DHA: What is it for and how to take it

DHA: what it is for and how to take it

DHA is one of the biologically active Omega 3 fats. But what does this mean? And, above all, what does it do? Let’s discover its properties, its effects on health, and how to take it.

The acronym is quite simple: DHA. Those who have taken supplements specifically designed for pregnancy may have read it on the packaging. Others may have heard of it trying to understand what those “good” fats everyone calls Omega 3 are for.

Its full name (docosahexaenoic acid) might sound less common, but the substance remains the same: it is an Omega 3 fat, one of those dietary fats not considered harmful to health, on the contrary. DHA is recognized for several health properties, so much so that both the aforementioned pregnancy supplements and other dietary supplements can list specific references to its beneficial effects on the label.

What is DHA for?

DHA plays an important structural role in the brain. It corresponds to 10-20% of the fats present in this organ and, among these, over 90% of the Omega 3. It becomes part of cell membranes, so it is important for producing new neurons; it also helps them survive.

Its very structure, characterized by the presence of double bonds that make it more articulated than the linear and rigid structure of saturated fats, makes neuron membranes more fluid, facilitating the transmission of nerve impulses. Moreover, it participates in axon growth (the prolongations of neurons through which the nerve impulse travels) and is involved in synapse formation (contacts between neurons allowing the passage of nerve impulses).

Remaining in the nervous system, DHA contributes to neuroplasticity, i.e., its ability to change its activity and reorganize its structure and functioning in response to stimuli.

Precisely for all these actions, DHA is recognized for its ability to promote the development and functioning of the brain and vision from intrauterine life and then after birth. This is why its requirements increase during pregnancy and breastfeeding.

During childhood and adolescence, it has been associated with better learning, memory, and cognitive development. The benefits for the brain continue even later in life; it even seems that DHA can counteract early stages of Alzheimer’s disease.

And it does not end there, because DHA also acts as a precursor of molecules involved in inflammatory processes (eicosanoids). Compared to eicosanoids produced from other fats (especially Omega 6), those synthesized using DHA tend to have an anti-inflammatory effect. Moreover, it is also a precursor of molecules that help resolve inflammatory processes.

Therefore, DHA helps keep inflammation under control, which if excessive or chronically present would increase health risks. The association between inflammation and numerous disorders is well known, for example cardiometabolic diseases, allergies, and difficulties in recovery after physical activity.

Finally, DHA is an ally of heart health (which it promotes by supporting its good function and helping maintain triglyceride and blood pressure levels within normal ranges).

How to know if you have an Omega 3 deficiency and what to eat to take DHA

A possible Omega 3 deficiency can be detected with a very small blood sample that can be performed independently at home.

The blood taken is used to evaluate the so-called HS-Omega-3 Index, which provides information on the percentage of DHA and EPA in red blood cells (the Omega-3 Index) and their levels in the blood.

The first tool to avoid these deficiencies or to remedy them is diet. The best source of DHA is undoubtedly fatty fish; sardines, tuna, and salmon are rich in it. However, the amount of DHA present in these foods can vary depending on factors such as the fish’s age or its processing; for example, smoked salmon contains just over a third compared to fresh salmon.

Other fish varieties are decidedly poorer sources of DHA because they are leaner by nature. Cod, for example, provides only 0.9 grams of fat per 100 grams, for a total of 350 mg of DHA. In 100 grams of sardines, there is at least 1 gram of DHA.

Terrestrial sources of Omega 3, such as walnuts, are not good sources of DHA. Instead, they contain its precursor (alpha-linolenic acid or ALA) which unfortunately, once absorbed, is not efficiently converted into DHA.

ALA is not a biologically active Omega 3, because it does not directly perform the beneficial effects attributed to Omega 3s. DHA is instead one of the direct agents responsible for these effects.

When to take DHA and how much EPA and DHA to take daily

We should all ensure, at any stage of life, an adequate intake of DHA, first of all considering that the minimum Omega 3 requirement is 250 mg per day of DHA + EPA (eicosapentaenoic acid, the other biologically active Omega 3).

Meeting this requirement also helps ensure good heart function. However, as mentioned, requirements increase in some particular circumstances:

• during pregnancy and breastfeeding, when women need 100-200 mg more DHA per day;
• up to 2 years of age, when children need 100 mg more per day.

Furthermore, the amount of Omega 3 to be taken daily increases if the goal is controlling high triglycerides or elevated blood pressure. In particular:

• to maintain triglycerides within normal range, 2 grams of DHA and EPA daily are needed;
• to maintain blood pressure within normal range, 3 grams of DHA and EPA daily are needed.

Who should not take Omega 3?

DHA is considered a generally safe molecule, even when taken as supplements and at high dosages. From this point of view, the only current recommendation is not to exceed a total daily intake of 5 grams of Omega 3.

However, as a precaution, it should be borne in mind that at high doses (for example 4 grams per day) Omega 3s can cause a moderate increase in bleeding time, i.e., the time needed to stop bleeding. This increase does not exceed normal limits and has not been associated with dangerous hemorrhages. In case of concurrent anticoagulant treatment, however, close monitoring is advisable, as it may be necessary to adjust the dosage of these other drugs accordingly.

Similarly, Omega 3 intake has been associated with an increase in transaminases. This increase also remains within normal limits. It is therefore advisable to monitor transaminase levels if Omega 3s (especially at high dosages) are taken and if there is concomitant liver damage.

Finally, in case of fish allergy DHA cannot be taken in fish form. Supplements are generally considered safe, especially if highly purified. However, for 100% safe intake it is sufficient to rely on products obtained from other marine-origin ingredients rich in Omega 3, particularly algal oil.

Sources

Italian Medicines Agency. bit.ly/3Amuhkk

Brenna JT. Efficiency of conversion of alpha-linolenic acid to long chain n-3 fatty acids in man. Curr Opin Clin Nutr Metab Care. 2002 Mar;5(2):127-32. doi: 10.1097/00075197-200203000-00002

Calder PC et al. Omega-3 fatty acids and inflammatory processes: from molecules to man. Biochem Soc Trans. 2017 Oct 15;45(5):1105-1115. doi: 10.1042/BST20160474

European Commission. Food and Feed Information Portal. Health Claims. Eu Register. Last viewed 22/04/2023

Italian Society of Human Nutrition-SINU, 2014. LARN – Reference intake levels for the Italian population: LIPIDS. https://sinu.it/2019/07/09/lipidi/

Weiser MJ et al. Docosahexaenoic Acid and Cognition throughout the Lifespan. Nutrients. 2016 Feb; 8(2): 99. doi: 10.3390/nu8020099