Omega-3 - The Fats That Have Everybody Smiling

"Good fats." Ask most teenagers, and they'll tell you there is no such thing. In a society that apportions press coverage to topics like "how to get buff for summer," "6 minute abs" and "the emerging threat of nuclear terrorism from rebel republics" in descending order, the notion that fats can be good for you is nothing if not an oxymoron. But for some reason, omega-3 fatty acids seem to get a pass. They're in the health food section at the supermarket and chemist. They're in the bread you buy. They're even included in several fruit juices. Everybody seems to agree, getting enough omega-3 in your diet is a must. But why?

As most people will tell you, omega-3 fatty acids have something to do with fish, and they're good for arthritis. True as they are, these more readily appreciated properties of omega-3 belie a much more exciting reality: these molecules may be beneficial for a number of health conditions.

In addition to the now considerable body of literature validating omega-3's role in the treatment and prevention of arthritis, strong evidence has emerged in recent years in support of omega-3's effectiveness in the treatment of depression. This article endeavours to review some of the proposed mechanisms of action by which omega-3 fatty acids mediate their effects against this illness.

Omega-3 Polyunsaturated Fatty Acids
Omega-3 polyunsaturated fatty acids are considered to be essential fatty acids - they are required for human health, but cannot be manufactured by the body. It is therefore necessary to obtain these acids from food, with fish (particularly fatty fish such as salmon, tuna, herring and mackerel) providing an excellent source.

There are three key types of omega-3 fatty acids that are used by the human body: alpha-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Once ingested, ALA tends to be converted into the 20- and 22-carbon fatty acids DHA and EPA, the two forms of omega-3 most favoured by the human body. Research has shown that these omega-3 fatty acids may be useful in reducing the risk of cardiovascular disease, cancer and inflammation associated with arthritis, as well as in combating depression and mental illness.

A 2006 comprehensive meta-analysis of numerous epidemiological and treatment studies investigating the effects of omega-3 intake on depression came to the conclusion that ‘deficits in omega-3 fatty acids have been identified as a contributing factor to mood disorders [1]. While bleaker weather conditions are correlated with an increased incidence of seasonal depression almost the world over, countries such as Iceland and Japan defy this trend in spite of receiving relatively little winter sunlight. Interestingly, the lowered rates of depression in these countries are strongly correlated with average seafood intakes far above those of people in most other countries. Numerous clinical trials investigating the effectiveness of taking omega-3 supplements for the treatment of depression have provided further support for these findings [2]. It seems that people are happier in places where they eat more fish.

Depression and Mental Illness
Depression is a common, serious condition afflicting up to one in every four females and one in every six males at least once during their lifetime [3]. Normally characterised by feelings of despair, unhappiness and dejected mood, the key symptoms of depression include mood swings, irritability, recklessness, fatigue, impaired cognition, listlessness, and increased alcohol and drug abuse.

There are numerous manifestations and degrees of depression, ranging from acute temporary forms of the condition, to more chronic, severe varieties. Each case is varied, although there are several leading theories that attempt to explain depression's aetiology. These explanations may be loosely categorised as either physiological or psychological.

Physiological
As every second, minute, hour and day ticks by, our feelings of happiness, confidence, motivation - and any lack thereof - are largely governed by nerve signal transmission in the central nervous system. It is estimated that there are over 100 billion nerve cells, known as "neurons," within the brain. At any given moment, more than 4 billion neurons are likely to be "firing" a signal along a particular neural pathway.

Most neurons contain several long finger-like projections ("dendrites") which protrude from the cellular nucleus to articulate with the projections of other neurons throughout the brain. At the point of articulation, there is typically a small space, or synapse, between the dendrites, across which signals are exchanged.

Signals travel across the synapses between neurons with the use of neurotransmitters. Each neurotransmitter substance is unique, and may be specifically affiliated with the transmission of signals relating to mood, motor activity, speech, or virtually any other function we may perform. The neurotransmitter serotonin (5-hydroxytryptamine), for example, is inherently involved in experiencing feelings of happiness. The point at which one neuronal extension meets another is known as the synaptic terminal, with the point at which a neuron transmits neurotransmitters into a synapse being referred to as the pre-synaptic terminal, and the point at which a neuron receives neurotransmitters from the synapse being referred to as the post-synaptic terminal. Once neurotransmitters are released into the synapse by the firing neuron, they travel across the synaptic cleft and are received by specific receptors on the post-synaptic terminal. Once a sufficient amount of neurotransmitters have been received by the post-synaptic neuron, the desired signal is potentiated along that cell to the next receiving neuron. Typically, surplus neurotransmitters remain in the synaptic cleft once signal potentiation is achieved. In order to avoid signal over-potentiation, these neurotransmitters are normally taken back up by the firing neuron in a phenomenon known as "reuptake."

Key physiological theories behind depression postulate that there is either an insufficient amount of the neurotransmitters governing mood, happiness and positive reinforcement being produced, or that there is a problem with their neurotransmission. Essentially, this leaves the door open for therapy in the attempt to rectify the problem - either by providing the body with additional neurotransmitter precursors or blocking neurotransmitter reuptake in order to increase signal potentiation - or to improve the effectiveness of the neurotransmission itself.

Psychological
Long before Freud started blaming our mental inadequacies on our mothers, it was widely accepted that impaired or sub-optimal cognitive processes may often be evidence of a deeper problem. Those thoughts at the forefront of people's minds are contained within their conscious, while many of the most powerful motivating factors underlying people's behaviour are ingrained within their sub-conscious, sometimes eluding conscious recognition altogether.