This is a problem with the medical establishment in the realm of nutrition. They are not taught nutrition and so they do not recognize nutritional problems and they are also unaware of their poor performance on doing so. And so there is a subset of unnecessary chronic disease.
I'd really like to see someone make a home device that can test for nutritional deficiencies at home. Feed someone something like Soylent, a known input, and then test the "output". And determine nutritonal deficiencies based on how the output differs from healthy individuals. This is already done clinically to an extent, but I think the ability to continuously/cheaply record a nutritional history would be invaluable for many. Blood tests just dont cut it. The body likes to keep blood parameters in far too narrow a range making it hard to deduce intracellular status from extracellular fluids except in critical situations.