Know Your Supplements

    Understand the 25 most important vitamins, minerals, and nutrients your body needs. Learn what happens when levels are too low or too high, and take control of your health with science-backed knowledge.

    Vitamin D

    Vitamin

    Vitamin D is a fat-soluble vitamin that regulates calcium and phosphorus absorption, playing a critical role in bone mineralization. It also modulates immune function, supports muscle health, and influences mood regulation through serotonin synthesis.

    25-Hydroxyvitamin Dng/mL
    203080100
    LowOptimalHigh

    When Deficient

    • Bone pain and increased fracture risk
    • Muscle weakness and fatigue
    • Depression and mood changes
    • Impaired wound healing
    • Frequent infections and illness

    When Overdosing

    • Hypercalcemia (elevated blood calcium)
    • Nausea, vomiting, and poor appetite
    • Kidney stones and renal damage
    • Excessive thirst and frequent urination
    • Confusion and disorientation

    Vitamin B12

    Vitamin

    Vitamin B12 (cobalamin) is essential for red blood cell formation, neurological function, and DNA synthesis. It plays a key role in maintaining the myelin sheath that protects nerve fibers and supports energy metabolism.

    Serum Cobalaminpg/mL
    2003009001,100
    LowOptimalHigh

    When Deficient

    • Megaloblastic anemia and fatigue
    • Peripheral neuropathy (tingling, numbness)
    • Cognitive decline and memory loss
    • Glossitis and mouth ulcers
    • Depression and mood disturbances

    When Overdosing

    • Generally considered safe in excess
    • Skin rashes (acne-like eruptions)
    • Headaches and dizziness
    • Gastrointestinal discomfort
    • Potential interaction with certain medications

    Magnesium

    Mineral

    Magnesium is involved in over 300 enzymatic reactions including energy production, protein synthesis, and nerve transmission. It supports muscle and nerve function, blood sugar control, blood pressure regulation, and bone health.

    Magnesium, Serummg/dL
    1.41.82.32.6
    LowOptimalHigh

    When Deficient

    • Muscle cramps and spasms
    • Anxiety, irritability, and insomnia
    • Heart palpitations and arrhythmias
    • Migraines and headaches
    • Fatigue and general weakness

    When Overdosing

    • Diarrhea and gastrointestinal distress
    • Nausea and abdominal cramping
    • Low blood pressure (hypotension)
    • Muscle weakness and lethargy
    • Cardiac arrest in extreme cases

    Iron

    Mineral

    Iron is a critical component of hemoglobin and myoglobin, responsible for oxygen transport throughout the body. It also supports energy metabolism, immune function, and cognitive development.

    Serum Ferritinng/mL
    1230200300
    LowOptimalHigh

    When Deficient

    • Iron-deficiency anemia and fatigue
    • Pale skin, brittle nails, and hair loss
    • Shortness of breath on exertion
    • Difficulty concentrating and brain fog
    • Restless legs syndrome

    When Overdosing

    • Nausea, vomiting, and abdominal pain
    • Liver damage and cirrhosis
    • Joint pain and skin discoloration
    • Heart failure and cardiomyopathy
    • Increased oxidative stress

    Zinc

    Mineral

    Zinc is essential for immune function, wound healing, and DNA synthesis. It acts as a cofactor for over 300 enzymes and plays a vital role in taste perception, fertility, and cellular growth.

    Zinc, Serummcg/dL
    6070120150
    LowOptimalHigh

    When Deficient

    • Impaired immune response and frequent infections
    • Loss of taste and smell
    • Delayed wound healing
    • Hair loss and skin lesions
    • Growth retardation in children

    When Overdosing

    • Nausea, vomiting, and diarrhea
    • Copper deficiency from chronic excess
    • Abdominal cramps and headaches
    • Reduced immune function paradoxically
    • Lower HDL cholesterol levels

    Vitamin C

    Vitamin

    Vitamin C (ascorbic acid) is a powerful antioxidant that protects cells from oxidative damage. It is essential for collagen synthesis, immune defense, iron absorption, and neurotransmitter production.

    Ascorbic Acid, Plasmamg/dL
    0.20.423
    LowOptimalHigh

    When Deficient

    • Scurvy (bleeding gums, loose teeth)
    • Easy bruising and slow wound healing
    • Fatigue and weakened immunity
    • Dry, rough, and splitting skin
    • Joint pain and swelling

    When Overdosing

    • Diarrhea and gastrointestinal upset
    • Kidney stones (oxalate type)
    • Nausea and abdominal cramps
    • Iron overload in susceptible individuals
    • Insomnia and headaches

    Omega-3 (EPA/DHA)

    Fatty Acid

    Omega-3 fatty acids (EPA and DHA) are essential polyunsaturated fats critical for brain function, cardiovascular health, and anti-inflammatory processes. They support cell membrane integrity and play a role in visual development.

    Omega-3 Index (EPA+DHA)%
    481216
    LowOptimalHigh

    When Deficient

    • Dry skin, eczema, and dermatitis
    • Poor concentration and brain fog
    • Joint stiffness and inflammation
    • Mood disorders and depression
    • Cardiovascular risk factors

    When Overdosing

    • Increased bleeding and bruising risk
    • Fishy aftertaste and bad breath
    • Gastrointestinal discomfort
    • Potential immune suppression
    • Elevated LDL cholesterol in some individuals

    Calcium

    Mineral

    Calcium is the most abundant mineral in the body, essential for building and maintaining strong bones and teeth. It also enables muscle contraction, nerve signaling, blood clotting, and heart rhythm regulation.

    Calcium, Total, Serummg/dL
    78.610.311.5
    LowOptimalHigh

    When Deficient

    • Osteoporosis and increased fracture risk
    • Muscle cramps and spasms
    • Numbness and tingling in extremities
    • Dental problems and tooth decay
    • Fatigue and low energy

    When Overdosing

    • Kidney stones and renal impairment
    • Constipation and bloating
    • Cardiovascular calcification risk
    • Impaired absorption of iron and zinc
    • Nausea and excessive thirst

    Vitamin A

    Vitamin

    Vitamin A is a fat-soluble vitamin critical for vision, immune function, and cell differentiation. It supports skin health, reproductive function, and acts as a powerful antioxidant in its provitamin form (beta-carotene).

    Retinol, Serummcg/dL
    20307280
    LowOptimalHigh

    When Deficient

    • Night blindness and dry eyes
    • Increased susceptibility to infections
    • Dry, rough skin and acne
    • Impaired growth in children
    • Poor wound healing

    When Overdosing

    • Liver toxicity and damage
    • Headache, nausea, and dizziness
    • Bone pain and increased fracture risk
    • Birth defects (teratogenic in pregnancy)
    • Skin peeling and hair loss

    Vitamin E

    Vitamin

    Vitamin E is a fat-soluble antioxidant that protects cell membranes from oxidative damage. It supports immune function, skin health, and helps prevent LDL cholesterol oxidation, reducing cardiovascular risk.

    Alpha-Tocopherol, Serummg/L
    55.719.925
    LowOptimalHigh

    When Deficient

    • Peripheral neuropathy (nerve damage)
    • Muscle weakness and coordination loss
    • Impaired immune response
    • Vision deterioration (retinopathy)
    • Increased oxidative stress markers

    When Overdosing

    • Increased bleeding risk (anticoagulant effect)
    • Nausea and gastrointestinal issues
    • Fatigue and muscle weakness
    • Interference with vitamin K metabolism
    • Increased hemorrhagic stroke risk

    Vitamin K2

    Vitamin

    Vitamin K2 (menaquinone) directs calcium into bones and teeth while preventing its deposition in arteries and soft tissues. It works synergistically with vitamin D and is essential for blood clotting and cardiovascular health.

    Dietary Intake (no routine blood test)mcg/day
    4590200300
    LowOptimalHigh

    When Deficient

    • Easy bruising and excessive bleeding
    • Weakened bones and osteoporosis
    • Arterial calcification risk
    • Poor dental health and cavities
    • Impaired blood clotting

    When Overdosing

    • Generally considered very safe
    • Possible interaction with blood thinners
    • Rare allergic skin reactions
    • Gastrointestinal discomfort at high doses
    • May affect anticoagulant therapy efficacy

    Selenium

    Mineral

    Selenium is a trace mineral that supports thyroid hormone metabolism, DNA synthesis, and antioxidant defense through selenoproteins. It plays a protective role against oxidative damage and supports immune function.

    Selenium, Serummcg/L
    70110165400
    LowOptimalHigh

    When Deficient

    • Thyroid dysfunction and fatigue
    • Weakened immune system
    • Cognitive decline and brain fog
    • Muscle weakness and pain
    • Increased susceptibility to illness

    When Overdosing

    • Selenosis (garlic breath, metallic taste)
    • Hair and nail loss or brittleness
    • Nausea, diarrhea, and skin rashes
    • Nervous system damage
    • Fatigue and irritability

    Folate (Vitamin B9)

    Vitamin

    Folate is essential for DNA synthesis, cell division, and amino acid metabolism. It is critical during pregnancy for neural tube development and supports red blood cell formation and homocysteine regulation.

    Folate, Serumng/mL
    352024
    LowOptimalHigh

    When Deficient

    • Megaloblastic anemia
    • Neural tube defects in pregnancy
    • Elevated homocysteine levels
    • Fatigue and weakness
    • Mouth sores and tongue swelling

    When Overdosing

    • May mask vitamin B12 deficiency
    • Sleep disturbances and vivid dreams
    • Gastrointestinal issues
    • Potential interference with seizure medications
    • Skin reactions in sensitive individuals

    Vitamin B6

    Vitamin

    Vitamin B6 (pyridoxine) is involved in over 100 enzyme reactions, primarily in protein metabolism. It supports neurotransmitter synthesis (serotonin, dopamine, GABA), immune function, and hemoglobin production.

    Pyridoxal 5'-Phosphate (PLP)nmol/L
    2030110200
    LowOptimalHigh

    When Deficient

    • Peripheral neuropathy and numbness
    • Depression and confusion
    • Weakened immune response
    • Dermatitis and cracked lip corners
    • Anemia and fatigue

    When Overdosing

    • Severe peripheral neuropathy
    • Loss of coordination (ataxia)
    • Numbness and tingling in extremities
    • Photosensitivity
    • Nausea and heartburn

    Iodine

    Mineral

    Iodine is essential for thyroid hormone synthesis (T3 and T4), which regulate metabolism, growth, and development. It is critical for brain development during pregnancy and early childhood.

    Urinary Iodine Concentrationmcg/L
    50100199300
    LowOptimalHigh

    When Deficient

    • Goiter (enlarged thyroid)
    • Hypothyroidism and weight gain
    • Cognitive impairment and brain fog
    • Fatigue and cold sensitivity
    • Developmental delays in children

    When Overdosing

    • Thyroid dysfunction (hyper or hypothyroidism)
    • Metallic taste and mouth burning
    • Nausea, diarrhea, and stomach pain
    • Thyroid inflammation (thyroiditis)
    • Skin rashes and acne-like lesions

    Potassium

    Mineral

    Potassium is a critical electrolyte that maintains fluid balance, nerve transmission, and muscle contraction. It plays a key role in heart rhythm regulation and helps counteract the effects of sodium on blood pressure.

    Potassium, SerummEq/L
    33.555.5
    LowOptimalHigh

    When Deficient

    • Muscle weakness and cramps
    • Heart palpitations and arrhythmias
    • Fatigue and general weakness
    • Constipation and bloating
    • Numbness and tingling

    When Overdosing

    • Cardiac arrhythmias (potentially fatal)
    • Muscle weakness and paralysis
    • Nausea and vomiting
    • Numbness and tingling sensations
    • Difficulty breathing

    Copper

    Mineral

    Copper is a trace mineral essential for iron metabolism, connective tissue formation, and neurotransmitter synthesis. It supports the immune system, acts as an antioxidant cofactor, and is vital for energy production.

    Copper, Serummcg/dL
    7075145170
    LowOptimalHigh

    When Deficient

    • Anemia unresponsive to iron supplementation
    • Neutropenia (low white blood cells)
    • Osteoporosis and bone fragility
    • Neurological symptoms and neuropathy
    • Impaired wound healing and pallor

    When Overdosing

    • Liver damage and cirrhosis
    • Nausea, vomiting, and abdominal pain
    • Kidney damage
    • Neurological symptoms (Wilson's disease-like)
    • Hemolytic anemia

    Chromium

    Mineral

    Chromium is a trace mineral that enhances insulin signaling and glucose metabolism. It plays a role in macronutrient metabolism and may support healthy blood sugar levels and lipid profiles.

    Chromium, Serummcg/L
    0.050.10.30.6
    LowOptimalHigh

    When Deficient

    • Impaired glucose tolerance
    • Insulin resistance symptoms
    • Elevated blood sugar levels
    • Increased cholesterol and triglycerides
    • Weight gain and sugar cravings

    When Overdosing

    • Kidney and liver damage
    • Gastrointestinal irritation
    • Headaches and dizziness
    • Skin rashes and hives
    • Mood changes and cognitive issues

    CoQ10

    Coenzyme

    Coenzyme Q10 (ubiquinone) is essential for mitochondrial energy production in every cell. It acts as a powerful antioxidant, supports heart function, and helps regenerate other antioxidants like vitamin E.

    Coenzyme Q10, Plasmamcg/mL
    0.30.51.62.5
    LowOptimalHigh

    When Deficient

    • Chronic fatigue and low energy
    • Heart failure symptoms and palpitations
    • Muscle pain (especially with statins)
    • Cognitive decline and brain fog
    • Increased oxidative stress

    When Overdosing

    • Insomnia and restlessness
    • Gastrointestinal upset and nausea
    • Headaches and dizziness
    • Skin rashes (rare)
    • Lower blood pressure (caution with meds)

    Vitamin B1 (Thiamine)

    Vitamin

    Thiamine is essential for carbohydrate metabolism and energy production. It plays a critical role in nerve function, muscle contraction, and the synthesis of neurotransmitters required for brain health.

    Thiamine Diphosphate, Whole Bloodnmol/L
    7078185250
    LowOptimalHigh

    When Deficient

    • Beriberi (wet or dry forms)
    • Wernicke-Korsakoff syndrome
    • Fatigue and irritability
    • Peripheral neuropathy
    • Loss of appetite and weight loss

    When Overdosing

    • Generally well tolerated in excess
    • Rare allergic reactions
    • Nausea and stomach upset
    • Restlessness and insomnia
    • Skin irritation at injection sites

    Vitamin B2 (Riboflavin)

    Vitamin

    Riboflavin is a key component of FAD and FMN coenzymes, essential for energy metabolism and cellular function. It supports antioxidant defense, red blood cell production, and the metabolism of other B vitamins.

    Riboflavin, Whole Bloodnmol/L
    137180370500
    LowOptimalHigh

    When Deficient

    • Cracked lips and mouth corners (cheilosis)
    • Sore, swollen throat and tongue
    • Skin inflammation and dermatitis
    • Light sensitivity and eye fatigue
    • Anemia and fatigue

    When Overdosing

    • Bright yellow-orange urine (harmless)
    • Generally considered very safe
    • Rare gastrointestinal discomfort
    • Increased photosensitivity
    • Potential itching or numbness

    Vitamin B3 (Niacin)

    Vitamin

    Niacin is vital for converting food into energy through NAD and NADP coenzymes. It supports DNA repair, cell signaling, cholesterol management, and plays a role in over 400 biochemical reactions.

    Urinary N1-Methylnicotinamidemcmol/day
    5.817.5115150
    LowOptimalHigh

    When Deficient

    • Pellagra (dermatitis, diarrhea, dementia)
    • Fatigue and depression
    • Inflamed skin, especially sun-exposed areas
    • Digestive problems
    • Cognitive impairment and confusion

    When Overdosing

    • Flushing (warmth, redness, itching)
    • Liver toxicity at high doses
    • Gastrointestinal issues and ulcers
    • Elevated blood sugar levels
    • Gout flare-ups from elevated uric acid

    Manganese

    Mineral

    Manganese is a trace mineral involved in bone formation, blood clotting, and metabolism of amino acids, cholesterol, and carbohydrates. It activates antioxidant enzymes (MnSOD) that protect cells from oxidative damage.

    Manganese, Whole Bloodmcg/L
    451520
    LowOptimalHigh

    When Deficient

    • Impaired bone growth and skeletal abnormalities
    • Reduced glucose tolerance
    • Altered fat and carbohydrate metabolism
    • Skin rashes and dermatitis
    • Impaired reproductive function

    When Overdosing

    • Neurotoxicity (manganism — Parkinson's-like)
    • Tremors and difficulty walking
    • Cognitive and behavioral changes
    • Respiratory issues from inhalation
    • Liver damage and impaired iron metabolism

    Phosphorus

    Mineral

    Phosphorus is the second most abundant mineral in the body, essential for bone and teeth formation, energy storage (ATP), and DNA/RNA structure. It supports kidney function and acid-base balance regulation.

    Phosphorus, Serummg/dL
    1.52.54.55
    LowOptimalHigh

    When Deficient

    • Bone pain and fragility (osteomalacia)
    • Muscle weakness and fatigue
    • Loss of appetite and weight loss
    • Numbness and tingling
    • Impaired growth in children

    When Overdosing

    • Calcification of soft tissues and organs
    • Impaired calcium absorption
    • Kidney damage and renal stones
    • Cardiovascular risk from vascular calcification
    • Diarrhea and gastrointestinal issues

    Biotin (Vitamin B7)

    Vitamin

    Biotin is a water-soluble B vitamin that serves as a coenzyme for carboxylase enzymes involved in fatty acid synthesis, gluconeogenesis, and amino acid metabolism. It is widely known for supporting hair, skin, and nail health.

    Biotin, Serumng/L
    2004001,2002,000
    LowOptimalHigh

    When Deficient

    • Hair thinning and hair loss
    • Brittle nails and skin rashes
    • Depression and lethargy
    • Numbness and tingling in extremities
    • Conjunctivitis and dermatitis

    When Overdosing

    • Interference with lab test results
    • Generally considered very safe
    • Skin rashes (rare)
    • Digestive upset at extreme doses
    • May affect thyroid test accuracy

    Why Understanding Your Supplements Matters

    Micronutrient deficiencies affect over 2 billion people worldwide, often without obvious symptoms until significant health damage has occurred. Knowing the role of each vitamin and mineral helps you make informed decisions about your diet and supplementation.

    However, more is not always better. Over-supplementation can lead to toxicity, organ damage, and dangerous interactions with medications. The key is finding your personal optimal range through regular blood testing and data-driven health tracking.

    LongevLab helps you decode your body's unique needs by tracking biomarkers over time, so you can supplement intelligently and optimize your healthspan with confidence.

    Download on the App Store

    Frequently Asked Questions

    What are the most common vitamin deficiencies?

    The most prevalent deficiencies worldwide include Vitamin D, Iron, Vitamin B12, Magnesium, and Folate. These are often caused by inadequate diet, limited sun exposure, or poor absorption due to gut health issues.

    Can you take too many supplements?

    Yes. Fat-soluble vitamins (A, D, E, K) accumulate in body tissues and can reach toxic levels. Even water-soluble vitamins and minerals can cause adverse effects at high doses. Always consult a healthcare provider and test your blood levels before supplementing.

    How do I know which supplements I need?

    The most reliable way is through comprehensive blood testing. Biomarker analysis reveals your actual nutrient levels, allowing for targeted supplementation rather than guesswork. LongevLab tracks these biomarkers over time to help you optimize your levels.

    Should I take supplements with food or on an empty stomach?

    Fat-soluble vitamins (A, D, E, K) and Omega-3s absorb better with food containing dietary fat. Iron absorbs best on an empty stomach with vitamin C. Magnesium and B vitamins can be taken with or without food, though food may reduce stomach upset.