What they are
Fat molecules have a long backbone of carbon atoms bound to hydrogen atoms. When a particular carbon is “saturated,” it forms a single bond with two other carbon atoms, and two hydrogen atoms. When consecutive carbons are “unsaturated,” they’re each only bound to a single hydrogen atom, allowing the neighboring carbon atoms to form a double bond with each other. This typically causes a bend in the carbon backbone.
Omega-3 fats are polyunsaturated fats with at least three pairs of unsaturated carbons, and multiple bends in the carbon backbone of the fat. These bends in the carbon backbone make the fat molecules less likely to stack up in an orderly fashion, thus making omega-3 polyunsaturated fats liquids at room temperature.
Omega-3 fats all have a double bond between the 3rd and 4th carbons from the end of the carbon backbone.
What they do
Omega-3 fats are fats with an unsaturated carbon at the third position from the end of the fat’s carbon backbone. There are four fats meeting this description: alpha-linolenic acid (ALA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Of these four fats, ALA, EPA, and DHA are considered essential fatty acids, meaning that they’re important for human health, and they must be consumed via diet, because your body cannot synthesize them.
EPA and DHA are the two most important omega-3 fats. They’re incorporated into cell membranes, and influence inflammation (reducing inflammation and platelet aggregation).
ALA is arguably nonessential on its own, but it can be converted to EPA and DHA, though this conversion isn’t particularly efficient (about 3-6% of ALA is converted to EPA, and about 2-4% is converted to DHA). However, it also suppresses the production of arachidonic acid, which is generally pro-inflammatory.
The recommended intake of ALA is 1.1g/day for women, and 1.6g/day for men. The recommended combined intake of EPA and DHA is 250mg/day.
Likelihood of tracking completeness: Very low
Omega-3 fats are not nutrients food manufacturers are required to disclose on nutrition labels. The vast majority of food manufacturers do not voluntarily list omega-3 fat content on nutrition labels, so most branded products in the MacroFactor database lack information on omega-3 fats. So, if you’d like to accurately track your omega-3 fat intake, you’ll need to make a point of mostly tracking “common foods,” which come from research-grade databases that have full nutrient reporting.
For more on when you can track using branded foods versus common foods when you’re trying to accurately monitor your intake of particular nutrients, you should check out this article.
Likelihood of insufficient intake: Low for ALA, high for EPA and DHA
Most adults in developed countries consume adequate amounts of ALA, but well below the recommended amounts of EPA and DHA.
For more on nutrients with a greater likelihood of insufficient or excessive intake, you should check out this article.
Signs of deficiency/insufficiency
The earliest signs of insufficient omega-3 intake are dermatitis and rough, scaly patches of skin. Severe omega-3 deficiencies can lead to poor vision due to retina damage, reduced immune function, mood disturbances, and impaired cognition.
Coldwater fatty fish, most notably salmon, is an excellent source of omega-3 fats. Flax seeds, chia seeds, hemp seeds, and walnuts (and products made from those nuts and seeds) are particularly good plant sources of omega-3 fatty acids.
If you’d like to learn more about micronutrients generally, there’s a five-part series on the MacroFactor website you might enjoy.