Vitamins from fruit vs pills – What your body absorbs best

Are only natural vitamins beneficial?

The belief in the benefits of only natural vitamins is based on the idea that "food-derived products" contain additional bioactive components (phytonutrients, flavonoids, etc.) that work synergistically with vitamins. It is also partially influenced by marketing, where the term "natural" is interpreted as "safer and more effective."

According to the expert, there is currently no proven advantage of natural vitamins over synthetic ones.

"Effectiveness and safety depend on the specific vitamin, its form (stereoisomer, certain salt form, etc.), dose, and clinical context. For example, according to PubMed data, vitamin C has similar bioavailability in both synthetic and dietary forms," Khaitovych said.

The expert explained that chemically and biochemically, the molecule of L-ascorbic acid (the chemical name for vitamin C - ed.) is identical regardless of its source.

He also noted that synthetic forms of vitamin D are prescribed in certain doses to prevent and treat rickets. Doctors recommend reducing doses or even pausing intake during the summer when vitamin D is naturally produced in the skin under UV exposure.

"Exceptions for synthetic and dietary vitamin forms occur when the same name covers different isomers or derivatives. For example, natural vitamin E (d-α-tocopherol) versus synthetic (dl-α-tocopherol), or folic acid versus methylfolate (the active form of vitamin B9 - ed.)," the professor explained.

In these cases, the molecular configuration and form affect metabolism and bioavailability.

"Additionally, in food, a vitamin is accompanied by a matrix of proteins, fats, and polyphenols, which can influence absorption or metabolic activity," Khaitovych added.

When synthetic vitamins can be more effective than natural ones

The expert noted that according to Advances in Human Biology, synthetic folic acid usually has higher bioavailability when taken orally.

"Its metabolism differs from natural forms, and at high doses it can accumulate in the blood as unchanged folic acid," the professor emphasized.

He explained that in certain conditions, such as atrophic gastritis, antimicrobial therapy, and in elderly people, the oral bioavailability of vitamin B12 can be reduced.

Therefore, for example, in older adults, doctors prescribe forms of vitamin B12 that bypass the gastrointestinal tract, such as injections or sublingual tablets.

What are the risks of overdosing on synthetic vitamins?

"According to Medscape, the main risks are associated with fat-soluble vitamins (A, D, E, K), which accumulate in tissues and can cause toxic effects. This includes hypervitaminosis A (liver dysfunction, increased intracranial pressure, fetal developmental defects with high doses during pregnancy) and hypervitaminosis D (hypercalcemia, kidney failure, etc.)," Khaitovych said.

He emphasized that some water-soluble vitamins can cause specific side effects at very high doses. For example, prolonged niacin intake can lead to liver toxicity, and vitamin B6 can cause neuropathy.

Is it possible to have an excess of natural vitamins?

"This is rarely described, although possible. For example, consuming large amounts of vitamin D from foods (like cod liver oil) combined with intense sun exposure," the expert explained.

He added that the kidneys easily excrete water-soluble vitamins (vitamin C and most B vitamins) under normal function, so toxicity from food sources is unlikely.

"However, in kidney failure, even water-soluble micronutrients can accumulate. Hypervitaminosis usually occurs with concentrated supplements," the professor stressed.

Synthetic vitamins are often not inferior to natural ones (illustrative photo: Freepik)

How vitamins are absorbed in children, adults, and the elderly

The expert noted that in young children, especially newborns, enzymatic systems are not fully developed, so certain vitamins require specifically adjusted doses or pharmaceutical forms.

In older adults, decreased stomach acidity and comorbid conditions, combined with the use of multiple medications, can impair vitamin absorption.

Therefore, doctors prescribe vitamins parenterally (bypassing the gastrointestinal tract) or in higher doses, while monitoring effectiveness and safety.

Can vitamin deficiencies be overcome through diet alone?

Khaitovych explained that in low- or middle-income countries, typical diets often fail to provide sufficient vitamins and minerals, so supplementation is justified.

"Additionally, doctors always prescribe folic acid to women two months before planning pregnancy and during the first trimester," the expert emphasized.

Vitamin-drug interactions: How important are they?

The professor said this is extremely important.

"Vitamins and minerals can alter the pharmacokinetics and pharmacodynamics of medications. For example, high doses of vitamin K can reduce the effect of the anticoagulant warfarin. High doses of niacin interact with lipid-lowering drugs and may increase liver toxicity. High doses of vitamin E can affect chemotherapy outcomes," he noted.

He added that many drugs, including proton pump inhibitors and metformin, reduce vitamin B12 absorption. Therefore, in cases of polypharmacy, especially among elderly patients, doctors must monitor interactions and adjust doses if necessary.

Seasonal vitamin intake: Marketing or necessity?

"Evidence-based research does not support the idea that daily multivitamin use in healthy adults reduces the risk of cardiovascular disease," Khaitovych said.

Thus, widespread seasonal courses without individual indications are not justified.

"However, certain vitamins depend significantly on region and season, especially vitamin D. Supplementation for older adults or those with limited sun exposure can be justified. Low blood levels of vitamin D are a direct indication for additional supplementation under a doctor's guidance," the expert added.

Previously, we wrote about the five primary signs of vitamin B12 deficiency.

We also covered daily habits to help increase vitamin intake.

Earlier, we explained why vitamin D can be potentially dangerous.

This material is for informational purposes only and should not be used for medical diagnosis or self-treatment. Our goal is to provide readers with accurate information about symptoms, causes, and methods of detecting diseases. RBС-Ukraine is not responsible for any diagnoses that readers may make based on materials from the resource. We do not recommend self-treatment and advise consulting a doctor in case of any health concerns.