Yes legumes may contain several anti-nutritional factors. The three main factors are:

- phasine, a protein that has a serious effect on the small intestine in some people. However, this protein is destroyed by cooking, so only raw beans pose a risk regarding its presence. Phasine though is destroyed only after a lengthy period of boiling the legume, and not by drying. Outbreaks of phasine poisoning are very rare.

- trypsin inhibitors, several of which are found in legumes. These are proteins that block the digestive enzyme trypsin; some of these inhibitors are heat resistant. The activity of these inhibitors impairs the digestion of proteins, which are thus not digested and absorbed. These trypsin inhibitors may result in malnutrition, especially in low-protein diets.

- phytates, or phytic acids, which are affected by heating, but require other processing (such as fermentation) for further neutralisation, which is still only partial. Also, soaking/germination (sprouting) reduces or eliminates phytates.

Still, legumes are an important source of proteins and should be part of a good and varied diet

Legumes such as dried beans, peas, lentils and peanuts contain important heart-healthy nutrients, antioxidants and approximately 8 grams of protein and 8 grams of fiber per serving. Serving size for peas, beans and lentils is around 80g or just over 3ozs but peanuts should be limited to 25g or 1oz servings. In fact it is a heart healthy diet – and it is also recommended by:

* The National Institutes of Health
* The American Heart Association
* The 2005 Dietary Guidelines for Americans
* US guidelines for treatment of high blood pressure
* and, the DASH diet formed the basis for the new USDA MyPyramid