Leguminous plants include the beans, lentils and peas. The leguminous plants produce seeds which are called pulses. Humans eat legumes including pulses and these provide high levels of many nutrients and are excellent sources of protein, starch and phytonutrients. Evidence suggests that regular consumption of leguminous plants may have particular health benefits and might be associated with protection from weight gain, metabolic syndrome and cardiovascular disease. For example, in one study, researchers1 investigated the diets of Puerto Rican men aged 45 to 64 years to identify the relationship between certain foods and cardiovascular disease. The results from the study showed that subjects who consumed higher amounts of starch from legumes (and rice) had significantly lower rates of myocardial infarction compared to those who consumed lower amounts. The authors concluded that complex carbohydrates in the form of legumes may be protective of cardiovascular disease.
Legumes have some nutritional properties that suggest they may be protective of Western lifestyle diseases such as cardiovascular disease. In particular, legumes are a rich sources of soluble fibre that falls into the subcategory of gums. These fibres may inhibit the digestion of starch by forming a physical barrier that inhibits the ability of digesting enzymes to interact with starch grains. In addition the soluble fibre may be able to form a physical barrier along the enterocytes of the gut, inhibiting absorption of the glucose that results from starch digestion. Soluble fibres possess this ability because they absorb water and form a gel-like substance in the gut. The inhibition of digestion of starch and absorption of glucose may have beneficial glycaemic effects that reduces nutrient overload on the cells. As nutrient overload is a probable cause of oxidative stress that in turn may cause insulin resistance, legumes may be protective of the metabolic syndrome, a condition that centres on the development of insulin resistant cells.
Legumes have beneficial glycaemic effects because of their fibre. However, those who eat high amounts of legumes also, obviously, eat fewer of other foods. This is an often overlooked aspect of nutrition. Many foods are beneficial because their consumption precludes intakes of other foods that might be damaging. Those who eat legumes really fall into two categories. Those who are poor and cannot afford Western foods, and those who are well off, and who likely live in Western nations, but choose not to consume Western foods. Both of these groups avoid the deleterious effects of Western foods and as a result are protected from Western lifestyle diseases. One group then has no choice but to avoid these foods and the other does, which is interesting because it suggests that when poorer countries develop their populations will switch from foods such as legumes and instead consume the typical Western diet, and this will in turn increase Western lifestyle disease rates. And this phenomenon is exactly what we observe.