Dietary supplements are products that support a normal diet with nutrients such as vitamins, minerals, amino acids, fatty acids, plant extracts or probiotics. They come as tablets, capsules, powders, drops or liquids.

Supplements are not medicines and are not used to treat disease. Their role is to support a need that your diet does not fully meet, so they do not replace balanced eating and healthy habits.

Supplements are easy to buy at pharmacies, supermarkets and online, so they are often taken without an identified need or a doctor’s advice. Yet unnecessary, unsuitable or interacting products may do more harm than good.

A common myth is “it’s just a vitamin, it can’t hurt.” In fact, every nutrient has a range the body needs, and too much can cause problems just as too little can. The goal of supplement use is to fill what is missing and avoid what is unnecessary.

A healthy adult with a balanced diet often does not need routine supplements. Still, they may be needed in some situations:

• A deficiency found in blood tests: Such as low vitamin D, vitamin B12, iron or folate.
• Times of higher need: Pregnancy and breastfeeding may call for supplements planned by a doctor.
• Restricted diets: Vegan or vegetarian diets and very low-calorie diets. During weight loss, nutrient needs are assessed together with your diet plan.
• Absorption problems: Some digestive diseases or previous stomach surgery.
• Long-term use of some medicines: Certain medicines can reduce the absorption of specific vitamins and minerals.

Symptoms alone are not a reliable guide. Tiredness, hair loss or dry skin can each have several causes, so an examination and blood tests come first. Hair loss, for example, may be linked to iron deficiency, a thyroid problem or a hormonal condition, and each needs a different approach.

At our clinic in Nişantaşı, Istanbul, supplement use is planned only after a need has been identified:

1. Your complaints, health history, medicines and current supplements are reviewed in detail.
2. The necessary blood tests are ordered and the results evaluated.
3. If a deficiency is found, the first step is to see what can be covered through proper nutrition.
4. If a supplement is needed, your doctor sets the product, dose and duration.
5. Follow-up blood tests at set intervals show whether to continue.

In some cases, such as absorption problems, giving nutrients through a vein may be considered. Treatments like IV Boost are also planned only after an examination and tests, on a doctor’s decision.

Using a supplement for longer than advised, or raising the dose yourself, is not recommended. A “more is better” approach can cause problems, especially with vitamins and minerals. If complaints return after stopping a supplement, the underlying cause of the deficiency should be investigated again.

Even supplements from natural sources can cause side effects and interactions. The most common issues are:

• Overdose: Vitamins A, D, E and K are fat-soluble and can build up in the body. Taken in excess for a long time, they may cause signs of toxicity.
• Drug interactions: St. John’s wort may change the effect of some antidepressants and birth control pills. High amounts of vitamin K may reduce the effect of some blood thinners.
• Absorption interactions: Calcium and iron may reduce the absorption of thyroid medicines and some antibiotics, so the timing of doses is adjusted.
• Bleeding risk: Fish oil and ginkgo may increase bleeding risk when taken with blood thinners.
• Stomach and digestive complaints: Iron and some minerals may cause nausea, constipation or stomach upset; the product or how you take it can be changed with your doctor.

Tell your doctor about all supplements before surgery or dental treatment. If you notice an unexpected sign such as a rash, palpitations, yellowing of the skin or severe stomach pain, stop the product and see a doctor. Keep supplements out of children’s reach; iron-containing products in particular can be dangerous for children.

Buy supplements from a reliable source and read the label carefully:

• Registration: In Türkiye, food supplements are supervised by the Ministry of Agriculture and Forestry, and the package should carry approval or registration details.
• Ingredient list: If you use more than one product, check that you are not taking the same ingredient twice.
• Exaggerated claims: Be cautious of products that claim to treat disease or work very quickly.
• Recommended use: Do not exceed the daily amount on the label, and do not use a product in place of a meal.
• Storage: Respect the expiry date and recommended storage conditions.

When the goal is immune system boosting, supplements are considered as one part of a holistic plan alongside nutrition, sleep and activity.