Cooking makes the fruits less nutritious

Are our soils and plants poor in nutrients?

What does the advertisement say?

If you believe the statements of many suppliers of dietary supplements, our nutrient supply currently looks critical to dramatic: Plant-based foods such as fruit, vegetables and grains are severely depleted in ingredients such as vitamins and minerals, you have to eat 10 times the amount of them to get the same Take in the amount of nutrients as before. The content of "vital substances" has been falling rapidly since the 1970s.

The reason given is depleted and polluted soils in agriculture, which led to a drastic loss of plant constituents. In addition, unripe harvested fruits, genetically modified seeds, UV radiation, long transport routes and storage times should contribute to nutrient losses. Since more and more quantity is being produced instead of quality, the soils cannot recover and one now has to resort to food supplements and vitamin juices.

What is the reality like?

Soil studies in intensively agricultural regions show that soils contain no fewer plant nutrients than they used to be. Rather the opposite is the case. In order to prevent too many nutrients, for example, regular soil examinations take place and fertilization must be carried out on time.

Neither can a general loss of vitamins or minerals be observed over the years in plant-based foods, as regular studies by the Max Rubner Institute show. The Federal Food Code (BLS), the national nutrient database, is updated there regularly. This is the basis for calculating the nutrient intake, for example in the national consumption studies. Nonetheless, these claims about “nutrient poverty in soils and plants” persist.

Since 2002 there has been a special paragraph in the European Food Supplements Directive (2002/46 / EC) against such misleading and frightening advertising. It says: "The labeling and presentation of food supplements and the advertising for them must not contain any information that claims or suggests that a balanced, varied diet generally does not allow adequate amounts of nutrients to be supplied".

Basically, vitamin and mineral contents in fruit, vegetables and grains depend on many factors, for example

  • the type of soil and the nutrient supply / fertilization of the soil
  • on the climatic conditions: e.g. B. Sun exposure, temperature, water supply
  • From the variety: Some apple varieties naturally have a very high vitamin C content such as Berlepsch, others a rather low one, such as Renette. The situation is similar with other types of fruit and vegetables. For example, the beta-carotene content of ten different types of red pepper can vary 30 times.
  • the degree of ripeness and the time of harvest,
  • the duration and type of storage: some types of vegetables can be stored for a long time without losing significant amounts of nutrients, for example beets or solid cabbages.

A certain mineral and vitamin content of the plant is essential for the metabolism, the structure or the regulation of the water balance of the plant. Plants that lack important nutrients for growing and thriving or for seed formation are hardly able to provide harvestable fruits and vegetables: The leaves change color, the plant becomes withered, withered or becomes more susceptible to diseases. A nutritional deficiency can therefore already be seen with the naked eye. Such production would be uneconomical for commercial fruit and vegetable producers.

Soils that have been washed out in the course of geological development mainly affect the trace elements iodine, fluorine and selenium. However, deficiencies can be prevented by enriching table salt, adding it to animal feed and, above all, our globalized diet.

Through imports, storage in modern cold stores and frozen products, we have a rich selection of fruit and vegetables all year round, and an unbalanced diet in winter with mainly cabbage, potatoes and beets as in previous centuries is no longer to be feared.

Some fruits are actually harvested unripe - but these are so-called "post-ripening fruits", whose ripeness is so advanced that they can still develop to the point of consumption after the harvest (for example bananas, avocados, etc.). This is usually achieved with the help of a ripening gas (ethylene). If they are stored too long, the vitamin C content can suffer. If fruits are harvested too early so that they are not ready for consumption, they do not taste good and also spoil more quickly.

What do table values ​​say?

If figures are given in nutrient tables, then these are not exact values, but the average of a more or less large range that was determined in studies. They are more of a clue or just reveal certain tendencies: A person who never consumes dairy products, hardly consumes vegetables and nuts rich in calcium and does not substitute calcium in any other form will have problems with the calcium supply.

The analysis methods are much more precise and specific today than they were in the 1960s or 1970s. For example, it is now possible to determine the content of individual carotenoids (beta-carotene, lutein, zeaxanthin, lycopene, etc.) instead of the total carotenoids. The preparation of the food samples can also be done differently.

This means that a simple comparison of table values ​​50 years old with today's data makes little sense. At least analysis values ​​of the same types of fruit and vegetables from the same region, which were examined with the same analysis methods, would have to be compared. Otherwise it is easy to give the impression that the nutrient content in food has decreased - although here actually "apples with pears" were compared.

  • Fruit and vegetables, both raw and gently cooked, provide many nutrients as well as secondary plant substances such as flavors or polyphenols. Beta-carotene in carrots and lycopene in tomatoes are only really usable for the human organism through chopping and cooking.
  • However, overcooking and keeping them warm for a long time destroy vitamins.
  • It is best to eat freshly harvested food and avoid long storage times. Seasonal and regional fruit and vegetables are good sources of nutrients and particularly tasty.
  • In winter there are fruits and vegetables from storage (for example apples, potatoes, cabbage, carrots, etc.); Citrus fruits and frozen vegetables or berries can enrich the menu.

 

Swell:


German Nutrition Society V .: Vegetables and fruits are not depleted in nutrients! Press information: Presse, DGE aktuell 06/2006 from May 2nd, in: Federal Center for Nutrition, Expert Forum: Fruit and Vegetable Garden, response from August 15th, 2012, viewed on December 14th, 2020

Kirchhoff E: Vitamin and mineral content of plant foods. In: German Society for Nutrition e. V., Bonn (2004): Nutrition Report 2004, pp. 207ff. DGE media service, Bonn.

Schäfer S: Terribly healthy. Despite many food scandals: Everyone can eat well today. Die Zeit, issue 13, March 2013

Buth C, Rainer S: Did fruit contain more vitamins in the past? NDR market. Transmission date: 08/06/2012 8:15 p.m.

Swiss Society for Nutrition: Vitamins - how to destroy them and how to conserve them. Tabula No. 2, April 2004, accessed on December 14, 2020

Max Rubner Institute, Karlsruhe, personal communication, June 23, 2017