[Kim Jaeho's Life Story]<202> Good Carbohydrates and Bad Carbohydrates

At one time, a "high-fat, low-carbohydrate diet" that involved reducing carbohydrate intake while consuming a lot of fatty foods was popular as a treatment for obesity. Based on the hypothesis that excessive carbohydrate intake causes obesity, this diet may temporarily reduce body weight, but if carbohydrates are excessively restricted, their important functions cannot be properly performed, and high fat intake can cause other problems, so it is not a healthy eating method.

Carbohydrates are compounds of carbon, hydrogen, and oxygen that perform several important functions within living organisms. They are the main components forming the backbone of DNA and RNA, which make up all cells, and are the primary source of energy in the form of blood sugar that supplies energy needed for all cellular activities, accounting for the largest portion of the nutrients we consume. Various substances produced when dietary fiber is broken down perform many beneficial functions for health.

To understand the health effects of carbohydrates, which are mainly used as an energy source, it is helpful to divide them into three types: simple carbohydrates, complex carbohydrates, and dietary fiber. Simple carbohydrates are carbohydrates with a simple structure, such as glucose or sugar, that can be easily absorbed in the small intestine. Complex carbohydrates are large and complex molecules made up of long and complicated chains of simple carbohydrates that must be broken down into simple carbohydrates before absorption.

Simple carbohydrates are absorbed quickly in a short time, causing blood sugar to rise suddenly and the duration of blood sugar supply to be short, which is especially harmful to diabetic patients. Complex carbohydrates, found abundantly in grains such as rice, wheat, and corn, cannot be absorbed in their complex form and must be broken down into simple carbohydrates by digestive enzymes before absorption. This breakdown takes a long time, so absorption is slow. There is no difference in how the body uses simple carbohydrates produced from complex carbohydrates and simple carbohydrates consumed directly from food.

Generally, complex carbohydrates are considered healthier than simple carbohydrates, but not all simple carbohydrates are bad, nor are all complex carbohydrates good. Simple carbohydrates found in fruits and vegetables come with important nutrients such as vitamins, minerals, antioxidants, and dietary fiber, which are beneficial to health. Processed foods like cookies, cakes, and carbonated drinks that contain only concentrated simple sugars without these nutrients are harmful.

Among simple carbohydrates, sugar is particularly harmful, so it is very important to reduce the intake of added sugars in foods. One molecule of sugar is broken down by digestive enzymes into one molecule of glucose and one molecule of fructose. Excessive intake of fructose is mostly converted into fat, causing various chronic diseases such as hypertension, diabetes, obesity, and hyperlipidemia, and it also promotes the progression of cancer, causing many problems (see Life Story episode 20).

It is true that complex carbohydrates are generally healthier than simple carbohydrates, but not all complex carbohydrates are healthy. Whole grains like brown rice and whole wheat, which have only the outer husk removed, are rich in important nutrients such as vitamins, healthy fats, and dietary fiber. However, refined grains like white rice and white wheat, which have the inner husk and germ removed, contain complex carbohydrates that are much less healthy than those in whole grains.

Dietary fiber is a type of complex carbohydrate with a complex structure that cannot be broken down into simple carbohydrates by human or animal digestive enzymes, so it cannot be used as an energy source but is a representative good carbohydrate. It is broken down by gut bacteria living in the large intestine, producing substances such as inulin, beta-glucan, pectin, and short-chain fatty acids (SCFA), which are known to play a significant role in preventing and healing obesity, diabetes, and cardiovascular diseases.

Additionally, dietary fiber absorbs lipids such as cholesterol as it passes through the gastrointestinal tract, lowering low-density lipoprotein (LDL) cholesterol and triglycerides, reducing the risk of heart disease, and inducing a feeling of fullness that reduces appetite and lowers the risk of obesity (see Life Story episode 21).

It is important to consume all nutrients in appropriate amounts; both underconsumption and overconsumption can be harmful to health. Carbohydrates, if consumed excessively over a long period, can cause problems such as obesity, so it is advisable to reduce intake to an appropriate level. At this time, it is good to reduce the intake of bad carbohydrates, that is, foods high in refined simple sugars and foods made from refined grains, while sufficiently consuming good carbohydrates, such as whole fruits, vegetables, and unrefined whole grain foods.

The U.S. Dietary Guidelines for Americans recommend eating within an appropriate calorie range, consuming a variety of vegetables, whole fruits, and whole grains sufficiently, and limiting sugar intake to less than 10% of daily calorie intake, which aligns with this perspective.

Jaeho Kim, Independent Researcher

This content was produced with the assistance of AI translation services.