How Cooking Affects Nutritional Content

cookingBy Jacquie Eubanks BSN, RN

To improve health and vitality and to fend off disease, we’re simply told to include a variety of fruits and vegetables in our daily diets.  Growing, harvesting, shipping, and storing all affect nutritional content and nearly all food preparation processes reduce the amount of nutrients in foods.  As nothing about nutrition is really simple, it holds true that processing and cooking methods affect various foods differently.  Food exposed to high heat, light and oxygen experience the highest nutrient loss.  While cooking can degrade some nutrients, it can also enhance the bioavailability of other nutrients. 

When it comes to cooking vegetables, there are always tradeoffs and there are numerous factors that determine how much the cooking of foods decreases the nutritional value.  For example, raw carrots contain polyphenols that are destroyed by cooking.  At the same time, boiled carrots have significantly higher levels of carotenoids.  Fresh tomatoes have lower lycopene content than cooked tomatoes.  For many plant foods, cooking breaks down thick, hard to digest cell walls creating more absorbable nutrients. Cooking also destroys potentially harmful microorganisms that may be present in our food supply.

Water soluble vitamins such as vitamin C, vitamin B complex, and polyphenols are the most likely to degrade during cooking, while fat soluble compounds such as vitamins A, D, E, and K, and some antioxidants are more likely to be retained.  The shortest cooking methods as well as cooking methods that use little or no water, appear to be the best at retaining maximum nutrition levels.  These three factors help determine how much nutritional value is maintained or lost through cooking:

Amount of water:  Unless you are making soup or stew or otherwise intend to consume cooking water, it’s best not to boil vegetables.  During boiling, much of the water soluble vitamins will leach out into the water.  If you throw that water down the drain, you’re throwing away your vitamins and minerals too.  Using the water to cook rice or couscous for example recaptures many of those lost nutrients. 

The heat factor:  To retain as many nutrients as possible, limit the amount of time food is exposed to heat.  Fried food has the highest nutrient loss.  Roasting or grilling are better methods for retaining nutrients of some vegetables such as asparagus, broccoli and peppers. 

Timing is everything:  The longer the cooking time, the more damaging the nutrient loss.  There are no valid reasons to expose food to high heat for extended periods of time.  Cooking a vegetable for a short time, even for a minute or two, can enhance its digestibility. 

The best cooking methods for minimizing nutrient loss: 

  • Pressure cooking creates steam using a very small amount of water, seals the nutrients inside the cooker, and quickly cooks the vegetables while retaining both color and nutrients. 
  • Steaming is a very effective way to cook vegetables and retain nutrients.  Bringing a small amount of water to a boil before adding vegetables to the steamer is best.  Tossing steamed veggies in a small amount of healthy oil helps to boost nutrient absorption. 
  • Microwaving requires very little water and is the most rapid method of cooking so there is very little nutritional loss.  Microwaving also preserves the maximum amount of antioxidants. 
  • Sautéing vegetables over high heat in a little bit of oil for a short time also minimizes nutrient loss and helps the body utilize fat soluble nutrients. 

The best vegetables are the ones you will eat and enjoy.  To get the most benefit from your vegetables and the widest range of nutrients, enjoy them in a variety of ways.  Buy fresh, in season vegetables and eat them as soon as possible to get the most health benefits.    

Greens Powder by Quantum Nutrition Labs –  Live-sourced super nutrition formula for optimal health.  Contains power grass, barley grass, wheat grass, chlorella and blue green algae. 

Buffered C Powder (C155) by Thorne Research –  This pure crystalline vitamin C with a blend of calcium, magnesium and potassium mineral ascorbates is ideal for individuals with sensitive or compromised digestive systems.

Polyphenol Nutrients by Pure Encapsulations –  A nutrient dense multivitamin with fully chelated minerals for optimal absorption. 

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