What is lactic acid good for?

November 18, 2025 •

3 min read

Lactic acid, a naturally occurring alpha hydroxy acid (AHA), is famously known for Cleopatra's practice of bathing in sour milk to enhance her skin's texture. So, what is lactic acid good for today? This versatile compound offers significant benefits for both skin health and internal well-being.

Quick Summary

Lactic acid acts as a gentle exfoliating and hydrating agent for skin, while its presence in fermented foods aids digestion and boosts immunity. It is also a key player in food preservation and provides a temporary energy source during intense exercise.

Key Points

Gentle Exfoliation: As a mild alpha-hydroxy acid (AHA), lactic acid effectively removes dead skin cells to reveal a brighter, smoother complexion.
Deep Hydration: Lactic acid acts as a humectant and is part of the skin's natural moisturizing factor, helping skin retain moisture.
Anti-Aging Support: By boosting collagen synthesis, it improves skin firmness and reduces the appearance of fine lines and wrinkles.
Promotes Gut Health: Lactic acid bacteria in fermented foods, like kimchi and yogurt, function as probiotics to support a healthy gut microbiome.
Natural Food Preservative: Historically used for food preservation, it creates an acidic environment that inhibits harmful bacteria and extends shelf life.
Dispels Muscle Soreness Myth: Lactic acid does not cause delayed onset muscle soreness (DOMS), which is actually caused by microscopic muscle tears.
Enhances Nutrient Absorption: Lactic acid from fermented foods can improve the body's ability to absorb vital nutrients, such as iron.

Understanding Lactic Acid: Beyond the Basics

Lactic acid is an organic acid with a wide range of applications, naturally produced by the body and created through the fermentation of carbohydrates by bacteria. While many people associate it with muscle fatigue during exercise, this is a misconception, as lactate is cleared from the muscles quickly. Its true benefits span from improving skin appearance to enhancing food quality and promoting gut health. Most lactic acid used in modern products, including many vegan-friendly options, is produced synthetically or through plant-based fermentation.

Lactic Acid in Skincare: A Gentle Exfoliant

As one of the most popular alpha-hydroxy acids (AHAs), lactic acid is prized in skincare for its efficacy and gentleness, making it suitable even for sensitive skin types.

How It Benefits Your Complexion

Exfoliation: Lactic acid works by dissolving the bonds that hold dead skin cells together on the surface, promoting a smoother and brighter complexion. This process, known as chemical exfoliation, accelerates cell turnover to reveal fresher, new skin underneath.
Hydration: Unlike some other exfoliants, lactic acid is also a humectant, meaning it attracts and binds moisture to the skin. It is a component of the skin's natural moisturizing factor (NMF), helping to improve overall hydration and strengthen the skin's natural moisture barrier.
Anti-Aging Effects: By stimulating collagen production, lactic acid can improve skin firmness and elasticity, which helps to reduce the appearance of fine lines and wrinkles.
Treating Hyperpigmentation: Regular use helps fade dark spots, acne scars, and other forms of discoloration by promoting cell renewal and inhibiting melanin production.
Acne Control: By clearing away dead skin cells that can clog pores, lactic acid helps prevent and manage acne breakouts.

The Role of Lactic Acid in Fermented Foods

Lactic acid bacteria (LAB), found in many fermented foods, are considered probiotics and offer significant benefits for digestion and immunity. The fermentation process naturally produces lactic acid, which preserves the food and creates a tangy flavor.

Supporting Gut Health and Immunity

Balanced Microbiome: Probiotic LAB, such as Lactobacillus and Bifidobacterium, help create a healthy, balanced gut microbiome. They lower the gut's pH, inhibiting the growth of harmful bacteria and promoting a thriving environment for beneficial microbes.
Enhanced Nutrient Absorption: Studies suggest that lactic acid-fermented vegetables can increase the body's ability to absorb iron. Lactic acid may also boost the absorption of flavonoids, which are powerful antioxidants.
Immune System Support: The health of the gut microbiome is closely linked to overall immune function. Consuming probiotic-rich foods with lactic acid can help reduce inflammation and strengthen the body's defenses.

Lactic Acid vs. Glycolic Acid: A Comparison

Lactic acid and glycolic acid are both popular AHAs, but they differ in their properties and uses due to their molecular size.


Feature	Lactic Acid	Glycolic Acid
Molecular Size	Larger molecules.	Smaller molecules, penetrates deeper.
Gentleness	Gentler and less irritating, ideal for sensitive or dry skin.	More potent and can cause more irritation, better for oily or resilient skin.
Hydration	Strong hydrating properties due to humectant nature.	Less hydrating than lactic acid.
Primary Function	Exfoliates the skin's surface and hydrates.	Penetrates deeper for more intensive exfoliation.
Best For	Dryness, sensitive skin, and gentle brightening.	Stubborn texture, fine lines, and sun damage.

A Note on Lactic Acid and Muscle Soreness

For decades, it was widely believed that lactic acid buildup caused the delayed onset muscle soreness (DOMS) experienced after a tough workout. However, this is a myth. Lactic acid (lactate) is a temporary byproduct of anaerobic exercise that is cleared from the muscles within an hour. The actual cause of DOMS is microscopic damage to muscle fibers that triggers a natural repair and inflammation process. In fact, lactate can even be used as a temporary energy source by the muscles during high-intensity activity.

Conclusion: The Versatile Benefits of Lactic Acid

From enhancing skin's health and appearance to enriching food and supporting a robust gut, the uses of lactic acid are diverse and impactful. It provides gentle, effective chemical exfoliation and deep hydration for the skin while acting as a natural preservative and probiotic agent in countless fermented foods. Understanding what lactic acid is good for reveals its broad positive influence on both cosmetic and nutritional well-being, proving it's far more than just a chemical associated with exercise burn. Incorporating it into a proper skincare routine or a diet rich in fermented foods can lead to measurable improvements in overall health.

For more information on the dietary benefits of lactic acid, see the in-depth analysis from Healthline.

Frequently Asked Questions

Yes, lactic acid is considered one of the gentlest AHAs due to its larger molecular size, making it suitable for sensitive and dry skin types when starting with a low concentration.

Fermented foods like yogurt, kefir, sauerkraut, kimchi, and sourdough bread are all rich sources of lactic acid bacteria.

Yes, the exfoliating properties of lactic acid help to unclog pores and clear away the dead skin cell buildup that can contribute to acne.

Lactic acid has a larger molecule, making it gentler and more hydrating, while glycolic acid has a smaller molecule that penetrates deeper for more intensive exfoliation.

While it can be derived from dairy, most lactic acid used in modern food and cosmetic products is made via plant-based fermentation and is suitable for vegans.

Modern research shows that the burning sensation during exercise is temporary lactate buildup, while delayed onset muscle soreness (DOMS) is caused by microscopic muscle fiber damage.

Start by using a low-concentration formula 1-3 times per week, typically at night, and always use daily sun protection since it can increase sun sensitivity.

Some studies suggest that lactic acid from fermented foods can increase the body's absorption of certain nutrients, such as iron.