We know the essential proteins, especially for our muscles … But how much to consume? In what forms? Why shouldn’t it be abused? We tell you everything.
Proteins are said to be “the bricks” of the human body: they are in fact used to build muscles and bones, skin and integuments (hair, nails), many enzymes, hormones, antibodies, cerebral neurotransmitters. . These macronutrients are large molecules, kinds of chains whose links are made up of amino acids which are articulated in a precise order to give each protein its particularity. There are 22 different amino acids, and if some can be synthesized by the body, 9 of them, called essential, must be provided by the diet. When we eat a protein food, it is broken down during digestion, and the body “re-knits” the proteins it needs …
Not too much protein for children
As long as the child is breastfed or bottle-fed, there is no question: infant foods are regulated to provide the right dose. But this becomes more complicated with dietary diversification: it is established that, from 5-6 months, many children consume too much animal protein, sometimes double the recommendation. “It overloads their kidneys (immature up to 3 years), and increases the risk of obesity. Do not force the dose: from 6 to 8 months, the ration is 10 g per day of meat or fish, the equivalent of 2 teaspoons. It increases over time to reach, at 5 years, 50 g per day or 1 egg. A child of this age should therefore not eat a whole hamburger, but barely half! It is not a question of depriving him, but of respecting his needs ”,explains Jeanne Laurent, dietician.
It is therefore important not to serve him again in the evening if he has eaten it at noon in the community. Pediatricians also advise up to 3 years to keep growth milk, less rich in protein than cow’s milk, certainly cheaper, but unsuitable.
Adults: neither too much nor too little …
The protein dose recommended by the National Food Safety Agency (ANSES) is 0.83 g per day and per kilogram of body weight for a healthy adult under 60 years of age (i.e. 50 g for a woman weighing 60 kg, and 70 g for a man weighing 85 kg). Here again, we tend to “do too much”: the INCA study (led by ANSES) showed that the average ration for French women was 73.5 g per day (100 g for men). An excess that induces a renal overload, and acidifies the body, which promotes demineralization, joint pain …
However, two categories of people must – slightly – increase their intake: the elderly and pregnant and breastfeeding women, with at least 70 g / day (i.e. 1.2 g per kilo of body weight). “In the elderly, it is sometimes difficult (with age, consumption tends to decrease, especially in women whose appetite for animal proteins often decreases from the menopause), yet essential: it is to limit natural muscle wasting linked to a change in protein metabolism (the body produces and stores less protein in the muscles) “, our expert notes. A 2016 Inserm study carried out in Bordeaux showed that sufficient protein intake (at least 1 g / kg / day) protected seniors from nearly 60% of the “risk of fragility” (fatigue, muscle weakness, slowness of walking, unintentional weight loss …).
>> Watch out for “protein cocktails” : some athletes and fitness enthusiasts greatly abuse proteins (with shakers or omelets with 4 egg whites) to “build muscle”. “This is really not a good idea, warns Jeanne Laurent, too high doses of animal proteins tire the kidneys (increasing the risk of renal pathologies) and leads to an increased amount of nitrogenous waste such as urea, ammonia and uric acid … The latter can cause tendonitis, joint pain and strains, but also gout attacks and kidney stones, especially if you do not drink enough! As for high-protein powder-based slimming diets, they should be avoided for the same reasons (in addition to being followed by a rebound effect, and away from a real diet). “
Animal or vegetable protein?
In France, 60% of protein intake is provided by animal products according to ANSES, which recommends not to neglect proteins of plant origin. However, we have heard a lot that the quality of the latter, linked to their proportions in certain essential amino acids, was not as good … So, should we fear the deficiency if we eat less meat? The answer is no: in France, many non-carnivores consume eggs and dairy products, sometimes fish. The NutriNet Santé study reports that the average dose of protein consumed was 84 g / day for carnivores and 64 g for non-meat eaters, which, for a woman weighing 60 kg, is still higher than the recommended intakes ( About 50 g).
As for the “lower” quality of vegetable proteins, it should not worry according to a study published in 2019 in the journal “Nutrients” which reveals that plants rich in proteins (legumes, nuts and seeds) are sufficient for a satisfactory intake in vegetarians (and even among vegans!), and that the variety of protein sources (we do not eat only rice or beans) makes it possible to provide a completely sufficient range of amino acids.
>> The recommended dose of protein does not equal the weight of the food : 70 g of protein is not 70 g of chicken breast, salmon, lentils or ham! It all depends on the protein ratio, which differs depending on the product. A point of reference to avoid cooking with your calculator? The piece of steak or cod in a meal is (approximately) the size of the palm of your hand, and the size of your closed fist is that of a ration of legumes or starches.
Our expert : Jeanne Laurent, dietician-nutritionist in Bordeaux.
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