Question

Harmful effects on health in pulses

Answer 1

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (≤1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2–4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3–8 wk for whole pulses and 4–12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (≥1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption.

Previous SectionNext SectionIntroduction

The worldwide prevalence of obesity has reached epidemic proportions (1). Because excess body fat is associated with the development of life-threatening chronic conditions such as heart disease, type 2 diabetes, and certain types of cancer (2,3), viable and sustainable solutions for sustainable weight loss and prevention of weight gain are urgently needed. Generally, selection of a diet high in fiber, low in energy density and glycemic load, and moderate in protein is thought to be particularly important for weight control (4). Such a diet may be achieved by regularly consuming food from certain food groups, including fruits, vegetables, and whole grains; some lean meats, nuts, and legumes; and limited consumption of food from other groups, including high-fat meats, sugar-sweetened beverages, bakery items, and highly processed foods. In this review, we will focus of the role of legumes, particularly the nonoilseed pulses (see terminology below), in energy regulation and successful weight control, highlighting the work that has been published in the past 10 y.

Previous SectionNext SectionTerminology: legumes, pulses, and beans

The pods or fruits of plants in the botanical family Fabaceae, or Leguminosae, are commonly known as legumes. Legumes include alfalfa, clover, lupin, green beans and peas, peanuts, soybeans, dry beans, broad beans, dry peas, chickpeas, and lentils. According to the FAO (5), a pulse is a type of legume that is exclusively harvested for the dry grain and therefore excludes peanuts and soybeans, which are harvested for their oil. Pulses are also sometimes referred to as grain legumes or pulse grains. The published literature often refers to the Phaseolus vulgarisspecies; these include kidney beans, haricot beans, pinto beans, and navy beans.Figure 1 shows a simplified scheme of the classification of different legumes.

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Legume classifications (5).

The health effects of soybeans and peanuts have been well studied. Although soybeans share some of the nutritional properties of pulses [e.g. high in fiber and protein, low glycemic index (GI)], they are thought to have unique health effects due to their high content of certain phytoestrogens such as isoflavones and other bioactive compounds (6). The effects of soybeans and soy protein (7–9) and peanuts (10–14) on body weight have been reviewed elsewhere and will not be covered here.

Previous SectionNext SectionMacronutrient and phytochemical profiles of pulses and energy regulation

Pulses have a unique nutritional profile consistent with several dietary composition factors thought to assist with weight control. They also contain several antinutrients that have been suggested to play a role in energy regulation (Tables 1 and 2). In particular, they are high in fiber, providing ∼7 g/0.5 c (120 mL) serving. Pulses are also relatively low in energy density (1.3 kcal/g or 5.3 kJ/g) and a good source of digestible protein (average of 7.7 g of protein/0.5 c). Pulse carbohydrates are slowly digested (see below), which allows some of the lowest GI among carbohydrate-containing foods. Pulse GI typically range from ∼29 to 48 (using glucose as the standa