These three botanical additions contribute additional plant polyphenols and a small extra amount of natural vitamin C, but their main scientifically suggested role is a potential improvement in cellular (leukocyte) uptake of vitamin C, not necessarily a higher plasma concentration (Calder, Kreider & McKay, 2025). Since the doses of these additions in this product are relatively small (43 mg, 30 mg and 4.3 mg) compared to the main dose of 1000 mg pure ascorbic acid, this represents more of a supportive than a key effect. The product's core effectiveness for immune/antioxidant support comes mainly from the vitamin C dose itself.

This is a difference in the scope of the manufacturer's label warnings and does not necessarily mean the product is less safe. With high additional doses of vitamin C (approximately 1000 mg per day and more), a prospective cohort study in men recorded roughly double the relative risk of developing kidney (oxalate) stones compared to non-supplementing individuals, while this association was not confirmed in women (Ferraro et al., 2016). Since the label does not explicitly state this warning, we recommend that people with a history of kidney stones or other risk groups consult a doctor before regularly taking this or any product with a similar dose.

AdvancedU does not claim that vitamin C treats or prevents the common cold. A Cochrane systematic review found that regular daily vitamin C supplementation (in the included studies mostly ≥200 mg/day) did not significantly reduce the likelihood of illness in the general population, but was associated with an approximately 8% shorter duration of colds when taken regularly, before the onset of symptoms (Hemilä & Chalker, 2013). The dose of 1000 mg per tablet considerably exceeds this studied range, but this does not guarantee a specific effect for you personally. For frequent respiratory infections, we recommend consulting a doctor to determine the cause.

Both products contain the same base dose (1000 mg of pure L-ascorbic acid), so the difference lies mainly in additional ingredients and transparency. BioTechUSA adds three precisely quantified botanical additions (lemon peel, rosehip, elderberry), which according to some data may support cellular uptake of vitamin C (Calder et al., 2025), justifying a somewhat higher price per tablet. Ostrovit is a cheaper, minimalist product without these additions, but its label explicitly warns about kidney stones and pregnancy, which BioTechUSA's does not. The choice depends on whether you value additional botanical ingredients or a lower price and more explicit safety warnings.