The right answer is Plants can synthesize all twenty amino acids. Humans must eat them to obtain ten amino acids.
By the ten amino acids I mean The eight essential amino acids and the two semi essential amioacids. (In the statement they mention twelve but it is incorrect).
It is not "a must" for humans to eat plants to obtain all the twenty amino acids, it is "a must" for ten of them.
The amino acids are organic groups containing at least one group of amines (-NH2) and a carboxylic group (COOH). Twenty amino acids forming the proteins are anchored in our genome; that's why they're called protein generators. In addition, there are about 250 amino acids that are not the source of the proteins. These are p. ex. those who form sugar.
What are essential and non-essential amino acids ?
The 20 protein amino acids are also known as the basic amino acids. They are distinguished into three different groups: essential, semi-essential and non-essential amino acids.
There are only eight amino acids essential to humans. They are said to be essential because the body can not manufacture them itself, and therefore needs external input. These are isoleucine, leucine, lysine, methionine, phentylalanine, threonine, tryptophan and valine.
Arginine and histidine are semi-essential amino acids. They will have to be assimilated through food.
Phenylalanine, histidine and tryptophan are synthesized by plants and microorganisms via shikimic acid.
The ten non-essential amino acids are synthesized by the body itself. These are alanine, asparagine, asparaginic acid, cysteine, glutamine, glutamic acids, glycine, proline, serine and tyrosine.
Warning: do not misunderstand the nomenclature of amino acids called "essential" or non-essential. A group of non-essential amino acids does not mean that these amino acids are less important than the semi-essential or essential amino acids. It is not a question of assessing whether the body is sufficiently supplied with amino acids. The actual protein requirements differ from person to person. The proportion of semi-essential or non-essential amino acids that the body makes or that it should manufacture depends on a variety of factors. Depending on age, physical and intellectual constraints, the body will need varying amounts of amino acids to remain efficient and healthy.
