What Nutrients Are Lost When You Boil Milk?

December 12, 2025 •

3 min read

Studies have found that boiling milk can reduce levels of water-soluble vitamins, with some B vitamins decreasing by at least 24%. When you boil milk, the high temperature can affect its overall nutritional value, but certain nutrients are more susceptible to heat degradation than others.

Quick Summary

Boiling milk causes a reduction in water-soluble vitamins like B-vitamins and folic acid, with some protein denaturing and affecting its digestibility. While fat-soluble vitamins and total fat content remain largely unaffected, heat can alter protein structure and reduce the bioavailability of certain minerals. The duration and intensity of boiling are key factors determining the extent of nutritional loss.

Key Points

B-Vitamin Reduction: Boiling significantly reduces heat-sensitive B-vitamins like riboflavin and B12, with studies showing losses of 24% or more.
Folic Acid Loss: Folic acid content is particularly vulnerable, with some research indicating a reduction of up to 36% when milk is boiled.
Whey Protein Denaturation: High heat denatures whey protein, which can affect its structure and slightly reduce its digestibility.
Minimal Mineral Impact: The overall mineral content, including calcium, is largely unaffected by boiling, though bioavailability can be slightly altered.
Gentle Heating is Best: To minimize nutrient loss, heat milk slowly over a medium flame and avoid a rolling boil.
Pasteurization vs. Boiling: Commercial pasteurization is a controlled process that causes less nutrient damage than household boiling, which uses higher temperatures.
Longer Heating Equals Greater Loss: The longer milk is boiled, the greater the degradation of heat-sensitive nutrients.

Boiling milk is a common practice in many cultures, often done to improve safety or alter texture for recipes. However, the process exposes milk to high temperatures that can diminish its nutritional profile. While pasteurization is a controlled heat treatment that minimizes nutrient loss, bringing milk to a full boil at home can cause more significant changes. Understanding what nutrients are lost when you boil milk can help you make more informed choices about your food preparation.

The Effect on Water-Soluble Vitamins

Water-soluble vitamins are the most vulnerable nutrients to heat destruction during the boiling process. Studies have specifically highlighted the significant reduction of B vitamins and folic acid. Milk contains B1 (thiamine), B2 (riboflavin), B6, and B12. Boiling can decrease these levels, with losses ranging from 24% to over 30% depending on the specific vitamin and heating time. Riboflavin can see a reduction of up to 27%, while folic acid can decrease by 36%. Any trace amounts of Vitamin C are also highly heat-sensitive.

Changes to Milk Proteins

Milk contains casein and whey protein. Boiling affects protein structure and digestibility. Whey protein is particularly susceptible to heat and denatures, which can make it slightly less bioavailable. Casein is more stable and less affected by boiling heat.

How Boiling Affects Fats and Minerals

Boiling also impacts fats and minerals. The overall fat content remains stable, though some long-chain fatty acids may convert into shorter-chain ones. While older research indicated significant calcium loss, more recent findings suggest a much smaller effect. Boiling may slightly reduce the bioavailability of calcium and phosphorus by altering their soluble state, but it doesn't destroy the minerals themselves. Intense heating in some ultra-pasteurized products can have a greater impact.

Comparison of Boiling vs. Pasteurization


Feature	Boiling (Household)	Pasteurization (Commercial)
Temperature	Around 100°C (212°F)	Lower temperature, e.g., 72°C for 15 seconds
Nutrient Impact	Destroys significant amounts of B vitamins, C, and folic acid	Minimal impact on most vitamins
Protein Effect	Denatures whey proteins, affects digestibility	Preserves protein structure and digestibility
Safety	Kills most bacteria, useful for raw milk	Kills harmful pathogens reliably and safely
Bioavailability	Can slightly reduce bioavailability of some minerals	Minerals remain highly bioavailable

Minimizing Nutrient Loss When Heating Milk

To minimize nutrient loss when heating milk, use gentle heating over medium heat and avoid a rapid boil. Turn off the heat as soon as small bubbles form. Stirring gently helps distribute heat and prevents scorching. If not used immediately after boiling, cool and refrigerate promptly.

Conclusion

Boiling milk, while useful for safety and cooking, does lead to some nutrient loss, particularly water-soluble B-vitamins and folic acid, which are heat-sensitive. The impact on major minerals like calcium is minimal, but whey protein structure can be altered. For commercially pasteurized milk, re-boiling is often unnecessary. Gentle heating methods can minimize nutrient loss. Understanding this trade-off is important for those relying on milk for specific vitamins. For more information on the impact of heat on milk, consult studies like those published by the National Institutes of Health(https://www.researchgate.net/publication/50286429_Study_to_evaluate_the_impact_of_heat_treatment_on_water_soluble_vitamins_in_milk).

Frequently Asked Questions

For commercially available, pasteurized milk, boiling is unnecessary for safety as harmful bacteria have already been eliminated. For raw or unpasteurized milk, boiling is a crucial step to kill pathogens.

No, boiling milk does not destroy calcium, which is a heat-stable mineral. However, the process can slightly alter the bioavailability of soluble calcium, but the total amount remains largely intact.

The most significant nutrients lost when boiling milk are water-soluble B vitamins, particularly folic acid (B9) and riboflavin (B2), which are highly sensitive to heat.

Yes, ultra-high-temperature (UHT) pasteurization, which heats milk to very high temperatures, can cause greater vitamin loss than standard pasteurization. However, many UHT milk products are fortified to compensate for these losses.

You can minimize nutrient loss by heating the milk slowly over a medium flame and removing it from the heat as soon as it begins to form bubbles. Avoiding repeated boiling also helps.

For some individuals with a milk protein sensitivity or mild lactose intolerance, boiling can make milk easier to digest. The heat denatures whey proteins and converts some lactose into other compounds, which can alleviate symptoms.

Re-boiling milk is not recommended as it further depletes heat-sensitive vitamins and can affect the flavor and texture. It is better to refrigerate boiled milk and reheat it gently just before consumption.