[Kim Jaeho's Life Story]<204> Plant-Based Protein and Animal-Based Protein

Protein is an essential nutrient used as a material for muscles, skin, hair, bones, and almost all parts and tissues of the body, as well as various enzymes and hemoglobin. It accounts for about 20% of the body's components, second only to water. If deficient, it can cause various problems such as impaired normal growth, reduced muscle mass, weakened immunity, and diminished heart and lung function, so it is important to consume an adequate amount.

There are many misconceptions about protein intake. Unlike carbohydrates or fats, protein is not stored in the body, so it must be consumed daily in the required amount, but eating too much is not good. When digesting protein, acid is produced, and the body uses calcium, an alkaline substance, to neutralize it. Therefore, consuming excessive protein for a long time can deplete calcium in the bones, potentially causing osteoporosis.

All proteins are complexes made by combining 20 types of amino acids, and different forms are created depending on the composition ratio of each amino acid, so there are many types. All living organisms create and use the proteins they need by varying the composition ratios of amino acids, and it is known that more than 10,000 types of proteins exist in the human body.

The difference between plant and animal proteins lies in how amino acids are obtained. Plants synthesize all necessary types of amino acids directly, but animals and humans, which cannot produce amino acids themselves, obtain the necessary amino acids by eating proteins from plants or other animals and breaking them down (digesting them), sometimes modifying the shape of some amino acids for use.

Some people believe that protein is found only in animal foods including meat or that eating meat is essential for protein intake, but this is not true at all. Protein is originally made by plants and transferred through herbivores to carnivores, so the protein in meat ultimately comes from plants. Naturally, there is no difference in the 20 types of amino acids that make up plant and animal proteins; only the composition ratios of amino acids differ for each protein.

The protein content in meats including beef and in beans or red beans is about 20-30%, brown rice is 8%, whole wheat is 14%, and nuts such as walnuts and peanuts contain about 15-25%, so plant foods also contain a lot of protein. Therefore, it is not necessary to eat meat solely for protein intake. This is why herbivores like cows, horses, elephants, and giraffes can maintain large bodies without eating meat.

Nine of the amino acids are essential amino acids that cannot be synthesized by the human body. Animal protein is a complete protein containing all essential amino acids in sufficient amounts, but some say that plant protein is often incomplete, lacking one or more essential amino acids. However, the essential amino acids lacking in one food can be easily supplemented by those in another food, so there is no need to worry.

Both plant and animal proteins are broken down into amino acids and absorbed in the body, then used to make the necessary proteins, so there is no difference in how the body utilizes them. Generally, people rarely consume protein alone, and when eating protein foods, other nutrients are also consumed together, so which protein is better should be judged by comparing the other nutrients contained.

From a nutritional perspective, the best protein foods are plant proteins rich in various antioxidants and dietary fiber, including beans and nuts (see Life Story episode 203), and among animal proteins, white meats such as fish, chicken, and duck are good. Red meats like beef and pork contain a lot of saturated fat and have been linked in many studies to increased risks of vascular diseases, diabetes, and various cancers, so it is better to eat them sparingly.

Processed meats made from red meat, such as ham, sausage, bacon, and hot dogs, are made by adding various substances including salt during processing, and are particularly unhealthy as they cause various chronic diseases. The International Agency for Research on Cancer (IARC) under the World Health Organization (WHO) classifies definite carcinogens as Group 1, probable carcinogens as Group 2A, and possible carcinogens as Group 2B; processed meats are classified as Group 1, and red meats as Group 2A.

Protein is widely found in many foods, so whether eating meat or vegetables, there is no need to worry about protein deficiency unless there is severe dietary imbalance. However, among animal protein foods, excessive consumption of red meat, especially processed meat, can be a major cause of chronic diseases such as vascular disease, diabetes, and cancer, so it should be limited.

Kim Jae-ho, Independent Researcher