What is DHA? Advantages of Recommending DHA Supplementation for Pregnant Women

DHA is a type of omega-3 fatty acid that holds particular benefits for brain tissue and cognitive function. It’s also a commonly supplemented nutrient among expectant mothers. DHA can be sourced from algae and fish, but are there any differences between algal oil DHA and fish oil DHA? Furthermore, who are the suitable candidates for supplementing with these sources? This article aims to delve into the comparison of DHA from different origins to determine which is preferable for various populations.

What is DHA Algal Oil?

Algae is a complex group of organisms that can be categorized into microalgae (phytoplankton) and macroalgae (seaweeds) based on size. Algae have a wide range of applications, including pigments (chlorophyll, carotenoids, etc.), fertilizers, water treatment, animal feed, health supplements, and even cosmetics. Today, we are specifically discussing one important health component found in microalgae, which is DHA.

Just like humans, fish also have enzymes that can synthesize DHA within their bodies, but the enzymatic activity is not very high. As a result, the majority of DHA in fish oil comes from the marine food chain. Small fish feed on plankton, medium-sized fish feed on small fish, and large fish feed on medium-sized fish, leading to a buildup of DHA through the food chain. Deep-sea large fish tend to have relatively higher DHA content. However, in recent years, due to ecological concerns, marine pollution, vegetarianism, and advancements in oil extraction technology, companies have started to develop DHA products derived from algae. This is what we commonly refer to as DHA algal oil, which is available in the market today.


Differences Between DHA Algal Oil and Fish Oil DHA

Both microalgae and fish oil contain DHA, but are there any differences between them? Let’s make a simple comparison!


Difference in Fatty Acid Composition

DHA algal oil primarily comes from certain microalgae that produce fatty acids. Although most algae have the ability to produce both EPA and DHA, the majority of species have a higher production of DHA than EPA. As a result, commercially available algal oil is mainly supplied in the form of DHA, with little to no EPA content. On the other hand, the Omega-3 fatty acids in fish oil are obtained through the marine food chain.

Therefore, commercially available fish oil products typically contain both EPA and DHA, with EPA content often exceeding DHA. The ratio of EPA to DHA at 3:2 has been confirmed by many studies to be most beneficial for heart protection and anti-inflammatory effects. It’s worth noting that EPA in fish oil has anticoagulant effects, and excessive or prolonged consumption may affect blood clotting. This is why there’s advice to avoid consuming fish oil before surgeries. However, some studies have not observed this effect [1].


Types of Fat Supply

There are three main types of fat supply available in the market: TG (Triglyceride), EE (Ethyl Ester), and rTG (Re-esterified triglyceride). Naturally occurring fatty acids are present in the TG form. To enhance the concentration of Omega-3 fatty acids, TG forms are often converted to EE forms using technology. However, clinical literature suggests that the body’s utilization of EE forms is less effective [2] [3]. Therefore, an additional processing step is applied to convert EE forms to rTG forms, which are currently considered the most absorbable and utilizable form of Omega-3 fatty acids.

Currently, almost all commercially available algal oil is supplied in the TG form. With the current processing technology, the concentration generally falls within the range of 20% to 45%, which is lower compared to the high concentration extraction process used for fish oil. This means that when supplementing with algal oil, you’ll also be consuming over half of other fats. On the other hand, rTG form fish oil with a concentration above 80% ensures that when supplementing with fish oil, you’re consuming a higher proportion of the desired fatty acids and fewer other fat sources.


Heavy Metal Contamination Management

Microalgae are mostly cultivated in closed cultivation tanks, making it relatively easier to control heavy metal contamination. Fish oil, on the other hand, is mainly sourced from marine fish, which may carry heavy metal contamination due to bioaccumulation effects. However, modern purification extraction techniques have largely eliminated most of the heavy metal contamination concerns. To ensure safe DHA supplements, whether from fish oil or algal oil, it’s recommended to choose products that have undergone third-party heavy metal testing to ensure product safety.


Considerations for Dietary Preferences

For strict vegans, algal oil is the only option when choosing DHA supplements. However, it’s important to pay attention to whether the capsules themselves are also plant-based.


Two Major Benefits of DHA Algal Oil for Expectant Mothers

The purpose of increasing DHA intake for expectant mothers is to provide benefits to the developing fetus. Therefore, it’s important to first understand during which stages of fetal development DHA is needed. According to current comprehensive clinical assessments, supplementing with DHA not only benefits the fetus but also helps replenish the mother’s own DHA needs during pregnancy.


The Developing Human: Clinically Oriented Embryology, 4th ed. Saunders, 1988. © Elsevier.

During the process of fetal development, various tissues and organs develop progressively as the weeks go by. Neural development is the earliest, starting rapidly around the third week, while eye development begins around the fourth week after implantation [4]. Current clinical research indicates a strong correlation between DHA and neural [5] [6] [7] as well as visual [8][9] development. Given the timing of central nervous system (CNS) and eye development in the embryo, it is recommended to start supplementing with DHA from early pregnancy.

In addition, when expectant mothers supplement with 600 milligrams of DHA daily, clinical studies have shown a reduction in the occurrence of early preterm birth and extremely low birth weight cases [10]. Furthermore, research has found that the DHA content in a mother’s body decreases by over 50% after giving birth compared to before, providing further evidence of the substantial DHA requirement during fetal development, which can deplete the mother’s DHA reserves[11].


How Much DHA Should Pregnant Mothers supplement?

Regarding how much DHA pregnant mothers should supplement, according to the recommendations from the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) for fetal and infant development, it is suggested to supplement with 300 milligrams of EPA+DHA per day or at least 200 milligrams of DHA per day [12].


When selecting algae oil, here are four key points to consider

  1. Ensure safety through testing for heavy metals (mercury, lead, cadmium, arsenic), plasticizers, polychlorinated biphenyls (PCBs), dioxins, and other contaminants.
  2. Due to the susceptibility of unsaturated fatty acids like Omega-3 to oxidation, check if the oil has passed oxidation indicators such as acid value (AV), peroxide value (PV), or total oxidation value (TOTOX).
  3. Choose rTG form for Omega-3 fatty acids, as their absorption is superior to EE form.
  4. Opt for a DHA content that matches the recommended daily supplementation of around 200 milligrams. Higher DHA concentration sources have a lower proportion of non-Omega-3 fatty acids, allowing for smaller supplement capsules, making it more convenient for pregnant mothers to take.

Further Reading: What nutrients should be supplemented during each stage of pregnancy? Experts explain the importance of DHA supplementation!


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