What are vitamins and why do they matter?

Vitamins are essential micronutrients for the functioning of our organism. They participate in processes such as energy production, immune system functioning, cell formation and neurological and hormonal balance.

They are divided into:

  • Water-soluble: B complex and vitamin C

  • Fat-soluble: A, D, E and K

This difference completely changes their behaviour in the body and also the associated risk.

When does vitamin use make sense?

Supplementation has clear indication in some scenarios:

1. Proven deficiency

  • Diagnosis by laboratory examination

  • Example: vitamin D, B12, iron deficiency

2. Specific physiological situations

  • Pregnancy (e.g. folic acid)

  • Elderly (higher risk of B12 and vitamin D deficiency)

  • Lactation

3. Clinical conditions

  • Diseases that cause intestinal malabsorption

  • Bariatric surgery

  • Restrictive diets (e.g. unplanned veganism → risk of B12 deficiency)

4. Guided strategic use

  • Athletes or individuals with high metabolic demand, with professional monitoring

Outside these contexts, use tends to have little or no proven benefit.

When to avoid indiscriminate use?

Supplementing without indication can generate two main problems:

1. False sense of security

The person believes they are "compensating" for inadequate habits with vitamins, which in reality does not happen.

2. Risk of excess

Mainly with fat-soluble vitamins, which accumulate in the body.

What are the risks of inadequate use?

Fat-soluble vitamins (A, D, E, K)

They have greater toxicity potential.

  • Vitamin A: can cause hepatic toxicity, neurological changes and teratogenic risk

  • Vitamin D: in excess → hypercalcaemia, which can lead to:

    • nausea

    • vomiting

    • mental confusion

    • arrhythmias

    • renal injury

  • Vitamin E: increased risk of bleeding

  • Vitamin K: can interfere with anticoagulants

Water-soluble vitamins (B complex and C)

Excess is generally eliminated in urine, but this does not mean absence of risk.

  • High doses of vitamin C → gastrointestinal discomfort, risk of kidney stone

  • Excess vitamin B6 → can cause peripheral neuropathy

"Do vitamins make your urine expensive?" What does this mean in practice?

This popular expression has merit.

When a person ingests water-soluble vitamins beyond what is needed:

  • the body absorbs what it needs

  • the excess is eliminated in urine

In other words, part of the supplement is simply not used, so it is literally discarded.

Additionally:

  • the urine can become more yellow (especially with B complex vitamins, such as riboflavin)

  • this does not mean extra benefit, but rather, only excretion of the excess

In practice: you pay for something your body does not use.

Is there benefit in using vitamins "for prevention"?

This is one of the greatest doubts and requires care.

In healthy people with balanced nutrition, there is no consistent evidence that routine supplementation reduces mortality or prevents chronic diseases.

Exceptions exist, but they are specific and should be individualised.

Smarter strategy

Before starting any vitamin, the safest reasoning is:

  1. Assess symptoms and clinical context

  2. Investigate with examinations when necessary

Correct first the foundation, which is nutrition, sleep and sun exposure (when applicable). Supplement in a targeted way, with defined dose and duration.

Conclusion

Vitamins are essential, but this does not mean that more is better.

There is an important difference between:

  • correcting a deficiency

  • and using supplementation without indication

The first improves clinical outcomes.

The second may be merely cost or risk.

The decision to supplement should be clinical, individualised and based on evidence.

Dr. Rebeca Soares Andrade. CRM- GO 39335