Ray Peat said:To provide usable energy to the over-stressed brain (and heart), R.L. Veech has advocated the use of ketones, but the pure chemicals are expensive to make. An easily available and inexpensive source of ketones (in the form of ketoacids, which can be converted to amino acids if they aren't needed for energy) is the juice extracted(with a centrifugal juicer) from raw potatoes, which also contains proteins and other nutrients. The juice can be scrambled like eggs, and is usually tolerated even by very debilitated people.
Source: Serotonin Newsletter March 2011