Does Vitamin B12 Get Destroyed by Heat? The Truth About Cooking and Nutrient Loss

October 12, 2025 •

4 min read

Vitamin B12 is crucial for nerve function, red blood cell formation, and DNA synthesis. But does vitamin B12 get destroyed by heat during cooking? Scientific studies confirm that heat can degrade this essential nutrient, with the extent of loss depending on temperature, time, and cooking method.

Quick Summary

Heat treatments can degrade vitamin B12, causing nutrient loss in foods like milk and meat. High temperatures and extended cooking times lead to more significant degradation, though the effect varies by food and method.

Key Points

Heat Causes Degradation: Cooking with heat, especially at high temperatures and for extended durations, can destroy vitamin B12.
Microwaves Can Inactivate B12: Studies show that microwaving can cause significant B12 losses by converting it to inactive, unusable forms.
Steaming Preserves B12 Best: As a cooking method, steaming minimizes nutrient loss compared to boiling because there is no direct contact with large amounts of water.
Boiling Washes Away B12: When boiling foods, water-soluble B12 can leach into the cooking water, and significant losses occur if this liquid is discarded.
The Food Matrix Offers Protection: In foods like milk, proteins bind to B12, offering some protection against heat degradation, although losses still occur at high temperatures.
Time and Temperature Are Key: Regardless of the method, cooking for shorter times at lower heat levels is key to maximizing vitamin B12 retention in foods.

Understanding Vitamin B12 and Heat Stability

Vitamin B12, or cobalamin, is a water-soluble vitamin that is not quite as sensitive to heat as other water-soluble vitamins like vitamin C or thiamine (B1). However, this does not make it indestructible. Research consistently shows that prolonged exposure to high temperatures can lead to significant degradation of the vitamin, reducing the nutritional value of the food being cooked. The degree of destruction is influenced by several key factors beyond just the temperature, including the duration of cooking, the pH of the food, and the presence of other compounds that might protect the vitamin, such as certain proteins.

Heat-induced degradation of B12 can also convert the vitamin into biologically inactive forms, meaning the body cannot utilize it effectively. For instance, a 1998 study found that microwave heating of milk converted a portion of the B12 into inactive degradation products. This is particularly relevant for individuals relying on cooked sources for their B12 intake, such as vegetarians consuming dairy or meat-eaters who cook their food well-done.

The Impact of Different Cooking Methods on Vitamin B12

Not all cooking methods are created equal when it comes to preserving nutrients. The method, temperature, and cooking duration all play a role in how much vitamin B12 survives the cooking process. Choosing the right technique can make a noticeable difference in your nutritional intake.

Boiling and simmering

Boiling is one of the less favorable methods for retaining water-soluble vitamins. The vitamin can leach out of the food and into the cooking water. If the water is discarded, a significant portion of the vitamin is lost. Studies have shown that boiling milk for an extended period, such as 30 minutes, can reduce B12 levels by up to 50%. For meat simmered in water, losses of up to 60% have been reported if the cooking liquid is not consumed.

Microwaving

Microwave cooking is often promoted as a healthy option due to shorter cooking times. However, some studies have shown surprisingly high losses of B12 during microwaving. A Japanese study found that microwaving milk, beef, and pork caused an appreciable loss of 30–40% of vitamin B12. This is believed to be due to the specific mechanism of microwave heating, which can alter the molecular structure of the vitamin and convert it into biologically inactive forms.

Roasting, grilling, and frying

Dry-heat cooking methods show variable results. Roasting and grilling can cause some vitamin B12 loss, but often less than boiling or microwaving if not overcooked. However, frying can be particularly damaging. One study on beef found that frying resulted in about 32% lower cobalamin content compared to raw meat. The high temperatures used in frying can degrade the vitamin, and losses also occur when juices containing the vitamin run off into the pan.

Steaming and pressure cooking

Steaming is a much gentler method that minimizes nutrient loss. Because the food is not directly in contact with water, the water-soluble vitamins are less likely to leach away. Pressure cooking is another good option, as it significantly reduces cooking time while trapping nutrients in a sealed, low-oxygen environment. Both methods are excellent choices for preserving the vitamin B12 content of your food.

Factors Influencing Vitamin B12 Degradation

Beyond the cooking method itself, several other factors can affect how much vitamin B12 is retained in your food:

Temperature and Time: The longer food is exposed to heat, and the higher the temperature, the greater the degradation. This is a primary driver of nutrient loss.
pH Level: Vitamin B12 is more stable in a neutral pH range and can be sensitive to both highly acidic and alkaline conditions.
Food Matrix: The surrounding food components can offer a protective effect. In milk, for example, whey proteins and caseins can bind with vitamin B12 and shield it from thermal degradation. This protective effect is one reason pasteurization often causes less B12 loss than expected from high temperatures.
Other Ingredients: The presence of certain compounds, like reducing agents (e.g., ascorbic acid/vitamin C), can accelerate B12 degradation.
Oxygen and Light Exposure: Oxygen and light can also play a role in the breakdown of B12, especially when combined with heat.

Cooking Method Comparison for Vitamin B12


Cooking Method	Heat Level	Time	Water Contact	B12 Retention (General Estimate)	Considerations
Boiling/Simmering	Medium-High	Medium-Long	High (direct)	Low to Medium	High losses if cooking liquid is discarded. Retained if liquid is consumed.
Microwaving	High (Internal)	Short	Varies (Low)	Medium-Low	Can cause molecular degradation, leading to inactive B12 forms.
Frying	High	Short-Medium	None	Medium-Low	Losses occur due to high heat and juices running off.
Roasting/Grilling	High	Medium	None	Medium to High	Varies with cut of meat and overcooking; better with medium doneness.
Steaming	Medium	Medium	Low (indirect)	High	Minimal nutrient leaching; excellent for preserving B12.
Pressure Cooking	High (Internal)	Short	Low	High	Short cooking time and sealed environment minimize degradation.

Conclusion: Minimizing B12 Loss Through Smarter Cooking

While the answer to "does vitamin B12 get destroyed by heat?" is a definitive yes, the extent of the damage is largely within your control. For nutrient-dense foods like meat and dairy, intelligent cooking methods can significantly reduce the amount of B12 lost. Opting for quick cooking methods, using less water, and consuming the cooking liquid can help you get the most out of your B12-rich foods. For individuals with deficiencies or those on a vegan diet, fortified foods and supplements are a reliable way to ensure adequate intake. Understanding the science behind nutrient degradation empowers you to make smarter dietary choices and maximize the nutritional benefits of your meals. For more comprehensive information, consult authoritative sources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

While microwaving can degrade nutrients, including a notable portion of vitamin B12, the claim that it destroys all nutrients is a myth. Nutrient loss depends on the specific food and heating time. Some studies indicate microwaving can preserve other vitamins better than boiling, though B12 is particularly sensitive to its molecular degradation effects.

To preserve the most B12 in meat, it is best to cook it quickly and avoid overcooking. Methods like grilling or roasting to a medium doneness are better than deep-frying. If you are simmering meat, use the cooking juices in a sauce to retain any B12 that has leached out.

Yes, heat treatment affects the B12 content in milk. Pasteurization causes minimal loss, but more severe heat treatments like Ultra-High Temperature (UHT) processing and prolonged boiling can cause significant degradation. Studies have shown up to 50% loss when milk is boiled for 30 minutes.

Yes, in addition to heat, vitamin B12 is sensitive to light, oxygen, and certain pH levels. Exposure to light can cause photodegradation, and it is unstable in strongly acidic or alkaline environments. Oxygen and some other ingredients can also degrade it.

B12 in supplements (often cyanocobalamin) is generally more heat-stable than the natural forms in food. However, adding it to food that is then cooked can still lead to some degradation. The best practice is to take supplements separately from hot meals for optimal absorption.

For those who do not eat meat, options include consuming dairy products, eggs, and foods fortified with vitamin B12, such as cereals, plant-based milk, and nutritional yeast. Vegans, in particular, should rely on fortified products or supplements to meet their needs.

The amount of B12 lost varies greatly, from minimal losses with gentle cooking (e.g., steaming) to significant reductions of 30-50% or more with methods like prolonged boiling, microwaving, or frying. Losses are also dependent on the food itself and other cooking conditions.