Can the human body survive by only consuming concentrated vitamin supplements? by Steven Fowkes
Answer by Steven Fowkes:
I doubt it. I think you may be describing a pill or powder variant of the "elemental" diet, which is composed of easily assimilated components of wild diets deemed essential or necessary for therapeutic purposes delivered in a liquid form, sometimes through a feeding tube. Although such diets are quite useful for short-term purposes related to variety of allergic and digestive problems, they are woefully inadequate for long-term health maintenance, possibly for reasons that are not yet well understood.
The components of elemental diets include vitamins, minerals, amino acids, fats and sugars. This is slightly different from your list in that it includes amino acids instead of proteins (amino-acid polymers), and glucose and fats as fuels (which you do not mention, but might have). Peptides are in between amino acids and proteins and can supply amino acids in hypoallergenic form. And starches (glucose polymers) could be included instead of glucose, too.
One recently-much-more-appreciated "negative" aspect of elemental diets is that they have a destabilizing influence of gut ecology. This is not so important when dealing with Crohn's disease, where the gut is experiencing severe (life-threatening) stress and is unable to heal itself. But in healthy, free-living humans, the microbiome is an essential aspect of health, one that cannot be substituted by placing living microorganisms into a pill or liquid. But even if you might take the position that fructooligosaccharides and other "fiber" could be added to support an ideal microbiome, we do not know how to do that yet. As far as I know, we do not even know how to culture the vast majority of gut-resident organisms that comprise a healthy human microbiome, whatever that may turn out to be. If this has been resolved in the last decade, please post a citation below.
Well known negative aspects of elemental diets are bad (!) taste and induced insulin resistance (diabetic tendencies). The "pill" might theoretically solve the taste issue, and (1) sugar polymers (slow-digesting starches), (2) ketone fuels (fat-derived carbohydrates) and (3) beta-hydroxybutyrate polymers (ketone polymers) might solve the insulin problem, but there are many more subtle issues, only some of which I can raise. Many people react negatively to the glutamate, aspartate and cysteine, which are the excitatory amino acids, and which are released too quickly when supplied in free amino acid and peptide forms. There are other food substances that are considered non-essential (our bodies can make them) but are required to greater degrees in people with particular constitutions or metabolisms (like nucleic acids in metabolically parasympathetic people, or a *lack* of glucose and rapidly digested starch in fast oxidizers).
I suspect that much of this will all be worked out in the near future (this century) due to the incentives of space industrialization/colonization and living beyond 120 years of age. One technology that I can envision being up to this challenge is an engineered microbiome, where microorganisms (1) would not (!) produce vitamin antimetabolites (i.e., would only make the human versions of B6 and B12), (2) would produce higher quantities of vitamins, nutrients and specifically chelated minerals for optimizing health and lifespan–quantities that are not found in a natural diet, and (3) would irreversibly chelate lead, mercury, bismuth, uranium, tin, arsenic, etc., ultimately in forms that could be collected in sewage treatment and sequestered from the environment.
The short answer is "no," now. And "maybe" in the future, by increasing the complexity of the science and art of such an effort.