Don’t miss out on these 9 essential amino acids

By Connie Capone
Published July 9, 2020

Key Takeaways

Our bodies require six essential nutrients to function, grow, and repair: carbohydrates, proteins, fats, vitamins, minerals, and water. Of these nutrients, the most misconceptions tend to be about protein. Debate swirls around the best food sources of protein and how much we need to consume on a daily basis. After all, every cell contains and requires protein—it’s everywhere in the body, from our skin and hair to our bones, muscles, and tissues. But it’s a little more complicated than that.

Amino acids are the building blocks of protein. They also help determine the quality of dietary protein. There are 20 amino acids in proteins, most of which our bodies can produce. The nine amino acids that we can’t produce include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. We must obtain these from food sources or supplements, the latter of which you might want to stay away from—but we’ll get to that later.

So, how do we ensure we’re getting enough of these nine essential amino acids in our diets? And how can understanding proteins help?

The importance of essential amino acids

Essential amino acid deficiency can have serious health effects. A review published in the Advances in Nutrition journal outlined several possible health risks for amino acid-deficient diets, including a slower rate of protein synthesis in cells and tissues, specifically in skeletal muscle. Because of this, dietary protein deficiencies contribute to cardiovascular dysfunction, increased risk for infectious disease, and the exacerbation of other nutrient deficiencies, including vitamin A and iron.

The spectrum of health complications that result from inadequate essential amino acid intake is wide. These include low appetite and vomiting, and a variety of mental health effects, such as mood swings and anxiety. Consuming too few essential amino acids also causes impaired antioxidative reactions, such as poor immune response, cardiovascular abnormalities, and tissue fluid retention. Losses of calcium from poor protein intake result in dental abnormalities, hair breakage and loss, and reduced production of hair pigment.

Essential amino acids: Sources and stats

What are the daily protein requirements needed to maintain overall health? The answer depends on age, physical activity level, state of health, and more. According to the US Department of Health and Human Services, the Recommended Dietary Allowance (RDA) is 0.8 g of protein per kilogram of body weight. Here are two estimates to give you an idea: An average woman between 19 and 30 years old would need roughly around 46 g of protein per day. An average man in the same age bracket would need around 56 g of protein per day.

What about the essential amino acids in those proteins? Here is the Institute of Medicine’s list of recommended daily amounts of the essential amino acids for adults (per kg body weight):

  • 5 mg of tryptophan

  • 14 mg of histidine

  • 19 mg of isoleucine

  • 19 mg of methionine (plus cysteine)

  • 20 mg of threonine

  • 24 mg of valine

  • 33 mg of phenylalanine (plus tyrosine)

  • 38 mg of lysine

  • 42 mg of leucine

According to the NIH, you’ll find amino acids in foods you typically associate with protein, including animal sources such as meats, milk, fish, and eggs, and plant sources such as soy, beans, legumes, nut butters, and grains (buckwheat, quinoa). Foods that contain all nine essential acids are called complete proteins. These include eggs, fish, beef, pork, poultry, and whole sources of soy (tofu, edamame, tempeh, and miso). Generally speaking, plant proteins have lower essential amino acid contents when compared to animal proteins. Still, contrary to popular belief, you can get all of the protein you need in your diet without consuming animal products.

In a study on the average Polish diet, researchers ranked 13 food categories according to protein and amino acid content. The results, published in Nutrients, showed that meat products were the main food category source of 6 essential amino acids. Grain products were the second leading food category in terms of essential amino acid content. In reference to the disparity of animal and plant sources of essential amino acids, the authors note, “health professionals should encourage vegetarians to include a variety of protein-rich foods, such as whole grains; legumes; beans, split peas and baked beans; soy products; nuts and seeds.”

The prevailing wisdom is that sourcing amino acids from whole, natural foods is preferable to obtaining them from supplements. In an amino acid supplement safety study, Timothy J. Maher, PhD, professor of pharmacology and associate dean of graduate studies, Massachusetts Colleges of Pharmacy and Health Studies, wrote, “The only safe form of amino acid ingestion is considered to be via protein in the diet.”

Dr. Maher also cited a report that assessed the safety of using amino acids as dietary supplements. The report was published by an ad hoc expert panel of scientists, assembled by the FDA and the Life Sciences Research Office of the Federation of the American Societies for Experimental Biology. After reviewing all existing literature on amino acid supplements, the group concluded that there is no nutritional rationale for supplementing amino acids, and that doing so can even be dangerous to health.

The panel found that amino acid supplements available on store shelves generally failed to provide sufficient information regarding their chemical composition, purity, shelf-life, and other required items. What’s more, they raised concerns that amino acid supplements might interact with prescription drugs, because research has found potential interactions between amino acids and antidepressants, opioids, and more.

Bottom line

The nine essential amino acids are crucial parts of a balanced diet and can be found in a variety of whole grains, beans and other legumes, plants, and lean animal proteins. As with any nutrient, more isn’t always better and research into the recommended amount of daily protein consumption for optimal health is ongoing.

As for amino acids, foods that are rich in the essential amino acids, from eggs and fish to tofu and lentils, help the body perform at its best, but there’s not enough evidence to suggest that consuming amino acids in supplements is helpful to health. It’s important to consider the full nutritional profile of the foods we consume. In general, if we aim for protein sources that are plentiful in many nutrients and low in saturated fat and processed carbohydrates, our essential amino acids intake will be sufficient.

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