It’s sometimes said that truly healthy people need no supplements, but personally I doubt that, except in perhaps a small fraction of cases. For one thing, illnesses can be hidden, so that we don’t who the truly healthy really are. Another is that it is difficult in our modern food system to naturally consume all the nutrients needed in the right quantities. For instance, it seems most people could use more omega-3 fatty acids and magnesium and vitamin D than they get from their environment. (Just to cite the three that came to mind the quickest.)
Renowned biochemist Bruce Ames, still going strong, has put forward a triage theory of nutrition. Basically, if a vitamin or mineral is in short supply, the body prioritizes its use for essential functions. These functions are likely to be oriented to short-term benefit. “Non-essential” functions are those more likely to be of benefit to health in the long run.
Here’s a recent paper by Ames in which he tested the triage theory: Adaptive dysfunction of selenoproteins from the perspective of the triage theory: why modest selenium deficiency may increase risk of diseases of aging
The triage theory proposes that modest deficiency of any vitamin or mineral (V/M) could increase age-related diseases. V/M-dependent proteins required for short-term survival and/or reproduction (i.e., “essential”) are predicted to be protected on V/M deficiency over other “nonessential” V/M-dependent proteins needed only for long-term health. The result is accumulation of insidious damage, increasing disease risk. We successfully tested the theory against published evidence on vitamin K. Here, we review about half of the 25 known mammalian selenoproteins; all of those with mouse knockout or human mutant phenotypes that could be used as criteria for a classification of essential or nonessential. Five selenoproteins (Gpx4, Txnrd1, Txnrd2, Dio3, and Sepp1) were classified as essential and 7 (Gpx1, Gpx 2, Gpx 3, Dio1, Dio2, Msrb1, and SelN) nonessential. On modest selenium (Se) deficiency, nonessential selenoprotein activities and concentrations are preferentially lost, with one exception (Dio1 in the thyroid, which we predict is conditionally essential)…. The same set of age-related diseases and conditions, including cancer, heart disease, and immune dysfunction, are prospectively associated with modest Se deficiency and also with genetic dysfunction of nonessential selenoproteins, suggesting that Se deficiency could be a causal factor, a possibility strengthened by mechanistic evidence. Modest Se deficiency is common in many parts of the world; optimal intake could prevent future disease.
So, it appears that if not enough selenium, a required mineral, is around, then certain enzyme functions will be compromised, leading to cancer, heart disease, and immune dysfunction, the last of which will predispose to infections and cancer.
So for optimal health, one wants to ensure that all nutrients are present. In the case of selenium, one 200 mg dose of selenium once a week should do the job.