DHA: what it is used for and how to take it
DHA: what it is used for and how to take it
DHA is one of the biologically active Omega 3 fats. But what does it mean? More importantly, what does it do? Let's find out its properties, its health effects and how to take it.
The acronym is quite simple: DHA. Those who have taken a supplement of those designed specifically for pregnancy may have read it on its packaging. Others may have heard about it trying to figure out what those "good" fats everyone calls Omega 3 are and what they are used for.
Instead, it may be that its extended name (docosahexaenoic acid) sounds less common, but the substance does not change: it is a fat in the Omega 3 series, thus one of those food-derived fats that are not considered hazardous to health, quite the contrary. DHA is recognized for a number of healthful properties, so much so that both the just-mentioned pregnancy supplements and other dietary supplements may carry specific references to its beneficial effects on the label.
What is DHA used for?
DHA plays an important structural role in the brain. Suffice it to say that it corresponds to 10-20% of the fats in this organ and, among them, more than 90% of Omega 3. Here 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, rigid structure of saturated fats, makes the membranes of neurons more fluid, facilitating nerve impulse transmission. In addition, it participates in the growth of axons (i.e., the extensions of neurons through which the nerve impulse travels) and is involved in the formation of synapses (the contacts between neurons that allow the passage of the nerve impulse).
Staying with the nervous system, DHA contributes to neuroplasticity, that is, its ability to change its activity and reorganize its structure and functioning in response to stimuli.
Precisely because of all these actions, DHA is recognized to promote brain and vision development and functioning from intrauterine life and, then, after birth. Therefore, its requirements increase in pregnancy and lactation.
During childhood and adolescence it has been associated with better learning, improved memory, and better cognitive development. However, the benefits to the brain continue even later in life; it even appears that DHA may counteract Alzheimer's in its early stages.
And it doesn't end there, because DHA also acts as a precursor to molecules involved in inflammatory processes (the eicosanoids). Compared with eicosanoids produced from other fats (particularly Omega 6) those synthesized using DHA have a tendentially anti-inflammatory effect. In addition, it is also the precursor of molecules that help resolve inflammatory processes.
Thus, DHA helps control inflammation, which if it reaches excessive levels or is chronically present would increase health risks. Indeed, there is a known association between inflammation and numerous disorders, for example, cardiometabolic diseases, allergies, and difficulties in recovery after sports activity.
Finally, DHA is an ally to heart health (which it supports by promoting its proper functioning and helping to maintain normal triglyceride and blood pressure values).
How to tell that you are deficient in Omega 3 and what to eat to get DHA
A possible Omega 3 deficiency can be detected with a very small blood draw that can be done completely independently, at home.
The blood drawn 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 weapon to avoid these deficiencies or remedy them is diet. The best source of DHA is undoubtedly fatty fish; for example, sardines, tuna, and salmon are rich in it. However, the amount of DHA present in these foods may vary depending on factors such as the age of the fish or its processing; for example, in smoked salmon it is a little more than one third of what there is in fresh salmon.
Other varieties of fish are significantly less good sources of DHA because they are, themselves, leaner. Cod, for example, provides only 0.9 grams of fat per pound, for a total of 350 mg of DHA. In contrast, a pound of sardines contains at least 1 gram of DHA.
In contrast, terrestrial sources of Omega 3, such as walnuts, are not good sources of DHA. In fact, 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. Instead, DHA is one of the direct contributors to these effects.
When to take DHA and how much EPA and DHA to take per day
We should all ensure that we have an adequate intake of DHA at any stage of our lives, first keeping in mind 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 to ensure the proper functioning of the heart. As mentioned, however, requirements increase under some special circumstances:
- During pregnancy and lactation, when the woman needs 100-200 mg more DHA per day;
- until the age of 2 years, when children need 100 mg more per day.
In addition, the amount of Omega 3 to be taken per day also increases if the goal is to control high triglycerides or high blood pressure. Specifically:
- To keep triglycerides in the normal range, it is necessary to take 2 grams of DHA and EPA daily;
- 3 grams of DHA and EPA per day is needed to maintain normal blood pressure.
Who shouldn't take Omega 3?
DHA is considered a generally safe molecule, even when taken in supplement form 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.
As a precaution, however, it should be kept in mind that at high doses (e.g., 4 grams per day) Omega 3s can cause a moderate increase in bleeding time, that is, the time it takes to stop bleeding. This increase does not lead to exceeding normal limits and has not been associated with dangerous bleeding. In the case of concomitant treatment with anticoagulants, however, it is advisable to monitor the situation closely, because the dosage of these other drugs may need to be adjusted accordingly.
Similarly, Omega 3 intake has been associated with an increase in transaminases. However, this increase also stops within normal limits. The advice, therefore, is to monitor transaminase levels if one is taking Omega 3 (especially at high dosages) and living, at the same time, with a damaged liver.
Finally, in case of a fish allergy, DHA cannot be taken in the form, precisely, of fish. Supplements are generally considered safe, especially if they are highly purified. However, for 100 percent safe intake, it is sufficient to rely on products made from other Omega 3-rich marine ingredients, particularlyalgal oil.
The main functions of DHA: brain, eyes and nervous system
Speaking of membranes, those richest in DHA are found in the nervous system and the eye.
Specifically, the brain contains nearly 3.5 grams of this Omega 3-an amount equal to about 8 percent of the total fatty acids and as much as 40 percent of all polyunsaturated fatty acids in this organ-concentrated mainly in the gray matter.
In the eye, however, DHA is an important component of the retina. Here, light is captured by specialized structures (the cones and rods) that are not, however, the only components of the retina, which also contains nerve cells. Its structure allows the transmission of the light signal to the optic nerve and, through it, to the brain.
The importance of DHA for vision and the brain is proven by numerous scientific studies; it is on the basis of these studies that EFSA (the European Food Safety Authority, responsible for authorizing claims about the benefits of nutrients for human health) allows food and food supplement manufacturers to use the claims that:
- DHA contributes to normal brain function;
- DHA contributes to the normal functioning of vision.
The role of DHA during pregnancy and in child development
These benefits of DHA start from the earliest stages of life. EFSA itself tells us this, and this is primarily why DHA requirements increase during pregnancy.
In fact, DHA is important for brain and vision development of the fetus and baby in the first 12 months of life. EFSA also authorizes the following claims:
- the mother's intake of DHA contributes to the normal development of the fetus' brain and eye;
- mother's intake of DHA contributes to the normal brain and eye development of the breastfed baby;
- DHA intake contributes to normal vision development in children up to 12 months of age.
Not surprisingly, this polyunsaturated fat is also one of the ingredients in formulas (so-called "infant formula").
The point is that, as mentioned, DHA is an important structural component of nerve cell membranes, to which it imparts flexibility and fluidity, improving not only the functioning of membrane proteins but also neurotransmission. It plays a role in the formation and survival of neurons, the growth of the extensions by which nerve signals are transmitted (the axons) and the formation of the structures through which they pass to other cells (the synapses), neuroplasticity, and protection from oxidative stress. Finally, it regulates gene expression, improves vascular tone in the brain, and regulates glucose uptake at the blood-brain barrier.
The effects of DHA on memory and concentration in adults
The scientific literature also suggests other roles of DHA in childhood, such as promoting motor development and good sleep and protecting against allergies. Not only that, since brain development is active throughout childhood, continues through adolescence, and continues into the late twenties, its brain-level benefits extend well beyond the early years of life.
This is why it is also often recommended to promote concentration in adults. What's more, studies conducted to investigate the benefits of Omega 3 against memory disorders in old age suggest that DHA, alone or in combination with EPA, can improve it in the elderly with mild memory problems.
The importance of DHA for visual health
The EFSA-authorized claim indicates to us that the importance of DHA for visual health does not end during childhood either. Its antioxidant and neuroprotective actions appear to be useful even in the presence of diseases that lead to vision loss. In addition, according to new models, DHA would play a key role in determining the speed of nerve impulse transmission, which, as pointed out by George Wald himself, a Nobel laureate in Medicine precisely by virtue of his discovery of the mechanisms of vision in the eye, cannot be accounted for by the downstream processes of visual pigment activation alone, which are too slow.
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