Food Additives – What Does It Mean?
There are many definitions of food additives. In the European Union, a food additive is defined as “a substance that is not normally consumed as food, but is intentionally added to food for technological purposes,” such as to extend shelf life or improve sensory qualities.
In publications from 10 years ago, it was reported that there were around 2,500 food additives, while the most recent scientific studies now identify more than 3,000 such substances. An increase of 500 new compounds over the last 10 years – this is a rapid growth. Food additives include:
- natural substances,
- synthetic substances not found in nature,
- synthetic substances identical to natural ones.
Harmful and allergenic – the side effects of food additives
Food additives can cause the same reactions as foods, plus they have other side effects. The harmful mechanism of action of these substances on the body is not fully known. However, it is known that they can be responsible for causing/exacerbating allergic disease or non-allergic hypersensitivity (atopic dermatitis, contact eczema, urticaria, asthma), as well as exhibiting toxic and irritant effects.
Adverse effects of food additives may include:
- skin (urticaria, eczema, angioedema, atopic dermatitis),
- gastrointestinal tract (nausea, vomiting, abdominal cramps, diarrhoea),
- respiratory system (rhinitis, hoarseness, asthma).
Sometimes these additives contribute to non-specific complaints, e.g. from the:
- urinary system (dysuric symptoms, isolated proteinuria, haematuria, involuntary bed-wetting in children),
- haematopoietic system (anaemia, thrombocytopenia, leukopenia, hypereosinophilia),
- osteoarticular system (bone and muscle pain with or without swelling),
- the nervous system.
The last group of disorders – psychological and neurological symptoms – is what we are most concerned about. Food additives cause headaches and dizziness, migraines, changes in disposition, general weakness, epileptic seizures, fainting, memory and concentration disorders, depressive symptoms. They can also promote neurotic reactions and contribute to chronic fatigue syndromes or the hyperkinetic child (ADHD).
The problem of hypersensitivity to food additives is thought to affect 1% of adults and 1-2% of children. In children with atopy, the risk is several times higher at 7%. Scientific studies show that most hypersensitivity to food additives is caused by:
- dyes (azo and non-azo),
- preservatives
- flavour enhancers (monosodium glutamate).
A daily intake standard has been set for each additive, which should not have an adverse effect on human health. But as we consume many products with such additives, there is an accumulation of doses and the likelihood of adverse effects increases significantly. The frequency of side effects is very difficult to estimate, as there are still no clear diagnostic methods for this group of products.
Types of food additives
Food additives in the European Union are designated by the symbol E, to which a number is assigned to indicate the type of substance:
- colours (E100-199),
- preservatives (E200-199),
- antioxidants and acidity regulators (E300-399),
- stabilisers, thickeners, emulsifiers, fillers (E400-499),
- others (E500 and above).
Colours
Colourants are indiscriminately added to a wide range of products: coloured sweets and drinks, candied fruits, canned red fruits, canned vegetables, sauces, condiments, marinades, fish pastes, smoked fish, cured meats, meat for burgers, powdered soups, soya chops, etc. Examples of such substances are:
- amaranth (E123),
- sunset yellow (E110)
- carmoisine (E122),
- tartrazine (E102),
- S green (E142),
- quinoline yellow (E104),
- indigocarmine (E132).
Dyes of less clinical relevance include:
- cochineal red (E124),
- 2G red (E128),
- Brilliant Black (E151),
- HT brown (E155)
- FK brown (E154).
These include both natural substances (e.g. E100 – curcumin) and artificially synthesised substances (e.g. coal tar derivatives such as E102 – tartrazine). They are added not only to foods, but also to medicines to make the colour of a capsule or tablet more attractive. Dyes, especially tartrazine, can cause allergic reactions, insomnia, distraction, depression. There are even publications that show that dyes in combination with benzoates are involved in hyperactivity syndromes in children. The dye E123 (amaranth) was withdrawn in the United States in 1975 due to adverse effects.
Preservatives
Preservatives are another large group of food additives. Synthetic preservatives induce skin lesions through the non-specific release of histamine and an increase in leukotrienes. These include:
- sorbic acid and its salts (E200-203),
- benzoic acid and benzoates (E210-213),
- p-hydroxybenzoic acid esters and their sodium salts (E214-E219),
- sulphur dioxide and sulphites (E220-228),
- nitrites (E249-250),
- nitrates (E250-252),
- propionic acid (E280),
- lysozyme (E1105).
Sulphites
Nitrateshave a direct vasodilating effect and increase intestinal permeability to various allergens. In contrast, sulphites (e.g. sodium pyrosulphite, potassium pyrosulphite) can cause a whole range of symptoms:
- attacks of dyspnoea,
- fainting spells,
- headaches,
- urticaria,
- skin rashes,
- erythema,
- pruritus,
- local swelling,
- difficulty swallowing,
- nausea,
- vomiting,
- abdominal pain,
- diarrhoea,
- changes in heart rate,
- increase in body temperature.
These preservatives are formed in the body during catabolic processes under the influence of the enzyme sulphite oxidase, the deficiency of which makes sulphites poorly tolerated in the diet.
Sulphites and their derivatives can cause asthmatic dyspnoea attacks both after inhalation exposure and after ingestion of foods containing them. There is a significant risk of anaphylactic reactions after consuming drinks and dishes in restaurants, due to the fact that there are large amounts of sulphites in the foods served there (salads, beer, wine, orange juice, vinegar, prawns, dried fish, fruit, herbs).
Benzoic acid
The commonly used benzoic acid has become an important problem for allergologists. This acid occurs naturally in plants, where it acts as a toxin against bacteria, moulds and yeasts. Some plants and fruits contain a lot of it (cloves, cinnamon, blueberries, blueberries, cranberries and others). Chemically synthesised, it is a preservative added to a great many food and cosmetic products.
Significant amounts of sodium benzoate are contained in: meat, fruit and vegetable preserves, ready meals, sweets, drinks, mayonnaise, marinades, salads. This preservative is also found in toothpaste, mouthwash, deodorants and medicines (which is also due to its expectorant properties).
Can cause or exacerbate: asthma, urticaria, rhinitis. Has irritant properties and causes frequent contact sensitisation (parabens). Results of animal studies have shown that it can weaken muscles and lead to damage to the development of the eyeball in rat foetuses. It is also a causative agent of behavioural disorders and hyperactivity, especially in developmental aged patients.
Other preservatives suspected of having sensitising properties include:
- biphenyl, diphenyl (E230),
- orthophenylphenol (E232),
- urotropine (E239).
Antioxidants
Antioxidants (E300-399), or antioxidants, include:
- ascorbic acid (E300),
- propyl gallate (E310),
- octyl gallate (E311),
- dodecyl gallate (E312),
- BHA (E320),
- BHT (E321).
Some antioxidants have beneficial effects (e.g. ascorbic acid), others have adverse effects (e.g. propyl gallate, octyl gallate, dodecyl gallate). They are found in all milk- and sugar-based products with a long shelf life, semi-finished products, ready-to-eat salads. They are also on the surface of citrus fruits. They are used as agents to prevent fats from going rancid. They are also found in confectionery fats and those used to make soups or condiments in cubes.
Gelling agents and thickeners
Gelling and thickening agents (E400-499) are added to toppings, creams, sauces, ice creams, cottage cheese. The most common applications are:
- propylene glycol alginate (E405),
- locust bean gum (E410),
- guar gum (E412),
- tragacanth (E413)
- acacia gum (E414),
- carboxymethyl cellulose (E466).
It is worth noting the amount of gum arabic and guar gum found in Orbit gum. People who read the labels will definitely steer clear of this product.
Stabilisers and emulsifiers
A minor risk when it comes to food additives are stabilisers and emulsifiers. Among the most commonly used are calcium carbonate (E170) and lecithin (E322). E170 is found, for example, in cake powder, cakes, biscuits, bars, wafers and other sweets, as well as in margarine, crisps and crackers. E322, on the other hand, is found, for example, in confectionery, ice cream, baked goods, chewing gum, ripened cheese and grape juice. However, in the case of lecithin, not even a daily intake limit has been established. It is included on the GRAS list of substances generally recognised as safe.
Taste and odour enhancers
Taste and odour enhancers are another group of food additives. Glutamic acid (E620) and monosodium glutamate (E621) are commonly used. Glutamic acid is a naturally occurring amino acid that is found – in varying concentrations – in a great many foods. It does not have a pronounced taste, but enhances the flavour intensity of other foods. It was first isolated in 1908. Prof. Kikunae Ikeda obtained glutamic acid from a seaweed (cotyledon).
Today, the scale of production of this flavour enhancer is alarming – it is synthesised at a rate of over 400,000 tonnes per year and added at a rate of 0.2-9.8/100 g to food products such as:
- stock cubes
- herb mixtures,
- seasonings for meat,
- herb and garlic salt,
- powdered and jarred soups and sauces,
- ketchup.
Glutamates (E620-625) can cause Chinese restaurant syndrome, which produces symptoms through the non-specific release of histamine from mast cells and granulocytes in hypersensitive individuals and through interactions with neuromediators in the central nervous system. These include symptoms such as:
- a feeling of heat in the back, neck, forearms and chest,
- swelling and redness of the face,
- chest pain,
- headache and muscle aches,
- nausea
- tingling sensation in the upper part of the body,
- palpitations,
- numbness in the neck, hands and back,
- bronchospasm,
- general tiredness.
Monosodium glutamate can not only cause adverse reactions, but can also increase the risk of overweight and obesity – by as much as three times (even when following a diet in line with preventive recommendations). It has a very adverse effect on neuromuscular conduction (causes excessive neuronal excitation). It can also contribute to behavioural changes and hyperactivity in children.
Sweeteners
Sweeteners, which are commonly added to beverages and confectionery, also interact with neuromediators in the central nervous system. These include:
- aspartame (E951), a sweetener that has been on the market for several decades, is a substance that is approximately 200 times sweeter than sucrose. It was created in 1967 and approved by the US Food and Drug Administration in the 1980s for use in the food industry. It is primarily used to reduce the calorie content of food and beverages. It contains the same number of calories as sugar (4 kcal/g), but because it takes very little to achieve the desired effect, it is considered a zero-calorie substance.
- cyclamic acid (E952) – i.e. the sodium or potassium salt of cyclamic acid – is one of the oldest synthetic sweeteners (since 1937) with a sweetness 30-50 times greater than table sugar.
Diagnosis of hypersensitivity to food additives
There are no standardised diagnostic methods (skin tests, laboratory tests) for detecting hypersensitivity to food additives. Elimination-provocation diets that exclude suspect substances are used to determine whether a person has such hypersensitivity. They are particularly important in the diagnosis of chronic urticaria, when clinical observations show that food additives may be the trigger for the disease. An IgE-mediated reaction should be ruled out at the outset of diagnosis, especially if the patient has had severe reactions (bronchospasm, Quincke oedema, anaphylactic reactions). Such reactions are very rare but can occur due to exposure to sulphites and parabens.
The elimination-provocation diets in the diagnosis of additive hypersensitivity must be completely free of processed foods and therefore include 100% home-prepared meals. They should be followed for at least four weeks. The menu may include, for example, bread without preservatives, potatoes, rice, millet, butter, vegetable oils, fresh milk, cream, yoghurt, cheese, fresh meat (preferably lamb or turkey), all vegetables (except artichokes, peas, mushrooms, spinach, tomatoes, olives), honey, salt, sugar, coffee, black tea.
If hypersensitivity reactions do not subside after a preservative-free diet, the restrictiveness of the diet is increased. The menu introduced in hospital usually includes only potatoes, rice and water (possibly also cauliflower, broccoli, cucumber, turkey, lamb and oil as a source of fat). Such a restrictive diet can be followed for 5-7 days.
A diet rich in food supplements
Once symptoms have completely resolved, a provocation test is undertaken. In the case of chronic urticaria, a provocation with high levels of dyes, benzoates, sulphites and antioxidants is anticipated.
If there is no reaction after a one-day provocation, we follow a diet containing food additives for subsequent days (as the effect may depend on the dose) or enrich it. Of course, we have to expect that systemic reactions may occur within 24 hours after ingestion of a substance.
Initially, if the history is not absolutely clear, no attempt is made to identify a single causal factor. We provoke with a mixture of food additives. If the test is negative, the patient should not be provoked with anything else. On the other hand, if it is positive, the composition of the mixture should be analysed. In provocation tests, not every substance is used separately, but products rich in multiple food additives. This better reflects the daily diet of a patient exposed to various substances added to foodstuffs available in shops. The provocation is carried out with, for example:
- tea with sweeteners and condensed or powdered milk or cream,
- low-calorie yoghurt or fruit cheese with dried fruit and cereal,
- juices, cold drinks, light cola,
- waffles, chocolate bars, crisps,
- spicy pizzas with ready-made sauces,
- canned tuna,
- smoked fish,
- shrimps,
- pre-packaged sliced bread,
- diet margarine,
- low-sugar jams,
- ready-made salads with mayonnaise or other dressings,
- sausages and cold cuts,
- yellow cheese.
If symptoms appear after a diet rich in food additives, a double-blind trial with individual additives or groups of additives, e.g. a mixture of colours, preservatives or artificial sweeteners, is advisable in further management.
Do food additives cause/exacerbate symptoms in chronic urticaria?
The 2022 recommendations of the European Academy of Allergy and Clinical Immunology (EAACI) indicate a potentially beneficial effect of a diet with food additive restriction in some patients with urticaria despite a lack of evidence in large double-blind controlled trials.
This prompted our clinic team to conduct our own study in a group of 110 patients hospitalised for urticaria and/or angioedema with suspected food additive hypersensitivity. In such patients, an inadequate response to antihistamines is often observed, necessitating intensification of treatment (with corticosteroids, adrenaline).
We selected 31 subjects for provocation trials, but 10 of them refused to perform them for fear of effects. In total, we performed 171 provocations with food additives (carmine, annatto, sodium pyrosulphite, azo dyes, sodium benzoate, monosodium glutamate). Patients with positive trial results followed elimination diets for 2 years and were reassessed 12 and 24 months after provocation.
What are the conclusions of this study? Those patients who conscientiously followed the elimination diet experienced a complete resolution or reduction of symptom exacerbations in 76%. In our study group, one in five patients saw an effect of food additives on the persistence of urticaria. Interestingly, IgE-dependent reactions to carmine and sodium pyrosulphite appeared to be predominant.
How do we protect ourselves from food additives?
Unfortunately, we don’t stand a chance with the thriving food industry. What we do have, however, is influence over what we eat. Here, special attention needs to be paid to young children. We must be aware of the dangers of feeding children, especially those with allergic conditions. Children’s meals should be prepared as far as possible from fresh, unprocessed products. Sweetened drinks, snacks and convenience products should be avoided. Adequate nutrition from the early months of life develops good eating habits, protects against many diseases of civilisation and allows for more effective treatment of patients with atopic diseases.
In addition to a conscious choice of products, we need correct labelling of articles by manufacturers, education of the public – not only by nutritionists and doctors, but also by teachers in schools and kindergartens.
