What do vitamins come from? Understanding their origins

November 18, 2025 •

5 min read

Vitamins are organic substances essential for normal growth and health in small quantities. For humans, these vital micronutrients primarily come from the foods we eat, supplemented by natural synthesis within our bodies and manufacturing processes.

Quick Summary

Vitamins originate from three main sources: natural food, internal bodily synthesis, and commercial manufacturing. Dietary intake from plants and animals is the most common way to acquire these essential nutrients. Some vitamins are produced internally or by gut bacteria, while others are created synthetically in labs for supplements and food fortification.

Key Points

Natural Food Sources: Most vitamins originate from plants and animals, and eating a varied diet of fruits, vegetables, and animal products is the primary way humans obtain these nutrients.
Bodily and Microbial Synthesis: Our bodies produce vitamin D through sun exposure, while gut bacteria produce some vitamin K and biotin; a small amount of niacin can also be synthesized from an amino acid.
Fortified Foods: To prevent widespread deficiency, vitamins are added to staple foods like cereals and milk during processing, a process known as fortification.
Synthetic Production: The majority of dietary supplements and food additives are synthetically manufactured in labs using chemical synthesis or microbial fermentation.
Bioavailability Differences: Natural vitamins often come with co-factors that aid absorption, whereas synthetic versions, while chemically similar, may not be absorbed as efficiently.
Water vs. Fat Solubility: How vitamins are sourced and retained differs based on solubility; fat-soluble vitamins (A, D, E, K) are stored in the body, while water-soluble vitamins (B and C) are not and require regular consumption.
Cooking and Stability: Water-soluble vitamins like C are sensitive to heat and can be lost during cooking, while other vitamins like E are more vulnerable to light and air.

The Primary Natural Source: Food

For the most part, we get our vitamins from the diet we consume. These essential organic compounds are created by plants, animals, or microorganisms and subsequently stored within their tissues. Eating a varied diet is the best way to ensure an adequate intake of these micronutrients.

Vitamins from Plant Sources

Plants are a powerhouse of vitamins, creating them as they grow and mature using energy from sunlight and nutrients from the soil. A diverse diet rich in fruits, vegetables, and grains will provide most of the water-soluble vitamins and many fat-soluble ones.

Vitamin A: Rich in orange and yellow vegetables like carrots, sweet potatoes, and pumpkins, as well as leafy greens such as spinach and broccoli.
Vitamin C: Abundant in citrus fruits (oranges, grapefruits), berries (strawberries), and vegetables (broccoli, bell peppers).
Vitamin E: Found in nuts, seeds, and vegetable oils.
B Vitamins: Many B vitamins, including B1 (thiamin) and B9 (folate), are found in whole grains, legumes, and leafy green vegetables.

Vitamins from Animal Sources

Animals obtain vitamins either by synthesizing them or consuming them from their diet. We then acquire these vitamins by eating animal products.

Vitamin A: Found in liver, eggs, and oily fish.
Vitamin B12: Uniquely found in animal products like meat, fish, eggs, and dairy, as it is produced by bacteria in their digestive tracts.
Vitamin D: Oily fish and eggs contain some vitamin D.
Vitamin K2: Found in poultry, eggs, and beef.

The Role of Our Bodies and the Sun

Our bodies are not simply passive recipients of vitamins; we have evolved some mechanisms for creating them internally or with the help of external factors.

Vitamin Synthesis

Vitamin D: Uniquely, our skin synthesizes vitamin D upon exposure to ultraviolet B (UVB) rays from sunlight. While some food sources exist, this is often the most significant source for many people.
Vitamin K and Biotin: The bacteria residing in our gastrointestinal tract are responsible for producing certain vitamins, including some forms of vitamin K (menaquinones) and biotin, though these may not be sufficient for our total needs.
Vitamin B3 (Niacin): Our bodies can synthesize a small amount of niacin from the amino acid tryptophan, though dietary intake remains essential.

Modern Sources: Fortification and Supplements

Beyond natural food and bodily processes, a significant portion of the vitamins in modern diets comes from industrial sources. This is crucial for preventing deficiency diseases, especially in populations with limited access to diverse foods.

Fortified Foods

Food fortification involves adding vitamins to staple food products during processing. This was implemented largely to address widespread deficiencies in the past and continues to be a public health strategy.

Examples of fortified foods: Milk with added vitamin D, flour and cereals fortified with B vitamins like folic acid and niacin.

Vitamin Supplements

For many, dietary supplements provide a concentrated source of vitamins, whether as single vitamins or in multivitamin formulas.

Natural source supplements: These are often derived by concentrating and extracting vitamins from whole foods, such as extracting vitamin C from oranges.
Synthetic supplements: The majority of supplements are manufactured in a laboratory setting using chemical processes. Synthetic vitamins are designed to mimic the molecular structure of naturally occurring vitamins. For example, fermentative production using microorganisms like yeasts or bacteria is a common, environmentally friendly method for creating vitamins like B2 and B12.

Comparing Natural and Synthetic Vitamin Sources

Both natural and synthetic vitamins provide essential nutrients, but they differ in their origin and how the body processes them. The bioavailability and presence of co-factors are key distinguishing factors.


Feature	Natural Food Sources	Synthetic Supplements	Fortified Foods
Origin	Plants, animals, and microorganisms	Lab-created chemical compounds	Vitamins added to processed foods
Bioavailability	High, often accompanied by other nutrients and phytonutrients that aid absorption	May be less readily recognized and absorbed by the body in some forms	Varies by vitamin and food matrix; often well-absorbed
Associated Nutrients	Contains a complex matrix of vitamins, minerals, fiber, and other beneficial compounds	Typically provides isolated, high doses of specific vitamins, potentially lacking co-factors	Designed to add specific nutrients back into foods that lost them during processing
Bio-identity	Comprises a group of related molecules (vitamers) that occur naturally	Often a single, isolated molecule that mimics the natural form	Can use both natural or chemically synthesized vitamins
Overdose Risk	Very low risk of toxicity from consuming a normal diet	Higher risk of overdose (hypervitaminosis) with excessive intake, especially with fat-soluble vitamins	Generally low risk as amounts are regulated

The Journey of Vitamins in the Body

Regardless of their source, vitamins are processed and utilized by the body in similar ways, though factors like solubility and cooking can affect their availability.

Solubility Matters

Fat-Soluble Vitamins (A, D, E, K): These are stored in the liver and fatty tissues. Because the body can accumulate them, they do not need to be consumed daily and excessive intake can be toxic.
Water-Soluble Vitamins (B vitamins and C): The body does not store these vitamins. Any excess is flushed out through urine, which means a constant supply through diet is necessary. However, some B vitamins can be stored in small amounts in the liver.

The Impact of Processing and Cooking

Vulnerability to Heat: Water-soluble vitamins, particularly vitamin C, are sensitive to heat and can be lost during cooking. Raw foods tend to be richer in these vitamins.
Bioavailability: Cooking can sometimes increase the bioavailability of certain nutrients by breaking down plant cell walls, but overcooking can destroy them.

Conclusion: Sourcing Your Vitamins

Vitamins come from a diverse array of sources, from the food we eat to the sun on our skin and the products created in a lab. For most healthy individuals, a balanced diet filled with a variety of fruits, vegetables, whole grains, and lean proteins provides a sufficient array of vitamins. However, specific needs, lifestyle choices, and underlying health conditions may require supplementation or consumption of fortified foods. By understanding the origins of vitamins, we can make informed choices to best meet our nutritional needs and support overall health.

A Note on Vitamin Supplements

While vitamins are vital for health, supplements are not always necessary for everyone. It is important to consult a healthcare professional before starting any new supplementation, as excessive intake can lead to health problems, especially with fat-soluble vitamins. The National Institutes of Health provides detailed resources on dietary supplements and recommended daily allowances.

National Institutes of Health Fact Sheets

Frequently Asked Questions

Vitamins from whole foods are often accompanied by a complex matrix of co-factors and nutrients that aid absorption, making them more bioavailable. However, synthetic vitamins are chemically identical and can be effective, though some people may absorb them differently.

The human body can produce some vitamins. It synthesizes vitamin D upon exposure to sunlight and creates a small amount of niacin from the amino acid tryptophan. Additionally, gut bacteria produce some vitamin K and biotin.

Fortified foods are products, like milk or cereal, that have had vitamins and minerals added to them. This practice is a public health strategy to combat vitamin deficiencies, especially in populations with limited dietary variety.

Fat-soluble vitamins (A, D, E, K) are primarily found in foods with natural fats, like dairy, eggs, and oily fish, and can be stored in the body. Water-soluble vitamins (B and C) are found in fruits, vegetables, and grains, cannot be stored, and are flushed out in urine, so they must be consumed regularly.

Cooking methods affect vitamin content differently. Water-soluble vitamins, like vitamin C, can be easily lost when exposed to heat or dissolved in water during boiling. Certain cooking methods can increase the bioavailability of some nutrients, but overall, it can lead to vitamin loss.

For most healthy individuals, a varied and balanced diet that includes a wide range of fruits, vegetables, whole grains, and lean proteins is sufficient to meet their vitamin needs. However, certain dietary restrictions, life stages like pregnancy, or medical conditions may necessitate supplementation.

While natural vitamin B12 is found only in animal products, synthetic vitamin B12 for supplements is produced industrially through microbial fermentation using specific microorganisms like Pseudomonas denitrificans or Propionibacterium freudenreichii.