Gallic acid is a phenolic acid, or bioactive compound, found in plants. It has antioxidant properties and may offer other health benefits.

Chemists have known about and used gallic acid for centuries. Still, it has only recently become more mainstream in the health community.

This article explains everything you need to know about gallic acid, including its benefits, downsides, and where to find it.

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Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is an antioxidant and phenolic acid found in most plants in various amounts (1).

It was used from the 12th to 19th centuries as a major component of iron gall ink, the standard writing ink in Europe. Today, it’s becoming more recognized for its potential health benefits.

Your body gets it from certain plant foods. While some lay sources suggest that gallic acid can also be found as a supplement, it appears to be sold in a form intended for chemical purposes.

Note that most of the existing research on gallic acid has been conducted in test tubes and animals. As such, there’s not enough evidence to determine this compound’s clear dosage recommendations, side effects, best uses, and safety issues in humans (2).

Food sources of gallic acid

Gallic acid is naturally found in a variety of plants — particularly in the bark of oak species and Boswellia dalzielii, an African tree.

What’s more helpful to most people is understanding which common foods provide it. Some of the best food sources of gallic acid include (3, 4):

  • strawberry
  • grape
  • banana
  • blueberry
  • apple
  • walnut
  • cashew
  • hazelnut
  • red wine
  • green tea
  • avocado
  • blackcurrant
  • guava
  • mango
  • mulberry
  • pomegranate
SUMMARY

Gallic acid is an antioxidant and phenolic compound found in many plants. Foods like nuts, berries, and other fruits that you may already include in your diet are good sources.

While more research is needed to determine the potential health benefits of gallic acid, current studies suggest that it may offer antimicrobial, anti-obesity, and antioxidant properties that could improve cancer and brain health.

May have antimicrobial properties

Gallic acid may help modulate your immune system and act as a natural defense mechanism against microbial infections (5).

One study developed an innovative light-enhanced antimicrobial treatment by exposing gallic acid to ultraviolet-C (UV-C) light. The sun gives off this type of invisible ultraviolet light, and it’s commonly used as a disinfectant (6).

The resulting antimicrobial activity was significant. In fact, the authors suggested that gallic acid exposed to UV-C light has potential as a new antimicrobial treatment in the food system (6).

Furthermore, a lab study found that gallic acid improved the shelf life of fresh black truffles. It did so by fighting a bacterial contaminant known as Pseudomonas (7).

Older and newer studies have similarly found that gallic acid fights other foodborne pathogens like Campylobacter, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, as well as a bacteria found in your mouth called Streptococcus mutans (8, 9, 10).

Overall, it appears that gallic acid may be a useful additive in the food industry (11).

May have anti-obesity properties

In one review, researchers examined the anti-obesity activities of gallic acid. Specifically, it appears to protect against inflammation and oxidative stress that can occur among people with obesity (12).

Some studies suggest that gallic acid reduces excessive fat storage in individuals with obesity by suppressing lipogenesis. Lipogenesis is the synthesis of fat from compounds like sugars within your body (12).

The compound may also improve insulin signaling and reduce oxidative stress and inflammation (12).

In one older study, overweight Japanese adults were given black Chinese tea extract rich in gallic acid, receiving a daily dose of 333 mg for 12 weeks. The treatment significantly reduced mean waist circumference, body mass index, and belly fat (13).

Still, other human studies have observed mixed results on the topic. Some older and newer studies have not found any benefit, while others have shown that gallic acid may improve certain mechanisms involved in obesity and quality of life (14, 15, 16, 17).

Overall, more research on the potential benefits of gallic acid on obesity and related health complications is needed.

May have antioxidant properties

Gallic acid is a strong antioxidant. This means that it helps fight oxidative stress that can otherwise damage your cells and lead to numerous chronic diseases (18, 19, 20).

Research suggests that the antioxidant power of gallic acid may be behind its speculated anticancer benefits and neuroprotective effects, which refers to its ability to protect brain structure and function (11, 21, 22).

One lab study found that while mango peel has its own antioxidant and anticancer properties, its gallic acid content is responsible for any antiproliferative activity. This means that gallic acid has a unique ability to help prevent the growth and spread of cancer cells (23).

Another lab study placed a layer of gallic acid on top of a surface of γ-AlOOH nanoparticles, or microscopic particles of an aluminum-containing mineral with antioxidant properties. This was found to enhance the antioxidant power of the nanoparticles (24).

Some research suggests that gallic acid helps protect against the decline of brain function by reducing inflammation and oxidative damage. It may also help protect against stroke (25, 26).

One animal study even suggested that gallic acid may have a protective effect on memory following a traumatic brain injury. This might be due to its antioxidant and anti-inflammatory activity (27).

The neuroprotective effects of gallic acid were also observed in an animal study. This study examined certain substances believed to protect against brain neurodegeneration among people with diabetes (28).

Despite these promising results, more studies in humans are needed to better understand how gallic acid’s antioxidant properties may benefit human health.

SUMMARY

Research indicates that gallic acid has potent antioxidant, antimicrobial, and even anti-obesity properties. Still, most studies were conducted in test tubes and animals, so human research is needed.

The most obvious downside of gallic acid is the lack of human research behind its use.

Gallic acid is best consumed through natural food sources, especially considering the lack of approved and well-studied supplements on the market.

That said, one dated animal study concluded that gallic acid is nontoxic up to a dose of 2.3 grams per pound (5 grams per kg) of body weight when taken by mouth (29).

Another animal study found that gallic acid given in doses of 0.4 mg per pound (0.9 grams per kg) of body weight per day for 28 days showed no signs of toxicity in mice (30).

Ultimately, further studies are needed to determine the best uses and dosages for humans (2).

SUMMARY

The biggest downsides to gallic acid are the lack of research in humans and the lack of well-studied supplements with research-backed dosage recommendations.

Gallic acid is a phenolic acid found in plants, especially fruits, nuts, wine, and tea. It has antioxidant, antimicrobial, and potentially even anti-obesity properties.

Through its main mechanisms, it may be particularly beneficial for conditions like cancer and brain health. It might also be useful as a food additive to prevent foodborne illness.

However, most of the available research on gallic acid has been conducted in test tubes and animals. Thus, it remains unclear whether its purported benefits apply to humans, too.

Plus, while some lay sources suggest that gallic acid can be found as a supplement, it appears to mainly be sold in a form intended for chemical purposes.

If you’re interested in the potential benefits of gallic acid, focus on natural food sources until more research has been conducted on gallic acid supplements.