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Impact of food additives on the composition and function of gut health
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Thursday, 15 June, 2023, 14 : 00 PM [IST]
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Dr S. Mohana Lakshmi
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Food Additives:
According to World Health Organisation (WHO), substances that are added to food to maintain or improve the safety, freshness, taste, texture, or appearance of food are known as food additives. Some food additives have been in use for centuries for preservation – such as salt (in meats such as bacon or dried fish), sugar (in marmalade), or sulfur dioxide (in wine).
Many different food additives have been developed over time to meet the needs of food production. Additives are needed to ensure processed food remains safe and in good condition throughout its journey from factories or industrial kitchens, during transportation to warehouses and shops, and finally to consumers.
Food additives can be derived from plants, animals, or minerals, or they can be synthetic. There are several thousand food additives used, all of which are designed to do a specific job in making food safer or more appealing. WHO, together with FAO, groups food additives into 3 broad categories based on their function.
Flavouring agents:
Flavouring agents – which are added to food to improve aroma or taste. There are hundreds of varieties of flavourings used in a wide variety of foods, from confectionery and soft drinks to cereal, cake, and yoghurt. Natural flavouring agents include nut, fruit and spice blends, as well as those derived from vegetables and wine. In addition, there are flavourings that imitate natural flavours.
Enzyme preparations:
Enzymes are naturally occurring proteins that boost biochemical reactions by breaking down larger molecules into their smaller building blocks. They can be obtained by extraction from plants or animal products or from micro-organisms such as bacteria and are used as alternatives to chemical-based technology. They are mainly used in baking for manufacturing fruit juices in wine making and brewing as well as in cheese manufacturing.
Other additives:
Other food additives are used for a variety of reasons, such as preservation, colouring, and sweetening.
Preservatives can slow decomposition caused by mould, air, bacteria, or yeast. In addition to maintaining the quality of the food, preservatives help control contamination that can cause foodborne illness, including life-threatening botulism.
Colouring is added to food to replace colours lost during preparation, or to make food look more attractive.
Non-sugar sweeteners are often used as an alternative to sugar because they contribute fewer or no calories when added to food.
Human Gut Composition:
The human gastrointestinal (GI) tract contains an abundant and diverse microbial community that gathers more than 100 trillion microorganisms. The density of bacterial cells in the colon has been estimated at 1011 to 1012 per millilitre which makes the colon one of the most densely populated microbial habitats known on earth. Each human’s gut microbiota is shaped in early life as their composition depends on infant transitions and external factors such as antibiotic use. Core native microbiota are shaped in early life (4–36 months) and after a child reaches 2–3 years old, a relative stability in gut microbiota composition has been demonstrated.
Healthy Human Gut Microbiome:
Each individual is provided with a unique gut microbiota profile that plays many specific functions. Human gut microbiome comprises of trillions of bacteria, viruses, and fungi that vary greatly in their spectrum. Richness and diversity of gut microbiota shaped in early life characterize a healthy gut microbiota composition, significant indicator of human health.
However, this optimal healthy gut microbiota composition is different for each individual. It plays an important role by helping the digestion of pulp in food, synthesizing vitamins and amino acids, helping in energy metabolism and storage, regulating the immune system, growing and developing nerve systems, even regulating our behaviours.
Common food additive alters gut microbiome
Gut Microbiome and Diseases:
Changes in the composition and function of gut microbiota have been associated with metabolic disorders, inflammation, and even neurological disease.
Effect of Food additives on composition and function of Human Microbiome:
Sweeteners
A) Artificial Sweeteners
Artificial sweeteners or non-nutritive sweeteners are known as low-calorie and sweet taste compounds. They are generally preferred by people who are on a low-calorie diet or have diabetes.
Saccharine (E954), Sucralose (E955), and Aspartame (E951)
Saccharine is an artificial sweetener, which tastes 350 times sweeter than tea sugar. It has been used in food products, such as chips, instant salep, carbonated drinks, and different diet food products. Sucralose, also called trichlorogalactosucrose, tastes 600–650 times sweeter compared to sugar. It has been used as a sweetener in energy-reduced soups, jams, jellos, marmalades, breakfast cereals, and fruit concentrates. Aspartame consists of two amino acids and one dipeptide and tastes 150–200 times sweeter than sugar. It is not only used in diet food products but also nonalcoholic beverages, gelatin desserts, low-calorie foods, gums and hot chocolates.
Artificial sweeteners, are reported to increase the number of Bacteroides spp. and bacteria in Clostridiales phylum in the intestine that induce glucose intolerance. Researchers also reported that saccharine might affect gut microbiota negatively, and thereby, cause liver inflammation.
Aspartame (E951) and Acesulfame-K (E950)
Acesulfame-K 200 times sweeter than sucrose. It has been used in diet foods, including bakery products, gums, desserts, and non-alcoholic beverages.
Consumption of aspartame and acesulfame-K changes bacterial diversity, thereby, increases the blood glucose level and affect the insulin resistance. Non-nutritive sweeteners have metabolic effects due to changes in gut microbiota, which may cause type 2 diabetes and other illnesses.
Saccharine (E954) + Neosperidine DC (E959)
Neosperidine DC is 1000–1800 times sweeter than sucrose. Sakkarine (E954) + Neosperidine DC (E959) increases the amount of Lactobacillus and lactic acid concentration, which indicated that artificial sweetener might affect the gut microbiota as prebiotics.
B) Sugar Alcohols
Sugar alcohols are organic compounds, a group of polyols, and are typically produced from sugars. They are less digestible because and some of them are fermented in the colon. Some of them are used as food additives.
Maltitol (E965)
Maltitol is 10–25% less sweet than sucrose. Maltitol is used as a sweetener, humectant, tissue agent, bulking agent and stabilizator in gums, delights and halva products.
The addition of maltitol (E965) 22.8 g/day to the chocolate products increases the amount of Bifidobacteria. The combination of maltitol and polydextrose increases both Bifidobacteria and Lactobacillus concentration.
Xylitol (E967)
Xylitol is a natural sugar alcohol found in many plants. It has been used in desserts, candies, reduced sugar jams and marmalades, and some bakery products as a sweetener and a humectant.
Xylitol (E967) affects intestinal microbiota. Xylitol consumption shifted intestinal microbial population from gram-negative to gram-positive bacteria.
Sorbitol (E420)
Sorbitol is a sugar alcohol, which naturally exists in fruits. Sorbitol is obtained from glucose and fructose after several chemical treatments. It is used in confectionaries, bakery products and low-calorie foods and gums as a humectant, sweetener, texturizer, bulking agent, and binder.
Sorbitol is used by some Lactobacillus species and used as a carbon source by human intestinal Bifidobacteria. Therefore, it is indicated that sorbitol has a potential prebiotic effect. Microbial population fed by sorbitol shifted from Gram-negative to Gram-positive.
C) Emulsifiers
Emulsifiers have similar effects with detergents.
Carboxymethyl Cellulose (E466) and Polysorbate 80 (E433)
Carboxymethyl cellulose is modified cellulose. It is used as a stabilizator, thickener, and suspension agent in drinks, fruit yogurts, whipped creams, sauces, diet food products, and ice creams. Polysorbate 80 is a synthetic emulgator, produced using fatty acids and ethylene oxide. It is used as an emulgator in candies, desserts, dairy products, soups, gums and special diet products. It is reported that, excessive increase in Ruminococcus gnavus and a decrease in Bacteroidales with carboxymethyl cellulose (E466) and polysorbate 80 (E433). In addition, metabolic syndrome symptoms like intestinal mucus density, low level of inflammation and fat deposition and disorder in glucose metabolism were also illustrated.
It is reported that with polysorbate 80, glycaemic tolerance disorder occurred, blood insulin level increased, hepatic enzyme level enhanced, hepatic mitochondria and gall bladder increased. Acetate, propionate and butyrate level were lowered in faecal. Many reports indicated that there is a relationship between emulgator, such as polysorbate 80 and obesity-related intestinal inflammation and liver dysfunction, thereby supported changes in gut microbiota.
D) Food Colorants
There have been several food colorants with oil-based and water-based properties.
Silver (E174) and Titanium Dioxide (E171)
Silver is a grey color natural metal and obtained from the silver gem. It is used as a colorant in candy and chocolate surface coating. Titanium dioxide is a natural white mineral. It is produced from natural sources using chlorine and sulphuric acid in chemical reactions. It is used as a colorant in gums, chocolates, candies, flavored fruit juices, and some dishes made with yogurt (e.g., haydari).
Reports revealed that, 28 days of exposure to silver (46, 460 and 4600 µg/L) caused a reduction of bacterial richness, an increase in dose-dependent Firmicutes and a decrease in Bacteroidetes.
In an acidic environment without UV light, titanium dioxide affects the bacteria surface; thereby, electrostatic interaction occurs and then inhibits E. coli cell division.
E) Flavour Enhancers
Flavour enhancers are used in a wide range of food types to reveal the flavour in foods. Monosodium glutamate is a well-known commonly used flavour enhancer.
Monosodium Glutamate (E621)
Monosodium glutamate (MSG) is used as a flavour enhancer in some food products, such as meatball mixtures, chicken pane mixtures, and meat bouillon.
MSG modifies gut microbiota diversity, specifically in colons and increased gut microbiota variety. MSG and fat promoted the colonization of microbes related to energy extraction in the gastrointestinal tract. MSG helped colonization of microbes, such as Faecalibacterium prausnitzii and Roseburia.
E) Thickeners
Thickeners are substances, which can increase the viscosity of liquids without substantially modifying their other properties.
Pectin (E440)
Pectin is a plant-based natural thickener and commercially produced from orange peels, apple sediments, and beet pulps. It is used as a thickener and emulgator in food products, such as ice cream, jams, marmalades, candies, some beverages, cheese, salep, and yogurt.
Fatty foods reduce the amount of Bacteroidetes phylum and increase the amount of Firmicutes phylum. However, pectin addition normalizes these variables. Reports suggested that consumption of pectin with fatty foods may cause remission of intestinal inflammation, and then, improved intestinal barrier functions.
Polydextrose (E1200) (PDX)
Polydextrose (E1200) produced synthetically from glucose and sorbitol [(E420(i)] by heating with citric acid (E330). Generally, it is used as a bulking agent, viscosity enhancer, humectant, and stabilizator in cookies and halva products.
Polydextrose has prebiotic function due to the change of composition and activity of gut microbiota, and it improves intestine functions.
G) Preservatives
Preservatives are used to maintain an existing condition or prevent damage likely to be brought by chemical (oxidation), physical (temperature, light), or biological (microorganisms) factors.
Benzoic Acid (E210)
Benzoic acid is a bacteriostatic agent, synthetically obtained and used as an antimicrobial preservative. It is preferred in a wide range of foods, such as sauces, pickles, acidic fruit juices, dried fruits, salty margarine, fruit and vegetable salads, sugary creams, and gums.
Benzoic acid reduced coliform and lactic acid bacteria and changed microbiota. The amount of E. coli in young and gram-negative bacteria in adults decreased. Benzoate affected gut microbiota positively by increasing lactic acid bacteria.
Even though most of the reports illustrated negative outcomes, few of them showed positive effects of food additives on the microbiota. Artificial sweeteners are highly likely to destroy glucose tolerance and support weight gaining by affecting microbiota negatively. Some additives such as sugar alcohols show similar properties as prebiotics.
(The author is director and principal, Amity Institute of Pharmacy, Amity University Madhya Pradesh, Gwalior. She can be reached at smlakshmi@gwa.amity.edu)
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