The body requires amino acids and choline to build cells. Choline is a nitrogen-containing compound, like protein, but it does not have the same structure. Proteins have a carboxyl group, but choline has none, it is a quarternary ammonium salt. It is involved in cell membranes (structural), myelin (structural) and also as a precursor to the neurotransmitter acetylcholine. 90% of the population does not get the AI, which is 7mg/kg, and that figure is simply to avoid overt liver dysfunction in depletion/repletion studies; it has nothing to say about optimal health or wellness, mentally or physically.

There is another confound: betaine. Betaine is a metabolic byproduct of choline in the body, but it is also found in diet. It is named for beets, (bee-taine) because it was first found in them. Betaine can spare choline.

There is yet another confound: different people are better/worse methylators, etc. and so will require more choline (or betaine, it can serve this role).

So, on to protein. The AI of 0.8g/kg is probably too low. My Nationsl Strength and Conditioning Association book has a chapter on nutrition, and it says 1.2g/kg – 2.2g/kg are useful for building muscle, so let’s put it at 1.5g/kg. This should require us to scale up the choline requirement as well.

7mg/0.8g = 8.75mg/g
8.75mg/g * 1.5g/kg = 13.13mg/kg

So, if you were, say, 80kg

80kg * 1.5g/kg = 120g protein
80 * 13.13mg/kg = 1050mg choline

Now, the choline requirement might not scale linearly with the protein requirement, so this might be overkill, but if you had something like the following:

4 eggs = ~500mg choline
400g beef = ~400mg choline

That is about 900mg choline, and ~120g protein, give or take, depending on the cut of beef. It is about 1300 calories