Lactic acid is made from glucose. In your body, cells break down glucose through a series of chemical steps, ultimately converting it into a smaller molecule called pyruvate. An enzyme called lactate dehydrogenase then transforms that pyruvate into lactic acid. The same basic principle applies to industrial production: bacteria ferment sugars from corn, sugarcane, or other plant sources to produce lactic acid at commercial scale.
How Your Body Makes Lactic Acid
Every cell in your body can produce lactic acid, and it starts with glucose, the simple sugar your bloodstream delivers as fuel. During the first stage of energy production (glycolysis), one molecule of glucose gets split into two molecules of pyruvate. When oxygen is plentiful, those pyruvate molecules move deeper into the cell’s energy machinery to generate a large amount of fuel. But when oxygen is limited, or when energy demand is high, your cells take a shortcut: they convert pyruvate directly into lactate using lactate dehydrogenase.
This shortcut is fast. It produces energy quickly, which is why your muscles rely on it during intense exercise, sprinting, or heavy lifting. The lactate your muscles generate doesn’t just sit there, though. It gets shuttled through the bloodstream to the liver, heart, and brain, where those organs use it as fuel. For decades, lactic acid was blamed for muscle soreness and fatigue, but it’s now understood as an important energy source that circulates throughout the body.
The version your body produces is almost entirely L-lactic acid, one of two mirror-image forms of the molecule. The other form, D-lactic acid, shows up in much smaller quantities and is primarily made by bacteria living in your gut rather than by your own cells.
Industrial Production From Plant Sugars
The global lactic acid market was valued at roughly $3.7 billion in 2025, and almost all of that comes from bacterial fermentation rather than chemical synthesis. Manufacturers feed sugars to specialized bacteria in large fermentation tanks, and those bacteria do essentially what your muscle cells do: they consume sugar and excrete lactic acid.
The primary feedstocks are starch-based crops like corn, cassava, and potatoes, along with sugar-based crops like sugarcane and sugar beet. These raw materials are expensive, accounting for over 30% of total production costs. Corn is the dominant source in North America, which holds about 45% of the global market. The process typically involves breaking down the starch into simple sugars first, then letting bacteria ferment those sugars into lactic acid over a period of days.
Several species of lactic acid bacteria handle this work. Some can even produce their own enzymes to break starch down into glucose before fermenting it, cutting out a processing step. Manufacturers fine-tune conditions like temperature, acidity, and nutrient levels to maximize how much lactic acid the bacteria produce from each batch of sugar.
Agricultural Waste as a Newer Source
Because food crops are costly and compete with the food supply, researchers have spent the last two decades developing ways to make lactic acid from agricultural waste instead. Plant material like corn stalks, wheat straw, rice straw, and sugarcane bagasse (the fibrous pulp left after juice extraction) all contain cellulose and other complex carbohydrates that can be broken down into fermentable sugars.
The challenge is that these materials are tough. Cellulose is tightly bound with other plant compounds, so it requires pretreatment (heat, acids, or enzymes) to release the sugars locked inside. Once freed, those sugars can be fermented just like corn starch. One promising result: processing the carbohydrate fraction of corn stalks yielded 0.796 grams of lactic acid per gram of starting material, with 90% of the output being lactic acid rather than unwanted byproducts. Research output in this area has grown steadily, with studies on wheat straw alone increasing from 6 publications in 1991 to nearly 300 total by 2022.
Chemical Synthesis From Petrochemicals
A small fraction of lactic acid is made without any biological process at all. The chemical route combines acetaldehyde (a simple organic compound derived from petroleum) with carbon monoxide and water in the presence of a catalyst. This method produces a 50/50 mix of L-lactic acid and D-lactic acid, unlike fermentation, which can be tuned to produce almost entirely one form. Because many applications, especially biodegradable plastics, require a specific form of lactic acid, fermentation has become the strongly preferred method.
Where All This Lactic Acid Ends Up
Food-grade lactic acid, nearly all of it produced by bacterial fermentation of plant sugars, is one of the most common food additives. It acts as a preservative, acidity regulator, and flavoring agent in everything from yogurt and pickled vegetables to packaged bread and beverages. It’s the same molecule that bacteria naturally produce during traditional fermentation of sauerkraut, kimchi, and sourdough.
Outside of food, the fastest-growing use is polylactic acid (PLA), a biodegradable plastic made by linking lactic acid molecules into long chains. PLA shows up in compostable packaging, 3D printing filament, and medical devices like dissolvable stitches. This demand is a major driver behind the market’s projected growth to $6.7 billion by 2033. Lactic acid also appears in skincare products as a gentle exfoliant and in cleaning products as a non-toxic disinfectant.
Whether it’s built inside a muscle cell during a hard workout or inside a fermentation tank from corn sugar, the chemistry is remarkably similar: sugar goes in, lactic acid comes out.