Give Peas a Chance

A guess post by Doug Evan, DO. Dahlicious is very grateful to Mr Evans for sharing his research and insights with us.

Give Peas a Chance

Regularly consuming peas, beans and lentils has many health advantages.

By Doug Evans, D.O.

Beans, peas, and lentils are all extremely health-promoting foods.  Virtually all of the longest living, healthy populations throughout the world—the people of Okinawa, Rural China, Azerbaijan, Tarahumara, and the Hunza — share one outstanding common dietary factor: they eat legumes several times a week1.  If you live and eat as these people do, you can expect a lowered risk of cardiovascular disease, cancer, diabetes, osteoporosis, menopausal problems, and even dementia.

Let’s look at legumes (beans, peas, lentils) and what makes them so health-promoting.

  1. The Protein Advantage

Legumes are a low-fat source of high-quality protein. Containing a good balance of all the essential amino acids, soy beans, for example, have higher levels of protein than even lean steak (steak derives 39% of its calories from protein). The greater the proportion of protein obtained from legumes, the healthier the longest-living populations tended to be.

Percent calories from protein in various legumes2:

Soybeans         45%

Tofu                43%

Broad beans    32%

Lentils             29%

Split peas        28%

Baked beans    26%

Kidney beans 26%

Lima beans     26%

Peas                 26%

Chick peas      23%

Another advantage is that the protein found in legumes is unlike animal protein, and does not cause a loss of calcium from the bones. Legumes also provide protection against cardiovascular disease and some forms of cancer.

  1. The High-fiber Advantage

Fiber in unprocessed plant foods, including legumes, is known to reduce the risk of cancer, specifically of the large intestines. Fiber also makes legumes a slow-releasing, low-GI food, great for stabilizing blood sugar levels. In addition, fiber reduces the risk of cardiovascular disease, partially by drawing cholesterol out of the body. Meat, eggs, and dairy foods contain no fiber.

Amount of fiber in one cup of3:

Baked beans    19 g

Soybeans         17 g

Split peas        16 g

Chick peas      12 g

Broad beans    9 g

Peas                 5 g

Legumes compare well with other high fiber foods, including berries (8 g), broccoli (5 g), oats (8 g), and spinach (4 g).

  1. The Mineral Advantage

 Legumes are a rich source of minerals, particularly calcium and iron.

Milligrams per 100 g portion4:

Calcium         Iron

Soy beans         226 mg          8.4 mg

Chickpeas         150 mg          6.9 mg

Baked beans     146 mg          6.8 mg

Although red meat is a rich source of iron, it is a very poor source of calcium. The iron in meat is called “haem” (or “heme”) iron, and it is a two-edged sword. On the one hand it is relatively easily absorbed, but because of this it becomes a potent source of free radical injury. Dairy products, in comparison, are a reasonable source of calcium but are low in iron.

  1. The Phytoestrogen Advantage

Legumes are the richest source of phytoestrogens (plant estrogens), often referred to as “flavonoids,” “isoflavones,” or “lignans.” Soy beans are exceptionally high in these phytoestrogens. A diet high in phytoestrogens has been found to5:

  • Reduce menstrual and menopausal problems (including legumes in your diet daily can reduce hot flashes).
  • Lower the incidence of cancers, particularly breast cancer, and to reduce the likelihood of its return. It has been firmly established that including soy, tofu, and tempeh in your diet is not only safe, but also provides extra benefits if you have or have had breast cancer, prostate, or colon cancer.
  • Reduce cardiovascular disease (most likely by lowering harmful cholesterol and triglycerides).
  • Increase bone density and strength (thereby avoiding or lessening osteoporosis).

In their groundbreaking study of the Okinawans— inhabitants of the islands in the southernmost part of Japan — Drs. Wilcox and Suzuki discovered that soy products in the diet, such as tofu, tempeh, and soy beans, were a significant factor in keeping bones strong and reducing the incidence of breast cancer. Furthermore, they found that the introduction of soy products into the diets of Americans (at similar levels) “resulted in significant increases in osteocalcin, a blood marker for bone formation,” indicating that these foods stimulated bone regeneration.

The Okinawans are renowned for being the longest living, healthiest people on earth, with low levels of heart disease, cancer, diabetes, and dementia. The elder Okinawans also have exceptionally strong bones, even though they seldom consume dairy products.

  1. The Arginine Advantage

Legumes are one of the richest sources of arginine, which is used by the endothelial cells lining the arteries to produce nitric oxide. Nitric oxide helps keep the blood flowing through the arteries by relaxing them and keeping them open, and making the endothelium surface slippery smooth. This is vital in preventing and reversing cardiovascular disease7. Fats and oils in our modern diet—including processed fats, trans fats, heated oils, animal and saturated fat—all suppress nitric oxide production.

6. Environmental Advantage

Legumes not only require less energy from fossil fuels to produce (compared to animal products) but they also directly reduce carbon dioxide in the atmosphere. They do this because, like all plants, they take in carbon dioxide (CO2) from the air and release oxygen (O2). Scientists are also impressed by the “nitrogen fixing” properties of legumes. They draw nitrogen into the soil, enabling other subsequent plants and crops to grow at a higher rate and, therefore, absorb even more CO28.

The United Nations has determined that the consumption of animal products, especially those intensively raised, comes at a high environmental cost. The UN has calculated that over 50% of the greenhouse effect could be attributed to animal food production (when fossil fuel expenditure such as refrigeration is included).  Furthermore, according to the US Environmental Protection Agency, the methane gas produced by livestock, for example, is 25 times more potent than carbon dioxide9.

Adding Legumes to Your Diet

If you are not accustomed to eating legumes, introduce them gradually. At first they can be a little difficult for some people to digest, leading to gas formation. They should be soaked for an hour or longer (according to their type and size), rinsed, and then cooked until soft. This removes most of the trypsin inhibitors, which prevent digestive enzymes from functioning efficiently. Most people find that tofu and tempeh are the most digestible forms of legumes.

Legume Naysayers

The idea that legumes contain significant levels of so called “anti-nutrients” is not well founded. Researchers and dieticians nowadays tend to shy away from the use of this term because they have found these anti-nutrients, including include phytates, lectins, and saponin, to actually be of overall benefit .

Phytates in legumes and whole grains do reduce the absorption of minerals such as calcium and iron. However, exhaustive studies have shown this effect to be “insignificant.” Moreover, phytates have been found to have beneficial antioxidant effects10.

Lectins, like “phytohemagglutinin,” are harmful in large doses. However, levels are high enough only in red kidney beans to be of any concern . When legumes, including kidney beans, are properly prepared, phytohemagglutinin and other lectins are degraded or eliminated11.

Although saponins, which are found in most plants, are resistant to digestion, any evidence that they may be harmful to human health is not forthcoming12.

The only consideration may be if you have been diagnosed as having low thyroid function. In this case, it is advisable to restrict your soy intake to approximately twice per week13.

Despite some recent bad press, particularly from ill-informed Paleo Diet advocates, legumes are proven to be both nutritious and delicious. For optimal health, a variety of legumes should play an important part in your diet. Give peas a chance!

References:

  1. Brenda Davis, RD. Lecture, “Paleo vs True Paleo,” Sydney, Feb 2015.
  2. Australian National & Medical Research Council, 2016
  3. Australian National & Medical Research Council, 2016
  4. Australian National & Medical Research Council, 2016
  5. Jane Plant, Your Life in Your Hands, Revised Edition, 2003
  6. B. Willcox, C. Willcox and M. Suzuki, The Okinawa Program, 2001
  7. Caldwell Esselstyn, Prevent and Reverse Heart Disease, 2007
  8. US EPA report Overview of Greenhouse Gases, 2014
  9. Atli Arnarson, PhD, Evidence Based Nutrition, 2016
  10. Kris Gunnars, BSc. Evidence Based Nutrition, 2016
  11. Joe Leech, RD. Evidence Based Nutrition, 2015
  12. Drs M. Messina and G. Redmond, “Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature.” US National Inst. Health, 2006