Consequently, these non-essential nutrients are really “conditionally essential,” and health experts do wrong to overemphasize just the essential nutrients we cannot make, and for optimal health we need to get these nutrients from nutritious foods – no wasted calories – and balanced supplements.
The body is programmed by its DNA, honed by 3.5 billion years of intense selective pressure to survive in the creatures who were in our direct line of descent, to fight the real enemy – deficiency, while doctors enjoy shadow boxing the imaginary enemy, excess.
Except for excesses of real toxins, the body handles reasonable excesses of the wimpy toxins doctors fret about reasonably well.
However, our bodies struggle with deficiencies – it “makes do and mends”. It borrows from stores and then makes the best substitutions that it can. Eventually, the body’s health breaks down.
It is not just us – it is every creature and as a rule, every nutrient. For example, yeast make their own vitamin B3, but they do not make an optimal amount and thus every growth medium for yeast has a B3 supplement.
What scientists have found out about these supplements (Peter Belenky et al., Cell 129, 473-484 (2007):
- Nicotinamide, the most popular form in multivitamins, shortens yeast replicative lifespan, perhaps by inhibiting sirtuins and PARPs, at least briefly whenever the medium is changed. Even a brief inhibition of sirtuins can derepress the expression of certain genes (net harmful?) and can increase replication of extrachromosomal rDNA. Even a brief inhibition of PARPs can lead to damage accumulating in DNA.
- Nicotinic acid has no effect on replicative lifespan in yeast.
- Nicotinamide riboside increases replicative lifespan in yeast, much as calorie restriction does. Both raise the equilibrium level of NAD+ in yeast about 2x, with an unknown percentage increase in the free NAD+, since they do not know exactly how much of the NAD+ is bound to proteins.
I doubt the effect is quite so simple in man – human lifespan is a function more of variables that are difficult to quantify.