Do Fruits and Vegetables Have Protein?
I’m sure you’ve heard that protein is the main building block of the human body but did you know that the human body has to break down nearly all of the protein consumed into individual Amino Acids (Free Amino Acids – FAAs) before they can be utilized by the body to build more proteins? (see – http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_aacids.html)
Amino Acids are the true building blocks.
Just this understanding alone would seem to point to the fact that we should be measuring the Free Amino Acid content of foods before relying on the protein content for nutrient availability and density.
So how important is protein? To put it into perspective, a newborn baby typically triples his/her body weight in the first year of growth while the percent of protein contained in mother’s milk is less than 1% (see https://www.ncbi.nlm.nih.gov/pubmed/392766). Yes, you read that right, less than one percent of mother’s milk is actually made up of protein. You’re probably asking – well if a baby triples his/her body weight in the first year, then where does he/she get the “protein” necessary for such a huge growth spurt? Let me repeat myself – the human body doesn’t actually use protein in it’s protein form but instead must break down protein into it’s individual amino acids (free amino acids) before it can be used by the body.
Amino Acids are the true building blocks.
Research shows that (see – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3967730/) “Exclusive breastfeeding for the first six months of life optimizes infant growth, development, and health and is beneficial to maternal health. Breast milk contains adequate nutrients, minerals, vitamins, and water for growing, but for reasons not completely understood, the mammary tissue of most mammals produces large amounts of non-protein nitrogenous compounds, including free (protein-unbound) amino acids (FAAs)”
What do they mean “for reasons not completely understood”? Of course mother’s milk contains large amounts of FAAs. It makes complete sense that mother’s milk would contain FAAs that can be utilized immediately by the growing infant.
While I realize that the above is a little off topic, it does help to answer the question “does fruit have protein?”
First and foremost – all fruit and vegetables contains protein – and while fresh RIPE fruit and vegetables may not contain large amounts of “protein”, fresh, RIPE fruit and vegetables do contain free amino acids (FAAs) which are the building blocks of protein and which are readily absorbed in the digestive track.
To date most research into the nutrient content of fruit and vegetables has focused on the amount of protein while there has been little research on the amount and type of free amino acids (FAAs) contained in fruit and vegetables. In the little research that has been done, it has been found that during the ripening process, which is when researchers generally test the protein content of fruit, proteins are being broken down by different protease into free amino acids (see – https://www.ncbi.nlm.nih.gov/pubmed/19876714).
Besides being the building block of proteins, FAAs provide another bonus. During the ripening process, in conjunction with other chemical constituents, FAAs are responsible for producing many of the flavors our taste buds respond to. This is why the flavor is so much better when fruit and vegetables are harvested when RIPE!!!
Here are some glaring examples of the FAAs found in fruit and vegetables –
Pawpaw – The most abundant free amino acids were arginine, glutamine and serine. Also present were isoleucine, leucine, methionine, phenylalanine, tryptophank and tyrosine – all of which are essential amino acids.
Tomato – “free amino acids increase dramatically during fruit ripening and their abundance changed differentially” (see – Free amino acid production during tomato fruit – https://www.ncbi.nlm.nih.gov/pubmed/19876714)
Apples – alanine, asparagine, arginine, carnosine, citrulline, cycstine, cystathionine, ethanolamine, glutamine, glycine, histidine, isoluecine, leucine, lysine, mathionine, ornithine, phosphoethanolamine, phenylalanine, serine, proline, sarcosine, serine, taurine, threonine, tryptophan, tyrosine and valine. (see the Australian Journal of Crop Science – http://www.cropj.com/maro_5_2_2011_154_161.pdf)
You get the point!
Remember – fruit and vegetables might not contain the large amounts of protein that beef has but instead has been gifted with something even better and much easier for your body to utilize – free amino acids.
So why are simple things sometimes so hard for science to tie together? HABIT. Many of humanity’s most important discoveries about the nutrient needs of the human body happened a long time ago and, due to technical limitations, have not been able to evolve, but now that technology has improved our ability to peer into the unknown, it just makes sense for humanity to once again revisit and re-evaluate some of those old viewpoints and develop a modern understanding of them.