How much Omega-3 to live a long life?

Omega-3 fats actively regulate the biological processes that determine how much and how we will age. A diet rich in their sources, possibly combined with supplementation targeted at “longevity” dosages, is a promising strategy to protect our health and our cognitive capital over the years.

Omega-3s play important structural and functional roles in the human body. The three main representatives of this family of nutrients are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

The first is the Omega-3 typical of plant-based foods; it is abundant, for example, in walnuts and flax seeds. EPA and DHA, on the other hand, are the so-called Omega-3s of marine origin, abundant in oily fish (such as sardines, anchovies, salmon and mackerel) and in fish, krill and microalgae oils.

Although ALA is the precursor of the other two, the efficiency with which it is transformed into EPA and DHA is extremely low. Some studies suggest that only 0.2% of the ALA taken through the diet is converted into EPA and that an even smaller 0.05% manages to be transformed into DHA.

In women these percentages seem to be higher than in men, but still insufficient to easily ensure that the daily requirements of EPA and DHA are met by taking ALA alone.

For this reason, even though only ALA meets the definition of an essential nutrient (which therefore must necessarily be taken through the diet), in practice EPA and DHA are also considered essential, and it is advisable to take them preformed within foods or food supplements.

In the human body, Omega-3s are found mainly as phospholipids in the membranes, whose fluidity and functionality they influence, or as triglycerides in the body's fat reserves. Their structural role underlies their impact on health and longevity.

Omega-3s, pillars of longevity

Scientific interest in Omega-3s in longevity medicine stems from research showing that people who have higher blood levels of these fats have a 15%-18% lower risk of dying from any cause.

This protective effect would depend first of all on the ability of EPA and DHA to counteract inflammaging, that is, the low-grade chronic inflammation – silent but harmful – that, by damaging tissues and organs, is one of the main drivers of ageing.

Omega-3s of marine origin act as powerful regulators of this phenomenon. In addition to counteracting the excess of Omega-6 (fats that are equally essential, but often pro-inflammatory and too abundant in the modern diet), they promote the production of molecules that act by switching off inflammation (resolvins, protectins and maresins), helping to prevent it from becoming chronic.

Furthermore, Omega-3s have been associated with the preservation of telomeres (the protective ends of chromosomes that tend to shorten during ageing) and with the slowing of molecular biological clocks, modifying DNA without altering the sequence of the genes it contains through a phenomenon known as methylation.

At the clinical level, the scientific literature suggests, for example, that the anti-inflammatory properties of Omega-3s slow the degradation of joint cartilage in conditions such as osteoarthritis, improving mobility and reducing reliance on painkillers. But the role of these fats as promoters not only of longevity, but also of a healthy longevity, depends on other factors too.

In fact, an adequate intake of Omega-3 has been associated with improved muscle strength and the stimulation of protein synthesis, suggesting interesting potential in counteracting sarcopenia – the loss of muscle mass and strength that, with advancing age, represents a primary risk to independence.

In addition, EPA and DHA help keep triglyceride levels and blood pressure within the normal range, significantly reducing cardiovascular risk. At the same time, ALA protects the heart and arteries, also helping to keep cholesterol levels normal.

Finally, Omega-3s are recognised allies of good eyesight as well. But their benefits are not evident only on a physical level: by promoting brain health, they also manage to support cognitive and psychological well-being.

The role of DHA in brain longevity

Indeed, the brain is, after adipose tissue, the most fat-rich organ in the human body: more than 50-60% of its weight is in the form of lipids, and 35% of its fats correspond to Omega-3.

DHA is the absolute protagonist, accounting for more than 90% of the total Omega-3 in the brain and 10-20% of its entire fat mass. It is a fundamental component of neuron membranes and its presence is particularly relevant in the grey matter, the part of the brain where information is processed.

By determining the structure of neuron membranes, Omega-3s facilitate the exchange of signals and nerve transmission; furthermore, they increase the release of neurotransmitters. To these functions are added important neuroprotective effects:

• the prevention of cell damage caused by oxidative stress due to the presence of reactive oxygen species;
• the regulation of signals that lead to programmed cell death, which is consequently inhibited.
  

The studies that have analysed the practical implications of these actions have associated the intake of adequate doses of Omega-3 with a reduction of about 20% in the risk of dementias and cognitive decline. This effect is dose-dependent: it is estimated that every increase in EPA and DHA of 0.1 g per day reduces the risk of cognitive decline by 8% - 9.9%.

Studies conducted on healthy adults with an average age above 76 years have associated high blood levels of Omega-3 with better memory, greater information-processing speed and a higher brain volume in specific regions of the brain (the entorhinal cortex and total white matter).

In patients with mild cognitive decline, taking DHA supplements has been associated with significant benefits in preserving hippocampal volume and memory functions. And in individuals without cognitive problems but with coronary heart disease, high dosages of EPA and DHA (over 3 grams per day) have been associated with a slowing of cognitive ageing of two and a half years.

An interesting fact concerns carriers of the APOE*E4 gene, a genetic risk factor for Alzheimer's: these people seem to benefit particularly from DHA supplementation, especially if started before the onset of symptoms.

Moreover, maintaining high blood levels of Omega-3 seems to be an effective strategy for psychological balance, capable of preserving not only memory but also emotional stability. Senile depression too, often underestimated, could benefit from an adequate intake of Omega-3, which seem to help fight the associated inflammatory processes.

It is important, however, to bear in mind that the effectiveness of Omega-3s can be influenced by other nutrients. For example, it seems that having an adequate amount of B-group vitamins available is a necessary requirement for these fats to be able to exert their beneficial effects on cognitive abilities.

How much Omega-3 for longevity?

The amount of Omega-3 to take depends on the benefit one would like to obtain. To promote good heart function, 250 mg per day of EPA+DHA is enough, whereas 2 or 3 g are needed to control triglycerides and blood pressure respectively. And although there are no established dosages against the disorders associated with inflammation, we know that 250 mg per day of DHA is needed for eye health and for the maintenance of normal brain functions.

Research on brain longevity points to higher dosages. Dose-response analyses indicate that maximum effectiveness for general cognitive function is achieved in a range between 1000 and 2500 mg per day. More specifically:

• for short-term memory and visuo-spatial functions, it is suggested to exceed 1000 mg/day;
• for global cognitive abilities, the peak of effectiveness is observed at around 1500 mg/day;
• for episodic memory (the part of long-term memory that allows you to remember the “what”, “where” and “when” of an event), the benefits seem at first to decrease and then to increase at high doses.
  

To date, research seems to leave little room for doubt: taking Omega-3 has positive effects on the body, is well tolerated and does not carry significant risks. The fundamental basis remains a diet rich in oily fish, considered the optimal source for ensuring a constant intake of EPA and DHA, but personalised supplementation represents a valuable tool in situations of deficiency or increased requirement, for the elderly and for people living alone.

In addition to classic fish oil, there are options such as cod liver oil, krill oil and microalgae oils, also suitable for those who follow vegetarian or vegan diets.

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