replicate the conditions that exist in the human gut. The World Health Organization has established an ADI of carrageenan as 0-75mg/kg/bw. An average
daily intake would be approximately 250mg/day, which is well towards the low end of the ‘safe’ spectrum. The animal studies that have linked carrageenan to intestinal inflammation and leaky gut have given the rats between 3,876-9,690mg/kg/bw. However, as we become more and more aware of inflammation being a factor in
other chronic disorders (such diabetes and atherosclerosis), some nutrition experts are still advising those at risk to avoid foods that bring on inflammation. This includes foods containing carrageenan.(7)

What to look for on a label: Carrageenan

3. Sodium benzoate

Where is it found? Fruit juices, carbonated drinks and pickles

What does it do? It’s an antimicrobial agent used to prevent bacteria from growing in foods.

Is it safe? Research funded by the FSA has suggested that the preservative sodium benzoate could be linked to the increased hyperactivity in some children. In addition, while sodium benzoate by itself isn’t dangerous, when it combines with vitamin C it can form benzene, which is a recognised carcinogen. However, the EFSA states that food products that contain both vitamin C and sodium benzoate express benzene levels that are well below the dangerous limit(1,9).

What to look for on a label: Sodium benzoate

4. Citric acid

Where is it found? Canned products

What does it do? It’s an antioxidant that preserves the colour of the product and
keeps the pH low.

Is it safe? Theoretically, as it is a naturally occurring substance, it should be safe. However, food industries have started making citric acid from corn. Corn-based citric acid contains some monosodium glutamate (MSG), so unless you have a severe corn allergy or are sensitive to MSG, it’s probably safe(9).

What to look for on a label: Citric acid – there is no way of telling if it is a corn-based citric acid or not unless you call the manufacturer

5. Guar gum

Where is it found? Foods such as ice cream, gravies, salad dressings, sauces and soups

What does it do? Guar gum is basically the ground endosperm of guar beans. The processed white powder has eight times the water-thickening ability of cornstarch. It is therefore used to thicken, bind and stabilise the ingredients in a range of foods. Guar gum flour can be used in recipes in place of white flour for those with gluten allergies.

Is it safe? Guar gum has shown to be safe in most cases. Other animal studies have shown that a high dose of guar gum results in a reduction in blood glucose, improved insulin sensitivity and weight loss. This has led researchers to wonder if similar benefits could be seen in humans. These studies are ongoing but many believe that there is
potential. One downside is that, as guar gum is a soluble fibre, it may have some adverse effects on the gastrointestinal system (i.e., bloating or increased gas), so it is best limited if you have irritable bowel syndrome(10).

What to look for on a label: Guar gum

6. Monosodium glutamate (MSG)

Where is it found? Asian food, salad dressings and canned soup

What does it do? MSG is a form of the naturally occurring chemical glutamate, which doesn’t taste of anything by itself but enhances other flavours – especially in savoury foods.

Is it safe? The jury is still out! Many people claim to have a serious sensitivity to MSG in foods (also known as ‘Chinese restaurant syndrome’); however, clinical studies have not found a clear, consistent link. Studies where human subjects were given very large amounts of MSG by itself (i.e., MSG crystals) did result in subjects experiencing mild symptoms; however, giving modest amounts in foods did not. Other studies have tested the idea that some people may be sensitive to MSG; however, there is now a general consensus that it is extremely rare. Recently, there has been a link between MSG and obesity but the evidence is conflicting here too. Researchers in rural China suggested that MSG intake was a strong predictor of obesity, even when controlling for other variables like total calorie intake. However, other studies have found no relationship. A further study found that MSG reduced satiety in the short term but increased it in the longer term. Yet another study found that obese women tasted MSG differently from normal weight women, and the obese women needed more of the MSG to get the same flavour hit.

What to look for on a label: MSG or anything with glutamate, hydrolysed protein isolates or concentrates and autolysed yeast

7. Sulfites

Where is it found? Dried fruit, vinegar and wine

What does it do? Sulfites are colour preservatives and antioxidants.

Is it safe? That depends. Some people are extremely sensitive to sulfites (i.e., anaphylactic reactions). However, sulfites do occur naturally in several kinds of food (including wine) and people who are sensitive to added sulfites are generally sensitive to these natural ones as well(11).

What to look for on a label: Sulphur dioxide, sodium sulfate, sodium and potassium bisulfate, metabisulfates. Naturally occurring sulfites are often not labelled though!

Take-home message

Additives in our food are a price we are paying for our 21st century lifestyle. Although governing bodies like the EFSA and the FSA claim that permitted food additives are safe, what the studies haven’t shown yet is the cocktail effect food additives have over a lifetime. Ultimately, as a dietitian, my advice would always be to focus on a diet that is centred on fresh and whole food and a lifestyle that supports as much scratch cooking as possible. Do that as much as you can and you won’t be part of the experiment!


Linia Patel has a BSc degree in biochemistry and physiology. Since graduating in 2006, Linia has taken up various leading roles in performance nutrition and public health.

This article first appeared in Fitpro Summer 2015. For references, click here.

Where to next? Check out fashionable foods in What’s in your cupboard?