What Vitamins Are Made From Animals? Key Animal-Sourced Nutrients

December 22, 2025 •

4 min read

According to the National Institutes of Health, vitamin B12 is found in a wide variety of animal foods, but not naturally in plant foods unless they are fortified. Understanding what vitamins are made from animals is crucial for planning a balanced diet, especially for those on plant-based regimens.

Quick Summary

Certain vitamins, notably B12, the D3 form of vitamin D, and preformed vitamin A (retinol), are predominantly or exclusively sourced from animal products. This guide explores these key nutrients, their primary food sources, and alternatives for plant-based diets.

Key Points

Vitamin B12: Found almost exclusively in animal products naturally, necessitating supplementation or fortified foods for vegans.
Vitamin D3: The more potent form of vitamin D, found in fatty fish, egg yolks, and liver, with vegan options derived from lichen.
Preformed Vitamin A: The retinol form is found in animal sources like liver, fish oil, and dairy, providing a direct source of the active vitamin.
Nutrient Absorption: The fat-soluble vitamins (A, D, E, K) require dietary fat for optimal absorption, which is a factor to consider when planning meals.
Strategic Planning: Anyone following a diet low in or devoid of animal products must consciously plan their intake of animal-sourced nutrients to avoid potential health complications from deficiency.

Essential Vitamins Sourced from Animals

While many essential vitamins are readily available from plant-based sources, some are primarily associated with or exclusively found in animal products. This makes them particularly important for individuals following vegan or vegetarian diets to monitor and potentially supplement. The most notable examples are vitamin B12, the D3 form of vitamin D, and preformed vitamin A (retinol).

Vitamin B12: Almost Exclusively Animal-Derived

Vitamin B12, or cobalamin, is a crucial water-soluble vitamin necessary for red blood cell formation, neurological function, and DNA synthesis. This vitamin is produced by certain bacteria and fungi, which animals consume, and the vitamin then accumulates in their tissues. Plants do not naturally contain vitamin B12, making animal products the primary natural dietary source for humans.

Meat and Poultry: Beef, lamb, and chicken are excellent sources, particularly organ meats like liver and kidneys.
Fish and Seafood: Clams, sardines, salmon, and tuna are exceptionally rich in B12.
Dairy: Milk, cheese, and yogurt provide good amounts of vitamin B12.
Eggs: A single large egg contains a decent quantity of B12, with higher concentrations in the yolk.

Vitamin D3: Primarily from Animal Fat

Vitamin D is a fat-soluble vitamin that plays a vital role in calcium absorption, bone health, and immune function. While the body can synthesize its own vitamin D from sun exposure, dietary sources are crucial, especially during months with limited sunlight. There are two main forms: D2 (ergocalciferol) and D3 (cholecalciferol). The D3 form is generally considered more effective at raising blood levels and is most readily found in animal products.

Oily Fish: Fatty fish like salmon, sardines, and mackerel are among the best dietary sources of vitamin D3.
Cod Liver Oil: This is an especially concentrated source of D3, often available as a supplement.
Egg Yolks: The vitamin D content of eggs is concentrated in the yolk.
Fortified Dairy: Many milk and dairy products are fortified with vitamin D, though the type added can vary.

Preformed Vitamin A: Retinol from Animal Tissues

Vitamin A is a fat-soluble vitamin essential for vision, immune function, and reproductive health. In the diet, it exists in two forms: preformed vitamin A (retinol), found in animal products, and provitamin A carotenoids (like beta-carotene), found in plants. The body must convert provitamin A into active vitamin A, a process that can be inefficient. Therefore, preformed vitamin A from animal sources is a more direct pathway for the body to obtain this nutrient.

Liver: Animal livers, particularly beef and fish, are incredibly rich sources of retinol.
Fish Oil: Cod liver oil is also a potent source of preformed vitamin A.
Dairy: Milk and cheese contain vitamin A, with fat content influencing the amount.
Eggs: The yolk contains preformed vitamin A.

Animal vs. Plant-Sourced Nutrients: A Comparison


Nutrient	Primarily Sourced From	Animal Sources	Plant Sources	Key Consideration for Vegans/Vegetarians
Vitamin B12	Animal Products	Meat, poultry, fish, eggs, dairy	Fortified foods (cereals, yeast, plant milk), supplements	Supplementation or fortified foods are essential for preventing deficiency.
Vitamin D3	Animal Products, Sun Exposure	Fatty fish, fish oil, eggs, fortified dairy	Specialized supplements from lichen, some mushrooms exposed to UV	D3 is more effective than the plant-derived D2 form, though vegan D3 is available.
Vitamin A (Retinol)	Animal Products	Liver, fish oil, eggs, dairy	Provitamin A carotenoids (carrots, spinach, sweet potatoes)	The body must convert plant carotenoids, so intake may need to be higher.
Vitamin C	Plant Products	Insignificant amounts in animal products	Fruits and vegetables (citrus, berries, peppers)	Vegans often consume more Vitamin C due to higher fruit and vegetable intake.
Vitamin E	Plant Products	Found in smaller amounts in some animal fats	Nuts, seeds, vegetable oils	Intake can be comparable or higher in plant-based diets.
Folate (B9)	Plant Products	Liver, eggs	Leafy greens, legumes, fortified grains	Intake is often higher in plant-based diets.

Conclusion: Strategic Dietary Planning

For most people, a diet including a variety of animal products provides a natural and reliable source of vitamins B12, D3, and preformed A. However, for those choosing a plant-based lifestyle, strategic dietary planning is essential. Fortified foods and supplements offer effective ways to obtain these crucial nutrients without consuming animal products. Consulting a healthcare professional or dietitian can ensure your diet meets all nutritional needs, regardless of your dietary choices. For more in-depth nutritional guidance and planning, resources like the Office of Dietary Supplements at NIH are valuable.

The Role of Fortified Foods and Supplements

For vegetarians and vegans, relying on fortified foods and dietary supplements is a well-established strategy to prevent deficiencies in nutrients like B12 and D. Fortified foods include breakfast cereals, plant-based milks, and nutritional yeast. Supplements are available in various forms, including tablets, sublinguals, and injections. The synthetic forms of these vitamins used for fortification and supplementation are often vegan-friendly, ensuring accessibility for all dietary preferences.

Frequently Asked Questions

Vitamin B12 is the only vitamin that is found almost exclusively in animal products in its natural form, including meat, fish, eggs, and dairy.

Historically, vitamin D3 was only from animal sources or sun exposure. However, vegan D3 is now available, sourced from lichens, while vitamin D2 comes from fungi.

Animal sources provide preformed vitamin A, or retinol, which the body can use directly. Plant sources contain provitamin A carotenoids, which the body must convert into usable vitamin A.

Among the best animal sources of vitamin B12 are organ meats like beef liver, as well as clams, sardines, and salmon.

Vitamin K1 is found in plants, particularly leafy greens. Vitamin K2 is synthesized by bacteria, which can happen in animal guts, and is also found in fermented foods.

Many processed foods are fortified to include vitamins typically associated with animal products. Examples include breakfast cereals, plant-based milks, and nutritional yeast fortified with vitamin B12.

Since vitamin B12 is not naturally present in plant foods, vegans who do not consume fortified foods or supplements are at a high risk of developing a B12 deficiency, which can lead to fatigue, memory loss, and nerve damage.