How much protein do you really need? Is it ok to get all of your protein from plant sources? What about red meat for protein? Is it really true that red meat is bad for you? 

These are just a few of the common questions people have about protein. And adding to the confusion, it seems like just when the science seems settled about protein, a new study comes out and upends everything you thought you knew! 

So let’s get an in-depth look at this vital, but somewhat controversial nutrient.

You can think of all the foods you eat as belonging to just one of three categories: carbohydrates, fats and protein. These three categories are known as “macronutrients” and are sometimes called “macros” for short. Although almost every food, such as peanut butter for example, has a mixture of fats, carbs and proteins, it’s convenient to group them in a specific macronutrient category according to the majority ingredient.

So while peanut butter is a good source of protein, it’s also high in fat, so normally nuts as well as nut butters are grouped in the “fats” category. Broccoli actually has a surprisingly high protein content per calorie of the vegetable, but you would have to eat a lot of it to get the same amount of protein contained in a 4 ounce steak. The majority ingredient in broccoli is carbohydrates, so broccoli, as are most other vegetables, is grouped in the “carbs” category. Foods with a high protein content, such as meat, dairy products and eggs are grouped in the protein category.

Protein - What Is It?

But exactly what is protein and what role does it play in the body? Carbohydrates and fats provide energy for the body, as the cells burn them for fuel. Protein, except in extraordinary circumstances, is not used for energy but comprises the building blocks for the tissues in your body, such as your bones, muscles, skin and hair. Proteins also play many other essential roles in the body and are critical components of antibodies that defend your body against bacteria and viruses, enzymes that power chemical reactions and even help form the hemoglobin that carries oxygen in your red blood cells. Plus, proteins also function in transport, storage and messenger roles as well.

Protein itself is interesting structurally, because it’s composed of long chains of building blocks known as amino acids. There are 21 of these amino acids and while your body can actually manufacture many of these from other molecules present in your body, there are nine amino acids (known as the “essential” amino acids) which cannot be made in the body and have to come from your food. 

These amino acid building blocks can be arranged in many different ways, so your body can manufacture literally thousands of different proteins using these 21 amino acids. Your body can also break down protein into its amino acid components and make new and different proteins from the building blocks. This is the ultimate in recycling!

Protein - How Much Do You Need?

So how much protein do you actually need every day?

There are varying schools of thought on this and one respected institution, the National Academy of Medicine has some guidelines. Keep in mind that in terms of an “ideal” amount of protein in the diet or even the optimal percentage of your calories that should come from protein, there is just not that much solid research to back up specific claims.

So this is the reason even the National Academy of Medicine allows such a wide range for acceptable daily protein intake, ranging from ten to thirty-five percent of total calories each day. Their minimum recommendation for daily protein intake is a little over 7 grams of protein for every twenty pounds (9kg) of body weight, which means someone who weighs 140 pounds (63.5kg) would need 50 grams of protein a day and someone who weighs 200 pounds (90.7kg) would require about 70 grams daily.

Another factor to remember is this: human beings are not lab rats, and it’s nearly impossible (not to mention unethical!) to conduct the types of rigorous, necessarily restrictive dietary studies in human populations that would give definitive answers to these types of questions. 

Although the consequences of protein deficiency are well known and include everything from loss of muscle mass to a decrease in immunity, these sorts of dramatic protein deficiencies are rarely seen in the United States and other developed countries. In fact, most healthy adults in the U.S. regularly consume more protein than is routinely recommended. 

Protein - It’s The Package That Counts

But research in this area suggests that it’s not the absolute amount of protein one consumes that has the biggest impact on health and metabolism, it’s the “package” that protein is wrapped in that can actually be the problem. In other words, it appears to be the protein source, not the exact amount of protein that is the largest factor in human health and disease.

For example, red meat (steak) is a great source of protein, but that protein comes packaged with other things that are not so good for you, such as saturated fat. Processed meats, such as ham, may have less saturated fat, but are loaded with sodium.

On the other hand protein coming from fish, such as salmon, is low in saturated fat and sodium, and is also high in the heart healthy omega-3 fatty acids. Plant based protein is even more impressive, with a cup of cooked lentils supplying 18 grams of protein, a whopping 15 grams of fiber and almost no sodium or saturated fats.

Research on the effects of animal based protein, particularly red and processed meat, is clear: regular consumption of these products increases your risk of heart disease and stroke, Type 2 diabetes, cancer, and higher risk of premature death. Research also shows that regular consumption of red and processed meats as well as full fat cheeses can contribute to unhealthy weight gain. 

Even though some people have had temporary success with high protein, high fat, low carbohydrate diets such as the so called “keto” diet, these diets are typically not sustainable and may contribute to high cholesterol and even kidney stone formation in some people. Also, cutting out whole classes of foods from your diet, such as fruit, whole grains and beans deprives your body of healthy vitamins, minerals, fiber and other plant-based phytonutrients that are important for optimal health.

One of the most interesting research findings that may also help to explain the detrimental effects red and processed meats have on human health is that these foods contain high levels of specific amino acids, including the amino acid methionine (say “muh-THIGH-oh-neen”) and a group of amino acids known as branched chain amino acids or BCAAs. 

While these amino acids are all essential for optimal human health and functioning, excessive circulating levels of these amino acids can be harmful to metabolism and purposefully restricting these amino acids is associated with gains in longevity and an improvement in metabolic health in many organisms. So it will likely come as no surprise that a high intake of animal protein, particularly red meat, exposes the body to increased levels of both methionine and BCAAs. Plant based protein sources have much lower levels of these particular amino acids.  

Protein - The Bottom Line

The bottom line? It certainly seems prudent, based on current research, to limit or even omit your consumption of red meat. Processed meats, such as bacon, sausage, hot dogs and the like should be eliminated entirely.

If you are going to consume animal protein, poultry, seafood and eggs are better choices. Dairy products, especially whole milk and cheese, should be consumed in limited amounts as well, with yogurt being the better choice.

Plant based sources of protein are plentiful and delicious and there are a wide variety of beans, legumes, nuts, seeds and whole grains from which to choose. There is also continuing innovation by companies to bring plant based “meats” to the market but you do need to be aware of high levels of saturated fat in some of these products. Buon appetito!

References:

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