What are food preservatives, and do they impact health?

Food preservatives, as their name suggests, help preserve foods. They protect against invasion from bacteria, fungi, and yeast and reduce the risk of foodborne illnesses like botulism. 

Like other added ingredients, preservatives used in the United States need approval from the country's Food and Drug Administration (FDA). 

In the European Union, they need to be okayed by the European Food Safety Authority (EFSA).

In this article, we list of some of the most common preservatives in the U.S. and Europe. And we look at the health concerns associated with some of them.

Because preservatives are a diverse bunch and almost ubiquitous in processed foods, this will be quite a journey. So, take a deep breath and off we go!

A list of preservatives

Before we dig into any health concerns, here are some preservatives you might see on ingredients lists in the U.S. and E.U. 

This list isn’t exhaustive, it just focuses on the most common preservatives.

But it is long. Just skimming it will give you an idea of the incredible number of chemicals in some of our food.

• 4-hexylresorcinol (E586): This prevents discoloration of shrimp and other crustaceans.

• Ascorbic acid (vitamin C, E300): This is also used to fortify foods, and erythorbic acid (E315) is a similar compound.

• Ascorbyl palmitate: This is often used to preserve frostings and fillings in baked goods.

• Benzoic acid (E210): This is an antimicrobial.

• BHA (butylated hydroxyanisole, E320): This is an antioxidant that stops food from going rancid.

• BHT (butylated hydroxytoluene, E321): This is an antioxidant that slows changes to a food's texture, color, and flavor.

• Borax (sodium tertraborate, E285) and boric acid (E284): Though it's banned from culinary use in the U.S., companies in the E.U. still use borax in caviar.

• Calcium ascorbate (E302): This form of vitamin C protects the color, flavor, and overall quality of foods and drinks.

• Calcium benzoate (E213): This is widely used in baked goods, and it's also added to soft drinks, fruit juices, soy milk, soy sauce, and vinegar.

• Calcium disodium ethylenediamine-tetraacetate (E385): This helps prevent loss of color and flavor. It also adds a salty taste, and it often appears in dressings, mayo, and canned goods.

• Calcium propionate (calcium dipropionate, E282): This inhibits mold in baked goods and other products.

• Caprylic acid (E570, octanoic acid, C8 Acid): This is an antimicrobial and flavoring used in cheese wraps and peeled fruits and veg.

• Citric acid (E330): This is an antimicrobial.

• Dimethyl dicarbonate (E242): This is used in alcoholic and nonalcoholic drinks to deter microbes.

• Ethyl p-hydroxybenzoate (ethylparaben, E214): This is an antifungal.

• Ethyl lauroyl arginate (E243): This is an antimicrobial used in some meat products.

• Heptylparaben: This is an antimicrobial in fermented malt beverages.

• Hexamethylene tetramine (E239): This is not approved in the U.S. and only used in Provolone cheese in the E.U.

• Lysozyme (E1105): This enzyme is generally extracted from chicken eggs, and it's used to make some cheese and wine.

• Methyl p-hydroxybenzoate (methylparaben, E218): This is an antifungal.

• Natamycin or pimaricin (E235): This is also an antifungal.

• Nitrites and nitrates: Among these are sodium nitrate (E251) and sodium nitrite (E250), which have antibacterial properties and are used in meats, particularly cured types.

• Nisin (E234): This fends off a broad range of bacteria, and it's used in processed cheese and some meat products.

• Octyl gallate (E311): This is used in margarine, peanut butter, and chewing gum.

• Potassium benzoate (E212): This prevents the growth of bacteria, yeast, and mold. It's common in packaged foods like sweets, condiments, drinks, spreads, and processed meats. The FDA hasn’t approved this compound, but it does allow the use of a similar one called sodium benzoate (E211).

• Propyl gallate (E310): This antioxidant stops foods containing fats and oils from going bad.

• Sodium erythorbate (E316): This helps cured meats keep their color and flavor.

• Sodium nitrate (E250) and sodium nitrite (251): This helps preserve processed meats and fish.

• Sorbate compounds: Among these are sorbic acid, sodium sorbate, potassium sorbate, and calcium sorbate (E numbers 200–203). They prevent the growth of yeasts and mold. 

• Sulfite compounds: These antibacterials include sulfur dioxide (E220), potassium metabisulfite (E224), potassium bisulfite (E228), potassium metabisulfite (E225), sodium bisulfite (E222), sodium metabisulfite (E223), and sodium sulfite (E221).

• Tertiary-butyl hydroquinone (TBHQ, E319): This antioxidant helps preserve foods containing fats and oils.

• Tocopherol (E306): This form of vitamin E is in a wide range of products to protect flavor and color. Other similar compounds are also preservatives, including alpha-tocopherol (E307), gamma-tocopherol (E308), and delta-tocopherol (E309).

Do preservatives affect health?

There’s no short answer to this. Even the compounds listed above are super varied. 

For instance, methylparaben is an insect pheromone, lysozyme is an enzyme from the whites of chicken eggs, ascorbic acid is vitamin C, and nisin is an antibiotic protein excreted by a bacterium. 

Scientists have tested each of these ingredients to check if they're safe for human consumption, but we don’t eat them individually like that. 

Although we’re not in the business of scaremongering, we simply don’t know what these cocktails of preservatives might be doing. 

Some food preservatives, like vitamin C, are nutrients. And in their doses in foods, they might benefit your health. Or at least, they might not be harmful. For others, the effects are less clear.

Controversies

Next, we’ll look at some preservatives that have faced controversies over the years. 

To be clear, we’re picking out a small number that do appear to have associated health concerns.

Sulfites

Manufacturers add sulfites to a wide range of foods because they’re cheap, effective, and nontoxic.

There are many forms, including sulfur dioxide, potassium metabisulfite, potassium sulfite, sodium bisulfite, and sodium metabisulfite.

Sulfites naturally occur in all wines, but manufacturers sometimes add them to stop fermentation, too.

Dried fruit manufacturers also use sulfites to stop the fruit from turning brown. For the same reason, restaurants once used sulfites in salad bars. 

Although sulfites aren’t toxic for most people, some people are sensitive to them. This can cause respiratory reactions, rashes, low blood pressure, and gut problems.

Although it's rare, for people who have this sensitivity, it can be life-threatening.

Sodium benzoate

Sodium benzoate is an antimicrobial food additive. Manufacturers add it to salad dressings, sodas, jams, juices, pickles, and other products — including fireworks.

Although the FDA and EFSA consider the amounts in food to be safe, there are some concerns.

Vitamin C is used as a preservative in some beverages, and it's naturally in products like juices and hot pepper sauces. 

In 2006, the FDA tested 100 beverages that contained both vitamin C and sodium benzoate. They found that four had more benzene than the Environmental Protection Agency considered safe in drinking water. 

The manufacturers reformulated each of these products, and retesting showed benzene levels to be back within safe limits.

Sodium nitrate

Manufacturers use sodium nitrate to color, flavor, and preserve foods. It’s most commonly used in processed meats and smoked fish.

Most recently, the French Agency for Food, Environmental, and Occupational Health & Safety released a statement calling for people to limit their exposure to nitrates and nitrites. 

They recommended that people consume no more than 5.3 ounces (150 grams) of deli meats weekly.

When nitrates enter your body, they break down into nitrites. When these mix with saliva or stomach acid, some are converted into nitrosamines, which are carcinogenic.

Although the risk is relatively small, it’s part of the reason why the World Health Organization’s International Agency for Research on Cancer (IARC) defines processed meat as carcinogenic to humans.

On this topic, the Center for Science in the Public Interest (CSPI) writes: “The use of nitrite and nitrate has decreased greatly over the decades because of refrigeration and restric­tions on the amounts used. The meat industry could do the public’s health a favor by cutting back even further.”

TBHQ 

Tert-butylhydroquinone, also called tertiary-butyl hydroquinone, 2-(1,1-dimethylethyl)-1,4-benzenediol, or just plain TBHQ, helps preserve foods that contain fats, like vegetable oil, snack foods, and cereals.

Early studies didn’t find any links between TBHQ and cancer. But according to the CSPI, a good quality government study found that the compound was linked to increased tumors in rats.

Other studies, however, have identified anticancer effects. So, the true effects of TBHQ are still unclear.

BHA

This preservative, also known as butylated hydroxyanisole, is an antioxidant that manufacturers add to some fatty or oily foods. It stops the fat from turning rancid.

It’s approved for use by the FDA and widely used in around 50 countries. Manufacturers add it to foods, food packaging, pet foods, cosmetics, and other products.

And the IARC classes it as a 2B carcinogen — “possibly carcinogenic to humans.”

These organizations reached this conclusion because studies showed that BHA causes cancer in mice, rats, and hamsters.

However, the tumors in these studies only occurred in the rodents' forestomachs.

Because humans don’t have forestomachs, the FDA doesn’t consider the findings relevant to humans.

Also, studies in guinea pigs (which aren’t rodents and don’t have forestomachs) found no increase in tumors.

Disrupting gut bacteria?

We know that the gut microbiome is vital for health. We also know that many food preservatives are designed to kill or hinder bacteria. 

So, it makes sense that some preservatives might disrupt this important ecosystem. Although we need more evidence, scientists are starting to spot some links.

For instance, a study from 2017 found that low levels of sulfites inhibited the growth of four species of “good” gut bacteria.

However, this was a laboratory study, not one with human participants, so we can’t necessarily extrapolate the results to humans. 

Another study, this time in mice, investigated three common preservatives: benzoic acid, potassium sorbate, and sodium nitrite. 

Still another mouse study tested sodium benzoate, sodium nitrite, and potassium sorbate. The researchers concluded that these compounds triggered dysbiosis — an imbalance in gut bacteria — in the animals.

Finally, a small study found that sulfite preservatives could alter the microbiome in human saliva. 

It’s too early to make firm conclusions, but it seems likely that at least some preservatives will affect the gut microbiome.

But we don’t know how this might influence health in the long run.

Wrapping up

Preservatives are an incredibly diverse group of compounds. Avoiding them entirely is neither possible nor necessary.

In general, choosing minimally processed and fresh foods when you can is a sensible path to a healthy diet. 

This way, you’ll avoid many of the added preservatives in processed and ultra-processed foods, whether they’re a health risk or not.