What are synthesized vitamins and how are they made?

December 18, 2025 •

4 min read

According to one source, most of the vitamins available on the market today, including those in fortified foods and supplements, are synthetic. So, what are synthesized vitamins? They are artificial nutrients manufactured in a laboratory to mimic the chemical structure of those found in nature.

Quick Summary

Synthesized vitamins are artificial nutrients created in a lab to replicate the molecular structure of naturally occurring ones. They are used in supplements and fortified foods to address nutritional deficiencies, but their bioavailability can differ from natural forms.

Key Points

Origin: Synthesized vitamins are manufactured in a lab using chemical processes, mimicking the structure of naturally occurring nutrients found in foods.
Bioavailability: The body may not absorb and utilize synthetic vitamins as efficiently as natural ones, as they often lack the full complex of synergistic co-factors.
Public Health Role: Despite potential differences, synthetic vitamins have been crucial for preventing widespread nutritional deficiencies through food fortification.
Cost and Availability: They are cheaper to produce and more readily available, making them accessible to a wide range of consumers in supplements and fortified foods.
Identification: Clues like chemical names (e.g., ascorbic acid), the prefix "dl" for vitamin E, and high potency on the label can indicate a synthetic vitamin.
Targeted Use: Synthetic supplements are particularly beneficial for individuals with diagnosed deficiencies, restrictive diets, or increased nutrient needs (e.g., pregnant women).

What are Synthesized Vitamins?

Synthesized vitamins, also known as synthetic vitamins, are nutrients that are industrially produced through a chemical process rather than being derived directly from natural food sources. They are designed to be chemically identical or at least structurally similar to the vitamins found in plants and animals. For example, the synthesized form of vitamin C is commonly known as ascorbic acid, which is produced in a lab, often from corn sugar. Similarly, synthetic vitamin B9, or folic acid, is the crystalline form of the naturally occurring folate found in leafy greens. While these compounds have a similar cellular function to their natural counterparts, the way the body recognizes, absorbs, and utilizes them can sometimes be different. The vast majority of supplements and fortified food products sold today contain these man-made nutrients due to their cost-effectiveness and scalability.

How Are Synthetic Vitamins Manufactured?

The manufacturing of synthetic vitamins is a complex industrial process involving chemical reactions in a factory setting. The specific method varies depending on the vitamin. For instance, the synthesis of vitamin C (ascorbic acid) typically starts with a sugar alcohol like d-sorbitol, which is derived from corn, and involves a two-step fermentation process. For other vitamins, manufacturers may use chemical precursors derived from sources like coal tar or petroleum.

The general process involves several key stages:

Sourcing Raw Materials: Chemical compounds, which are often not food-based, are procured as starting points. For example, some B vitamins are historically derived from coal tar.
Chemical Synthesis: A series of chemical reactions are performed to build the vitamin molecule. The complexity of these reactions and the number of steps depend on the final product.
Purification: The synthesized product must be purified to remove impurities and byproducts from the manufacturing process. This stage can sometimes involve harsh chemical solvents.
Formulation: The final, purified vitamin is then processed into a usable form, such as a powder for capsules or a tablet with binders and fillers.

Natural vs. Synthesized Vitamins: A Comparison

The debate over the superiority of natural versus synthetic vitamins is ongoing. While some argue their chemical similarity makes them equivalent, others highlight differences in absorption and effectiveness. Here is a comparison highlighting the key differences:


Feature	Natural Vitamins (from whole foods)	Synthesized Vitamins (from a lab)
Source	Derived from whole food sources (plants, animals).	Produced artificially through industrial chemical processes.
Molecular Structure	Found in complex with co-factors and other synergistic nutrients (e.g., bioflavonoids with Vitamin C).	Often isolated, lacking the full complex of co-factors.
Bioavailability	Typically higher; the body is optimized to absorb and utilize nutrients from food.	Can be lower or inconsistent; absorption can vary significantly (e.g., synthetic Vitamin E is less absorbed).
Cost	Generally more expensive to extract and produce.	Inexpensive to mass-produce, leading to widespread use in supplements and fortified foods.
Synergy	Benefits from synergistic effects of other nutrients in whole food matrix.	Isolated nature may limit synergistic interactions.
Purity & Additives	Minimal processing, potentially retaining allergens.	May contain fillers, binders, artificial colorings, and preservatives.

The Role of Synthetic Vitamins in Public Health

Despite potential differences in bioavailability, synthesized vitamins play a crucial role in preventing widespread nutritional deficiencies. The fortification of staple foods like flour, milk, and cereals with synthetic vitamins has significantly reduced the incidence of deficiency diseases in many parts of the world. For example, the addition of synthetic folic acid to grain products is a proven public health measure to reduce neural tube defects in newborns.

Specific populations may also benefit from targeted synthetic vitamin supplementation, often under medical guidance. These include:

The elderly: May require additional vitamin D and B12 due to decreased absorption.
Vegans and vegetarians: At higher risk of vitamin B12 and iron deficiencies.
Pregnant women: Folic acid supplements are routinely recommended to reduce neural tube defect risks.
Individuals with diagnosed deficiencies: Supplementation can effectively correct specific deficiencies.

Conclusion

Synthesized vitamins are man-made nutrients that replicate the chemical structure of those found naturally in food. While they are often cheaper and more widely available than their natural counterparts, they can differ in terms of absorption and efficacy due to the absence of natural co-factors. The primary distinction lies in their origin and the presence of synergistic compounds found in whole foods. While natural vitamins from a balanced diet are generally preferred for optimal health, synthesized versions have a vital role in preventing deficiencies, fortifying foods, and providing targeted support for specific populations. Informed consumers should be aware of the differences and discuss their individual needs with a healthcare provider to make the best choice for their health. For more detailed scientific studies, reputable sources such as the National Institutes of Health can be a valuable resource.

How to Identify Synthetic Vitamins

Look for specific clues on product labels to identify if a vitamin is synthetic:

Chemical names: Labels listing chemical names like "ascorbic acid" instead of a food source (e.g., "acerola cherry extract") typically indicate a synthetic product.
"dl" prefix: For vitamin E, the synthetic form is often labeled as "dl-alpha-tocopherol," while the natural version uses a "d" prefix (e.g., "d-alpha-tocopherol").
High potency: Extremely high, standardized doses far exceeding the Recommended Daily Allowance (RDA) are common in synthetic products.
Low cost: Mass-produced synthetic supplements are generally much cheaper than those sourced from whole foods.

Frequently Asked Questions

The main difference is their origin. Natural vitamins are extracted from whole foods and contain accompanying co-factors, while synthesized vitamins are artificially manufactured in a lab and are typically isolated compounds.

While not all, the vast majority of vitamins in modern dietary supplements and fortified foods are synthetic due to the lower cost and ease of mass production.

Not always. While some synthetic forms, like folic acid, are well absorbed, others, such as synthetic vitamin E, have been shown to be less bioavailable than their natural counterparts.

Ascorbic acid is the most common example of a synthesized vitamin, which is the man-made version of natural vitamin C found in fruits and vegetables.

For most people and when taken in recommended doses, synthetic vitamins are safe. However, excessive intake, especially of fat-soluble vitamins (A, D, E, K), can lead to toxicity, which is less likely with whole-food sources.

Look at the ingredients list. Synthetic supplements will typically list chemical names for nutrients (e.g., 'calcium carbonate' instead of 'from oyster shell') and may advertise very high, standardized dosages.

Synthetic vitamins are used to fortify foods because they are inexpensive to produce and offer a stable, standardized dose that helps prevent widespread nutritional deficiencies in the population.