Osmolytes work differently from electrolytes. Where sodium and potassium move water by shifting charge across a cell's membrane, betaine is drawn into the cell itself, where it helps the cell hold water and stay stable under stress. It is the same role betaine plays in your kidneys and in plants, and it is why an osmolyte pairs naturally with the electrolytes in Trace.
Betaine also stays cleanly inside a fast. It is calorie-free and carries no digestible carbohydrate, so it does not raise blood sugar, and in a randomized controlled trial betaine did not increase insulin and left insulin sensitivity unchanged.[1] It contains no complete protein or free amino acids to switch on growth signaling, and over the 12 weeks of that same trial it did not change IGF-1 or body weight.[1] In short, betaine supports hydration without delivering the sugar or amino acids that would break a fast.
