What are pulses?
According to the Food and Agricultural Organisation of the United Nations and the Global Pulse Confederation pulses are a type of leguminous crop that are harvested solely for the dry seed. Dried beans, lentils and peas are the most commonly known and consumed types of pulses. Pulses do not include crops which are harvested green (e.g. green peas, green beans)—these are classified as vegetable crops. Also excluded are those crops used mainly for oil extraction (e.g. soybean and groundnuts such as peanuts) and leguminous crops that are used exclusively for sowing purposes (e.g. seeds of clover and alfalfa). For this reason soybean and peanuts have not been included in this blog.
What are some examples of pulses?
You probably already eat more pulses than you realize! Popular pulses include all varieties of dried beans, such as kidney beans, lima beans, butter beans, broad beans (fava beans) and black beans. Chickpeas, cowpeas, black-eyed peas and pigeon peas are also pulses, as are all varieties of lentils.
Staples dishes and cuisines from across the world feature pulses, from hummus in the Mediterranean (chickpeas), to a traditional English breakfast (baked navy beans) to Indian dal (peas or lentils).
Tinned or dried: which is better for you?
There is very little nutritional difference between tinned and dried beans except for the added salt (sodium) to tinned beans. To reduce salt consumption choose no salt or salt reduced brands and rinse the beans thoroughly before use to remove most of the added salt. Cooked beans (whether home cooked or tinned) will keep in the refrigerator for up to 3 days. Dried beans if stored in a cool, dark, dry place in an airtight container will keep for around 12 months.
Protein contributed by pulses to the diet
There are 20 common amino acids found in food eight of which are essential for adults (nine are essential for infants) and must therefore come from food as the body cannot make these indispensable amino acids (1). In general pulses lack sufficient methionine and tryptophan amino acids, but have sufficient isoleucine and lysine amino acids. Cereals/grains have the opposite strengths and weaknesses, making them a perfect match for pulses that are ‘complementary’ and together contain all the essential amino acids in quantities sufficient to support health (2).
For most healthy vegetarians it is not necessary to balance amino acids from plant sources at each meal if protein intake is varied and energy intake is sufficient (1). Vegetarians can receive all the amino acids they need over the course of a day by eating a variety of whole grains, legumes, seeds and nuts (2).
Pulses and disease prevention
Pulses are recommended as an important part of a healthy diet because recent evidence confirms that pulses help protect against developing chronic disease such as heart disease, diabetes and cancer. There is strong evidence that regularly eating pulses can reduce the risk of colorectal cancer (3).
In 2010, a study by Harvard involving over 80,000 women compared various proteins in the diet in relation to the development of cardiovascular disease. In the analyses of individual protein sources, higher intake of red and processed meats were associated with increased risk, whereas higher intakes of fish, nuts, and beans were associated with decreased risk. Most importantly, the replacement of beef with beans in the diet demonstrated the most significant benefit to health (6).
The Australian Guidelines to Healthy Eating recommend legumes because they provide a valuable and cost efficient source of protein, some essential fatty acids, soluble fibre, insoluble fibre, resistant starch and important micronutrients such as iron, folate and magnesium to name a few (see Pulses Pantry for the nutrient content of individual pulses). The value of legumes as a nutritious food is reflected in their inclusion in both the ‘meat and alternatives’ food group as well as the ‘vegetables’ food group” (4).
Pulses and Climate Change
A recent American study projected that the routine substitution of beans for beef, regardless of any other climate control strategy, could achieve over 50% of the reductions needed to meet the 2020 Paris Accord greenhouse gas emissions target for the US. This shift would make available 42% of US cropland. This shift from ‘beef to beans’ offers an alternative climate policy option that could significantly mitigate climate change and illustrates the benefits of animal to plant protein food shifts. Evidence suggests that beans are almost certainly, significantly better for the health of humans, and the planet, alike (7).
What about the embarrassing side effects of eating pulses?
What about wind? The main culprits are their large indigestible sugars (raffinose, stachyose and verbascose) which zip straight through the system to the large intestine where the resident healthy bacteria make hay you might say: they ferment the indigestible sugars and then feast on them. Gas is a natural outcome. Some beans seem to be “windier” than others and some people don’t seem to suffer to the same extent. Acclimatize your large intestine by eating small amounts regularly and rinsing dried beans before soaking them if cooking from scratch, then rinse and drain 2-3 times before cooking. Be sure to discard the soaking water. With tinned beans, rinse and drain them really well. Why all this washing? Well, those indigestible sugars are water soluble and this helps to wash them away (5).
1 Moldanado, S 2013 Legumes: the super foods that should be regulars on your plate, Basic Health Publications, USA
2 Rolfes, SR Pinna, K & Whitney, E 2012, Understanding Normal and Clinical Nutrition, 9th edition, Wadsworth, USA
3 National Health and Medical Research Council. A review of the evidence to address targeted questions to inform the revision of the Australian Dietary Guidelines. 2011. Commonwealth of Australia
4 Australian Guidelines for Healthy Eating 2013, Australian Government, https://www.eatforhealth.gov.au/
5 Glycaemic Index Foundation, Keep Good Carbs and Carry On, http://www.gisymbol.com/7 7
6 Bernstein, A M Sun, Qi Hu, F B Stampfer, M J Manson, J E & Willett, W C 2010, ‘Major Dietary Protein Sources and Risk of Coronary Heart Disease in Women’, Circulation, 122, pp.876-883 viewed 14 July 2017, http://circ.ahajournals.org/content/122/9/876#T3
7 Harwatt, H Sabaté, J Eshel, G Soret, S & Ripple, W 2017, ‘Substituting beans for beef as a contribution toward US climate change targets’, Climate Change, Vol 143, Issue 1-2, pp.261-2710, viewed 14 July 2017, https://link.springer.com/article/10.1007%2Fs10584-017-1969-1