Survival Nutrition: Complementary Proteins

For general health at all times, and especially if any short- or long-term disaster affects your food supply, you should be armed with some basic knowledge of nutrition. This article focuses on protein, one of the three macronutrients needed for health and survival.

* A complete protein provides all essential amino acids and sufficient total protein.
* An incomplete protein is either low in one or more essential amino acids, or low in total protein.

There are eight essential amino acids, and several semi-essential amino acids. But I’ll simply it for you. The vast majority of dietary patterns on the face of the earth, whether based on cereals (grains, pseudo-cereals), pulses (beans, peas, etc.), seeds/nuts, or tubers (potato, yam, etc.) provide sufficient amounts of all essential amino acids, with a few exceptions. The essential amino acids that are most likely to be lacking in any diet are lysine (lacking in grains), or methionine (lacking in pulses), or tryptophan (lacking in various foods). Even though other amino acids are essential, for practical purposes they are unlikely to be in short supply, as long as you have some source with sufficient total protein.

The typical Western diet is too high in total protein. Our culture promotes the excessive consumption of meat, poultry, and cheese. According to the CDC, Nutrition for Everyone — Basics, Protein, an adult needs only about 46 to 56 grams of protein per day. The average American gets about twice that amount of protein. The Institute of Medicine gives a more detailed summary of protein requirements here: Dietary Reference Intakes: Macronutrients.

If some disaster restricts the food supply, you might find yourself unfortunately compelled to eat a healthier diet, one with less meat and cheese, and more vegetable sources of protein. Meat, poultry, fish, milk, eggs, and cheese are all complete proteins — high in protein with sufficient percentages of each essential amino acid. But not all vegetable sources of protein are as complete. Sometimes, to obtain a complete protein from grains, tubers, and vegetables, two or more complementary sources of protein must be combined.

* Complementary proteins are two or more incomplete protein sources, which together provide adequate amounts of all essential amino acids and adequate total protein.

It is true that many vegetable sources of protein are not complete, and need to be complemented by other protein sources. However, there are some common misconceptions about which sources of protein are complete, and which are complementary to one another. The following chart has been published in similar form in various sources. It was popularized many years ago in the book “Diet for a Small Planet”.

However, the chart is not entirely accurate.

You can find out if a protein is complete or not at: BitterPoison.com, which takes the USDA nutrition data and analyzes the essential amino acid content compared to the Institute of Medicine’s recommended amounts of each amino acid as a percent of total protein. A score of 1.00 is 100% of the recommended percentage. However, total protein is still a concern. You need both: enough total protein and the right percentages of each essential amino acid within that total protein.

Dairy sources of protein:
Milk and various cheeses are each high in protein and have all essential amino acids in ideal or nearly ideal percentages. Yogurt has less than the ideal percentage of tryptophan, an essential amino acid, but still has enough tryptophan to be considered complete for practical purposes. So, contrary to what the above chart suggests, no complementary proteins are needed with dairy.

Many legumes are a complete protein — like dairy, they need no complementary protein to provide sufficient essential amino acids. Complete protein legumes include:
split peas (dried)
cowpeas (dried)
chickpeas (any)
soybeans (mature seeds, not Edamame)

In general, the mature legumes — allowed to dry on the vine — are a better protein source than the same legume picked and shelled green, i.e. before maturing fully. So, for example, the Edamame type soybeans, picked fresh, are not a complete protein; they have one third of the protein of dried soybeans and not enough methionine (an essential amino acid).

The legumes that are not complete proteins tend to lack only methionine. The chart is correct in this respect. Those legumes that are not complete benefit more from being paired with grains or seeds than with dairy. Although dairy is a complete protein, it is not high enough in methionine to compensate for the lack of that amino acid in certain legumes. Of the three (grain, seeds, dairy), dairy has the least amount of methionine.

Grains tend to be lacking in lysine. An adult needs between 2 and 3 grams of lysine per day; the ideal percent of lysine is 5.1% according to the Institute of Medicine. However, according to the U.N.’s FAO (food and agricultural organization), the ideal percent is 4.5%. But even if the percent of lysine is somewhat less than ideal, a population can still survive in good health. This is proven by the fact that millions of persons have survived for many generations with wheat or rice as their main protein source, despite the low percent of lysine in those grains. So grains such as rice and wheat have less lysine than ideal, but still enough lysine to be sufficient.

To improve the lysine content of your food, the chart is correct that dairy is a good complement to grains. Many dairy sources, especially cheeses, are high in lysine. The best protein and lysine sources are the hard cheeses, especially those that are lower in fat. These have less water and less fat, and hence more protein. Examples include low-fat Swiss cheese, parmesan cheese, Romano cheese, and hard cheddar cheeses.

But the complementary protein chart is not entirely accurate in indicating that legumes complement grains. Some legumes provide little additional lysine because they are low in total protein. For example, green peas (fresh) are only 5.4% protein, and green (snap) beans are only 1.8% protein. The low total protein means that they cannot offer much lysine to complement the grains.

By comparison, dried split peas are 24.5% protein and have a higher percent of lysine as well. Soybeans and adzuki beans (both as mature dried seeds) are high in protein and high in lysine, as are lentils and chickpeas. Lentils are not a complete protein; they lack methionine — except if they are sprouted. Lentils are one of the few seeds that have a better essential amino acid profile after sprouting.

The complementary protein chart indicates that seeds are a good complement to legumes. This is also inaccurate. Sunflower seeds have less than the ideal percent of lysine (at only 88% of ideal). However, they are so high in total protein that they provide more lysine than many complete proteins. So sunflower seeds are, for practical purposes, a complete protein. Pumpkins seeds are high in total protein and have an ideal essential amino acid profile, so no complement is needed. Seeds tend to be high in methionine, so they do improve the essential amino acid profile of legumes. But both seeds and legumes are too high in fiber. You might not want to eat only legumes and seeds as your protein sources.

Pseudo-cereals, like amaranth and quinoa (keen-wa), are usually classified with grains. From a culinary point of view, they are used in recipes much like wheat and rice. But technically each is a dry hard fruit with a single seed at its center. Amaranth and quinoa are each a complete protein: high in total protein and having all essential amino acids in ideal proportions. No complementary protein is needed. Amaranth and quinoa are also excellent backyard garden sources of protein. As pseudo-cereals, they have no hulls, and so they are much easier to process from garden to table. You simply thresh the grain (remove it from the plant) and then clean and wash it. Quinoa must be thoroughly rinsed to remove bitter saponins. But you are spared from the difficult and time-consuming step of hulling.

The complementary protein chart makes no mention of tubers, even though tubers are one of the main protein staple foods in the world. Potatoes are nearly a complete protein. They are somewhat lacking in leucine, in terms of percent (87% of ideal); but anything over 80% is usually sufficient for practical purposes. Yams (true yams) and sweet potatoes lack only lysine (76% and 82% of ideal, respectively). But the main issue with tubers is the low total protein. Most tubers are less than 2% protein. So they need a complementary source of protein, not so much because of their essential amino acid percentages, but to provide more total protein. For this purpose, any high protein source is useful: cheese, or seeds, or dried legumes.

I’ll close with a few comments about food storage and protein. My short list of the better stored protein sources includes:

white pasta (keeps indefinitely)
white long-grain rice (keeps indefinitely)
dried peas, beans, lentils (keep indefinitely)
nuts and seeds (limited shelf-life)
peanut butter (limited shelf-life)
cheese (keeps indefinitely if frozen)
canned beans and chickpeas (not snap beans, which are too low in protein)

More on survival nutrition in later posts.

– Thoreau

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