The World's Healthiest Foods

Cooking and Nutrient Loss

While most animals thrive on diets consisting almost exclusively of raw, uncooked food, few human cultures have evolved or been sustained without incorporating some aspect of cooked food into their eating practices. At the World's Healthiest Foods, we encourage inclusion of both raw and cooked foods into the daily meal plan. We believe there is every reason to make the most from the nourishment available in both types of food.

The way that food is cooked is absolutely essential for avoiding unnecessary nutrient loss. Five minutes can make an enormous difference in the nutritional quality of a meal. (This is about the time it takes to walk away from the stove, answer the phone, and say that you can't talk right now because you are in the middle of cooking). In addition, every food is unique and should be treated that way when it comes to cooking temperatures and times. We refuse to simmer spinach for more than 2-3 minutes. But we know that kale needs to steam for 6-8 minutes. Head over to our Good Tasting Healthy Recipes to get all the details about each food and the unique cooking approach it deserves.

The traditional rules about heat, water, time, and nutrient loss are all true. The longer a food is exposed to heat, the greater the nutrient loss. Being submersed in hot water (boiling) creates more nutrient loss than steaming (surrounding with steam rather than water) if all other factors are equal. The lower nutrient loss from steaming is the main reason we recommend it so often in our recipes. We just can't think of any valid reason to expose a food to high heat and boiling water for any prolonged period of time, for example, more than twenty minutes. We even get our butternut squash steamed in that length of time!

With our very precise and short cooking times, you're unlikely to get a nutrient loss of more than 30% with most nutrients. In general, you're likely to get nutrient losses in the 5-15% range. This range is dramatically lower than the losses than occur in food processing, or in many cafeterias and restaurants where food is routinely overcooked (in Table 1, you will find a presentation of research results that have looked at how various cooking and preparation methods may impact nutrient loss from select foods). Processed foods often have nutrient losses in the 50-80% range - as much as ten times the amount that occurs with the World's Healthiest Cooking. The 5-15% nutrient loss that occurs with careful, minimized heat and water exposure is often a worthwhile loss, because it is accompanied by other changes in the food that can support out health. These other changes include improved digestibility, and the conversion of nutrients into forms that are more easily absorbed.

Table 1

Food Nutrient Method % Nutrient Loss
broccoli vitamin C blanch 47%
carrots folate boiling 79%
carrots beta-carotene canning 27%
cauliflower folate boiling 69%
grapefruit juice folate canning <5%
milk vitamin B12 boiling (2-5 minutes) 30%
mixed vegetables vitamin C blanching (3-5 minutes) 25%
mixed vegetables vitamin C boiling (10-20 minutes) 55%
mixed vegetables vitamin C canning 67%
mixed vegetables pantothenic acid canning 20-35%
mixed vegetables vitamin B6 canning 40-60%
navy beans calcium cooking 49%
navy beans copper cooking 59%
navy beans iron cooking 51%
navy beans magnesium cooking 65%
navy beans manganese cooking 60%
navy beans phosphorus cooking 65%
navy beans potassium cooking 64%
navy beans selenium cooking 50%
navy beans zinc cooking 50%
onions flavonoids boiling 30%
peanuts lysine cooking at 150F (90 minutes) 20%
peanuts lysine cooking at 150F (150 minutes) 40%
soybeans thiamin boiled 48-77%
spinach calcium blanching 0%
spinach flavonoids boiling 50%
spinach magnesium blanching 36%
spinach phosphorus blanching 36%
spinach potassium blanching 56%
tomato juice folate canning 70%