The debate between raw & cooked foods on its perceived benefits for health, is never ending. There are raw protagonists, for whom cooking is the worst thing that happened to humans. Then there are people, who are fine with either of them, which consists of most of the population.
Whenever we talk about raw foodies, they are the ones who majorly consume foods which are uncooked, unheated, and unprocessed. For someone to eat raw food diet, they should be consuming 70% of their foods in raw form.
Foods like raw vegetables and fruits, nuts, seeds, fermented foods, sprouts, raw dairy etc. all come under the gamut of raw foods. Mostly, people who consume raw foods are vegetarians or vegans. But there are people who eat meat, fish and poultry, along with raw foods.
Acc. to the beliefs of raw foodies, in process of cooking, most nutrition is destroyed, and it also destroys the natural enzymes present in food, which overall makes the cooked food, toxic in nature.
But that’s not how things really work, when we study a subject scientifically. Both raw and cooked foods have their respective benefits, and it’s a combination of both, which gives you overall health benefits.
When it comes to cooking, evidence suggests that, humans adapted to a cooked diet at least 275,000 years ago.
For digesting food, the body secretes a range of enzymes. For e.g. lipase, amylase, trypsin, chymotrypsin etc. On the other hand, the foods which we eat, also contain enzymes that help us in digesting them.
The argument of raw foodies is that, cooking destroys all the enzymes in the food, and as a result, your body has to secrete more of its own enzymes to digest food, which is an extra stress on the body, and can lead to enzyme deficiency.
The logic seems fine, but there is absolutely no scientific study or evidence to back this theory of belief. This is because the human body secretes ample enzymes to digest its food. And the enzymes produced by the plant is to help in the growth of the plant, and not to help in human digestion. On top of that, till date there is no evidence of any adverse health effect of eating cooked food, because lack of enzymes.
In fact, acc. to a study, digestive enzymes can be absorbed into blood, reaccumulated by the pancreas, and reutilized, instead of being reduced to their constituent amino acids in the intestines. This is called an enteropancreatic circulation of digestive enzymes.
Irrespective of the method used for cooking, there will be always some amount of nutrition loss during cooking. A study, found that losses during cooking were 34.6, 30, 52.2, 45.9 and 32.2% in case of ascorbic acid, thiamine, riboflavin, beta-carotene and folic acid respectively.
Another study found that, almost 50% of the thiamine is lost during cooking. The cooking losses of thiamine were particularly large in rice and green vegetables. The loss of thiamine largest in boiling, followed by baking, parching and frying.
Similarly, a study found that, heating time has significant effect on the vitamin C content of all the vegetables, as the heating time increases, the percentage loss of vitamin C increases too. Vitamin C is easily destroyed by excessive heat and water, as well as exposure to air. For retention of vitamin C in cooked foods, it is recommended that foods containing vitamin C be cooked as fast as possible with less heat and small amount of water.
On the other hand, the fat soluble vitamins i.e. A, D, E & K generally unaffected by cooking. Though vitamin A may show some losses.
A study found that, prolonged cooking in both pressure cooking and boiling resulted in a significant loss in Fe and Ca. A significant loss of ascorbic acid and Beta-carotene were observed during 2 cooking methods, the greater loss was during boiling.
Cooking methods also play an important role in nutrient preservation and loss.
A study found that, cooking losses are particularly high in minerals of vegetables. Among various cooking methods, loss of mineral was largest in squeezing after boil and in soaking in water after thin slice, followed by parching, frying and stewing.
The measures to prevent cooking loss are (a) eating the boiled food with the soup, (b) addition of small amount of salt in boiling, (c) avoidance of too much boiling, (d) selection of a cooking method causing less mineral loss (stewing, frying or parching).
Another study, investigated the effects of five domestic cooking methods, including steaming, microwaving, boiling, stir-frying, and stir-frying followed by boiling (stir-frying/boiling), on the nutrients and health-promoting compounds of broccoli.
The results show that all cooking treatments, except steaming, caused significant losses of vitamin C & glucosinolates. In general, the steaming led to the lowest loss of total glucosinolates, while stir-frying and stir-frying/boiling presented the highest loss.
However, cooking has its own benefits. For e.g. the previous study showed that, pressure cooking and boiling resulted in significant destruction in the anti-nutrients like phytates, tannins and trypsin inhibitors, specially found in grains, and improved protein digestibility.
Phytic acid is a naturally occurring chemical in grains that can partially block the availability of the grain minerals, including iron and zinc.
Also, cooking food, increases the digestibility of food, enhances the taste and aroma, and help absorb nutrients better. Studies have shown, cooking helps in complete gelatinisation of starch, efficient denaturing of proteins, and killing of food borne pathogens.
Our digestive system isn’t equipped to deal with starchy sources of carbohydrates, like rice, pasta, or potatoes, unless we cook them first. The heat transforms hard-to-digest starch into a gelatinous gel and disperses the molecules in a way that allows access for our digestive enzymes.
Cooking of food played a major role in human evolution partly by providing an increase in net energy gain. For meat, cooking compromises the structural integrity of the tissue by gelatinizing the collagen. Hence, cooked meat should take less effort to digest compared to raw meat (https://bit.ly/3D4ZfiE).
In simple terms, better digestion of food, means better absorption of nutrients, and that’s why there are many foods which provide more nutrient when cooked.
Another benefit of cooking food is its increase in antioxidant content. For e.g. carotenoids. The study showed that, cooking helps increase the extractability of phytochemicals, resulting in a higher concentration with respect to the raw material.
A study found that, cooking tomatoes reduced their vitamin C content by 29%, while their lycopene content more than doubled within 30 minutes of cooking. Also, the total antioxidant capacity of the tomatoes increased by over 60%.
The study concluded that thermal processing enhanced the nutritional value of tomatoes by increasing the bioavailability of lycopene content and total antioxidant activity and busted the notion that processed fruits and vegetables have lower nutritional value than fresh produce.
Similarly, another study showed that, heating at 115deg C for 25 min significantly elevated the total antioxidant activity of sweet corn by 44% and increased phytochemical content such by 550% and total phenolics by 54%, although 25% vitamin C loss was observed.
Yet another study found an overall increase in total antioxidant content, in cooked vegetables like carrots, broccoli & zucchini.
In case of eggs two types of proteins are present – Conalbumin protein can bind together with iron and blocks its availability, and Avidin protein which can bind together with biotin (B- vitamin) making it unavailable. The cooking of eggs helps denature both of these proteins, and can increase the availability of both iron and biotin from eggs (https://bit.ly/3HoxPa8).
Cooking food, helps destroy and eliminate harmful bacteria, that may cause food-borne illnesses. Foods most commonly associated with diarrhoea are raw or undercooked sea foods like meat, shrimps, clams and fish. Traditional way of cooking meat i.e. boiling it for several hours, is highly recommended, which can kill bacteria (https://bit.ly/3Y5aCiL).
Raw foods may harbour pathogens. That why, cooking food thoroughly and eating it as soon as it is cool enough for consumption would control the majority of contaminants in food and a significant number of foodborne illnesses (https://bit.ly/3J5nfG5).
Eggs can also be a source of infective organisms. Salmonella can easily pass through the shells of newly-laid eggs, especially in wet contaminated environments. Unpasteurized milk is another source of organisms like brucella and salmonella, which cause food-borne infections (https://bit.ly/3J5nfG5).
Acc. to a study, while the renunciation of heating of a single food in most cases has no direct consequences for the nutrition of an individual (not taking into account the inactivation of food-borne pathogens and the destruction of natural toxins), the strict renunciation of any warming/heating and processing has strong consequences, making a well-balanced nutrition with a great choice of food products difficult. This is mainly due to the fact that some harmful ingredients are only rendered harmless by cooking, and that some foods get eatable after cooking or baking only (e.g., pasta, rice, bread, cakes, and likewise hot beverages, such as tea or coffee).
Here is a list of foods you can eat raw or cooked (https://bit.ly/3XrnM9O):
Foods That Are Healthier Raw
- 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 anti-platelet 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
- 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 more beta-carotene than raw carrots.
- Potatoes: The starch in potatoes is nearly indigestible until a 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.