Is Lactose Found in Curd? What to Know for Your Diet

December 28, 2025 •

4 min read

While milk contains a significant amount of lactose, the fermentation process that creates curd dramatically alters its composition. During this process, live bacteria cultures consume some of the lactose, converting it into lactic acid. This results in a finished product with a much lower lactose content, often making curd easier to digest than unfermented milk for many individuals with lactose sensitivity.

Quick Summary

Curd, or dahi, is a fermented dairy product with lower lactose levels than milk due to the fermentation process. Beneficial bacteria break down milk sugar, resulting in a product that is often better tolerated by those with lactose sensitivity, though it is not completely lactose-free.

Key Points

Lactose is Present, But Reduced: Curd does contain lactose, but the fermentation process significantly lowers the amount compared to milk.
Probiotics Aid Digestion: The live bacterial cultures in curd produce lactase, the enzyme needed to break down lactose, aiding digestion for lactose-sensitive individuals.
Fermentation Time Matters: A longer fermentation period generally results in lower lactose content in the finished curd.
Straining Reduces Lactose Further: Straining curd to make hung curd or Greek yogurt removes much of the whey, which holds residual lactose.
Tolerance Varies by Individual: The degree to which one tolerates curd depends on their specific level of lactose sensitivity.
Curd vs. Yogurt Distinction: While often used interchangeably, the terms can refer to different preparation methods that influence lactose content and probiotic cultures.
Curd Offers Benefits Without Discomfort: For many, curd provides a source of calcium and protein that is more digestible than milk, without the typical symptoms of lactose intolerance.

Understanding Lactose and the Fermentation Process

Lactose is a complex sugar, or disaccharide, made up of glucose and galactose molecules. It is naturally present in milk and other dairy products. For the body to digest lactose, it needs the enzyme lactase to break it down into simpler sugars that can be absorbed. People with lactose intolerance produce insufficient amounts of lactase, leading to digestive issues when they consume dairy.

Curd, known as dahi in India, is produced through a fermentation process involving lactic acid bacteria. These bacteria consume the lactose in the milk and produce lactic acid. This not only thickens the milk and gives curd its characteristic tangy flavor but also significantly reduces the overall lactose content. The longer the fermentation, the lower the lactose level generally becomes.

The Science Behind Lower Lactose in Curd

Bacterial Action: The starter culture, which can be a small amount of old curd or buttermilk, is added to warm milk. This introduces millions of lactic acid bacteria, such as Lactobacillus bulgaricus and Streptococcus thermophilus, which begin to feast on the lactose.
Lactose Conversion: As the bacteria break down the lactose, they produce lactic acid, which causes the milk proteins to coagulate and form the semi-solid curd.
Reduced Content: Since a portion of the lactose is converted during fermentation, the final product has a much lower lactose concentration than the milk it originated from.

Curd vs. Yogurt: A Point of Clarification

The terms 'curd' and 'yogurt' are often used interchangeably, but there can be key differences, particularly in how they are prepared. Indian curd, or dahi, is typically made by fermenting milk with natural lactic acid bacteria from a previous batch or even natural sources like chili stems. Yogurt, especially commercial varieties, is made with specific, controlled bacterial cultures. Greek yogurt, for example, is further strained to remove whey, concentrating the protein and further reducing the lactose content. While both undergo fermentation that lowers lactose, the type of culture and process can affect the final lactose levels.

Factors Affecting Lactose Levels in Curd

Several factors can influence the final lactose content of curd:

Fermentation Time: A longer fermentation period allows the bacteria more time to consume the lactose, leading to a lower final concentration.
Starter Culture: The type of bacteria in the starter culture and their activity level can affect the efficiency of lactose breakdown.
Preparation Method: Home-set curd, for example, may have a different lactose profile than commercially produced curd.
Straining: Straining curd to make hung curd (similar to Greek yogurt) removes whey, which contains much of the remaining lactose. This can lead to a significantly lower lactose content.

Comparison: Lactose in Curd vs. Other Dairy


Dairy Product	Lactose Content	Tolerability for Lactose-Sensitive Individuals
Milk	High (approx. 4.8% in cow's milk)	Low. Can cause significant digestive upset.
Curd (Dahi)	Low (Reduced significantly)	Moderate to High. Often well-tolerated due to lower lactose and probiotics.
Strained Curd (Hung Curd)	Very Low	High. Most lactose is removed during the straining process.
Hard Cheese (e.g., Cheddar)	Very Low	High. Most lactose is removed during the cheese-making process.
Ice Cream	High	Low. High sugar and lactose content.

The Digestive Benefits of Curd for the Lactose Sensitive

The reason many people with lactose intolerance can enjoy curd without discomfort is twofold. First, the reduced lactose content means there is less milk sugar for the body to process. Second, the live and active cultures (probiotics) in curd produce the lactase enzyme, which can help break down the residual lactose in the gut. These probiotics also improve overall gut health, which can alleviate symptoms like bloating and gas associated with poor digestion. This makes curd a viable option for those who wish to include dairy in their diet but struggle with traditional milk products. It's an excellent source of calcium and protein for those who need to avoid milk.

Conclusion

In summary, yes, lactose is found in curd, but in significantly lower amounts than in the milk it is made from. The fermentation process, driven by beneficial bacteria, converts a substantial portion of the lactose into lactic acid, making it much more digestible for individuals with lactose sensitivity. While a severely lactose-intolerant person may still experience symptoms, many with mild to moderate sensitivity can enjoy curd. Opting for well-fermented or strained curd can further reduce the lactose content. For many, curd offers a path to enjoying dairy's nutritional benefits without the typical digestive discomfort associated with milk.

How to enjoy curd with a lactose sensitivity

For those with a lactose sensitivity, incorporating curd into your diet can be a great way to enjoy dairy without discomfort. The key is to start slow and listen to your body. Begin with a small serving of well-fermented curd to see how you react. As your tolerance builds, you can increase your portion size. You can also opt for strained curd, which has even less lactose, or use curd in recipes that pair it with other foods. Remember that individual tolerance levels can vary, so finding what works best for you is important. For more comprehensive information on lactose intolerance and dairy consumption, see the resources provided by The Dairy Alliance.

Frequently Asked Questions

No, curd is not completely lactose-free because it is made from milk. However, the fermentation process significantly reduces its lactose content, making it much lower than in regular milk.

Curd is easier to digest because the bacteria used in fermentation consume some of the lactose. Additionally, the live cultures in curd produce lactase, which helps break down the remaining lactose in your digestive system.

Both curd and yogurt have reduced lactose compared to milk due to fermentation. However, commercially prepared yogurt is made with specific bacterial strains, while curd (dahi) can be more variable. Greek yogurt, which is strained, has an even lower lactose content than regular curd or yogurt.

Yes, a longer fermentation time allows the lactic acid bacteria more opportunity to break down lactose. This means a curd that has been fermented longer will typically have a lower lactose concentration.

Individuals with severe lactose intolerance may still experience symptoms from the residual lactose in curd. For them, lactose-free curd or other dairy alternatives might be a safer option. It's best to test personal tolerance with a small amount.

Hung curd is a strained curd from which excess whey has been removed. The majority of the lactose remains in the whey, so hung curd has an even lower lactose content than regular curd, though it is not completely lactose-free.

You can make curd at home using lactose-free milk, which has already been treated with the lactase enzyme. The fermentation process will then further ensure the curd is easy to digest.

If you are lactose-sensitive, introduce curd into your diet slowly. Start with a small amount and observe how your body reacts before increasing your intake.