Baking zucchini bread without egg yolks I'm trying to reduce cholesterol in my diet and have switched to using egg whites (from a carton) instead of whole eggs.  This substitution usually works out OK, but when I make zucchini bread -- and other quick breads -- the loaves don't rise as well as they used to, and they tend to be drier.  

I'm doing a 1:1 substitution using the guide on the carton (1egg is approx. 2oz), so I assume that a lot of the problem is that I'm missing the fat from the egg yolks.  Is this correct, and if so, what can I use instead that will be low in cholesterol?
Genetics is actually the greatest affect on cholesterol.  Consumption of dietary cholesterol has very little correlation to serum cholesterol in your body and the amount of cholesterol you're going to save by leaving out the egg yolks vs. the impact it has on the resulting bread will hardly be worth it.

However, if you wish to proceed then I'd recommedn simply adding about a tablespoon of vegetable oil in replacement of the egg yolks that are being omitted.

The fat in the egg yolks is going to assist in minimizing gluten development.  Since you've omitted the fat there is probably a bit more gluten formation taking place and thus the fact that it doesn't rise as well.  Egg whites have a drying effect on baked goods so that is why the bread is drier than before.