In Edible Form
For millennia humans have processed their food to make it keep longer, and improve its taste and consistency. To start with there were probably various types of earth ovens, where embers or heated stones were placed in a hollow along with food that was wrapped in large leaves.1
After these introductory experiments by the cooks on the savanna, the various ways to prepare food have steadily increased. Salting, preserving and roasting. Fermenting, coating, marinating, breading and poaching; the list goes on and on. Only our imagination sets limits on how we can process food. Not every way is equally good, however, at least not from a health standpoint.
Positive Effects of Heating
Heating kills bacteria and makes it easier for the body to digest carbohydrates, such as starch in potatoes. In addition, many plants contain poisonous substances that are depleted or break down during heating.
In some cases cooking makes the cell walls of plants open up so that nutrients are released. This applies for example to beta-carotene, a precursor to vitamin A, which is found in carrots. Cooked carrots are thus more nutritious than raw carrots.2
Heating Also Has Negative Effects
In other cases heating means that water-soluble vitamins in vegetables pass into the water, reducing the nutritional value. This applies in particular if you boil vegetables for a long time in too much water.
When some foods are heated to a high temperature, such as in baking, deep-frying and roasting, acrylamide, a carcinogenic substance, is formed. Chips, French fries, coffee, crackers and cookies can in some cases contain considerable amounts of acrylamide.3
A good way to keep the quantity of acrylamide down is to only let fried potatoes, toast or baked goods get golden-yellow rather than dark brown. The acrylamide content increases the darker the food gets when cooked. In soft bread the acrylamide content is highest in the crust. Acrylamide is not formed by boiling.
Smoking meats or fish can produce high quantities of the substance PAH, which is also carcinogenic and forms with various incineration processes.
PAH is also formed with grilling, regardless of whether a charcoal, electric or gas grill is used. The risks of PAH are markedly reduced if you keep fat from dripping down into the embers and forming fumes.3
Avoid Processed Food
Meat products that have been smoked, processed with nitrite or preserved in some other way increase the risk of type 2 diabetes as well as colorectal cancer. Examples are sausage, bacon, smoke-cured pork, smoked ham and liver sausage. A large obesity study in 2014 also showed a clear connection between meat products and cardiovascular disease.4
What then Should I Eat?
After this review, the question may start to creep up on you: What in the world should I eat? Everything seems hazardous!
A basic rule may be to avoid processed food and food that is subjected to high temperature for a long time. Here we offer a few specific tips about how form and preparation can make food healthier:
- Boiled food or food that is baked is generally more nutritious than fried, deep-fried or grilled food.
- Ready-to-eat food and store-bought cookies and crackers usually contain higher amounts of trans fats than home-made versions. If for various reasons you prefer ready-to-eat food, then make use of the list of ingredients as a guide to good products.
- A home-made pizza on a rye flour crust or a hamburger with whole-grain bun can be a healthier alternative to traditional varieties. Sometimes small means can produce great effects without having to give up dishes that you like.
- Mashed food produces a faster rise in blood sugar. For example, mashed potatoes make blood sugar rise faster than boiled potatoes. Fruit soup and fruit creams raise blood sugar faster than whole fruits (prepared creams and soups also often have added sugar).
- Try to eat berries in their natural form, which have high fiber content. As soon as berries are mixed in jam or cream it becomes unhealthy.
- Fruit too is best eaten in as natural a form as possible. One of the most common misunderstandings is that juice and nectar are nutritious. But they contain just as many carbohydrates as soda and produce a rapid rise in blood sugar. Whole fruits on the other hand have a lot of fiber and antioxidants in the peel and membranes.
- In general calories in liquid form, e.g. in soda and juice, are deceptive because they almost never produce a sense of fullness.
- Whole-grain bread produces a slower rise in blood sugar.
- Antioxidants have best effect if they are taken by way of fruit and green vegetables instead of as dietary supplements in tablet form. Dietary supplements often do not give the natural balance and interaction between antioxidants. Studies have shown that supplements of e.g. vitamins or omega-3 in the form of tablets do not have any positive effect on health.4
Of course it makes a big difference what foods we eat. Their form and method of preparation however are possibly even more important. You’ve probably heard much of this before. But it is one thing to nod in recognition when you read a list of tips, and something else again to consistently apply them on a daily basis.
How can you personally improve the form of your food?
1. Lindeberg, S. Maten och folksjukdomarna.
2. Helgegren H et al., Bra mat vid typ 2-diabetes
4. Rosén M. Sanningen om mat och hälsa