Vitamin Sources
Part of Nutrition Science
A practical reference mapping each essential vitamin to its best food sources, with emphasis on locally producible, storable, and seasonally available options for communities without access to commercial supplements.
Why This Matters
Knowing that a vitamin exists is not enough. Knowing which specific foods provide it — and how to produce, preserve, or find those foods in a subsistence context — determines whether a community actually avoids deficiency. This is a practical field reference: not comprehensive biochemistry, but a working guide to which foods to prioritize, produce, and protect.
The emphasis here is on sources available in a post-industrial context: foods that can be grown in gardens, raised on small farms, foraged from local land, or preserved through basic techniques. Supplementation is not assumed. What can be produced locally, raised in quantity, and stored through the winter is what matters.
Fat-Soluble Vitamins
Fat-soluble vitamins (A, D, E, K) require dietary fat for absorption and are stored in body fat and liver tissue. They do not need to be consumed daily — adequate intake in one period builds stores that sustain the body through periods of lower intake. This storage capacity is valuable in seasonal food environments.
Vitamin A
Vitamin A has two dietary forms: preformed vitamin A (retinol) from animal foods, and provitamin A carotenoids (beta-carotene) from plant foods. Beta-carotene must be converted to active vitamin A in the body — at roughly a 6:1 efficiency ratio, and less efficiently when vitamin A status is already adequate.
Best sources:
- Beef liver: 6,582 mcg per 100g (overwhelming abundance — one serving per week covers weekly needs)
- Chicken liver: 3,296 mcg per 100g
- Egg yolk: 149 mcg per egg
- Full-fat dairy: moderate amounts
- Sweet potato: 961 mcg beta-carotene per 100g
- Carrots: 835 mcg beta-carotene per 100g
- Dark leafy greens (kale, spinach): 241-469 mcg beta-carotene per 100g
- Orange-yellow fruits (cantaloupe, apricots): moderate beta-carotene
Practical priority: Liver once or twice a week plus daily orange/yellow vegetables or dark greens. Carotenoids are better absorbed with dietary fat — eat orange vegetables with fat (olive oil, butter, cream).
Vitamin D
Vitamin D is unique because the primary source is endogenous synthesis from sun exposure, not food.
Sunlight synthesis: exposing face and arms to midday UVB for 20-30 minutes generates 10,000-25,000 IU of vitamin D3 in fair-skinned adults. Dark-skinned individuals require 3-5 times longer. Below 37° N latitude in winter, UVB intensity may be insufficient. Above 50° N latitude, winter synthesis is essentially impossible.
Dietary sources:
- Cod liver oil: 448 IU per teaspoon (the traditional solution to northern winter deficiency)
- Fatty fish: salmon 570 IU per 100g; mackerel 360 IU; sardines 193 IU
- Sun-dried mushrooms: up to 1,600+ IU per 100g (when dried gill-side-up in direct sunlight — exposing the gills maximizes D2 synthesis)
- Egg yolk: 37 IU per egg (from pasture-raised hens; factory eggs have minimal D)
- Liver: moderate amounts
Practical strategy for northern communities: Cod liver oil or fatty fish are the essential dietary bridges. Sun-drying mushrooms through summer and storing them provides a useful winter supplement. Daily midday sunlight through spring, summer, and autumn builds body stores.
Vitamin E
Vitamin E is an antioxidant found in fatty foods. Deficiency is rare when fat intake is adequate. Most common risk is in extremely low-fat diets or fat malabsorption.
Best sources:
- Sunflower seeds: 35 mg per 100g
- Almonds: 26 mg per 100g
- Wheat germ oil: 150 mg per 100g
- Sunflower oil, olive oil: moderate amounts
- Dark leafy greens: small amounts
- Egg yolk: moderate amounts
Practical priority: Regular consumption of nuts and seeds; use of plant-based oils for cooking and dressing.
Vitamin K
Vitamin K exists as K1 (phylloquinone, from plants) essential for blood clotting, and K2 (menaquinone, from fermented foods and animal products) important for bone and cardiovascular health.
K1 sources:
- Kale: 817 mcg per 100g
- Spinach: 483 mcg per 100g
- Parsley: 1,640 mcg per 100g
- Broccoli: 102 mcg per 100g
- Cabbage: 76 mcg per 100g
K2 sources:
- Natto (fermented soybeans): 939 mcg per 100g — extraordinary concentration
- Hard cheese (aged): 76 mcg per 100g
- Soft cheese: 57 mcg per 100g
- Butter: 15 mcg per 100g
- Egg yolk: 32 mcg per 100g
- Chicken liver: moderate amounts
Practical priority: Dark leafy greens for K1 (eat several times weekly). Fermented foods and dairy for K2. Communities producing natto (fermenting soybeans with Bacillus subtilis) have a remarkable K2 source.
Water-Soluble Vitamins
Water-soluble vitamins (C and all B vitamins) are not stored in significant quantities and must be consumed regularly. They are also more vulnerable to destruction by heat, water, and oxidation during cooking and storage.
Vitamin C (Ascorbic Acid)
Best sources:
- Bell pepper (red): 128-190 mg per 100g
- Parsley (fresh): 133 mg per 100g
- Kiwi: 93 mg per 100g
- Broccoli (raw): 89 mg per 100g
- Brussels sprouts: 85 mg per 100g
- Strawberries: 59 mg per 100g
- Citrus (orange, lemon, lime): 50-70 mg per 100g
- Kale (raw): 49 mg per 100g
- Sauerkraut: 15-35 mg per 100g (fermentation retains C well)
- Rose hips: 400-2,000 mg per 100g
- Potato (cooked with skin): 10-15 mg per 100g
Practical priority: A combination of raw or lightly cooked vegetables daily, sauerkraut in winter, and rose hip tea as a backup. See also the dedicated scurvy article.
B Vitamins — see the dedicated water-soluble vitamins article for detailed B vitamin sources.
Organizing Food Production Around Vitamin Security
A community garden and animal husbandry program designed around vitamin security would prioritize:
High-priority garden crops for vitamin production:
| Crop | Key Vitamins | Storage Compatibility |
|---|---|---|
| Kale, collards, chard | C, K1, folate, beta-carotene | Root cellar months |
| Sweet potato | Beta-carotene (A), C, B6 | Root cellar months |
| Carrots | Beta-carotene (A), K1 | Root cellar months |
| Cabbage (for sauerkraut) | C, K1, folate | Fermented, months |
| Dried legumes | Folate, B1, B2, iron | Years (dried) |
| Garlic, onions | C, B6 | Months dry storage |
| Bell peppers | C, A, B6 | Can/preserve; eat fresh |
| Winter squash | Beta-carotene, B vitamins | Months dry storage |
High-priority animals for vitamin production:
| Animal | Key Vitamins Provided | Notes |
|---|---|---|
| Chickens (eggs) | A, D, B12, choline, riboflavin | Daily supply; pasture access key for D |
| Dairy animals (cow, goat) | A, D, B12, riboflavin, B5 | Milk, yogurt, cheese |
| Pigs (liver) | A, B12, folate, niacin, B6 | One pig provides months of liver supply |
| Fish (especially fatty) | D, B12, omega-3 | Smoked or salted for storage |
Vitamin Interactions and Absorption
Knowing sources is not enough without understanding absorption modifiers:
- Fat-soluble vitamins require fat — beta-carotene from raw carrots without dietary fat is poorly absorbed; cook carrots in butter or drizzle with oil
- Vitamin C enhances iron and folate absorption — combining C-rich foods with iron/folate-rich foods increases uptake
- Vitamin D enables calcium absorption — adequate D turns calcium intake into bone mineral; without D, dietary calcium is largely wasted
- B12 requires adequate stomach acid — elderly people and those on antacid treatments absorb B12 poorly from plant foods; animal products with intrinsic factor binding are more reliable
- Vitamin K2 and D3 work synergistically — both are needed for calcium to be deposited in bone rather than soft tissue
Foraging as Vitamin Insurance
Wild plants often contain higher concentrations of vitamins than cultivated equivalents, because they have not been selectively bred for yield, sweetness, or appearance at the expense of nutrient density. Integrating seasonal foraging into community food practice adds a vitamin buffer that cultivation alone cannot match:
- Nettles (Urtica dioica): Vitamin C, A, K, calcium, iron — boiled or steeped
- Dandelion (whole plant): Vitamin A, C, K, folate — leaves eaten raw or cooked
- Wild garlic/ramsons: Vitamin C, antimicrobial
- Purslane: Omega-3s and vitamin C — uncommonly high for a land plant
- Chickweed: Vitamin C, calcium
- Elderberries (cooked): Vitamin C, anthocyanins
- Pine needles (any species): Vitamin C — fresh needles steeped in hot water
- Wild mushrooms (sun-dried): Vitamin D2
Establishing a community foraging calendar — what is available when and where — effectively extends the cultivated vitamin supply with zero additional agricultural labor.