The Guide to Vitamins

Vitamins are small organic compounds your body needs in tiny amounts to grow, repair, fight illness, and run every cell properly. You cannot make most vitamins yourself, so you must get them from food (plants or animals). Without enough vitamins, normal biochemical reactions slow down or stop, leading to fatigue, poor immunity, nerve issues, and chronic health problems.

Why Vitamins Matter

Vitamins act as helpers (cofactors) for enzymes that power thousands of reactions inside cells. Discovered starting with vitamin B1 (thiamine) in 1910, vitamins are classified as essential nutrients because the body requires them daily from diet. Below is a clear breakdown of each major vitamin: where it comes from, what it does, and common functional deficiency signs (symptoms that appear even when blood levels are “normal”).

Vitamin A

Found in: Liver, cod liver oil, eggs, dairy, orange/yellow vegetables (carrots, sweet potatoes, butternut squash), dark leafy greens (spinach, kale).

What it does: Supports vision (especially night vision), immune function, skin and mucous membrane health, cell growth and reproduction.

Deficiency symptoms: Night blindness, dry eyes/skin, frequent infections, slow wound healing, rough/bumpy skin, dry hair, increased acne or skin issues.

Vitamin B1 (Thiamine)

Found in: Pork, whole grains, legumes (beans, lentils), nuts/seeds, fortified cereals, brewer’s yeast.

What it does: Converts food into energy, supports nerve function, heart muscle health, and brain clarity.

Deficiency symptoms: Fatigue, irritability, poor concentration (“brain fog”), muscle weakness, nerve tingling/pain, rapid heartbeat, digestive upset, low mood.

Vitamin B2 (Riboflavin)

Found in: Dairy (milk, yogurt, cheese), eggs, organ meats, almonds, spinach, mushrooms, fortified cereals.

What it does: Helps break down fats, proteins, and carbs for energy; protects cells from oxidative stress; supports healthy skin, eyes, and red blood cells.

Deficiency symptoms: Cracked lips/corners of mouth, sore/red tongue, dry/scaly skin, light sensitivity, fatigue, mouth ulcers, anemia signs.

Vitamin B3 (Niacin)

Found in: Poultry, fish (tuna, salmon), peanuts, mushrooms, whole grains, fortified breads/cereals.

What it does: Supports energy production, DNA repair, cholesterol balance, skin health, and brain function.

Deficiency symptoms: Fatigue, depression/anxiety, memory issues, rough/red skin (pellagra in severe cases), digestive problems, headaches.

Vitamin B5 (Pantothenic Acid)

Found in: Meat, poultry, fish, eggs, dairy, avocados, broccoli, whole grains, mushrooms.

What it does: Helps make energy from food, supports adrenal hormone production, cholesterol synthesis, and wound healing.

Deficiency symptoms: Fatigue, numbness/tingling in hands/feet, irritability, digestive issues, muscle cramps, poor stress tolerance.

Vitamin B6 (Pyridoxine/Pyridoxal)

Found in: Poultry, fish, organ meats, potatoes, bananas, chickpeas, fortified cereals, sunflower seeds.

What it does: Involved in protein metabolism, neurotransmitter production (serotonin, dopamine), red blood cell formation, hormone balance.

Deficiency symptoms: Mood swings, depression, confusion, anemia, nerve tingling, weakened immunity, PMS symptoms, mouth sores.

Vitamin B7 (Biotin)

Found in: Eggs (yolks), liver, nuts/seeds, salmon, sweet potatoes, avocados, cauliflower.

What it does: Supports energy from fats/carbs/proteins, healthy hair/skin/nails, nerve function.

Deficiency symptoms: Hair thinning/loss, brittle nails, red/scaly rash (especially face), fatigue, depression, tingling in hands/feet.

Vitamin B9 (Folate)

Found in: Dark leafy greens (spinach, kale), legumes, citrus fruits, asparagus, broccoli, fortified grains.

What it does: Essential for DNA synthesis, red blood cell formation, brain development, mood regulation.

Deficiency symptoms: Fatigue, weakness, irritability, brain fog, anemia, mouth sores, elevated homocysteine (heart risk), poor fetal development if pregnant.

Vitamin B12 (Cobalamin)

Found in: Animal products (meat, fish, eggs, dairy), fortified plant milks/cereals (for vegans).

What it does: Supports nerve health, red blood cell production, DNA synthesis, energy, mood.

Deficiency symptoms: Extreme fatigue, brain fog, memory loss, numbness/tingling, balance issues, depression, anemia, sore tongue.

Vitamin C

Found in: Citrus fruits, bell peppers, strawberries, kiwi, broccoli, Brussels sprouts, tomatoes.

What it does: Powerful antioxidant, supports collagen for skin/joints/vessels, immune function, iron absorption, wound healing.

Deficiency symptoms: Fatigue, frequent infections, slow healing, bleeding gums, easy bruising, dry skin, joint pain.

Vitamin D

Found in: Sunlight exposure, fatty fish (salmon, mackerel), egg yolks, fortified dairy/milk alternatives, mushrooms.

What it does: Regulates calcium for bones/teeth, supports immune balance, mood, muscle function, inflammation control.

Deficiency symptoms: Bone/joint pain, muscle weakness, frequent illness, low mood, fatigue, hair loss, slow healing.

Vitamin E

Found in: Nuts/seeds (almonds, sunflower seeds), spinach, broccoli, avocados, vegetable oils.

What it does: Major antioxidant protecting cell membranes, supports immune function, skin health, blood vessel integrity.

Deficiency symptoms: Nerve/muscle damage (tingling, weakness), vision issues, weakened immunity, dry skin.

Vitamin K

Found in: Dark leafy greens (kale, spinach), broccoli, Brussels sprouts, fermented foods (natto).

What it does: Essential for blood clotting, bone health (calcium placement), cardiovascular protection.

Deficiency symptoms: Easy bruising/bleeding, poor bone density, increased fracture risk, heavy periods, calcification of soft tissues.

Summary

Vitamins are not optional, they are required daily for every cell to work properly. The B vitamins especially act as co-factors for energy, nerves, mood, and immunity. Most people do not get optimal amounts from diet alone due to processed foods, soil depletion, stress, and absorption issues. At Jones Chiropractic & Functional Medicine we focus on whole-food sources first, then targeted supplementation when needed to restore function and help you feel your best.

Disclaimer: The content presented on this website serves educational and informational purposes and is not meant to replace professional medical advice, diagnosis, or treatment. Consult your doctor for any inquiries concerning medical conditions. Do not disregard or delay seeking professional medical advice based on information obtained from this website.