What foods produce lactic acid in the body?

December 21, 2025 •

4 min read

Fermentation is one of the oldest and most effective methods of food preservation, with evidence dating back thousands of years. This ancient process, driven by microorganisms, is the primary way that many popular food items become rich in lactic acid, a compound also produced naturally within the human body during metabolic activity.

Quick Summary

The body primarily produces lactic acid during intense exercise and from carbohydrate metabolism, while many common foods contain it as a byproduct of bacterial fermentation for preservation and flavor.

Key Points

Fermented Foods: Many common foods like yogurt, sauerkraut, and kimchi contain lactic acid produced by bacterial fermentation, which acts as a natural preservative and flavor enhancer.
Internal Production: Your body's own cells, especially muscle cells, produce lactic acid (lactate) by breaking down carbohydrates for energy, particularly during intense exercise or normal carbohydrate digestion.
Not a Waste Product: Lactic acid is not a waste product but a vital energy source and signaling molecule used by various tissues like the heart and brain.
Muscle Soreness Myth: The long-held belief that lactic acid buildup causes delayed muscle soreness has been disproven; the primary cause is muscle damage from exercise.
Gut Health: The lactic acid bacteria in fermented foods can act as probiotics, supporting a healthy gut microbiome, which in turn benefits digestion and immune function.

Fermented Foods Containing Lactic Acid

When we talk about foods containing lactic acid, we are primarily referring to fermented foods. In a process called lacto-fermentation, beneficial lactic acid bacteria (LAB) consume the natural sugars (carbohydrates) in the food and convert them into lactic acid. This not only imparts a signature tangy flavor but also acts as a natural preservative by creating an acidic environment that inhibits the growth of harmful bacteria.

Dairy Products

Dairy is one of the most common sources of food-based lactic acid. The bacteria consume the milk sugar, lactose, to produce lactic acid, which also helps to thicken and curdle the milk.

Yogurt and Kefir: These products are made by fermenting milk with specific starter cultures of LAB. This process creates the characteristic thick texture and sour taste.
Cheese: The production of many cheeses involves lactic acid fermentation. The acid causes milk proteins (casein) to coagulate, forming curds.
Buttermilk: Traditional buttermilk is the acidic liquid left behind after churning butter and contains live bacterial cultures.

Fermented Vegetables

Fermenting vegetables with salt or brine encourages the growth of natural LAB present on the surface of the plants.

Sauerkraut: Shredded cabbage is fermented in its own juices to create this tangy condiment.
Kimchi: This spicy Korean staple is made by fermenting various vegetables, most commonly napa cabbage and radish.
Pickles: Pickling cucumbers and other vegetables in a salt brine relies on lacto-fermentation to develop its sour taste and preserve the product.

Fermented Grains and Legumes

Lacto-fermentation isn't limited to dairy and vegetables; it's also a key process for many grain-based and legume-based foods.

Sourdough Bread: A sourdough starter is a culture of wild yeast and LAB that ferments the flour, creating organic acids that give the bread its distinctive flavor.
Miso and Soy Sauce: These fermented soy products are staples of Japanese cuisine, with the fermentation process introducing lactic acid and other compounds that create their unique, savory flavor profile.
Idli and Dosa: Indian rice and legume batters are fermented to create these popular dishes.

Cured Meats and Beverages

Salami and Sausages: Some varieties of cured meat use bacterial fermentation to produce lactic acid, which lowers the pH and helps to preserve the meat while developing flavor.
Kombucha and Sour Beer: Certain fermented beverages rely on LAB to produce lactic acid alongside yeast, contributing to their sour taste.

The Body's Internal Lactic Acid Production

Aside from consuming it in food, the body constantly produces lactic acid (often referred to as lactate when released into the blood) as part of normal metabolic processes.

Carbohydrates and Exercise

During high-intensity exercise, your body uses glucose and other carbohydrates for energy. When oxygen supply is limited relative to energy demand, your cells break down glucose through a process called anaerobic glycolysis, which produces lactate as a byproduct. This lactate is not a waste product but a fuel source that can be used by other parts of the body, including the heart and brain, for energy. The perception that lactic acid buildup causes delayed muscle soreness has been disproven; muscle soreness is actually caused by microtrauma to muscle fibers.

Carbohydrate Metabolism in Digestion

Recent research from UC Berkeley shows that intestinal cells also convert dietary glucose from a meal into lactate before it is even released into the blood. This process helps manage the glucose surge after eating carbohydrates and demonstrates lactate's role as a major energy carrier, even at rest.

Fermented Foods vs. Carbohydrate Metabolism: A Comparison


Feature	Lactic Acid from Fermented Foods	Lactic Acid from Carbohydrate Metabolism
Source	Produced by lactic acid bacteria (LAB) during fermentation of sugars.	Produced by human cells (primarily muscle and red blood cells) during glycolysis.
Initiating Factor	Controlled growth of specific microorganisms in a food matrix.	The body's energy demands, especially under anaerobic conditions during intense exercise or normal digestion of carbs.
In the Body	Introduced via consumption, contributes to gut microbiome, and may act as a probiotic.	Produced internally, used as fuel, and serves as a signaling molecule throughout the body.
Main Function	Food preservation, flavor, and texture enhancement.	Energy production, energy distribution (as lactate shuttle), and cell signaling.
Example Foods	Yogurt, sauerkraut, kefir, miso, sourdough bread.	Any carbohydrate-rich food (e.g., bread, pasta, sugary drinks) that the body breaks down for energy.

Conclusion: Lactic Acid is Not the Enemy

Contrary to a long-held misconception linking lactic acid directly to muscle soreness, lactate is a vital component of both our diet and our internal metabolic processes. Whether it's derived from the bacteria in a tangy forkful of sauerkraut or a product of your body's energy creation during a tough workout, lactic acid serves crucial functions. Including a variety of fermented foods in your diet can support gut health and introduce beneficial probiotics, while understanding the body's internal production can help you better fuel and recover from exercise. The science of lactic acid is evolving, but what's clear is its beneficial and multifaceted role in health and nutrition. For a deeper scientific dive into the role of lactic acid in food, you can explore detailed research available on the National Center for Biotechnology Information website(https://www.ncbi.nlm.nih.gov/books/NBK234703/).

Frequently Asked Questions

No, the lactic acid consumed from fermented foods and the lactic acid produced during exercise are two separate processes. Fermented foods contain lactic acid from bacterial activity, while your body produces it from carbohydrate metabolism during physical exertion.

In common usage, the terms are often used interchangeably, but technically they are slightly different. In the body, lactic acid quickly dissociates into lactate and a hydrogen ion. Lactate is the form that is transported and used for energy.

No, the theory that lactic acid causes Delayed Onset Muscle Soreness (DOMS) has been debunked. Lactic acid is cleared from the muscles and blood quickly after exercise. Muscle soreness is now understood to be the result of microscopic damage to muscle fibers.

The liver and kidneys primarily filter lactic acid from the blood, converting it back into glucose in a process called gluconeogenesis. Other tissues, like the heart and brain, also use lactate directly as fuel.

Yes, lactic acid and the bacteria that produce it in fermented foods are generally considered beneficial. They can improve gut health, support the immune system, and enhance nutrient absorption.

Not necessarily. Some commercially pickled foods are made with vinegar and are not fermented. True lacto-fermented pickles, which contain beneficial bacteria, are made with a salt brine.

In normal, healthy individuals, the body effectively clears lactic acid. However, a buildup known as lactic acidosis can occur due to medical conditions, such as sepsis, and indicates a serious underlying issue.