Are Vitamins Destroyed During Cooking?

Vitamins are natural substances in food that play an important role in metabolism. They help your body break down food and release nutrients so you can grow, have energy and fight infections. Water-soluble vitamins are the most unstable when cooked or stored improperly. Eat a combination of raw and cooked foods for the greatest nutritional benefits, says registered dietitian Jenna Wunder of the University of Michigan Health Systems.

Vitamins B and C

Water-soluble vitamins B-complex and C are needed in very small amounts in the body. These vitamins need to be replaced in the diet daily because they dissolve in water and your body does not store them. Excess or unused vitamins are eliminated in urine. Vitamins B and C become unstable during high-temperature cooking. The B-complex vitamins make up eight distinctive vitamins: thiamin, riboflavin, niacin, vitamin B-6, folate, vitamin B-12, biotin and pantothenic acid. These vitamins help the body maintain normal appetite, good vision, healthy skin and a healthy nervous system, and help to obtain energy from food. Vitamin C functions as an antioxidant. It is needed to support healthy gums and teeth, wound healing, formation of bone and cartilage, and to increase absorption of iron.

Foods Affected

Foods high in vitamin C are vegetables and citrus fruits such as broccoli, strawberries, melon, green pepper, tomatoes, dark green vegetables and potatoes. Sources of thiamin include pork, whole grains, enriched grain products, peas, meat and legumes. Thiamin losses depend on the cooking method. Riboflavin is found in liver, milk, dark-green vegetables, whole and enriched grain products and eggs. It is very sensitive to light. Fish, poultry, meat and peanuts contain niacin. Vitamin B-6 and folate are sensitive to heat and might be destroyed during cooking. Food sources of B-6 and folate include pork, whole grains, vegetables and meat. Vitamin B-12 is found only in animal sources of food such as eggs, fish and milk. Biotin and pantothenic acid are found in liver, egg yolk, fresh vegetables and whole grains.


Foods high in water-soluble vitamins B and C become less nutritious when handled, prepared and cooked, according to Colorado State University Extension. To conserve nutritional value, keep cooking times short. Water-soluble vitamins are destroyed and lost to water when heated. Steaming vegetables instead of boiling can preserve the nutritive value of these foods. It's best to refrigerate fresh produce, keep milk and grains away from strong light and use the cooking water from vegetables to prepare soups to save vitamins.


Taking mega doses of vitamins is not recommended as large amounts of supplements can be toxic to your health. A deficiency of B-complex or C vitamins is rare but can happen. Eating from all of the food groups and following the U.S. Department of Agriculture's Dietary Guidelines can help you have a well-balanced diet and avoid deficiencies. A supplement of folate, or folic acid, might be needed for women planning to become pregnant to prevent neural tube defects . Vegans also might need vitamin B-12 supplements if no animal-based foods are consumed. Speak to your doctor or dietitian about your diet if you have concerns.