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Explore our complete vitamin guides — from daily dosage and deficiency symptoms to the best food sources and supplement recommendations. All content is evidence-based and regularly reviewed.
Vitamins are organic compounds required in small amounts for normal physiological function. With the exception of Vitamin D (synthesised from sunlight) and Vitamin K2 (produced by gut bacteria), virtually all vitamins must be obtained from food or supplements — your body cannot manufacture them.
They function as coenzymes, antioxidants, hormones, and structural components across virtually every system in the body. Deficiency — even subclinical — impairs immune function, energy metabolism, bone health, neurological integrity, and gene expression long before obvious symptoms appear.
Each vitamin has a distinct chemistry, absorption mechanism, storage capacity, and set of target tissues. Understanding the differences between them helps you make informed decisions about diet, supplementation, and when to seek medical testing.
Absorbed with dietary fat via the lymphatic system. Stored in liver and fatty tissues — body builds reserves. Can accumulate to toxic levels with chronic excess. Require fat in the meal for absorption. Less frequent intake is adequate.
Absorbed directly into the bloodstream. Not stored significantly — excess is excreted in urine (with the exception of B12). Cannot accumulate to toxic levels under normal circumstances. Require more regular dietary intake.
Each guide covers benefits, deficiency symptoms, daily dosage by age, the best food sources, supplement guidance, risks, and an interactive tool to help you understand your own intake.
Essential for calcium absorption, immune defence, and gene regulation. Deficiency affects over 1 billion people worldwide and is the most common preventable vitamin deficiency.
A powerful antioxidant essential for collagen synthesis, immune function, and iron absorption. Unlike most animals, humans cannot synthesise Vitamin C — we depend entirely on diet.
Essential for nerve myelin synthesis, red blood cell formation, and DNA production. Found almost exclusively in animal foods — deficiency is the most common nutritional concern for vegans.
The first vitamin ever identified (1913). Essential for night vision, immune epithelial barriers, reproduction, and gene regulation. Comes in two forms: retinol (animal) and beta-carotene (plant).
Activates 17 proteins for blood clotting (K1) and calcium regulation in bones and arteries (K2). Subclinical K2 deficiency is remarkably common in Western populations and largely unrecognised.
Essential coenzyme for synthesising serotonin, dopamine, GABA, and norepinephrine. Also clinically proven for PMS relief and morning sickness — but the only water-soluble vitamin that can cause neuropathy from over-supplementation.
Most vitamin deficiencies develop silently — symptoms appear only after months or years of depletion. Blood testing is the only reliable way to know your actual status.
Routine laboratory testing is recommended for nutrients where deficiency or excess may significantly impact health (e.g., vitamin D, B12, ferritin). It helps accurately assess the need for supplementation, avoid overdosing, and monitor the effectiveness of correction.
Testing is appropriate when symptoms suggest a possible deficiency or imbalance (e.g., fatigue, weakness, hair loss, sleep disturbances). This approach helps confirm or rule out nutrient-related causes and prevents unnecessary supplementation.
For certain vitamins and minerals, the need for testing or supplementation should be determined individually based on health status, medical history, and lifestyle. Consulting a healthcare professional helps define the right strategy and avoid self-prescription errors.
Always consult a qualified healthcare provider before starting any vitamin supplementation, especially at doses above the RDA.
The information provided on CleverHabits is intended for educational and informational purposes only. Content published on this website should not be considered medical advice, diagnosis, or treatment. The information presented is not intended to replace consultation with a qualified healthcare professional, physician, or medical provider. Health information, including topics related to nutrition, vitamins, dietary supplements, and lifestyle habits, may not be appropriate for every individual and should not be used as a substitute for professional medical guidance. Always seek the advice of your physician or another qualified healthcare professional regarding any questions you may have about a medical condition, symptoms, dietary changes, supplementation, or lifestyle decisions. Never disregard professional medical advice or delay seeking medical attention because of something you have read on this website. If you believe you may have a medical emergency, contact your doctor or emergency medical services immediately.