Hello bean scouts, welcome back to Matt’s Bean Blog. After a short hiatus I am back, to bring you the best bean information I can find. This post will cover the environmental impacts of beans on our water supply and how to deal with bean related gas.

I am known to advocate a legume (beans, peas, lentils, etc.) based diet, and one of my reasons for following and promoting this diet is my belief that it is a more sustainable diet for our globe. Currently, the amount of livestock that is required to feed our planet has a hefty list of environmental impacts. Pastures and rangelands around the globe have been degraded by livestock through overgrazing, soil compaction, and erosion. Livestock are also largely responsible for deforestation (forests are cleared to make room for crops and pastures), which leads to CO2 emissions and extinction of forest species. Livestock also use and pollute our fresh water, and are a major source of many other pollutants. My question is, could legumes be a more sustainable alternative to meat consumption? Although I have often assumed that it would be, I have never actually examined how effective legumes would be as an alternative to meat. Starting on earth day, I began to compare land, water, and energy usage for producing legumes vs. meat. This first post will focus on water.

A quick note, legumes are often split into two groups, forage legumes and edible legumes. Edible legumes are also known as pulses. I may use the terms legume and pulse interchangeably in this post.

Although an individual human only needs half a gallon of water for daily drinking, the average human requires about 793 gallons of water to produce its daily food needs. This fact is especially reflected in the relative size of agricultural water withdrawals compared with municipal and industrial water withdrawals. Globally the agricultural sector uses 70 percent of all water withdrawals; a very significant footprint. However, measuring and comparing the global water footprint of certain products is very difficult. This is because some regions use water more or less efficiently, some farming methods are more or less efficient, and there are very different ways that agriculture can use water. The Water Footprint Network divides water into three categories, green water, blue water, and grey water. The blue water footprint refers to surface and ground water consumed, the green water footprint refers to rainwater consumed, and the grey water footprint refers to the amount of freshwater required to assimilate or dilute pollutants from that product (this will vary widely depending on local requirements for water safety. In countries with fewer environmental regulations less grey water will be used to dilute the pollutants used in agriculture. Some nations may also have fewer pollutants).

Pulses (aka legumes) require on average 420 gallons of green water per pound of crop (gal/lbs), 19 (gal/lbs) blue water, and 97 (gal/lbs) grey water, for total of 536 (gal/lbs). Chicken meat requires on average 468 (gal/lbs) green water, 41 (gal/lbs) blue water, and 62 (gal/lbs) grey water, for a total of 571 (gal/lbs). Pig meat requires on average 648 (gal/lbs) green water, 61 (gal/lbs) blue water, and 82 (gal/lbs) grey water, for a total of 791 (gal/lbs). Beef requires on average 1904 (gal/lbs) of green water, 73 (gal/lbs) blue water, and 60 (gal/lbs) grey water, for a total of 2036 (gal/lbs). However it is important to keep in mind that these are global averages, that don’t show differences between countries and production styles within countries. For example, industrial beef raised in the USA, requires 389 (gal/lbs) green water, 47 (gal/lbs) blue water, and 73 (gal/lbs) grey water, compared to grazed beef raised in the USA, which requires 2523 (gal/lbs) green water, 69 (gal/lbs) blue water, and 78 (gal/lbs) grey water. For another example, lentils grown in North America require no blue water, however in India they require 45 (gal/lbs) blue water. On the other, hand lentils grown in the US require 1022 (gal/lbs) of grey water compared to India’s 117 (gal/lbs) of grey water, either because of environmental standards or fewer pollutants.

As you can see this is rapidly turning into a rabbit hole. This whole process has left me with many questions and very few answers. One big question is why do pulses require so much grey water? Especially when compared to animals, which defecate? I hope to do more investigation into the question of water, but for now, I would like to leave you with something definitive. According to waterfootprint.org, globally, pulses require an average of 1.19 liters of water to produce 1 calorie, 19 liters of water to produce 1 gram of protein, and 180 liters of water to produce 1 gram of fat; while chickens (the most efficient source of protein acquired from meat that was listed on the website) require 3 liters of water to produce 1 calorie, 34 liters of water to produce 1 gram of protein, and 43 liters of water to produce 1 gram of fat. So it would seem, globally, that legumes are a more efficient user of our water, at least when it comes to producing calories and protein.

I also want to talk about flatulence. Legume related gastrointestinal distress is an issue that I have been avoiding. This is because I felt, until recently, that any fear of passing gas has been cosmetic. My opinion was that gas isn’t the problem, the problem is our anti-gas culture. Flatulence is both normal and healthy, and so I have tried to normalize gas rather than prevent it. However, for some individuals gas can be excruciatingly uncomfortable, and for many gas is the main reason beans are avoided. Because of this I am on the hunt for a solution.

So why do beans make humans gassy? Beans contain complex carbohydrates called oligosaccharides, which are fermented by the bacteria in our guts. One product of this fermentation is carbon dioxide, which makes up most of the gas in a fart.

Personally, my recommendation for preventing gas is to cook beans well and consume them regularly. Well cooked beans will be more digestible than undercooked beans. Use the five bean method to determine if beans are well cooked and avoid adding sugar or acid to your pot of beans until they are completely cooked. If you are interested in starting a bean rich diet, wean yourself onto beans. Your gut flora needs time to adapt to your new diet. Once you are eating more bean, maintain this diet. There are also many herbs and spices that are used to combat gas. Collectively these spices are called carminativa and include cumin, epazote, kombu, anise, cardamon, sage, oregano, thyme and many others. Carminativa are more of a traditional folk remedy, but after 10,000 years of bean eating, I am positive that there must be a lot of truth in tradition. Finally for those who seek a more modern cure there are drugs that contain simethicone. Simethicone is an anti foaming agent, and it prevents bloating by making gas bubbles in your gut bigger, which makes the gas easier to pass.

After all of this, I would like to return my first point. Gas is healthy. Gas is a sign that you are consuming soluble fiber, and soluble fiber is good for you. People who consume more fiber live longer and have a lower risk of death from heart disease. Oligosaccharide fermentation also creates short chain fatty acids, which have many health benefits. So eat beans and fart proudly.

Links:

http://www.nationalgeographic.com/what-the-world-eats/

http://waterfootprint.org/en/resources/water-footprint-statistics/