We are regularly encouraged to enjoy more omega-3 in our diet.
The fatty acids can be found in oily fish, such as mackerel and salmon, and have been found to promote brain health.
Indeed, taking supplements regularly has been found to ward off dementia.
However, despite their almost identical name, omega-6 fatty acids are a bit more complicated.
According to the Arthritis Foundation, they are necessary for normal growth and development, such as bone health, metabolism, reproduction and healthy skin and hair.
The are found naturally in meat and oils, such as sunflower oil.
Your body cannot produce them, so they need to come from diet or supplements.
It is important they are in balance with omega-3.
This is because too much omega-6 can trigger the body to produce pro-inflammatory chemicals.
However, in the Western diet, many people consume far too much omega-6, and not enough omega-3.
This is particularly worrying since research has linked omega-6 to depression.
A 2005 study published in the journal Molecular Biology found that increased levels of the omega-6 fatty acid, arachidonic acid, in brains was associated with depression.
Research by Ohio State University in 2014 also found an increase risk of arthritis, heart disease and type 2 diabetes in those who had a higher omega-6 to omega-3 ratio.
While most people should probably cut down, there are some groups who could be deficient in omega-6.
Signs you need more eczema or dry, irritated skin, water loss, hair loss, drying eyes, arthritis and high cholesterol.
Complications from deficiency include heart arrhythmias, infection and the inability to heal, kidney damage, sterility, growth problems, behaviour problems and miscarriage.