Human beings need macronutrients (proteins, lipids and carbohydrates) for their correct nutrition. In turn, it need micronutrients, in much more modest amounts, but absolutely essential: they are vitamins and minerals.
In a very general way we can say that the Western diet is abundant in macronutrients. We consume an excess of proteins (which does not mean that they cover all our qualitative needs), lipids (fats) and carbohydrates but we cannot say the same about micronutrients. The current diet, with little fresh fruit and vegetables, tends to be depleted of vitamins and the same occurs with minerals, although for different reasons. Without going excessively to the nutritional tables, it is possible to affirm that if we eat very varied we can cover the entire spectrum of necessary nutrients. If instead our diet is based on hamburgers or exclusively on pasta and salads, of course not (although it might seem that low-calorie diets are healthier, they actually often have serious deficiencies).
We can mess around with most of the nutrients except for iron, which is very delica. In te matterfact, its deficiency is a serious matter in all the diets of the planet, to the point that it is thought that 30% of the world's population has deficiencies. No joke: that 2 billion human beings have problems related to nutritional iron is something to take into account.
Iron deficiency ranges from a deficiency that is never detected to severe anemia, decreased intellectual abilities or less resistance to exertion.
Let's see how it happens. Iron is found in very small amounts in the human body. An adult man "contains" 4 grams while the adult woman has just 2.5 grams. Despite its low presence, it is vital in the constitution of hemoglobin, the essential enzymes of cellular metabolism (cytochromes, catalases and peroxidases) as well as myoglobin of the muscle (hence the lack of iron translates into less resistance against effort that we mentioned earlier).
Iron in the human body is subdivided into two large groups:
- heme iron, present in hemoglobin and representing 65% of the total.
- non-heme iron, composed of non-heme enzymes, transferrin and reserves.
Hemoglobin allows the daily transport of 700 to 1000 liters of oxygen per day to the cells and therefore makes daily use of iron. Instead myoglobin and ferritin are forms of iron stores, the former for the muscles and the latter for storage in the liver. That is, something good had to have the iron, at least it is stored in our body. It can be said that our body is quite thrifty with regard to iron; however, it is a real disaster when it comes to absorbing it and also because of the losses that suffers.
Iron content of food (milligrams per 100 grams):
Fruits ............................ 0.1 to 0.3
Potatoes ........................ 0.7
Spinach ......................... 4
Legumes ....................... 6
Lentils .......................... 7
Beef ............................. 1.2 to 2.5
Pork ............................. 1
Beef liver ..................... 8
Blood sausage ............. 14
Breakfast "all bran"...... 14
Wheat germ ................. 9
Mussel ......................... 7
Pistachio ...................... 7
From the above list it can be deduced that animal foods (meat, liver, blood sausage, mussel) are the richest in iron followed by legumes.
Spinach, extolled by the ineffable Popeye, is rich in iron but not too much either.
The problem is not really the amount of iron in the food, but the absorption capacity of the human body. Heme iron, which is found in all foods of animal origin, is absorbed much better than non-heme iron, which is mainly vegetal.
In the first we can reach 25% while in the second we reach a maximum of 5%. Thus we have that in a serving of 100 grams of legumes, of the 7 mg available we can absorb a maximum of 0.35 grams. The same amount of mussels would allow us to absorb 1mg, if it were from calf liver 1.6mg and if it were breast milk we could absorb 30% of the iron from it.
How much iron do we need on a daily basis?
We have said before that iron works in our body almost like a "closed circuit", in a very economical way. Even so there are losses that must be compensated. In adult men, this loss is around 1 mg of iron / day while women, due to the menstrual cycle, can lose a daily average of 1.3 mg. In general, the problem linked to nutritional iron is more important in women than in men.
The recommended intakes per day in mg are:
Infants from 3 to 12 months ........................... 9 mg
Children up to 12 years ................................. 10 mg
Adolescents in full "stretch" .......................... 15 mg
Adult male .................................................... 10 mg
Women throughout the fertile cycle ............. 18 mg
Women after menopause .............................. 10 mg
Pregnant women .......................................... 20 to 30 mg
Lactating women .......................................... 20 mg
Let us remember that of these quantities only a part is absorbed, which is why they are not exaggerated at all. For our diet we have to calculate said absorption according to the type of food eaten and the group to which we belong.
If we only take iron through vegetarian diets, we must use some tricks such as promoting absorption with the intake of juices rich in vitamin C or supplementing the diet with pharmaceutical products.
The iron problem
The phenomenon by which humans absorb such a low proportion of iron is unique. The same is not the case with other minerals where the absorption rate can exceed 90%.
The reason for this "failure" of our system is probably due to the inheritance of a long past as hunters. For millions of years, homo sapiens or the hominids that preceded him were hunters and gatherers, so that his body was prepared to absorb only heme iron from prey (fish and meat). When the agricultural revolution took place 12,000 years ago, the diet was severely modified and meat became a minor nutrient. This meant that the iron now had to come from cereals and vegetables, the so-called non-heme iron. In fact today we are still learning to absorb it. This is demonstrated by studying primitive communities that feed as we did millions of years ago. For example, the Kalahari Bushmen lack the iron problem, as do the Maasai, whose food comes mainly from livestock (milk, meat and blood).
Also the presence of inhibitors can decrease the absorption of iron, such as tea, coffee, phosphates and diets very rich in cellulosic vegetable fibers.
Iron deficiency has been associated with anemia since the earliest times of mankind. It was the typical disease of the young woman, manifested by extreme paleness and general weakness. This disease was produced by the reduction of circulating hemoglobin and worsened when the woman's menstrual cycle began, hence the association.
Until recently it was considered the visible form of iron deficiency but today many harmful effects on health are known, anemia being only the tip of the iceberg. In underdeveloped or developing countries, it is clear that the lack of availability of foods rich in iron is the triggering factor for the various pathologies associated with iron deficiency.
In developed countries, the lack of iron in the diet is caused by the decrease in its general contribution, especially because some foods such as legumes or offal are no longer so common in our daily diet.
I have said that anemia is the tip of the iceberg. Every time someone goes to the doctor's office with obvious signs of anemia, there are many other people who do not do it because their symptoms are not so clear but the origin of their disease is identical. It may be a decrease in physical capacity to exertion, a lower resistance to infections, a reduction in intellectual capacity or various disturbances that occur during pregnancy, among other possible warnings of the lack of the mineral.
The highest risk groups are infants, children and adolescents, as well as women during menstruation and pregnant women. As continuous risk groups we have women from their first menstruation to menopause and the elderly, the latter due to the poor diet they usually eat.
What should we do?
In serious cases we must go to the doctor who will surely advise us to take mineral supplements. This is a short to medium term solution and should not be extended beyond what is reasonable. It is best to modify our diet carefully. I say careful because it is true that we would consume much more iron if we were full of steaks and entrecots, but we would also abuse saturated fat that would eventually lead to heart disease.
My advice is to include legumes in our diet almost daily, mainly lentils, white beans, chickpeas, soybeans, etc. As it is non-heme iron, it is advisable to accompany these meals with fresh orange juice. We can eat 2 to 4 eggs per week - be careful with cholesterol - so that the yolk will add about 6 mg of iron.
Once a week we can eat some animal product rich in iron of animal origin. Chicken, beef or lamb liver would be recommended as long as they are of reliable origin. Unfortunately, the liver of animals usually contains toxins as a result of the rearing method, so I practically only opt for animals classified as organic or, in this order of preference, the liver of suckling pig, then that of free-range chicken and finally that of veal.
We can also eat beef or pork occasionally, but it would be preferable to eat turkey or chicken because of their lower content of saturated fat. Blood sausage contain a lot of iron and are recommended a maximum of once a week. It is advisable to eat cereals with a high iron content every morning. Generally all cereals are artificially fortified with iron and other vitamins. There are no limitations on this product.
Eating mollusks such as mussels and fish represents an important contribution of iron, although it is necessary to consider, as in the case of meat, the amount of toxins that they unfortunately incorporate as a result of marine pollution. Spinach is also a good solution without limitation of any kind: we can take it cooked or the tender sprouts in salad.
