Just what is the place of beans and legumes in the dietary programs we recommend?

It’s an interesting question, and one that we get asked quite regularly, particularly when developing diet plans and protocols for vegetarians or vegans.

There’s no denying that beans and legumes have a rich culinary history. Nearly every culture has a traditional legume based dish that often forms a cheap, staple part of the diet. As in all things, moderation and balance is key. In this article we take a look at three reasons why we don’t recommend beans as a primary protein source.

Beans Impact on Weight Loss & Blood Sugar Control

Two of the biggest reasons people come to our clinic is for assistance in losing weight, and assistance in controlling blood sugar levels, often the two are quite closely related.

Both weight and blood sugar levels respond well to diets high in protein, high in good fats, high in fibre and low in carbohydrates. So how do beans and legumes stack up in this equation:

Let’s take a quick look at the macronutrient makeup of a few of the common beans used regularly for food (values expressed as mg/100g).

Bean	Protein	Fat	Carbohydrates
Chickpeas (canned)	4.95	1.14	22.61
Lentils (boiled)	9.02	0.38	20.13
Kidney Beans (canned)	5.26	8.97	9.93

The first thing that springs immediately to mind, is that even though beans are referred to as a vegetarian protein power house, they are still low in overall protein, with in some cases almost an almost 5:1 between carbohydrates and protein.

In all fairness to the humble legume, the carbohydrates found in beans are generally complex carbohydrates. Whilst they will still increase blood sugar levels, the affect on blood sugar is not quite so bad as refined carbohydrates, such as pastas and breads. The resulting blood sugar spike may be even further reduced by including another high protein source, such as eggs, or consuming with a low carbohydrate, high fibre food such as part of a salad.

While the right beans might not impact blood sugar levels, they will impact weight loss, particularly if using a ketogenic / low carbohydrate approach to weight loss. It is very hard for someone regularly consuming beans and legumes to lower carbohydrate intake enough to begin burning fat.

How Beans Impact Nutrient Absorption

There’s been a lot written about how beans affect nutrient absorption and with good reason! While on paper beans represent a veritable plethora of minerals and nutrients, in reality they are often a potent anti nutrient.

In addition to the macronutrients we have spoken about above, beans and legumes are high in nutrients known as phytates. Somewhat similar to the B vitamin inositol, phytates, and in particularly phytic acid, lock away many of the minerals in legumes preventing our bodies from properly absorbing them. Some of the minerals that are affected by the phytates include zinc, iron, calcium and magnesium. In clinic we regularly find quite serious deficiencies of zinc, iron and magnesium particularly associated with low immune function, auto-immune conditions and fatigue.

While some dismiss the impact that phytates make on availability of key minerals, this can in fact be quite a serious issue where legumes play a large role in the diet, ie. as the main protein source. One study analysing the role phytates played in the absorption of Iron, found that dephytinization increased iron absorption from grains by almost a factor of 7 [1]. A number of studies have shown similar results with the absorption of Zinc.

For anyone utilising beans and legumes as a preferred protein source, it is particularly important to follow proper soaking and cooking guidelines to deactivate or reduce phytate and other anti nutrient concentrations. This includes water pH, extra lemon juice or vinegar may be particularly important in Brisbane where water has a pH of 8.˜

Legume variety	Optimal water pH	Soaking time	Best Soaking Medium
Black beans	5.5	18-24 hours	Water with lemon juice, vinegar or whey added
Lentils	5.0	10 hours	Water with lemon juice, vinegar or whey added
Fava beans	4.0	10 hours	Water with lemon juice, vinegar or whey added
Dried and split peas	7.0 to 7.5	10 hours	Plain soft water with pinch of baking soda
Brown, white & kidney beans	7.0	18-24 hours	Plain soft water

(Table taken from: http://www.westonaprice.org/food-features/492-putting-the-polish-on-those-humble-beans.html)

Fermentation is another particularly effective method of bean preparation that has a long history in many Asian cultures. Commonly used fermented bean products include tempeh, miso and nato. While miso is particularly used as a condiment, and nato takes a little adjustment, tempeh is a particularly good source of vegetarian protein.

Beans & Complete Proteins

We mentioned earlier that every major culture seems to have a traditional, bean dish in their diet. One interesting thing to note is that most traditional bean dishes will combine beans with either a cereal, grain or dairy. Mexican pinto bean based dishes are typically served with wheat or corn based tortilla, or an Indian curry might be served with rice or paneer. These ancient cultures knew, that beans on their own did not make a complete protein.

Proteins are broken down by the body into amino acids that are then used to build up various bodily tissues including: skin, cartilage, muscle etc. There are 23 main amino acids, of which 9 are considered to be essential amino acids, that can not be manufactured in our body and must be sourced from externally. Plant based protein sources typically have what is referred to as limiting amino acid. This does not technically mean that the amino acid is not present, rather that it might be present in significantly reduced quantities. The following chart shows some of the limiting amino acids for different types of non-animal protein.

Foods	Limiting Amino Acid	Complementary Food
Legumes	Tryptophan, Methionine	Grains, nuts and seeds
Grains	Lysine, Isoleucine, Threonine	Legumes and dairy
Nuts & Seeds	Lysine, Isoleucine	Legumes

The ancient cultures intrinsically knew this, and their food choices show how complementary foods have been used to ensure complete protein intakes both at each meal and across the day.

For many of our clients, digestive issues (such as IBS, Chron’s or Celiac’s), blood sugar levels, auto-immune conditions or weight loss goals means that consuming grains is not the best idea. In these situations, a diet that is based heavily on beans and legumes as the primary protein source, without the additional amino acids provided by the complementary food, may develop deficiencies of particular amino acids. These deficiencies can result in a wide diversity of symptoms, affecting almost every area of the body. A tryptophan deficiency for example has been associated with:

• fibromyalgia;
• depression and mood disorders;
• Down’s syndrome;
• pre-menstrual syndrome;

Would You Like to Know More?

Why not make a time to talk with our Naturopath today. We will work with you to implement a dietary program that will help treat any of a number of common lifestyle conditions including auto-immune conditions and arthritis, high blood sugar levels, insulin resistance and diabetes or digestive conditions such as IBS, Chron’s and Celiac.

References

[1] Hurrell RF, Reddy MB, Juillerat MA, Cook JD, Degradation of phytic acid in cereal porridges improves iron absorption by human subjects.