Which Vitamin is Less in Pasteurized Milk? Understanding Nutrient Loss

December 28, 2025 •

4 min read

Pasteurization is a vital food safety process that heats milk to kill harmful pathogens, but this treatment does affect some vitamins. This process leads to a common question for health-conscious consumers: which vitamin is less in pasteurized milk? The most significant reductions occur in water-soluble, heat-sensitive vitamins, notably vitamin C and folate.

Quick Summary

Pasteurization reduces the levels of certain heat-sensitive, water-soluble vitamins in milk, with the most notable losses affecting vitamin C and folate. Fat-soluble vitamins and minerals are largely unaffected by the process.

Key Points

Vitamin C and Folate Reduction: Water-soluble vitamins like C and folate are the most heat-sensitive and show the most significant reduction in pasteurized milk, though their initial levels are low.
Fat-Soluble Vitamins are Stable: Vitamins A, D, E, and K are fat-soluble and largely protected from heat-related degradation during the pasteurization process.
Fortification Compensates: Many milk products are fortified with vitamin D and sometimes vitamin A to replace any minor losses and increase nutritional value, making them superior sources of these specific nutrients compared to raw milk.
Minimal B Vitamin Impact: With standard pasteurization, the reduction in B vitamins like riboflavin (B2) and B12 is minimal, and milk remains a good source of these nutrients.
Nutrient Loss is Minimal for Safety: The minor loss of some vitamins is a small trade-off for the critical health benefit of destroying disease-causing bacteria, a primary purpose of pasteurization.
Balance with Other Foods: Any vitamin losses are easily offset by consuming a balanced diet with a variety of fruits, vegetables, and other nutrient-rich foods.

The Primary Vitamin Loss: Vitamin C

Among all the vitamins naturally present in milk, vitamin C is arguably the most susceptible to destruction during the pasteurization process. This is because ascorbic acid, the chemical name for vitamin C, is highly sensitive to heat and oxygen. While raw milk contains a trace amount of vitamin C, the heating process involved in pasteurization typically reduces this level significantly, or even eliminates it entirely. However, it's important to note that milk is not considered a primary source of vitamin C in most modern diets, with fruits and vegetables providing far higher concentrations. Therefore, the loss of this particular nutrient is generally considered to be nutritionally insignificant for overall daily intake.

Other Water-Soluble Vitamin Changes

Beyond vitamin C, other water-soluble vitamins, primarily those from the B-complex family, can also experience minor reductions during heat treatment. While these losses are often minimal with standard pasteurization methods, some studies and processing variations can lead to more noticeable effects.

Folate (Vitamin B9)

Folate, or folic acid, is another water-soluble vitamin that is sensitive to heat. Research has shown that pasteurization can cause a significant loss of folate in milk, particularly in the form of 5-methyl-tetrahydrofolate, the most abundant folate form. The folate content can also be further reduced by longer storage times. However, like vitamin C, milk is not the main dietary source of folate, and these losses can be easily compensated for by a balanced diet rich in leafy greens, legumes, and fortified grains.

B Vitamins (Thiamin, Riboflavin, B12)

Different B vitamins react differently to heat. Thiamin (B1) and Riboflavin (B2) are generally quite stable during standard pasteurization methods, with only minimal reductions observed. In fact, even with minor decreases, milk remains an excellent source of riboflavin. Vitamin B12 is also relatively heat-stable, with minimal losses during pasteurization, though some sources suggest more significant losses in more severely heated products like ultra-pasteurized or sterilized milk.

The Resilience of Fat-Soluble Vitamins

In contrast to their water-soluble counterparts, the fat-soluble vitamins—A, D, E, and K—are largely unaffected by the pasteurization process. Since these vitamins are stored in the milk fat, they are protected from heat-related damage during pasteurization. Additionally, to ensure adequate levels of vitamin D and sometimes vitamin A, many countries have mandatory fortification programs for commercially sold pasteurized milk. This means that store-bought pasteurized milk is often a superior source of vitamin D compared to raw milk, which contains very little naturally.

Nutritional Comparison: Pasteurized vs. Raw Milk

To provide a clear perspective on the nutritional differences, let's compare the impact on various nutrients between raw and pasteurized milk. It is important to note that nutritional content can vary based on factors like the cow's diet and seasonality, but the effect of processing remains consistent.


Nutrient	Effect of Pasteurization	Raw Milk vs. Pasteurized	Notes
Vitamin C	Significant loss or complete elimination due to heat.	Higher in raw (trace amounts).	Nutritionally insignificant as milk is not a primary source.
Folate (B9)	Notable reduction due to heat sensitivity.	Higher in raw.	Fortification can add back this nutrient in some products.
Riboflavin (B2)	Minor decrease, but remains a strong source.	Slightly higher in raw, but difference is minimal.	Often lost more through light exposure than heat.
Vitamin B12	Minimal loss with standard methods.	Similar in both types of milk.	Fortification can sometimes be a factor.
Vitamin D	Trace amounts lost, but most is fortified.	Very low in raw milk.	Commercial pasteurized milk is a much better source.
Calcium	Unaffected; minerals are heat-stable.	No significant difference.	An excellent source of calcium in both forms.
Protein	Minimal denaturation of whey proteins, but no impact on nutritional quality.	No significant difference in quality or quantity.	Casein, the main milk protein, is highly heat-stable.

Why Pasteurization is Still Essential

While some vitamins are reduced, the health benefits of pasteurization far outweigh the minor nutritional trade-offs. The process of heating milk to a specific temperature for a set time effectively eliminates dangerous pathogens such as E. coli, Salmonella, and Listeria. These bacteria can cause severe illness, hospitalization, and even death, especially in vulnerable populations like children, the elderly, and pregnant women. The US Centers for Disease Control (CDC) and other public health organizations strongly advocate for consuming only pasteurized milk and milk products.

Compensating for Minor Vitamin Losses

The small reductions in vitamins that occur during pasteurization are not a cause for concern in a well-rounded diet. Here are some simple ways to ensure you get all the nutrients your body needs:

Eat a variety of fruits and vegetables: Since milk is a poor source of vitamin C anyway, get your daily dose from citrus fruits, bell peppers, strawberries, and broccoli.
Include leafy greens and legumes: Beans, lentils, and spinach are excellent sources of folate.
Look for fortified products: Many breakfast cereals and other food items are fortified with B vitamins and other essential nutrients.
Get sunlight: Your body naturally produces vitamin D when exposed to sunlight. For those with limited sun exposure, relying on fortified milk or supplements is a great option.
Diversify your dairy: While milk is a nutrient powerhouse, consuming other dairy products like yogurt and cheese also contributes to your overall nutritional intake.

Conclusion: The Balanced Perspective

The answer to "which vitamin is less in pasteurized milk?" is a nuanced one. While heat-sensitive, water-soluble vitamins like C and folate do see a reduction, the impact on overall health is minimal due to their low concentration in milk to begin with. The fat-soluble vitamins and key minerals remain largely unaffected, and fortification policies ensure adequate levels of vital nutrients like vitamin D. Ultimately, the minimal nutritional changes caused by pasteurization are a small price to pay for the significant public health benefit of eliminating dangerous pathogens. Enjoying pasteurized milk remains a safe and nutritious choice as part of a balanced and healthy diet. For more detailed information on the benefits of pasteurization and dairy nutrition, the Dairy MAX organization offers informative resources.

Frequently Asked Questions

No, pasteurization does not destroy all vitamins. The process primarily affects water-soluble vitamins like C and folate, which are heat-sensitive. Fat-soluble vitamins, including A, D, E, and K, are largely unaffected.

Vitamin C is the most heat-sensitive vitamin in milk and is often eliminated by the pasteurization process. However, milk is not a significant source of vitamin C, even in its raw form.

From a food safety and vitamin D perspective, fortified pasteurized milk can be considered healthier. While raw milk has trace amounts of vitamin C that are lost, pasteurized milk is a much more reliable and potent source of vitamin D due to fortification, and most importantly, it is free of dangerous bacteria.

Some B vitamins, like folate and to a lesser extent riboflavin, can see minor reductions during pasteurization. However, milk remains a good source of many B vitamins, and these losses are not considered nutritionally significant.

You can easily compensate for the minimal vitamin losses by eating a balanced diet. Incorporate plenty of fruits, vegetables, leafy greens, and legumes, which are excellent sources of vitamin C and folate.

Yes, exposure to light can cause further degradation of some vitamins, particularly riboflavin (B2). Opaque or paper cartons protect the milk from light better than clear plastic bottles.

No, minerals like calcium and phosphorus are very heat-stable and are not significantly affected by the pasteurization process. Milk remains an excellent source of these essential minerals.