Is There a Carbohydrate in Milk? The Definitive Guide to Lactose

November 22, 2025 •

3 min read

Milk is a complex and highly nutritious food, containing a balanced mix of proteins, fats, vitamins, and minerals. The carbohydrates in milk come from a natural sugar called lactose, which makes up around 5% of its composition and is a key energy source.

Quick Summary

Milk contains the natural sugar lactose, which is its primary carbohydrate source and is composed of glucose and galactose. An average 8-ounce glass of dairy milk has approximately 12 grams of carbohydrates, mainly from this lactose. Understanding milk's carbohydrate content is important for dietary planning and managing conditions like lactose intolerance.

Key Points

Lactose is the primary carbohydrate: The carbohydrate in milk is almost exclusively lactose, a naturally occurring sugar also known as milk sugar.
Consistent carb count in cow's milk: All varieties of dairy milk, including whole, skim, and low-fat, contain a similar amount of carbohydrates, about 12 grams per 8-ounce serving.
Fat content does not affect carbs: Skimming the fat from milk (to make low-fat or skim milk) does not significantly change the carbohydrate content, as lactose is in the watery portion of the milk.
Lactose intolerance is a digestive issue: Many people have difficulty digesting lactose due to a shortage of the enzyme lactase, not an allergy to milk protein.
Low-carb alternatives are available: For low-carb diets or severe lactose intolerance, unsweetened plant-based milks like almond or macadamia are excellent substitutes with minimal carbohydrates.
Benefits beyond energy: Lactose can aid in the absorption of minerals like calcium and magnesium and has prebiotic effects that support gut health.

The Primary Carbohydrate: Lactose

Milk contains a specific type of carbohydrate known as lactose, often referred to as 'milk sugar'. This disaccharide is composed of two simpler sugar units: glucose and galactose. Lactose is the only common sugar of animal origin and is found in the milk of all mammals, including cows, goats, and sheep. For human infants, lactose serves as a critical energy source and provides galactose, which is essential for the development of nervous tissue.

How the Body Processes Lactose

To be absorbed by the body, lactose must first be broken down into its component sugars. This process is carried out by the enzyme lactase, which is produced in the small intestine. For most people, lactase effectively digests the lactose, and the resulting glucose and galactose are absorbed into the bloodstream. However, for a significant portion of the global population, lactase production declines after childhood, leading to lactose malabsorption. In these individuals, undigested lactose travels to the large intestine, where it is fermented by gut bacteria, causing symptoms like gas, bloating, and diarrhea.

Carbohydrate Content in Different Milk Types

While the fat content varies significantly across different types of dairy milk, the carbohydrate content remains surprisingly consistent. This is because the lactose is dissolved in the watery portion of the milk, which is not removed during the skimming process.

Comparison Table: Carbohydrates in Dairy and Plant-Based Milks


Milk Type	Carbohydrates (g) per 8oz	Key Considerations
Whole Milk	12g	Higher in fat and calories, same carbs as lower-fat dairy milk.
Skim Milk	12g	Much lower in fat and calories, same carbs as whole milk.
Lactose-Free Milk	12g (as simple sugars)	Lactase enzyme is added to break down lactose into easier-to-digest simple sugars.
Unsweetened Almond Milk	1-2g	Very low in carbohydrates and calories, suitable for low-carb diets.
Unsweetened Soy Milk	4-5g	Contains fewer carbs than dairy milk but higher protein than other plant-based milks.
Unsweetened Coconut Milk	6-7g	A moderate carb option, depending on the brand and whether it's sweetened.

The Impact of Lactose on Diet

For individuals with lactose intolerance, understanding the carbohydrate source in milk is crucial for dietary management. Instead of completely avoiding dairy, many can manage their symptoms by choosing lactose-reduced products, aged cheeses, or smaller portions of milk. Lactase enzyme supplements can also be taken to aid in digestion. Lactose itself offers health benefits, such as enhancing the absorption of minerals like calcium and magnesium, and it has a relatively low glycemic index.

Low-Carb Alternatives and Considerations

For those following a ketogenic or very low-carbohydrate diet, the 12 grams of carbohydrates in a single cup of dairy milk can quickly use up their daily carb allowance. In such cases, plant-based alternatives like unsweetened almond or macadamia milk are often preferred due to their very low carb counts.

Unsweetened almond milk: A popular keto-friendly option with only 1–2 grams of carbs per cup.
Unsweetened soy milk: Offers a good protein source for those avoiding dairy, with 4–5 grams of carbs per cup.
Heavy cream: High in fat and low in carbs, making it a suitable option for adding richness to keto recipes in small quantities.

However, it is important to check the nutrition labels on all plant-based milk products, as sweetened versions can contain significant amounts of added sugars and, consequently, a higher carbohydrate count. For instance, sweetened almond milk can have as many carbs as dairy milk.

Conclusion

In summary, yes, there is a carbohydrate in milk, and it is primarily the natural sugar known as lactose. This lactose is consistent across all types of cow's milk, regardless of fat content. Lactose serves as a vital energy source and aids in mineral absorption, but its digestion depends on the enzyme lactase, which many people produce less of as they age. For those with lactose intolerance or individuals following low-carb diets, numerous low-lactose or dairy-free alternatives exist, such as aged cheeses, yogurt, or unsweetened plant-based milks. Understanding the carbohydrate source in milk empowers consumers to make informed choices that best suit their dietary needs and health goals.

Visit the U.S. Dairy official website to explore more on dairy nutrition.

Frequently Asked Questions

The carbohydrate found naturally in milk is lactose, a naturally occurring sugar. Added sugars are not typically present in plain milk, but they can be found in flavored milks like chocolate milk.

Lactose intolerance is a digestive problem caused by the body's inability to produce enough lactase to break down lactose, leading to bloating, gas, and diarrhea. A milk allergy, however, is an immune system reaction to milk proteins, such as casein and whey, and can cause more severe symptoms.

An 8-ounce glass of regular cow's milk, regardless of its fat content (whole, skim, or 2%), contains approximately 12 grams of carbohydrates, mostly from lactose.

Yes, lactose-free milk contains carbohydrates. It has the same carbohydrate content as regular milk, but the lactose has been pre-broken down into the simpler sugars, glucose and galactose, making it easier to digest for those with lactose intolerance.

Unsweetened plant-based milks, such as almond, macadamia, and soy, are excellent low-carb alternatives to dairy milk. However, it is essential to check the label, as sweetened varieties can have a higher carbohydrate count.

Many people with lactose intolerance can still consume small amounts of dairy, and some fermented products like aged cheeses and yogurt contain less lactose, making them more tolerable.

The fat content in milk has no impact on its carbohydrate content. Whether it's whole milk with higher fat or skim milk with almost no fat, the amount of lactose remains virtually the same.