What it is
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.
A polyunsaturated fat is a fat with at least two 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 polyunsaturated fats liquids at room temperature.
What it does
Some of the polyunsaturated fat you consume is comparable to monounsaturated fat. It’s just “normal” fat that provides energy and aids in the absorption of fat-soluble vitamins without being particularly beneficial or harmful in any specific sense. However, polyunsaturated fats include three essential fatty acids (specific fats that the body can’t synthesize, but that are necessary for human health and wellbeing) – omega-6 linoleic acid, and omega-3 EPA and DHA. Check out the articles on these three specific polyunsaturated fats for more on their biological functions.
There are specific intake recommendations for essential omega-3 and omega-6 polyunsaturated fats, but not for polyunsaturated fats in general. But, most of your overall fat intake should come from mono- and polyunsaturated fats, rather than saturated fats. So, your general polyunsaturated fat intake should scale with your overall fat intake.
Likelihood of tracking completeness: Very low
Polyunsaturated fat is not a nutrient food manufacturers are required to disclose on nutrition labels. The vast majority of food manufacturers do not voluntarily list polyunsaturated fat content on nutrition labels, so most branded products in the MacroFactor database lack information on polyunsaturated fat. So, if you’d like to accurately track your polyunsaturated 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: Very low
Relatively low and relatively high intakes of general polyunsaturated fat aren’t going to cause problems in isolation. You could potentially consider your overall polyunsaturated fat intake to be too low if your saturated fat intake is too high, or if your intake of essential polyunsaturated fatty acids is too low, but the more direct “culprits” in those scenarios would be the excessive saturated fat intake or insufficient essential fatty acid intake.
For more on fat recommendations, check out the articles on dietary fats, saturated fats, omega-3 fats, and omega-6 fats.
For more on nutrients with a greater likelihood of insufficient or excessive intake, you should check out this article.
Signs of deficiency/insufficiency
There are specific problems associated with insufficient intake of essential polyunsaturated fats (omega-3 and omega-6 fats) and overall dietary fat, but not polyunsaturated fat in general.
Most nuts and seeds (particularly hemp seeds, flax seeds, sunflower seeds, and walnuts) have high polyunsaturated fat content. The oils derived from the aforementioned seeds and nuts also have high polyunsaturated fat content, along with safflower oil, grapeseed oil, and corn oil.
If you’d like to learn more about micronutrients generally, there’s a five-part series on the MacroFactor website you might enjoy.