In 1951 J. M. Bijvoet, A. F. Peerdeman, and A. J. van Bommel showed, using x-ray crystallography, that the absolute arrangement of
atoms in space
for sodium rubidium tartarate could be determined.
Most other nutrients, on the other hand, are more actively transported - there are certain receptors lining those intestinal cells (cells called enterocytes, if anybody cares) that pull salts, sugars, amino acids, etc. through the intestinal lining into the cells in exchange
for other compounds (e.g. they'll pull in a hydrogen ion at the same time as an amino acid, then exchange the new hydrogen
atom for a
sodium molecule later.)