Legumes: The Pulse of Nutrition

Contributed by Maggie Collins, MPH, RDN, CDCES, DipACLM

Pulses are the dried seeds of legume plants and include beans, lentils, and peas. This group of foods has incredible health promoting properties to help prevent, manage, and reverse diseases, so we can consider them as the pulse of nutrition. To make things even better, pulses are inexpensive and have been a staple of the diets of many cultures around the world.

Difference Between Legumes and Pulses

Legumes are part of the Leguminosae family of plants[1], which is a type of plant that produces pods with seeds inside. Botanically speaking, a legume refers to any part of the plant, such as the leaves, stems, and pods. Pulses refer to the edible dried seeds within the pods of the legume (i.e., beans, lentils, peas, and chickpeas). Although soybeans and peanuts are legumes, the Food and Agriculture Organization of the United Nations (FAO) does not include them in the classification of pulses, since they are much higher in fat than the pulses previously described.

Some publications and organizations still use the term legumes to refer to pulses, including the Academy of Nutrition and Dietetics (AND) and the Dietary Guidelines for Americans (DGA), but what they mean by using the term is usually explained to avoid confusion.

Nutrition Characteristics of Pulses

See Table 1 below for examples of selected pulses describing the amount of these nutrients.

• Low Fat and Low-Saturated Fats: pulses are naturally low in fat and have a negligible amount of saturated fats. To remain this way, care should be taken when preparing dishes with pulses to minimize adding extra fat to the final product, but starting off your dish preparation with a food that is already low in fat is an advantage for those watching their fat intake (See article on the Many Faces of Fat).
• Cholesterol-Free: as cholesterol is only found in animal products, pulses can be enjoyed as a cholesterol-free food.
• Low-Sodium: pulses are naturally low in sodium. Canned varieties and adding salt when preparing them may add a significant amount of sodium to the final product, so those watching their sodium intake should be careful to season their pulses mainly with herbs and spices and minimize the use of salt.
• High Source of Fiber: this is one of the areas where pulses shine and where a lot of their health benefits are drawn from. One cup cooked of most pulses will provide around 50% of the recommended daily fiber intake (see Table 1 for some examples).
• Significant to High Source of Folate: pulses contain a very good amount of folate, a B vitamin involved in the synthesis of our RNA and DNA and the metabolism of proteins [2-4]. Folate is a crucial vitamin for women planning a pregnancy as it helps to prevent neural tube defects, but it also has an important role in keeping some cancer-promoting genes “turned off” [5].
• High Source of Protein: pulses are one of the most convenient and versatile plant-based protein options. Studies show that those who eat plant-based protein instead of animal-based protein live longer and better [6, 7]. For more on specific information on plant-based proteins, see article on The Truth About Protein.
• Significant to High Source of Iron: iron is a component of hemoglobin and myoglobin, proteins that distribute oxygen to the tissues and muscles, respectively. Iron is an important mineral necessary for growth, development, normal cellular functioning, and for the synthesis of some hormones and connective tissue [8].
• Significant to High Source of Magnesium: magnesium is another important mineral, involved in energy production, protein, DNA, and RNA synthesis, nerve and muscle function, blood glucose and blood pressure control, and many other functions in the body [9].
• Significant to High Source of Phosphorus: phosphorus is part of the composition of bones, teeth, DNA, RNA, cell membrane structure, and is involved in energy production from the metabolism of food [9, 10].
• Significant Source of Potassium: potassium is present in all parts of the body as it is involved in maintaining fluid volume inside the cells. Potassium also helps to balance the impact of sodium in the body, contributing to a more balanced blood pressure [11].
• Significant to High Source of Zinc: zinc is a mineral involved in several aspects of cell metabolism, our immune function, taste and smell, wound healing, protein and DNA synthesis, and cell division [12].
• Significant Source of Phytochemicals: phytochemicals are substances found in plants that promote health benefits. Pulses contain many phytochemicals that are involved in protection from coronary heart disease, some types of cancer, diabetes, high blood pressure, and inflammatory diseases [5, 13].

Health Benefits Associated with Pulses

• Helps with Maintaining a Healthy Body Weight

Due to higher fiber intake and slower digestion rate, replacing high-calorie foods with pulses has been shown to assist with weight management [14].  These fiber-packed foods make it easier to feel full sooner and stay full longer than meals that do not contain pulses [15, 16].

• Helps with Blood Sugar Control

There is a vast array of scientific evidence pointing to the regular consumption of pulses as an effective dietary intervention to prevent and treat diabetes [17-20]. When pulses are added to the meal, they lower the blood sugar response from that meal for several reasons:

• • Their fiber content slows down the emptying of the stomach and causes the carbohydrate in that meal to be released slowly;
  • They contain substances that inhibit the enzymes required to digest starch, so some of the starch in beans ends up not being absorbed [21];
  • The starch that is not absorbed serves as food to the bacteria in our gut, which in turn release a substance called propionate that slows the emptying of the stomach on the next meal. This is named by some scientists as “the second-meal effect”[22-24];
  • It displaces less favorable food options [19] .

• Decreases the Risk for Cardiovascular Disease

Studies show that consuming pulses (at least ~ ½ cup cooked four times a week) can lower the risk for cardiovascular disease [13, 25, 26]. The reasons are similar to what was already described for blood sugar management, in addition to a lipids-lowering effect (cholesterol and triglycerides) caused by their high fiber content [27], and a positive impact on blood pressure, platelet activity, and inflammation [28].

• Decreases the risk for Colorectal Cancer

The American Cancer Society estimates that colorectal cancer (CRC) is the third leading cause of cancer death in the United States [29]. Pulses have been associated with a decreased risk for this type of cancer [30]. The Adventist Health Study-I has found that individuals consuming pulses more than twice a week were 47% less likely of developing colon cancer than those individuals consuming pulses once a week or less [31].

The components of pulses that are thought to be protective against cancer are:

• • Their dietary fiber fermented by our gut bacteria into butyrate, which has anti-carcinogenic and anti-inflammatory properties;
  • The low impact on blood sugars due to its reduced rate of carbohydrate digestion and absorption;
  • Other components such as tannins, saponins, and phytochemicals have anti-carcinogenic antioxidant effects [28].

Considering the evidence that being overweight or obese can also increase the risk of several types of cancer (such as endometrial cancer, esophageal adenocarcinoma, gastric cardia cancer, liver cancer, kidney cancer, multiple myeloma, meningioma, pancreatic cancer, colorectal cancer, gallbladder cancer, breast cancer, ovarian cancer, and thyroid cancer), we can say that pulses can indirectly contribute to decreasing the risk for these cancers too [32] as they can assist with maintaining a healthy weight.

• Increases Longevity

If pulses have been associated with major health outcomes such as healthy weight, better blood sugar control, cardiovascular health, and reduced risk for cancer, it only makes sense to presume that those who eat from this group regularly live longer. One study looked at this hypothesis amongst elderly people from Japan, Sweden, Greece and Australia and found that legumes intake was the most important dietary predictor of survival in these groups [33].

How Often Should We Consume Pulses

The Dietary Guidelines for Americans (DGA) recognizes that a higher intake of pulses is associated with positive health outcomes, and it sets their recommendation of pulses intake on a 2,000-calorie healthy diet to 1.5 cups cooked per week [34]. Shockingly, even at this modest amount it is estimated that over 80% of the U.S. population does not meet this goal.

The World Cancer Research Fund (WCRF) and the American Institute for Cancer Research recommend including pulses in most meals to help meet their recommendation of at least 30 g dietary fiber daily [35], as a high-fiber diet has been associated with a reduced risk for some types of cancer. Some lifestyle centers choose this approach and serve pulses with every meal. When I was a dietitian student intern at the former Lifestyle Center of America (LCA) I had experienced beans being served for breakfast for the first time in my life and I loved it. Since then, I have adopted the same goal of including pulses in most meals for myself, for my clients, and for anyone in my circle of influence.

Aside from all the health benefits, pulses are among the cheapest source of nutrients we can find. One study looked at 98 vegetables to compare the cost of nutrients concentrated in foods per penny.  They found that dried pinto beans, kidney beans, lentils, and black beans were the most affordable source of nutrients [36]. There is no excuse not to incorporate this wonderful food group on our plates every day.

How to Prepare Pulses to Maximize Nutrition and Prevent Unpleasant Side-Effects

Some people experience bloating and gas production after eating beans. This may be caused by an intolerance to high levels of Oligosaccharides, which is a type of carbohydrate present in legumes [37]. Some of those oligosaccharides are not digested and end up being fermented by our gut bacteria, resulting in production of flatulent gases and bloating in some people [38].

Solutions:

1. Soaking dry beans for at least three hours and changing the water before cooking can reduce this fermentation.
2. Gradually increasing the amount of pulses you eat may allow for the gut bacteria to adapt to the amount and types of fiber being introduced.
3. Experiment with different types of pulses to identify specific intolerances.
4. Use activated charcoal may be useful to relieve symptoms. There is scientific evidence that activated charcoal can contribute to reduce excessive intestinal gas production. The European Food Safety Authority (EFSA) recommends taking 1g activated charcoal at least 30 minutes before consuming a meal that has shown before to be problematic in terms of excessive gas production, and 1 g after the meal [39]. Caution: excess use of charcoal may result in decreased amounts of some nutrients absorbed by your body.  Consult your healthcare provider for specific recommendations and to prevent supplement-drug interactions.

Historically, soaking and sprouting pulses have also been recommended to help to reduce phytic acid (aka phytates), which tends to bind to minerals in foods (such as zinc, iron, and calcium) decreasing their intestinal absorption [40]. This concept is being challenged by studies looking at bone mineral density that found that a higher intake of phytates has been associated with a lower risk for osteoporosis [41, 42]. In addition, phytic acid activity as an antioxidant is being studied for its potential in cancer prevention and treatment [43, 44].

It is very important to only consume pulses that are well cooked as there are reports of food poisoning outbreaks when uncooked or partially cooked beans have been consumed, leading to severe vomiting and diarrhea [45, 46]. The reports referred exclusively to kidney beans and there were no pathogens found in the samples of the beans served indicating that there are toxic compounds present on those beans that are destroyed with cooking. It is possible that those toxic compounds may be found in other pulses as well, so the same principle of cooking them well should apply.

Cooking methods include a slow-cooker, a regular pot on the stove, or a pressure cooker. For beans or peas, a ratio of 2 cups of water per cup of pulses is usually a good amount. Lentils typically require a bit more water, so a ratio of 2.5 cups of water for each cup of lentils is a good place to start. This water amount may need to be adjusted based on the individual preferences. Cooking time should be based on the final product’s texture being soft to chew. An online search for a basic recipe for each type of pulses can serve as an estimate time for the cooking method of choice. After being cooked, any leftovers pulses should be:

• Refrigerated within two hours;
• Consumed within 3-4 days;
• or frozen for up to three months for later use [47].
• Defrosting the frozen product should be done by transferring leftovers from the freezer to the refrigerator the day before;
• Reheat leftovers to an internal temperature of 165 degrees F.

Pulses can be prepared in a variety of ways to also please our taste. Versatile and healthy recipes using pulses can be easily found in websites that promote a whole food plant-based diet. For example, the website pulses.org/us has a variety of recipes, although not all are exclusively plant-based they can be easily modified to eliminate the animal products. Some suggestions to include pulses to our daily menu are:

• Beans or lentils stews;
• Curry with lentils or garbanzo beans;
• Beans, peas, or lentil soups;
• Beans added to salads;
• Lentil-based loaf;
• Vegetarian chili beans;
• Hummus and other bean-based spreads;
• Chickpea eggless omelet;
• Chickpea-based cookies or cakes;
• Black bean brownies;
• Bean-based dairy-free Alfredo sauce;
• Roasted chickpeas;
• Beans or lentil-based pasta products;

Pulses In the Bible

Pulses were part of the original diet (Genesis 1:29) designed for eternal life and happiness. Although pulses are only mentioned a few times in the Bible (2 Samuel 17:28, Ezekiel 4:9), it seems they were a staple food throughout history. Incidentally, Esau sold his birthright to Jacob for a stew of lentils (Genesis 25:29-33).

The word “pulse” is mentioned in Daniel 1:12 and Daniel 1:16 as part of the special diet requested by Daniel and his friends, but the Strong’s concordance gives the definition of the original Hebrew word translated as pulse as a generic for something sown. In other words, Daniel and his friends probably requested to be served a total plant-based diet, rather than only beans, lentils, or peas [48]. For more on the outcome of this 10-day biblical dietary trial refer to the article Finding True Joy in Eating.

Will we eat pulses on the new earth? As Isaiah 65:21 and 22 indicates, we will build and plant on the new earth, so it seems to me that any healthy plant that was part of the garden of Eden can be cultivated again.

What does the Seventh-Day Adventist Health Message Have to Say about Pulses

Beans, lentils, and peas are described by as part of a wholesome diet (Christian Temperance and Bible Hygiene, 222.3), but with the warning that “Some persons cannot digest peas and beans” (Counsels on Diet and Foods, 198.3), Ellen White herself being one of them (Letter 322, 1905).

Summary

Pulses are a wonderful food group, a gift from God offered in a variety of types to please our taste while providing for a healthy body. They are easy to find in most places of the world, being an inexpensive source of nutrition. They can be prepared in many ways to offer variety to the diet and encourage its consistent intake.

While the goal is to incorporate pulses in most meals, care should be taken for those who are not used to eating them regularly to gradually increase the amount consumed to prevent gastrointestinal discomfort.

Soaking pulses seems to be more important to reduce bloating and gas in sensitive individuals rather than being a mandatory step to enhance absorption of nutrients.

Those who have a health condition or an intolerance that prevents them from eating pulses, should consult with a registered dietitian if possible to guarantee the health benefits provided by this food group are met with other dietary choices.