Is Dairy Milk Acidic? Understanding pH and Its Effects

November 21, 2025 •

2 min read

With a typical pH range of 6.4 to 6.8, fresh dairy milk is indeed slightly acidic, though it is often considered near-neutral. This pH can be influenced by several factors, including the animal's health, diet, and milk processing. The misconception that milk is alkaline often stems from its ability to temporarily soothe acid reflux symptoms, but this is a complex issue.

Quick Summary

Dairy milk has a slightly acidic pH, typically ranging from 6.4 to 6.8, which is close to neutral. Its acidity increases as it sours due to lactic acid fermentation. Multiple factors, such as the animal's diet and health, influence this pH. The body's overall acid-base balance is not significantly altered by dietary choices like consuming milk.

Key Points

Slightly Acidic: Fresh dairy milk has a pH between 6.5 and 6.7, making it slightly acidic but very close to neutral.
Lactic Acid Development: The acidity of milk increases over time as bacteria ferment lactose into lactic acid, causing it to sour.
No Systemic pH Change: Diet, including dairy intake, does not significantly alter the body's internal acid-base balance due to powerful natural buffering systems.
Temporary Reflux Relief: The fat and protein in milk can provide temporary relief for heartburn, but milk can also stimulate stomach acid production, potentially worsening symptoms.
Influential Factors: Milk's pH is influenced by the animal's health (e.g., mastitis), diet, and processing methods like evaporation.
Varying Dairy Acidity: Fermented dairy products like yogurt and cheese are significantly more acidic than milk.

The Science of Milk's pH Level

The pH scale measures how acidic or alkaline a substance is, with 7.0 being neutral. Fresh cow's milk typically has a pH between 6.5 and 6.7, placing it slightly on the acidic side but close to neutral. This slight acidity is a natural part of milk's composition, which includes water, lactose, proteins, fats, and minerals. Lactic acid is the main component contributing to this.

Factors Influencing Milk's pH

Milk's pH is dynamic, affected by bacteria fermenting lactose into lactic acid, animal health and diet, and processing. Different species also produce milk with varying pH levels.

Milk's Complex Role in the Body

There's a misconception that milk's slight acidity negatively affects the body's acid-base balance, often linked to the 'acid-ash' hypothesis.

The Acid-Ash Hypothesis and Dairy

The acid-ash hypothesis suggests foods affect body pH post-digestion, categorizing dairy as acid-forming. However, this theory is not supported by current science; the body's buffering systems maintain blood pH regardless of diet. Research refutes links between dietary acid-forming foods and issues like osteoporosis, noting milk provides bone-supporting nutrients.

Temporary Relief for Acid Reflux

Milk may offer temporary acid reflux relief by coating the esophagus, but its fat and protein content can also increase stomach acid production, potentially worsening symptoms for some.

Comparison: Dairy Milk vs. Plant-Based Alternatives


Feature	Dairy Milk (Cow's)	Oat Milk	Almond Milk
Typical pH Range	6.5–6.7	Close to neutral, approx. 6.65–7.0	Close to neutral, approx. 6.65–7.0
Effect on Acidity	Slightly acidic	Often pH neutral or slightly alkaline	Often pH neutral or slightly alkaline
Primary Acid	Lactic acid (increases with age)	Primarily from added ingredients	Primarily from added ingredients
Buffering Effect	Contains natural buffering agents	Limited buffering properties	Limited buffering properties
Protein Content	High	Low to moderate	Low
Calcium Content	High, naturally bioavailable	Varies, often fortified	Varies, often fortified

The Dynamic Acidity of Dairy

Milk's acidity changes with time, and other dairy products like yogurt (pH 4.0–4.6) and cheese (pH 4.4–5.3) are significantly more acidic due to fermentation and processing. Buttermilk is also more acidic than regular milk.

Conclusion: A Balanced Perspective on Milk Acidity

Fresh dairy milk is slightly acidic, a characteristic of its natural makeup, including lactic acid. Its pH fluctuates due to factors like animal health and age. Scientific evidence does not support the notion that milk creates an acidic environment in the body; the body's pH is tightly regulated. While milk may temporarily ease acid reflux, it does not alter systemic acid-base balance. Consumers should consider these details in relation to their health needs and diet.

{Link: Dairy Council of California https://www.dairycouncilofca.org/news/is-milk-acidic-or-alkaline}

Frequently Asked Questions

Milk contains natural buffering agents, such as phosphate, which help resist changes in pH and keep it stable, even with a slight natural acidity. It can act as a buffer to neutralize some other substances, but its own intrinsic pH is just below neutral.

For some, the fat in milk can relax the lower esophageal sphincter, potentially leading to or worsening acid reflux symptoms. However, for others, the temporary coating effect of milk can provide soothing relief. The effect varies by individual.

Processing methods like pasteurization and homogenization have only a minimal effect on milk's pH. The most significant changes in acidity occur over time as milk spoils due to lactic acid fermentation.

No, scientific evidence does not support the acid-ash hypothesis, which categorizes milk as an acid-forming food. The body's own regulatory systems prevent diet from affecting the blood's pH.

Plant-based milks like oat or almond milk often have a pH closer to or slightly above neutral, meaning they are less acidic than dairy milk. Their acidity profile is also less dynamic over time since they lack lactose for fermentation.

Milk curdles when its pH drops low enough (around 4.5) to cause the casein proteins to clump together and precipitate out of the solution. This is what happens when you add vinegar or lemon juice to milk.

Fresh milk has a very slight natural acidity due to its composition. Spoiled milk, however, develops significantly higher acidity and a lower pH as lactic acid bacteria multiply and convert lactose into larger amounts of lactic acid.