Did you ever wonder why your doctor advises you to take one HIV combo with food and another without it, while with a third, eating is up to you? Here’s a brief gustatory guide to optimizing your med menu:

Take with food:
A stomach full of food is a good place to be for some HIV meds, as it usually means acid and fats are present. Stomach acids—secreted when food is present—are needed to dissolve and absorb the protease inhibitor (PI) Reyataz (atazanavir). Most PIs, including Viracept (nelfinavir), Aptivus (tipranavir), Norvir (ritonavir) and Invirase (saquinavir) are fatlike molecules that need to be emulsified with dietary fats for our mostly watery bodies to be able to absorb them.

Take on an empty stomach:
Food in the gut slows the transit of drugs, increasing their absorption. But some drugs are absorbed properly only if they can get through the stomach quickly, so no food is best. The non-nuke Sustiva (efavirenz) gets into your bloodstream well enough without food; fat-laden food causes too much to be absorbed, upping your side-effect risk. Acid is enemy numero uno for the nuke Videx EC. Stomach acid chews up Videx before it can slip from the gut into the bloodstream. “EC” means it’s coated to withstand those acids. If the drug hangs around in the stomach waiting for food to be digested, the protective coating will be destroyed and too little of the drug will reach the small intestine. The PI Crixivan (indinavir) is absorbed best if it passes through the stomach quickly. With a Norvir boost, Crix loses its food restriction.

Take food, or leave it:
Food doesn’t affect absorption of the other HIV meds, but some folks find that a bit of grub (like a few crackers with cheese or peanut butter) with some nukes cuts nausea. A healthy side order, indeed.