Doc. Earm’s ‘K-Health’: The Paradox of Minerals and Fasting

*Editor’s note: K-VIBE invites experts from various K-culture sectors to share their extraordinary discovery about the Korean culture.

By Yung E. Earm (Professor Emeritus, Department of Physiology, College of Medicine, Seoul National University; Research Fellow, Department of Physiology, Anatomy and Genetics, University of Oxford )

◇ The Hidden Dangers of Minerals

Vitamins and minerals are often cited as essential elements of a healthy diet. But did you know that among minerals, there are harmful ones that should never be consumed?

First, let’s clarify what minerals are. When we hear the word “minerals,” many people think of mineral water. Mineral water refers to water that contains trace amounts of minerals such as calcium, magnesium, and potassium.

So, minerals essentially mean those substances—calcium, magnesium, potassium, and similar elements. In fact, the word “mineral” itself means mineral, ore, or inorganic substance, and is also called “inorganic matter.” You may recall learning about inorganic substances in science class.

Inorganic substances are nutrients obtained from the minerals that make up rocks or soil, and they are defined as nutrients that do not contain carbon. When we say “minerals,” it might sound like they are good for our health, but once you dig into the definition, you realize not all are safe to consume.

Indeed, some of the minerals we commonly ingest can be harmful to the human body. A typical example is aluminum—a light, soft, silvery-white metal used to make beverage cans and foils. Many people wonder why anyone would eat aluminum, but in fact, people often do.

This is because antacids, commonly taken for heartburn, contain large amounts of aluminum. While most of it is filtered out by the body and thus deemed safe in small amounts, aluminum can accumulate in nerve cells and act as a toxin, impairing neural function like other heavy metals.

Smokers, for instance, ingest various minerals through tobacco. Ironically, most of them are harmful—such as nickel, cadmium, and lead. You may have heard of “Itai-Itai disease,” which broke out in Japan from the late WWII era into the postwar period.

That disease was caused by cadmium buildup in the body, which gradually depleted calcium and weakened bones. The result was fragile skeletal structures prone to fractures all over the body, causing excruciating pain. The suffering was so severe that the disease was named “Itai-Itai” (literally, “It hurts, it hurts”).

In the past, cadmium poisoning was common, not just due to smoking. For example, beer is known for its foam, and in the past, breweries often used heavy metals to enhance foam quality. As a result, beer drinkers frequently suffered cadmium poisoning—until the practice was banned once the dangers became known.

Lead poisoning is another serious issue. Lead is present not only in tobacco but also in exhaust fumes. Because lead adheres to fine dust particles, it directly affects the respiratory tract and can also enter the digestive system through contaminated food or water.

Once inside the body, most lead accumulates in bones, slowly leaching into the bloodstream. Severe cases can lead to anemia, kidney damage, and reproductive dysfunction. Accumulated lead in the brain may cause paralysis, blindness, mental disorders, memory loss, or other serious neurological diseases.

Lead is particularly dangerous because, compared with other heavy metals, it takes much longer for its concentration to decrease in the body.

Mercury poisoning is another growing concern. Mercury is still used today in dental amalgams, thermometers, barometers, blood pressure devices, pharmaceuticals, pesticides, mercury batteries, and fluorescent lights. It’s well-known that large fish like tuna and swordfish accumulate mercury, which is why pregnant women are advised not to eat them. For the general public, fish and shellfish remain the primary sources of mercury exposure, so it’s best to limit consumption of species known to contain high mercury concentrations.

◇ The Power of 12-Hour Daily Fasting

Now that we’ve discussed what to eat and what not to eat, let’s consider how to eat. The key point I want to emphasize is that we should develop the habit of fasting for at least 12 hours a day—meaning we should spend half the day without food. Our digestive system needs rest, too.

Fasting may sound intimidating, but it’s actually not that difficult. Simply avoid eating between dinner and breakfast. For example, if you finish dinner at 7 p.m., then don’t eat anything until 7 a.m. the next morning. In other words, avoid late-night snacks.

Why is a 12-hour fast necessary? Because our bodies need downtime. Just as we rest after working all day, so do our digestive organs like the stomach and liver. Even a small snack forces these organs to keep working.

Most importantly, mitochondria—the tiny organelles inside cells, often called the “powerhouses” of the body—need adequate rest. They generate the energy we live on. The reason we eat food is so that mitochondria can produce energy. Cyanide is fatal precisely because it shuts down mitochondrial function.

Another vital benefit of fasting is giving cells time to “self-clean.” A 12-hour fast allows cells to clear out waste and regenerate.

In 2016, the Nobel Prize in Physiology or Medicine went to Japanese scientist Yoshinori Ohsumi, who discovered the process of autophagy—from the Greek “auto” (self) and “phagein” (to eat), meaning “self-eating.”

Autophagy is the process by which cells, under stress, aging, or nutrient shortage, break down unnecessary proteins for recycling—essentially removing cellular waste.

When the body fasts, the liver first breaks down glycogen, then burns fat for energy. Autophagy reduces inflammation, improves blood sugar control, strengthens mitochondrial function, enhances immunity, and increases beneficial gut bacteria. It also helps balance gut flora and normalizes appetite regulation. In short, a 12-hour fast provides a refreshing rest for countless cells in the body.

Interestingly, plant cells also contain an energy-generating organelle: the chloroplast. Chloroplasts capture sunlight through chlorophyll to synthesize sugars, which animals then consume to sustain life.

Both mitochondria and chloroplasts originated from bacteria, which is why mitochondria have their own DNA separate from the cell’s nuclear DNA. Fascinatingly, mitochondrial DNA is inherited solely from the mother. By tracing mitochondrial lineages, scientists can trace human ancestry back to early hominins in Africa, such as Lucy (Australopithecus afarensis).

It’s reminiscent of how Jewish tradition follows matrilineal descent. Ultimately, bacteria are the foundation of life itself—supporting animal cells, plant cells, and all living beings on Earth. Which means, in a sense, we must treat bacteria well.