Vitamin Loss in Cooking

When you want to feed your children the most nutritious food you can, it's just as important to select a proper cooking method as it is to select the foods themselves.  While most minerals hold up extremely well to all temperatures and cooking methods, vitamins are easily lost depending on how the food is prepared.  It's helpful to know how some vitamins are destroyed, and what you can do to preserve as many as you can.

Fat Solubility

Vitamins that dissolve in fat, and therefore leach out of food when cooked in fats like butter and oil, include Vitamins A, D, E and K.  Because excess amounts of these vitamins are stored in the body, and not eliminated like water-soluble vitamins, it isn't imperative that you receive high doses everyday.

However, to retain these vitamins when cooking, it is advised that you refrain from frying the food or otherwise cooking it in fat.  Broiling or baking would be the superior option for retaining these vitamins in food.

Foods rich in the fat-soluble vitamins include:

• Vitamin A:  Liver, sweet potatoes, carrots, dark leafy greens such as kale and collard greens, butternut squash, dried apricots and cantaloupe.  
• Vitamin D:  Fish (particularly raw or oil-packed) such as herring and salmon, fortified products (including soy, dairy and cereal products), and eggs.
• Vitamin E:  Nut and seed products such as sunflower seeds and almonds, wheat germ and olive oils, green olives and cooked spinach.
• Vitamin K:  Dark leafy greens (here they are again, and also a great plant source of calcium), broccoli, Brussels sprouts, asparagus and cabbage.

Water Solubility

Water-soluble vitamins are those that dissolve in water, and are lost primarily when food is boiled or otherwise prepared in water.  These vitamins need to be in the diet daily, as they are eliminated from the body throughout the day, primarily through urine.

The water-soluble vitamins are Vitamin C and the B complex vitamins:  Thiamin, riboflavin, niacin, Vitamin B6, folic acid, Vitamin B12, pantothenic acid, and biotin.  All of these vitamins are easily lost in the storage and preparation of foods.

Some information on the vitamins follows:

• Vitamin C:  Vitamin C is very unstable, and is lost when exposed to water or heat, and also when a food is dried.  Therefore, one of the best sources for Vitamin C is from fresh, raw food:  Fruits like oranges, grapefruits, strawberries, tomatoes and dark green leafy vegetables.  When you are cooking, use as little water as possible and cook for as short a time as possible.
• B Complex Vitamins:  In general, you will find an abundance of the B Complex Vitamins in animal foods, especially liver, and whole grain products.  Eggs, fish, leafy vegetables, legumes and milk also provide many of the B Vitamins in good, healthy amounts.  All of them leach out of food into cooking water and many are destroyed by alkalinity and sulfites (which are added to many dried foods to retain color); some are destroyed by too much exposure to light (riboflavin) and long exposure to heat (thiamin).  Despite the loss of vitamins, it is important you always cook meat thoroughly!

Tips on Vitamin Preservation

Save cooking water.  Whatever water you use to boil vegetables, use it to prepare rice, make gravy, add to soup, or make a sauce.

Avoid peeling and cutting.  Vegetables that remain in one piece will retain more nutrients than those that are chopped or peeled prior to cooking.  Only peel when absolutely necessary, as a wealth of vitamin nutrition is in or just beneath the skin.

Prepare food fresh.  Foods that are cooked, then stored and reheated later, lose a lot of nutrition.  Vegetables prepared in advance lose roughly a quarter of their Vitamin C, for example, after 24 hours.

Steam, or use very little water when boiling.  Steaming retains a lot more of the water-soluble vitamins than does boiling, as the water doesn't come into contact with the food.  When you do boil, however, use a minimum of water.  Remember that leafy greens cook down and while four cups of cabbage doesn't seem like it can cook in one cup of water, give it a chance.

Baking and toasting.  When you're baking, the addition of baking soda raises the alkalinity of the product and destroys thiamin.  While you can't avoid the "baking" part of baking, you can avoid over-toasting any bread you might make (or purchase) to keep from further destroying thiamin:  Toast it just so it's golden around the edges, and no more.

Roast and grill.  Your best bets for meat are to prepare them with dry heat:  Roasting and grilling.  Don't overcook your meat, as this leads to unnecessary further nutrient loss (not to mention that it's incredibly disrespectful to the cow who gave his life to put that amazing steak on your table when you cook it anything past medium for an adult).  Don't be afraid to use fully-cooked drippings to prepare gravies.

Stir-fry, don't fry-fry.  Deep frying is horrible, and destroys nearly all of the fat-soluble vitamins in your food as well as adding on too many additional fat calories.  Stir-frying, however, which uses a minimum of oil and a minimum cooking time, isn't too bad.  Slice your foods very thin to limit how much time is needed to cook in this high-heat method.  

Most Importantly...

Eat at home.  See how your food is selected, stored and prepared!