Polyunsaturated fats in food

Where polyunsaturated fats are found

The ω-3 polyunsaturated fatty acids are the most ancient, as they are typical of the aquatic kingdom; as such they are widely represented in algae, marine organisms and fish that feed on them. Other sources are not very widespread: significant concentrations are found in flax seeds and their oil, in hemp and to a lesser extent in canola and soybean oils. The nutritional importance of ω-3 polyunsaturated fatty acids is such that today some foods, such as milk and eggs, are fortified with them directly or indirectly (for example by increasing the content of ω-3 in the feed or by selecting cultivars richer).

The precursor of omega three, alpha-linolenic acid, cannot be synthesized by the body and as such must necessarily be introduced with the diet. Once ingested, the body can transform it into the respective semi-essential fatty acids.

The ω-6 polyunsaturated fatty acids are widespread throughout the vegetable kingdom and are abundant in sunflower oil, peanut, grape seed and corn oil. Although an essential nutrient, linoleic acid - progenitor of ω-6 - it is generally consumed in more than sufficient if not excessive quantities.

Presence of essential fatty acids (EFA) and semi-essential fatty acids in food Omega 6 series Foods

Cis linoleic acid (LA) *
Gamma-linolenic acid (GLA)
Diomo-gamma-linolenic acid (DGLA)
Arachidonic acid (AA)

Olive and seed oil
Blackcurrant oil, borage oil, evening primrose oil
Breast milk
Dairy products, meat, human milk, shellfish

Omega 3 series Foods

Alpha-linolenic acid (ALA or LNA) *

Eicosapentaenoic acid (EPA)
Docosahexaenoic acid (DHA)

Linseed, hemp, soy and canola oil

Fish oil, herring, salmon, whale
Fish oil, some algae

(*) The fatty acids marked with an asterisk are essential, the others semi-essential

In polyunsaturated fatty acids the double bonds are not adjacent, but separated by a methylene group (-CH2-).

A separate case is given by some polyunsaturated fatty acids with conjugated double bonds, such as the so-called CLA (conjugated linoleic acid). Present in meat and dairy products obtained from ruminants, conjugated linoleic acid has a pair of double bonds separated by a single methylene group (simple bond), hence the adjective "conjugate". Slimming, antioxidant and anticancer properties have been ascribed to this nutrient, but the usefulness of a supplementation has been reduced by the possible negative implications that emerged in some studies.

Essential fatty acids in food

FOOD (100 g) ω-3 ω-6 ω-6:ω-3 DHA (g) EPA (g) LNA (g) * total (g) total (g) - Salmon oil 18,232 13,023 1,061 35,311 1,543 0,04 : 1 Liver oil
of cod 10,968 6,898 0,935 19,736 0,935 0,05 : 1 Sardine oil 10,656 10,137 1,327 24,093 2,014 0,08 : 1 Caviar 3,801 2,741 0,017 6,789 0,081 0,01 : 1 Mackerel 1,401 0,898 0 2,670 0,219 0,08 : 1 Coho salmon
(wild) 0,656 0,429 0,157 1,474 0,206 0,14 : 1 Coho salmon (farmed) 0,821 0,385 0,075 1,281 0,349 0,27 : 1 Anchovy or alice 0,911 0,538 0 1,478 0,097 0,07 : 1 Tuna 0,890 0,283 0 1,298 0,053 0,04 : 1 Herring 0,862 0,709 0,103 1,729 0,130 0,08 : 1 Flax seed 0 0 22,813 22,813 5,911 0,26: 1 Linseed oil 0 0 53,304 53,304 12,701 0,24 : 1 Walnut oil 0 0 10,400 10,040 52,890 5,27 : 1 Dried walnuts 0 0 8,718 8,718 33,717 3,87 : 1 Dried almonds 0 0 0 0 12,648 - Peanuts 0 0 0,170 0,170 10,535 61,97 : 1 Salted dried pistachios 0 0 0,263 0,263 13,636 51,85 : 1 Soy lecithin 0 0 5,135 5,135 40,178 7,82 : 1 Olive oil 0 0 0.761 0,761 9,763 12,83 : 1

* LNA = undifferentiated alpha-linolenic acid

SOURCE: "Essential Fatty Acids in Food" was compiled based on data provided by the US Department of Agriculture