diet
4 interactions related to diet
lithium + sodium
Lithium and sodium are handled by the same transporters in the kidney and compete for reabsorption. Eating much less sodium than usual causes the kidneys to hold on to both sodium and lithium, which can push lithium levels up toward toxicity; a sudden large increase in sodium can flush lithium out and drop it below the level needed to control mood. The amount of sodium matters less than keeping it steady.
levothyroxine + fiber
Dietary and supplemental fiber can bind levothyroxine in the gut and modestly reduce how much of each dose is absorbed. When fiber intake is high or variable around the time of dosing, this can nudge TSH upward and make a stable dose harder to settle on. The effect is real but generally modest, and it is managed mainly by timing and consistency rather than by avoiding fiber.
fermented foods + maois
Fermented foods accumulate tyramine when bacteria break down the amino acid tyrosine during fermentation. MAOIs block the monoamine oxidase enzyme that normally clears dietary tyramine in the gut wall and liver, so the tyramine reaches the bloodstream and triggers a surge of norepinephrine. This can produce a sudden, dangerous rise in blood pressure (a hypertensive crisis).
tofu + levothyroxine
Tofu is one of the most concentrated sources of soy protein in the diet. Soy protein binds levothyroxine in the gut and reduces how much of the drug is absorbed, and case reports describe TSH rising when soy-heavy foods like tofu are added to a previously stable levothyroxine regimen. The effect is modest in most adults but clinically relevant in sensitive patients, and it is managed by timing.