If You Eat Too Much Peanut Butter, You're More Susceptible To This Nutrient Deficiency
Vegan diets and plant-based eating are continuing to rise for reasons such as animal welfare, carbon footprint reduction, or simply health. When someone chooses to give up meat (or simply eat less meat), the question always seems to be, "Can you get enough protein?" The truth is that with a well-planned vegan or plant-based diet, you can get plenty of protein from regular foods such as beans, nuts, and seeds.
Nutritional deficiencies can occur when you stick to the same protein sources, however. Plant-based proteins are considered "incomplete" proteins because they lack enough of the essential amino acids found in animal-based foods such as meat, dairy, and eggs. Your body needs 20 amino acids, but you need to get nine of them from food. It's not that plant-based proteins don't have these amino acids, but instead, there aren't enough of them to consider them "complete" proteins. If peanut butter is your only source of protein, your diet could be deficient in the essential amino acid methionine.
Amino acids in peanut butter
Amino acids make up proteins that are used by the body. Imagine amino acids like ingredients in a recipe. Combining certain ingredients makes one food, whereas a combination of other ingredients makes another. Some of these amino acids combine to make hormones and neurotransmitters. Others will help build muscle tissue. Amino acids also provide energy, support your immune system, and help metabolize fat. The essential amino acids you need from food are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Peanut butter is still good for you because it has all of these essential amino acids, but it's much lower in methionine. Methionine plays a role in detoxification, metabolism, and repair of soft tissues. You need this amino acid to help your body absorb zinc and selenium. You need 19 milligrams of methionine for each kilogram of body weight. That means someone weighing 150 pounds needs 1,295 milligrams of this amino acid. Two tablespoons of peanut butter provide 84 milligrams, which is just 6% of the recommended amount. Compare that with a Grade A large egg that has just about the same amount of protein but 210 milligrams of methionine. Peanut butter also has about half the lysine and threonine of an egg.
What to pair with peanut butter
You don't have to give up peanut butter or eat a ton of it to get enough amino acids. You can pair peanut butter with other protein sources to fulfill any nutritional shortfalls. An ounce of chia seeds gives you another 167 milligrams of methionine to put you at 19% of your daily needs for this amino acid. Add a scoop of soy protein powder along with peanut butter to your breakfast smoothie to get more than half of your daily methionine and almost all the rest of your amino acids. You could also make a peanut sauce to top your edamame. A 100-gram serving of edamame provides an additional 141 milligrams of methionine. It's also a good source of lysine and threonine.
Although edamame, tofu, and tempeh aren't considered complete proteins, they have a considerable amount of the nine essential amino acids you need every day. A 100-gram serving of tofu provides at least 50% of the recommended amounts of seven essential amino acids. A cup of cooked quinoa gives you at least 18% of all of your essential amino acids, and adding a 100-gram serving of black beans to your quinoa will help fill out your nutritional needs.