Alfalfa (or lucerne as it is often called in the UK) is part of the legume family of plants making it a cousin of clover, peas and beans and, depending on how much there is in a food, it can be good or bad.
In it's whole form, alfalfa is widely regarded as a superfood for humans and, in small amounts, can be very beneficial for our dogs. It is a good, natural source of a whole host of nutrients including plenty of vitamins and minerals - most notably iron, magnesium, manganese, vitamin A, C, E and several B vitamins, as well as good quality fibre.
Since alfalfa also contains a fairly high proportion of protein, it can also be used in larger amounts as a protein supplement. Since dogs generally do a lot better on meat proteins than vegetable-derived forms, this is not something we recommend.
As a rule of thumb, if you see alfalfa listed in the top half of the ingredients list, chances are it is there as a cheap source of protein and is probably best avoided. In the bottom half, it is much more likely that it is just a small amount to provide valuable micronutrients and is no cause for concern.
Find foods containing Alfalfa / Lucerne See the full Ingredient Glossary