A Swiss study has found that people who take vitamins indiscriminately may increase their risk of cancer by up to 27%. While vitamins are essential for health, excessive or improper supplementation can actually harm the body.

Water-Soluble vs. Fat-Soluble Vitamins：

1. Water-soluble vitamins—such as B-complex vitamins and vitamin C—dissolve in water and are usually excreted in urine when consumed in excess.

2. Fat-soluble vitamins—including vitamins A, D, E, and K—are absorbed along with fat and stored in body tissues, making it easier for them to accumulate and cause toxicity if overused.

In most cases, a well-balanced diet provides adequate amounts of vitamins. However, many people mistakenly turn to supplements, often consuming them in excess, which can be more harmful than helpful.

Vitamin Supplementation Should Be Personalized：

Vitamin supplementation is not one-size-fits-all. While deficiencies can lead to health problems, excessive supplementation can also trigger new health issues. Here are a few examples:

A lack of vitamin A can lead to symptoms like dryness in the eyes and impaired vision. Sources: carrots, liver.

Vitamin C deficiency can result in mouth ulcers and dry skin. Sources: citrus fruits, bell peppers.

Vitamin D deficiency can affect bone health. Sources: sunlight, cod liver oil.

Vitamin E deficiency may weaken immunity and dry out the skin. Sources: leafy greens, nuts.

That said, not everyone needs extra vitamins. For example:

Vegetarians may lack vitamin B12.

Pregnant women need more folic acid.

As people age, their bodies may become less efficient at absorbing vitamin D through diet alone.

The Risks of Over-Supplementation：

Recent research highlights the dangers of over-supplementing certain vitamins:

Too much vitamin A can cause liver damage and symptoms of toxicity.

Excessive vitamin D may lead to high calcium levels or kidney stones.

Long-term vitamin E overuse has been linked to fatigue, nausea, and even bleeding issues.

Overconsumption of fat-soluble vitamins is particularly concerning because the body cannot easily eliminate the excess.

Some vitamins, like vitamin B3 (niacin), may even increase cancer risk or promote tumor growth if taken inappropriately, according to the Swiss study.

How to Supplement Vitamins Safely？

1. Eat a balanced diet: A diet including 300–500g of dairy, 200–350g of fruits and vegetables, and 120–200g of animal-based foods is usually sufficient to meet vitamin needs.

2. Supplement only when needed: Special groups—like pregnant women, seniors, or people with chronic illnesses—should only take vitamins under medical or nutritional supervision.

3. Avoid excessive doses: More is not always better. Stick to recommended daily amounts and avoid self-medicating with high-dose supplements.

The 4 Vitamins to Be Especially Careful With：

While vitamins are crucial for health, these four can pose serious risks when taken in excess:

Vitamin A: Can cause yellowing of the skin and liver toxicity with long-term overuse.

Vitamin D: May cause kidney stones and dangerously high calcium levels if over-supplemented.

Vitamin E: High doses over time may lead to fatigue, dizziness, or bleeding problems.

Vitamin K: Large doses can cause hemolytic anemia and elevated uric acid levels.

Final Thoughts

For most people, a healthy, varied diet provides all the vitamins the body needs. Supplementation should be based on individual needs and done under professional guidance. Avoid taking vitamins blindly—doing so could lead to serious health risks instead of benefits.