Last update and review: November 6, 2020.
A short summary.
In their 1990 (1) study, Kimura and Itokawa investigated “cooking losses of minerals in foods”. The results are informative and can be used to optimize nutritional content of a diet.
The study by Kimura and Itokawa, 1990 (1).
Experimental materials and methods.
The table below gives a general description of the experimental methods, that is of the foods and methods of cooking. Unfortunately, as we will see further, the information on home cooking methods is not complete.
Vegetable salad cooked at home lost on average 21% of the different minerals it contains.
Unfortunately, the authors (1) do not state clearly for how long they cooked salad and what was the medium. Was it water? Given the information on other cooking methods, the duration of cooking in this case was probably short, several minutes.
Spinach lost between 40% and 90% of the different minerals it contained after 1 minute of cooking in CH₃COOH.
As a rule of thumb, expect that boiling of porc for a long time will result in a loss of 50% or more of its different minerals.
The table above is interesting. It clearly shows the time of cooking. We can see that the loss of minerals is quite impressive even after just several minutes of cooking.
Conclusions.
Loss of minerals by cooking is an important factor in nutrition. It turns out that meat loses a lot of minerals during cooking. If the broth from the meat that you eat is frown away, your intake of minerals may be suboptimal despite high meat content of your diet. Meat that is not perfectly fresh may contain a lot of histamine. Heat does not destroy histamine and the only way to reduce its content is to allow some histamine to leak into the brouth during cooking. We need then to throw away the broth. But if we also throw away with the brouth a large proportion of minerals, this way of reducing histamine is not the best idea.
Vegetables also lose minerals during cooking rather quickly. This can be exploited to enrich a diet in minerals, especially for those who have digestive issues when eating vegetables themselves.
Selected references:
1. Kimura M, Itokawa Y. J Nutr Sci Vitaminol (Tokyo). 1990;36 Suppl 1:S25-32;