First of all, I'll tell you for the mayonnaise which we buy from the super market and not for the homemade. Mayonnaise has 4 types! Bet you'd never noticed that! It's the regular, reduced fat, light and fat free. The most common ones are the regular and the light! Let's check out their nutrition facts! Regular mayo: 1ts contains--> 57 kcal, 4,9g fat, 3,5g carbs and 0,13g protein. Light mayo: 1ts contains--> 49kcal, 4,9g fat, 1,23g carbs and 0,13g protein. As you may see their differences aren't that obvious! Little less calories and carbs.
Many manufactorers use olive oil and others vegetable oil! You can check the ingredients label for that. The better choice is the one with olive oil which might reduce your cardiovascular disease risk and or high cholesterol.
But let's face the truth.. Too many fat and carbs. The best thing you can do is to choose a homemade! Ask your mother, grandmother or you can try it for yourself (you never know!). It's common sence that the things we make with our own hands are better than a huge machine! You can choose the eggs and no preservatives! A little secret when you start making it, keep your bowl warm (not hot) and your mayo will become more fluffy!