What are DHA supplements made from?

November 27, 2025 •

4 min read

Over 75% of newborns worldwide do not receive adequate DHA, an omega-3 fatty acid critical for brain and eye development. DHA supplements are designed to bridge this nutritional gap, but many consumers are unsure about their origins and manufacturing processes.

Quick Summary

DHA supplements are predominantly derived from marine sources like fish and krill oil or sustainable plant-based microalgae. Production involves extracting, purifying, and concentrating these oils to create potent and safe dietary supplements.

Key Points

Diverse Origins: DHA supplements can come from animal sources like fatty fish (fish oil) and krill, or from plant-based sources like marine microalgae.
Algae is the Foundation: The omega-3s in fish are accumulated from their diet of microalgae, making algae the original source of DHA.
Vegan Alternative: Algal oil offers a vegan-friendly, sustainable, and pure source of DHA, produced in controlled fermentation tanks to avoid ocean contaminants.
Rigorous Processing: All DHA supplements undergo extensive processing, including extraction, purification (like molecular distillation), and stabilization with antioxidants to ensure purity and potency.
Different Forms Matter: The chemical form of the oil—triglyceride (TG), ethyl ester (EE), or phospholipid (PL)—influences its bioavailability, affecting how easily the body absorbs it.
Informed Choice: Choosing a DHA supplement involves considering dietary preferences, sourcing ethics, and verification of third-party testing for purity and sustainability.
Not Just for Humans: DHA is not only a key building block for human nutrition but is also used in animal feed to increase omega-3 levels in farmed fish and other livestock.

Docosahexaenoic acid (DHA) is a long-chain omega-3 fatty acid vital for human health, particularly for brain, eye, and heart function. Since the human body's conversion of plant-based ALA (alpha-linolenic acid) to DHA is highly inefficient, supplements provide a necessary, direct source for many. While fish oil was traditionally the primary source, the industry has evolved to offer sustainable and vegan alternatives.

The Primary Sources of DHA Supplements

DHA supplements come from two main types of sources: marine animals and marine microalgae. The original source of the omega-3s is actually microalgae, which are then consumed by other marine organisms.

Fish Oil

Fish oil is the most common and widely recognized source for DHA and eicosapentaenoic acid (EPA) supplements. Fatty, cold-water fish are rich in these omega-3s, which they accumulate by eating microalgae and smaller fish. Common sources include:

Salmon
Mackerel
Herring
Sardines
Tuna

Krill Oil

Krill oil is extracted from tiny shrimp-like crustaceans, such as Antarctic krill, that feed on phytoplankton containing DHA. Krill oil contains DHA and EPA in phospholipid form, which some studies suggest may be more easily absorbed by the body than the triglyceride form found in fish oil.

Algal Oil (Vegan)

Algal oil is the direct, plant-based source of DHA, making it an excellent option for vegetarians and vegans. The oil is harvested from single-cell marine microalgae, such as Schizochytrium sp., which are cultivated in controlled, enclosed tanks through fermentation. This process provides a sustainable, clean alternative to fish oil, free from potential ocean contaminants like mercury.

The Manufacturing Process: From Source to Supplement

Regardless of the source, the oil undergoes a multi-step process to ensure purity, potency, and stability.

1. Sourcing and Extraction

For fish oil, wild-caught fish are sourced from specific fisheries. The oil is then extracted from the fish tissue, typically using rendering methods. For algal oil, microalgae like Schizochytrium are grown in large fermentation tanks using plant-based feedstocks like sugarcane. The DHA-rich oil is then extracted from the algal biomass.

2. Purification and Concentration

Crude marine oils often contain impurities and other compounds. Manufacturers use advanced techniques to remove these. Molecular distillation is a key process that removes heavy metals, PCBs, and other contaminants, while also concentrating the omega-3s to reach specific EPA and DHA levels. This ensures the final product meets stringent international purity standards.

3. Encapsulation and Stabilization

Once purified, the oil is ready for encapsulation. This is typically done using soft gel technology, where a soft, airtight capsule is formed around the oil. Antioxidants like tocopherols (vitamin E) or rosemary extract are often added to protect the highly sensitive polyunsaturated fatty acids from oxidation and spoilage.

Comparison of DHA Supplement Sources


Feature	Fish Oil	Krill Oil	Algal Oil
Source	Oily, cold-water fish like salmon and mackerel.	Small, shrimp-like crustaceans (krill).	Marine microalgae grown in tanks.
Primary DHA Form	Triglyceride (TG), though some highly concentrated oils are ethyl ester (EE) form.	Phospholipid (PL), which may have slightly higher bioavailability.	Triglyceride (TG), with variants tailored for specific applications.
Vegan-Friendly	No	No	Yes
Environmental Impact	Concerns over marine ecosystem sustainability and overfishing.	Ecosystem sustainability concerns, as krill are a base food source for other species.	Generally considered a highly sustainable option; production does not deplete marine resources.
Contaminants	Requires extensive purification to remove heavy metals and pollutants.	Contains lower levels of contaminants than fish oil, but still requires processing.	Grown in controlled environments, making it naturally free from ocean contaminants.
Aftertaste	Can result in a 'fishy' aftertaste or burps, though refining helps.	Often less 'fishy' aftertaste reported due to phospholipid form.	No fishy aftertaste.

Understanding Different Oil Forms

Not all DHA oil is created equal. The chemical structure of the fatty acid, whether triglyceride (TG), ethyl ester (EE), or phospholipid (PL), affects its bioavailability—how well your body can absorb and use it.

Triglyceride (TG) Form: This is the natural form found in fish and algae. It is generally well-absorbed by the body.
Ethyl Ester (EE) Form: Often used in high-concentration supplements for medical purposes. It must be broken down by the body, a process that can be less efficient than with TG or PL forms.
Phospholipid (PL) Form: Found in krill oil, this form is believed to have superior bioavailability and absorb more readily into the bloodstream.

How to Choose the Right DHA Supplement

When selecting a DHA supplement, consider your dietary preferences, health goals, and ethical concerns. Vegans and vegetarians will need an algal oil supplement, which is also an excellent option for those who wish to avoid fish. If you choose fish oil, look for products that are third-party tested and certified by organizations for sustainability, purity, and concentration. For example, look for seals from the Marine Stewardship Council or third-party lab testing certifications.

Conclusion

DHA supplements are a valuable tool for ensuring adequate intake of this essential omega-3 fatty acid. They are primarily derived from either marine animals, notably fatty fish and krill, or from cultivated marine microalgae. The manufacturing process involves sophisticated extraction, purification, and stabilization to deliver a pure and potent product. For those seeking an alternative to fish-derived products, algal oil provides a clean, sustainable, and highly effective vegan source. Understanding these different origins and processes empowers you to make an informed choice that aligns with your health and environmental values.

Corbion. (n.d.). AlgaPrime™ DHA Algae Omega-3.

Frequently Asked Questions

The main difference is the source. Fish oil DHA is derived from the tissues of fatty, cold-water fish, whereas algal oil DHA comes directly from microalgae that are cultivated for this purpose. Algal oil is a direct, vegan source, while fish accumulate DHA by consuming algae.

Yes, vegan DHA supplements from algal oil are highly effective. Studies have shown that algal oil provides similar increases in blood DHA levels to fish oil. It is the same omega-3 fatty acid, just sourced differently.

High-quality DHA supplements, whether from fish or algae, undergo a process called molecular distillation to remove heavy metals like mercury and other contaminants. Algal oil, grown in controlled environments, is naturally free from these ocean contaminants.

A fishy aftertaste is typically associated with fish oil supplements, particularly if they have undergone oxidation or are of lower quality. Algal oil supplements, being plant-based, do not have a fishy smell or aftertaste.

The triglyceride (TG) form, found naturally in fish and algae, is generally better absorbed by the body than the ethyl ester (EE) form, which is often used for higher concentrations. Some people experience better absorption from the phospholipid (PL) form found in krill oil.

Algal oil DHA supplements are produced by growing specific microalgae species, like Schizochytrium sp., in large, enclosed tanks using fermentation. The DHA-rich oil is then extracted, purified, and encapsulated.

DHA in infant formula is sourced and processed similarly to adult supplements, often utilizing algal oil due to its defined composition and safety profile. It is added to support healthy brain and eye development in babies.