"The dose makes the poison" – this old wisdom helps to understand the modern vitamin dilemma. Between supermarket shelves and social media promises, many assume that more is automatically better. However, those seeking high performance, longevity, and a strong immune system require precision rather than pill roulette.

Vitamins are organic micronutrients that the body needs for energy production, cell protection, and metabolic processes. They act as cofactorshelper molecules that activate enzymes, antioxidantsmolecules that intercept oxidative damage from free radicals, or building blocks for signaling pathways. Fat-soluble vitamins (A, D, E, K) are stored; water-soluble vitamins (C and B group) must be supplied regularly. Important: "Natural" does not automatically mean "risk-free," and "high dose" does not mean "highly effective." Intelligent micronutrient management combines high-quality foods with targeted, indication-based supplementation.

A solid vitamin base correlates with better immune function, lower inflammatory activity, and stable energy. Vitamin C from citrus fruits provides antioxidants and polyphenols such as hesperidin, which lower inflammatory markers and support immune cell function; studies show that daily orange juice can reduce postprandial inflammation and lower C-reactive protein over weeks ^[1]. At the same time, research warns against the assumption that "more is better": overdoses – particularly from vitamin A and certain B vitamins – have been associated with neurological problems ^[2]. For those following a strictly plant-based diet, vitamin B12 is a special case: since plants do not produce B12, the risk of neuro- and hematological deficiencies increases without supplementation, undermining performance directly ^[3]. Another often underestimated factor is interactions with medications; particularly in polypharmacy, supplements can enhance or weaken the effects of medications ^[4].

Large population data show how closely dietary quality and micronutrient status are linked: in a national study involving over 10,000 adults, while more fruit and vegetable consumers achieved higher vitamin C levels, many still failed to meet recommended intake values despite sufficient amounts of fruits and vegetables; targeted supplements reduced the risk of deficiency, but the source mattered – sugary drinks often provided the lion's share of "vitamin C," which diminishes dietary quality ^[5]. The evidence for vitamin C in infections presents a nuanced picture: reviews find no consistent benefit of high-dose ascorbic acid for the prevention or treatment of the common cold; routine use cannot be justified ^[6]. Recent reviews suggest that oral administration may shorten symptoms of acute respiratory infections and that IV vitamin C in hospitals improves certain parameters; however, high-quality, current studies are lacking, especially regarding prevention, and there is no evidence for the prevention or treatment of COVID-19 through oral intake ^[7]. The situation is particularly clear regarding vitamin B12 and plant-based diets: since unfortified plants provide no B12, recent evaluations show high deficiency rates, especially among pregnant vegans – with risks for neurological, vascular, and immunological functions; reliable supplementation is not a "nice-to-have" but a necessity ^[3]. Finally, the intertwining of supplements and medications is coming into focus in an aging, performance-oriented population: international data document frequent combinations and increase the risk of interactions, such as absorption disorders or add-on effects on blood coagulation; structured inquiries and pharmaceutical care are recommended as effective countermeasures ^[4].

- Build your foundation with real foods: Eat colorful fruits and vegetables daily (e.g., berries, citrus fruits, leafy greens, cruciferous vegetables). This improves vitamin C intake and provides inflammation-modulating polyphenols; population data show that people with high fruit and vegetable intake are less likely to have vitamin C deficiencies – supplements can fill gaps but cannot replace the quality of the source ^[5].
- Rely on natural vitamin C sources for immune strength: Incorporate citrus fruits and berries into breakfast and snacks. Vitamin C plus citrus polyphenols like hesperidin support barrier function and reduce inflammation; regular consumption can reduce postprandial inflammation ^[1].
- Supplement B12 consistently with a plant-based diet: As a vegan or vegetarian, choose a B12 supplement (e.g., cyanocobalamin or methylcobalamin) in adequate dosage and regularly check your status, especially during pregnancy and lactation, to prevent neurological and hematological deficiencies ^[3].
- Avoid mega doses: Resist the impulse to take high doses of vitamins. Excessive intake – particularly of vitamin A and some B vitamins – is associated with neurological side effects ^[2].
- Clarify interactions: Inform your doctor and pharmacist about all supplements. Pay attention to the timing of mineral preparations and certain medications, and have your setup regularly checked, especially when taking multiple medications ^[4].
- Be realistic about colds: Use vitamin C from foods regularly; in the case of acute infections, short-term supplementation may shorten symptoms but does not replace sleep, hydration, and basic nutrition. No general prevention or therapy recommendation for high-dose vitamin C can be derived ^{[6] [7]}.

True high performance does not come from the largest pill but from the best strategy: high-quality foods as a foundation, targeted supplements where evidence and needs are clear. Start today with more fruits and vegetables, ensure B12 in a plant-based diet, and discuss supplements with professionals. Precision instead of overdose – this is how you sustainably build health, energy, and longevity.