Which essential nutrient is the first that will cause debilitating illness if supply is insufficient

Question

While reading about the US requirements for food labeling (How to Understand and Use the Nutrition Facts Label) about essential nutrients it became obvious that that label is far from complete.

Currently it is just required to list a small subset of vitamins, minerals etc., for example: Water, Energy, Protein, Fat, Cholesterol, Carbohydrate, Fiber, Sugars, Minerals, Calcium, Iron, Vitamin C, Vitamin A…

This is clearly a very rough, an incomplete list and compiled for almost entirely different reasons, I can only guess at. One guess would be trying to help to prevent, in the name of public health, those types of malnutrition that are most commonly seen over all in Americans, not those that would have the fastest onset.

Asking the world's favourite search engine for example "first micro-nutrient to cause deficiency" yields mainly results applicable for plant growth, where people seem to have pondered this question more frequently in the past compared to human nutrition. Similiar search terms were equally unsatisfactory.

So I keep wondering, phrased in a very naive way on purpose: what is the most "important" essential (the most limiting nutritional factor?) nutrient to be consumed regularly enough to avoid any type of deficiency (serious malnutrition)?

Obviously the essential micro-nutrients are all important at least in the mid- and long term, hence their name. But which are really needed most frequently almost or really daily?

One isolated example is vitamin C and scurvy caused by a serious lack of vitamin C in a diet. Wikipedia for example claims that:

Typically, scurvy is caused by a lack of vitamin C in the diet. It takes at least a month of little to no vitamin C before symptoms occur.

That seems quite a long time for relative malnutrition that will not cause concrete and visible or clinically relevant symptoms. But I seem to be unable to find such a list and I am even hampered in compiling a list of essential nutrients and the possible problems when 'time until the symptoms of malnutrition/deficiency develop' is a central criterion to be involved.

For B12 it seems to take a very long time until symptoms develop, for fat-soluble vitamins it is similarly prolonged interval but my guess is that water soluble vitamins and some minerals would be less suitable to skip on while remaining healthy.

As evidenced by our human past, general energy deficiency causing starvation is not really part of this inquiry, since it presents a larger problem in itself. So it is not about water, energy, fats, protein or carbohydrates.

That situation in question would entail: all micro-nutrients (and macro) kept at recommended levels or above, only one single of the essential micro-nutrients deprived. Which micro-nutrient deprivation causes the first signs of malnutrition the fastest. This would be applicable for an otherwise and previously healthy and well fed adult, not necessarily for children.

Answer 1

Since you have listed water as one of the nutrients, then clearly insufficient water will rapidly lead to renal failure and death.

If you don't want to include water, then one of the water soluble vitamins since these are not stored in the body in significant amounts as opposed to fat soluble vitamins. And you've already answered with Vitamin C which is correct and can occur in 1-3 months. In studies conducted on prison "volunteers" signs of deficiency appeared at 4 weeks.

Thiamine is another crucial water soluble vitamin. Liver thiamine stores are depleted in 18 days and

A deficiency in thiamine leads to decreased activity of thiamine-dependent enzymes that triggers a sequence of metabolic events leading to energy compromise. Neuronal death often occurs in certain neuronal populations that have high metabolic requirements and high thiamine turnover.15 Areas commonly affected by thiamine deficiency are the mediodorsal thalamic nucleus, mammillary bodies, the periaqueductal gray matter, and the floor of the fourth ventricle, which includes the ocular motor, vestibular nuclei, and the cerebellar vermis.16 Lesions also may involve the fornices, the hippocampus, the area round the third ventricle, the quadrigeminal bodies, and the cortex.17 The predilection to affect memory circuits is responsible for the most important sequela of Wernicke’s encephalopathy— Korsakoff’s psychosis.18

Thiamine deficiency should be suspected in alcoholics presenting with confusion since they have poor diets, but also since alcohol inhibits thiamine absorption. It should also be considered in some forms of heart failure.

Detecting which nutrient causes symptoms first would be difficult without controlled trials and in the modern era, the historical experiments conducted on prisoners and conscientious objectors would now be considered unethical.