Why do we cook?
Cooked Foods Will Be Easier to Chew and Digest, and at times be healthier than raw.
What nutrition do we get out of the foods we eat:
Chewing is the first step in the digestive process.
Chewing breaks down large pieces of food into small particles that are easier for your body to use as fuel.
Cooking food First, the process of:
It breaks down some of its fibers and plant cell walls, so the body can digest it.
Cooking also generally improves the taste and aroma of food.
Properly cooking grains and legumes not only improves their digestibility but also reduces the number of anti-nutrients they contain.
The digestibility of food is important because your body can only receive a food’s health benefits if it’s able to absorb the nutrients.
Foods Better Raw Than Cooked:
Broccoli: Raw broccoli contains three times the amount of sulforaphane, a cancer-fighting plant compound than cooked broccoli does.
Cabbage: Cooking cabbage destroys the enzyme myrosinase, which plays a role in cancer prevention (If you choose to cook cabbage, do so for short periods).
Onions: Raw onion is an antiplatelet agent, which contributes to heart disease prevention. Cooking onions reduces this beneficial effect.
Garlic: Sulfur compounds found in raw garlic have anti-cancer properties. Cooking garlic destroys these sulfur compounds.
Foods That Are Healthier Cooked
The nutrient content is often altered during cooking
Asparagus: Cooking asparagus breaks down its fibrous cell walls, making folate and vitamins A, C, and E more available to be absorbed.
Mushrooms: Cooking mushrooms helps degrade Agaritine, a potential carcinogen found in mushrooms. Cooking also helps release ergothioneine, a powerful mushroom antioxidant.
Spinach: Nutrients like iron, magnesium, calcium, and zinc are more available for absorption when spinach is cooked.
Tomatoes: Cooking greatly increases the antioxidant lycopene in tomatoes.
Carrots: Cooked carrots contain up to six times more beta-carotene than raw carrots.
Potatoes: The starch in potatoes is nearly indigestible until the potato is cooked.
Legumes: Raw or undercooked legumes contain dangerous toxins called lectins. Lectins are eliminated with proper soaking and cooking.
Meat, fish, and poultry: Raw meat, fish, and poultry may contain bacteria that can cause food-borne illnesses. Cooking these foods kills harmful bacteria.
We should always ask ourselves which way should we cook, so vegetables keep their vitamins.
Which cooking method retains the most nutrients?
#1: Steaming.
Steaming is the gentlest and healthiest way to prepare food, which keeps most nutrients.
#2: Grilling.
Grilling lets you get maximum nutritional value from your vegetables and helps food retain its truest flavor.
Cooking food improves digestion and increases the absorption of many nutrients.
For example, the protein in cooked eggs is 180% more digestible than that of raw eggs.
The following nutrients are often reduced during cooking:
Water-soluble vitamins: vitamin C and the B vitamins
Fat-soluble vitamins: vitamins A, D, E, and K
Minerals: primarily potassium, magnesium, sodium, and calcium.0
Boiling, simmering, and poaching
….are water-based cooking methods. These techniques differ by water temperatures.
Poaching: is less than 180°F (82°C)
Simmering: is 185–200°F (85–93°C)
Boiling: is 212°F (100°C)
Vegetables are generally a great source of vitamin C, but a large amount of it is lost when they’re cooked in water.
Boiling reduces vitamin C content more than any other cooking method. Broccoli, spinach, and lettuce may lose up to 50% or more of their vitamin C when boiled. Because vitamin C is water-soluble and sensitive to heat, it can leach out of vegetables when they’re immersed in hot water.
B vitamins are similarly heat sensitive. Up to 60% of thiamine, niacin, and other, B vitamins may be lost when meat is simmered.
However, when the liquid containing these juices is consumed, 100% of the minerals and 70–90% of B vitamins are retained.
On the other hand, boiling fish was shown to preserve omega-3 fatty acid content significantly more than frying or microwaving.
So it can be said, boiling doesn't hurt omega-3 fats and if you, use the cooking water as a soup or broth your dish retains B & C vitamins.
Grilling and broiling
Grilling and broiling are similar methods of cooking with dry heat. Grilling provides the best-tasting foods.
However, up to 40% of B vitamins and minerals may be lost during grilling or broiling when the nutrient-rich juice drips from the meat.
Also, grilling generates potentially cancer-causing substances.
Microwaving:
Microwaving is an easy, convenient, and safe method of cooking. Short cooking times and reduced exposure to heat preserve the nutrients in microwaved food.
Microwaving is the best method for retaining the antioxidant activity of garlic and mushrooms.
20–30% of the vitamin C in green vegetables is lost during microwaving, which is less than most cooking methods.
Sautéing and stir-frying: In general, this is a healthy way to prepare food.
With sautéing and stir-frying, food is cooked in a pan over medium to high heat in a small amount of oil.
These techniques are very similar, but with stir-frying, the food is stirred often, the temperature is higher, and the cooking time is shorter.
Cooking for a short time without water prevents the loss of B vitamins, and the addition of fat improves your body's absorption of plant compounds and antioxidants.
One study found that the absorption of beta-carotene was 6.5 times greater in stir-fried carrots than in raw ones.
Blood lycopene (relatively popular in most studies about cancer-fighting) levels increased 80% more when people consumed tomatoes sautéed in olive oil rather than without it.
On the other hand, stir-frying has been shown to significantly reduce the amount of vitamin C in broccoli and red cabbage.
Frying:
Frying involves cooking food in a surplus of fat — usually oil — at a high temperature. The fat used for frying also makes the food taste very good.
The food is often coated with batter or breadcrumbs. It’s a popular way of preparing food because the skin or coating maintains a seal, which ensures that the inside remains moist and cooks evenly.
Fatty fish are the best sources of omega-3 fats, which have many health benefits. However, these fats are very delicate and prone to damage at high temperatures.
Frying tuna has been shown to degrade its omega-3 content by up to 70–85% while baking causes only minimal losses.
Frying preserves vitamins C and B vitamins,
Frying also increases the amount of fiber in potatoes by converting their starch into resistant starch (see Notes).
When oil is heated to a high temperature for a long period, toxic substances called aldehydes are formed. Aldehydes have been linked to an increased risk of cancer and other diseases.
Reheating oil also increases aldehyde formation.
Notes:
Resistant starch:
Resistant starch is starch, including its degradation products, that escapes from digestion in the small intestine of healthy individuals. Resistant starch occurs naturally in foods, but it can also be added as part of dried raw foods, or used as an additive in manufactured food.
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Steaming:
Steaming is one of the best cooking methods for preserving nutrients.
Steaming broccoli, spinach, and lettuce reduce their vitamin C content by only 9–15%.
Tips to maximize nutrient retention during cooking
Here are 12 tips to reduce nutrient loss while cooking.
The bottom line is that no one cooking or preparation method is superior for preserving 100 percent of the nutrients in a vegetable.
According to a review by researchers at the University of California, Davis, as much as 55 % of the vitamin C in vegetables is lost during home cooking (compared with raw). Vitamin C is also easily degraded by heat.
Use as little water as possible when poaching or boiling. Keep the cover tightly sealed. Use this water to cook Quinoa, rice, or other starch.
Cook vegetables for only a few minutes whenever possible.
Use the liquid left in the pan after cooking vegetables in the dish's final preparation.
All lost nutrients and vitamins are still in there.
Add back juices from the meat that drip into the pan. When you let a steak rest, the juices have a chance to go back through the well-done sections of the steak, collect the juices and use in its sauce.
Don’t peel vegetables until after cooking them. The nutrients in fruits and vegetables are concentrated just below the skin.
Try to eat any cooked vegetables within a day or two, as their vitamin C content may continue to decline when the cooked food is exposed to air.
Reheating cooked vegetables destroys vitamins.
Cut food after rather than before cooking. When food is cooked whole, less of it is exposed to heat and water.
When cooking meat, poultry, and fish, use the shortest cooking time needed for safe consumption.
Do not cut vegetables into very small cubes, as the surface area of vegetables interacts with oxygen and destroys vitamins.
Do not soak vegetables in water to prevent discoloration (browning). 40% of water-soluble vitamins are lost during soaking.
Salads should be prepared just before serving and should be served in closed dishes to prevent excessive exposure to air.
Do not keep milk open or exposed to light, as considerable destruction of riboflavin can occur.
Summary of food and CoFoodg:
How are nutrients affected by the cooking process?
The heat diminishes vitamins and phytonutrients (beneficial plant compounds other than vitamins or minerals) in fruits and vegetables.
The longer they cook, and the higher the temperature, the greater the nutrient destruction.
Steam, don’t boil: To get the maximum nutritional benefits, you need to cook vegetables correctly.
Even chopping food can begin to erode some of the nutrients
Fat-soluble nutrients such as vitamins A, E, and K are more stable and fare better during cooking.
So do carotenoids (e.g., beta-carotene, alpha-carotene, lycopene, lutein), antioxidants found in leafy greens, carrots, winter squash, and sweet potato.
Microwave cooking helped maintain the highest levels of antioxidants in beans, beets, artichokes, asparagus, garlic, onion, and spinach.
Microwave cooking increased antioxidant activity in eggplant, corn, peppers, and Swiss chard.
Spinach retained nearly all of its folate when microwaved, but lost most of the B vitamin when boiled on the stove.
Cruciferous vegetables – cabbage, cauliflower, broccoli, bok choy, Brussels sprouts – contain an enzyme called myrosinase, which, when you chop or chew these vegetables, converts glucosinolates (phytochemicals) to anti-cancer compounds called isothiocyanates.
Polyphenols – phytochemicals plentiful in kale, spinach, and broccoli – are also susceptible to degradation during cooking.
In minerals like iron, calcium, magnesium, potassium, and sodium, the loss is only in the range of 5 to 10 percent no matter how the vegetable is cooked.
Steaming led to the lowest loss of glucosinolates in broccoli, while stir-frying and boiling (both higher-heat cooking methods) caused the greatest loss.
Examples of functional foods: | ||||
Functional component | Functional food | Potential benefit | ||
1. Carotenoids | ||||
α – carotene | Carrots | Neutralize free radicals which may cause damage to cells | ||
β – carotene | Fruits and vegetables | Reduces risk of prostate cancer | ||
lycopene | tomatoes | Cancer-fighting | ||
2. Dietary fiber | ||||
Insoluble fiber | Wheat bran | Reduces risk of breast or colon cancer | ||
β – Glucan | Oat, rye | Reduces risk of cardiovascular diseases | ||
3. Omega-3 fatty acid | Fish oil, walnuts | Reduces risk of cardiovascular diseases | ||
Improve mental and visual function | ||||
4. Conjugated linoleic acids | Cheese, meat products | Improve body composition, reduce risk of certain cancer | ||
5. Flavonoids | Neutralize free radicals and reduce the risk of cancer | |||
Anthocyanin | Fruits (berries) | |||
Catechins | Tea | |||
Flavanones | Citrus | |||
Flavones | Fruits and vegetables | |||
What Takes Nutrients Out of Food? | ||||
Nutrient: | Heat | Air | Water | Fat |
Vitamin A | X | X | ||
Vitamin D | X | |||
Vitamin E | X | X | X | |
Vitamin C | X | X | X | |
Thiamin | X | X | ||
Riboflavin | X | |||
Vitamin B6 | X | X | X | |
Folate | X | X | ||
Vitamin B12 | X | X | ||
Biotin | X | |||
Pantothenic acid | X | |||
Potassium | X | |||
Many vegetables (such as tomatoes, eggplant, asparagus, and green beans) retain 80 percent or more of their vitamins regardless of the cooking method.
Functional foods are generally considered as those foods that are intended to be consumed as part of a normal diet and that contain biologically active components which offer the potential for enhanced health or reduced risk of disease.
Functional foods: People are starting to look at food as a prescription for health. Functional Foods are ingredients beyond their basic nutritional values that are medically beneficial.
Physiological benefits and reduces the risk of chronic disease beyond basic nutritional function.
Examples include tomatoes, broccoli, citrus fruits, leafy vegetables, and many more.
Functional foods are generally a rich source of minerals, vitamins, essential fatty acids, and dietary fiber.
Functional food can also be processed with biologically active substances such as nutraceuticals, phytochemicals, or other antioxidants and probiotics.
Nutraceuticals are the extracts of functional foods.
Functional foods can be classified as:
Probiotics: These are the live bacteria that improve gut health, and prevent lactose intolerance and constipation. They also provide some essential vitamins (B9, B12) in the body.
Conventional food: This includes whole food like whole cereal grains and legumes, fresh fruits, and vegetables. They are a rich source of vitamins, antioxidants, fibers, and minerals.
Designed food: They are nutraceutical-incorporated foods and are designed for boosting specific body functions and helping with diseases like heart disease, diabetes mellitus, and cancer.
FYI
Appendix:
Nutrition Vocabulary
Nutrition news is all around us. A lot of the newsworthy topics are peppered with hard-to-define words. While some terms may be familiar to you, the key is to become acquainted with a variety of terms so that you can make informed decisions about your food choices.
Let’s look at a few terms:
1. Free Radicals-our bodies naturally produce these chemicals that attack and damage healthy cells.
The most common free radical in humans is an oxygen molecule that has become electrically charged.
Oxidation damages cell structure and can potentially lead to illnesses such as type 2 diabetes, heart disease, and cancer.
Individuals can also be exposed to free radicals found in our environments such as smoke, pollution, and cigarette tar.
In addition, more free radicals are produced under stress.
2. Antioxidants-chemicals found naturally in plants such as vitamins C, E, and beta-carotene.
They help to neutralize free radicals and keep cells healthy.
To understand the difference between free radicals and antioxidants, consider the way sliced apples turn brown when exposed to air. The “browning” effect of the apple slices is due to free radical damage or oxidation. However, you can prevent the browning from occurring by using lemon juice or fruit freshener, which contains vitamin C, an antioxidant. To get plenty of antioxidants in your diet, consume brightly colored fruits and vegetables, herbs, and nuts.
3. Trans Fatty Acids-these fats act like saturated fat in the body, elevating blood cholesterol levels and increasing our risk for heart disease.
These fats have also been found to lower our good cholesterol or HDL levels.
Trans fats result from changing the chemical structure of liquid fat and making it more solid at room temperature.
To decrease your intake of trans fats, use liquid oils rather than solid fats and if you choose to eat processed foods look at the label carefully.
4. Isoflavones-natural chemicals believed to have disease-fighting effects and are found mainly in soy foods.
Despite conflicting data, FDA maintains that eating foods such as soy milk, tofu, soy nuts, and tempeh may reduce the risk for heart disease as well as certain cancers.
5. Omega-3 Fatty Acids-these building blocks of fat are found in certain kinds of fish and plant
foods.
Omega-3’s may lower the risk of heart disease; reduce artery inflammation and boost
immunity.
ADA recommends eating 2-3 fish meals per week.
Other sources of Omega-3s include walnuts, flaxseed, and flax oil.
6. Phytochemicals-these substances are part of all plant-based foods, including fruits, vegetables, nuts, and grains.
Phytochemical intake has been linked to the prevention of cancer and heart disease.
a phytochemical called lycopene, which is present in the red pigment of tomatoes, pink grapefruit, and watermelon.
Fat-soluble vitamin:
Vitamin A:
Preformed vitamin A is present in animal food sources only, such as fish liver oil, and egg yolk.
Vitamin A is also formed in the body in the form of provitamin A carotenoids, which include β – carotene and other carotenoids.
Pro-vitamin A occurs in plants such as carrots, mango, and dark green leafy vegetables like spinach, papaya, amaranth, and coriander.
Stability of vitamin A:
Relatively stable to heat in the absence of oxygen
Susceptible to oxidation in the presence of light and oxygen
Unstable under the influence of mineral acid, but stable in alkali.
Functions of vitamin A:
Epithelium tissue functions as a barrier and forms the body’s first line of defense against infection.
Regulation of gene expression: Retinoic acid acts as a hormone to affect gene expression and thereby influence numerous physiological processes.
Vitamin D:
The two most important forms are:
Vitamin D2 = Ergocalciferol
Vitamin D3 = Cholecalciferol
In animal tissue, 7 – dehydrocholesterol, which occurs naturally in the epidermal layers, can be converted by UV radiation to vitamin D3. Therefore, vitamin D is sometimes called the sunshine vitamin.
Food sources of vitamin D: fish liver oil, egg, milk, and fortified foods.
Functions of vitamin D:
Vitamin D is essential for the efficient utilization of calcium by the body.
Active forms of vitamin D enhance innate immunity and inhibit the development of autoimmunity.
Vitamin D plays a role in insulin secretion under a condition of increased insulin demand.
Adequate vitamin D level is important for decreasing the risk of high blood pressure.
Vitamin E:
Vitamin E refers to the family of eight antioxidants.
Stability of vitamin E: Vitamin E is lost in significant amounts during the refining and deodorization of vegetable oil.
Heating, frying, storage, etc. all reduce vitamin E concentration in oil.
Food sources of vitamin E: vegetable oil, nuts, whole grain, and green leafy vegetables.
The function of vitamin E:
Vitamin E acts as an antioxidant and prevents chain reaction of lipid destruction.
Vitamin E enhances blood vessel properties.
Vitamin K:
The word vitamin K is derived from the German word “koagulation” which refers to coagulation (blood clotting).
Note: I am currently reading that vitamin K should be taken with vitamin D because vitamin K prevents the calcium derived from D from forming in the arteries and sends it to the bone instead.
Stability of vitamin K: Vitamin K is slowly decomposed by atmospheric oxygen but is readily destroyed by light. It is stable against heat but unstable against alkalis (Sodium, Potassium).
Food sources of vitamin K: Spinach, cabbage, oranges, fish, liver, meat, and egg
Water-soluble vitamin:
Thiamine (vitamin B1)
Thiamine helps in glucose utilization by nerve tissues.
Sources: yeast, liver, outer layer of cereal grain, lean meat, soybean
Riboflavin (vitamin B2)
Helps in an oxidation-reduction reaction. Exhibits antioxidant functions.
Critical for the metabolism of carbohydrates, fat, and protein
Food sources: yeast, liver, milk, wheat germ, egg, green leafy vegetables, germinated legumes.
Niacin (vitamin B3)
Plays a role as a coenzyme (like a key fits a lock) in as many as 200 enzymes.
Important for the synthesis of fatty acids and cholesterol
Food sources: Yeast, liver, legumes, peanuts, outer coat of cereals, meat, fish.
Pantothenic acid (vitamin B5)
Generate energy from food (fat, carbohydrate, and protein)
Important for the synthesis of fat, cholesterol, and steroid hormone.
Food sources: yeast, liver, kidney, egg yolk, legumes, and nuts.
Pyridoxine (vitamin B6)
There are different forms of vitamin B6. Animal tissue contains pyridoxal and pyridoxamine while plants contain pyridoxine.
Plays a role in the generation of glucose from amino acids (gluconeogenesis)
Important for the synthesis of neurotransmitters and components of (blood) hemoglobin.
Food sources: meat, fish, egg, soybean, spinach.
Biotin (vitamin B7)
Biotin is required by all organisms.
Biotin is required for the synthesis of fatty acids.
Required for metabolism of leucine (essential amino acid).
Critical to act in the metabolism (use the energy it produces) of cholesterol and fatty acid.
Food sources: egg yolk, liver, yeast.
Folic acid (vitamin B9)
Plays an important role in DNA metabolism
Required for metabolism of several important amino acids (protein building blocks).
Food sources: yeast, liver, spinach, amaranth, mint. Intestinal bacteria also synthesize large amounts of folate.
Cyanocobalamin (Vitamin B12)
Largest and most complex of all vitamins.
Plays a role in the production of energy from fat and protein. Plays a role in the synthesis of hemoglobin.
Functions as a cofactor for many enzymes.
Only bacteria can synthesize vitamin B12.
Sources: meat, poultry, fish, and to a lesser extent in milk. It is not generally present in plant products or yeast.
L- Ascorbic acid (vitamin C)
Vitamin C occurs in all living tissue.
Man, apes, monkeys, and some other animals cannot synthesize vitamin C.
Vitamin C is required for the synthesis of collagen and neurotransmitters.
It is a strong antioxidant.
Sources: guava, cabbage, citrus fruits. Animal sources such as milk, and liver also contain vitamin C.
Deficiency: “scurvy” relating to bleeding of gums, joint pain and hair, and tooth loss.
