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Food protein: three big challenges of today

Eating animals is not obligatory for good health

On March 8th, 2022 |
5 mins reading time
1
Eating animals is not obligatory for good health
Francois Mariotti
François Mariotti
Professor of Nutrition at AgroParisTech
Key takeaways
  • In the research community, everyone agrees that animal products are not essential for good health.
  • Adults and children in France currently consume more protein than they need to meet their needs.
  • It is important to understand that the biological utility of proteins is not limited to muscles. All cells in any organism are largely composed of protein.
  • All recommended diets include a much higher intake of plant than animal products. It is clear that eating a plant-based diet is good for your health.

This is one issue that does not real­ly divide the nutri­tion research com­mu­ni­ty very much. Every­one agrees, with more or less reser­va­tion on cer­tain points, that ani­mal prod­ucts are not indis­pens­able for main­tain­ing good health. In real­i­ty, the dif­fer­ences gen­er­al­ly cen­tre on pre­cise points: are we con­sid­er­ing the health of the indi­vid­ual or of a pop­u­la­tion? The opti­mal­i­ty or via­bil­i­ty of the diet?

François Mar­i­ot­ti, pro­fes­sor of nutri­tion at AgroParis­Tech and an expert in pub­lic health nutri­tion helps us unrav­el these issues, which can be dif­fi­cult to under­stand if we do not have a good knowl­edge of nutri­tion. It should be not­ed that the frame­work of this inter­view focus­es sole­ly on the issue of human health and food with­out tak­ing into con­sid­er­a­tion oth­er major issues such as ani­mal ethics or the neg­a­tive exter­nal­i­ties of live­stock farming.

Chem­i­cal­ly speak­ing, there is no dif­fer­ence between so-called ani­mal pro­teins and so-called plant pro­teins. Based on this obser­va­tion, can we con­sid­er that a strict­ly plant-based diet that is well man­aged can meet the pop­u­la­tion’s pro­tein needs?

François Mar­i­ot­ti. We often hear that the pro­teins con­tained in plants lack one or more amino acids, the basic units of mol­e­cules such as pep­tides and pro­teins. And it is impor­tant to under­stand what is meant by this because it is often mis­un­der­stood. The rea­son­ing behind the fact that cer­tain pro­teins con­tained in plants are lim­it­ing is based on a vir­tu­al sit­u­a­tion. In the­o­ry, we can imag­ine an indi­vid­ual con­sum­ing only a par­tic­u­lar pro­tein (from wheat, rice, eggs, etc.) in a quan­ti­ty just suf­fi­cient to cov­er his or her nitro­gen require­ments, i.e., to meet his or her total pro­tein needs. From this fic­ti­tious sit­u­a­tion, we ask whether this indi­vid­ual ingests enough of each amino acid to cov­er his or her amino acid requirement.

With this type of rea­son­ing, one can arrive at the above-men­tioned con­clu­sion that such and such an amino acid is miss­ing in such and such a pro­tein – essen­tial­ly lysine in cere­als. But it is clear that this sit­u­a­tion is pure­ly the­o­ret­i­cal. First­ly, peo­ple do not con­sume only one par­tic­u­lar pro­tein, sec­ond­ly, the pro­teins con­tained in plants com­ple­ment each oth­er very well and third­ly, adults and chil­dren in France today con­sume more pro­tein than is nec­es­sary to meet their needs. We can there­fore con­clude that the pro­teins con­tained in plants could meet the total pro­tein needs of the pop­u­la­tion with­out any prob­lem, except in spe­cial cas­es (main­ly peo­ple suf­fer­ing from or at risk of malnourishment).

Amino acids

While in com­mon lan­guage we often asso­ciate pro­teins with mus­cles, it is impor­tant to under­stand that their bio­log­i­cal util­i­ty goes far beyond that. All cells, no mat­ter which organ­ism we are talk­ing about, are large­ly com­posed of pro­teins. They play essen­tial roles:

• Enzy­mat­ic, allow­ing cer­tain essen­tial chem­i­cal reac­tions to take place;

• In the immune sys­tem, for exam­ple anti­bod­ies which are glycoproteins;

• Or struc­tural­ly, the cytoskele­ton (an organelle found with­in our cells) which gives shape to our cells is com­posed of pro­tein filaments.

To make pro­teins, our body needs twen­ty amino acids, nine of which are essen­tial, i.e. our body can­not make them itself like oth­er mol­e­cules such as vit­a­mins. They must there­fore be pro­vid­ed by the diet to meet our nitro­gen require­ments and enable our body to man­u­fac­ture most of the mol­e­cules that make it up.

There are nutri­ents (vit­a­mins, min­er­als, fibres, trace ele­ments) that are present in ani­mal prod­ucts and absent from plant prod­ucts con­tain­ing pro­teins and vice ver­sa. Can we meet our needs for these com­pounds with a strict­ly plant-based diet?

These dif­fer­ences are called the “pro­tein pack­age” to char­ac­terise the nutri­ents asso­ci­at­ed with the pro­teins con­tained in ani­mal and plant prod­ucts. And this is where the ques­tion becomes more com­pli­cat­ed, because when we go with­out ani­mal prod­ucts, it is not so much the pro­teins that are prob­lem­at­ic but rather cer­tain asso­ci­at­ed com­pounds. The same is even more true if we go with­out plants.

In pub­lic health, we ask our­selves ques­tions about safe­ty in rela­tion to these issues. Will an indi­vid­ual who stops con­sum­ing ani­mal prod­ucts, or even prod­ucts of ani­mal ori­gin, be able to obtain, via oth­er foods, suf­fi­cient quan­ti­ties of com­pounds of inter­est such as vit­a­min B12, iron, zinc, cal­ci­um, iodine, and the omega‑3 fat­ty acids eicos­apen­taenoic acid (EPA) and docosa­hexaenoic acid (DHA)?

Dietary rec­om­men­da­tions depend on a num­ber of fac­tors such as the extent to which the diet is plant-based. The prob­lems are not the same for flex­i­tar­i­ans, pesco-veg­e­tar­i­ans, lac­to-ovo veg­e­tar­i­ans or veg­ans, and the diver­si­ty of the diet. For exam­ple, for vit­a­min B12, sup­ple­men­ta­tion is jus­ti­fied in lac­to-ovo veg­e­tar­i­ans and is essen­tial in veg­ans or seri­ous neu­ro­log­i­cal prob­lems may occur in the short term. For the oth­er com­pounds, the ques­tion lies rather in the degree of veg­an­i­sa­tion and the dif­fi­cul­ty of bal­anc­ing one’s diet. This is still pos­si­ble but requires knowl­edge and atti­tudes that are not read­i­ly available.

To com­pen­sate for this, plant foods can be enriched with cer­tain impor­tant nutri­ents. In France, these enriched foods are not wide­ly avail­able on the mar­ket, even though they are of real inter­est to pub­lic health, giv­en that more plant-based diet impacts pop­u­la­tions that are far removed from the “hip­ster” car­i­ca­ture, often young and in pre­car­i­ous sit­u­a­tions and there­fore at high nutri­tion­al risk.

We know that eat­ing a plant-based diet is good for your health, but to what extent?

All rec­om­mend­ed diets include a much high­er con­sump­tion of plant than ani­mal prod­ucts. It is clear that there are health ben­e­fits to mov­ing towards a more plant-based diet, often to a greater degree than sug­gest­ed by rec­om­men­da­tions that con­sid­er para­me­ters such as cul­tur­al norms and gen­er­al pop­u­la­tion feasibility.

Per­son­al­ly, I think there is no point, nutri­tion­al­ly speak­ing, in cut­ting out ani­mal prod­ucts that have inter­est­ing nutri­tion­al con­tri­bu­tions. To illus­trate my point, I find a ben­e­fit in cut­ting out red meat, where­as I find no ben­e­fit – again from a nutri­tion­al point of view – in cut­ting out fish, espe­cial­ly fat­ty fish. Nev­er­the­less, it is pos­si­ble to do with­out ani­mal prod­ucts and prod­ucts of ani­mal ori­gin, as we men­tioned ear­li­er, but from a strict­ly human health point of view, this is prob­a­bly not the best diet, which would be a pre­dom­i­nant­ly plant-based diet with a small amount of ani­mal products.

If you had to give a sum­ma­ry answer to this com­plex prob­lem, where even with pre­cise answers it is dif­fi­cult to see clear­ly, what would you say?

The point to remem­ber in the field of nutri­tion is that we need to make the right diag­noses and know what to look out for. Ques­tions about the pro­tein needs of chil­dren if they don’t eat meat or eat very lit­tle meat are still being played out in pub­lic debate, but these are out­dat­ed ques­tions that have been set­tled. On the oth­er hand, we must focus on what can be prob­lem­at­ic in lac­to-ovo veg­e­tar­i­an or veg­an diets, such as the sta­tus of iron, zinc, cal­ci­um, and iodine.

Final­ly, I would like to add that it is not par­tic­u­lar­ly use­ful to oppose ani­mal and plant sources as a whole from a nutri­tion­al point of view and that rather we should rea­son in terms of food cat­e­gories as dietet­ics pro­fes­sion­als do. There are ben­e­fi­cial ani­mal foods – poul­try for exam­ple – and even very ben­e­fi­cial ones such as fish, and plant foods to be avoid­ed such as refined cere­als. Con­verse­ly, there are very ben­e­fi­cial plant foods such as fruit and veg­eta­bles, whole­grain cere­als, legumes and nuts and ani­mal foods to be avoid­ed such as red meat and cold cuts.

Interview by Julien Hernandez