Plants make enzymes that ‘insert’ a double bond into (desaturate) fatty acids at positions w3 and w6 to make w3 and w6 fatty acids, but humans do not produce these enzymes. This means that LA and ALA are not essential to plants because plants can make them, but they are essential to us because we cannot make them ourselves. They must therefore be present in our foods if we are to be healthy, and they usually come from plant sources.
Our richest source of ALA is flax oil. Safflower oil is our richest source of LA. Hemp seed oil contains w6 and w3 essential fatty acids in an ideal long-term ratio of 3:1.
W3 consumption has decreased to one sixth the level found in our food supply in the 1850s. W6 consumption has doubled in that time, drastically changing the ratio of w6 to w3 in our food supply. This change is reflected in the makeup of our tissue fats and in our health.
Flax, our richest source of w3s, provides a quick way to make up for long-standing, widespread w3 deficiency. W3 deficiency can be reversed by a dozen 250 mL (8.5 ounce) bottles of good-quality flax oil consumed over the course of a few months.
Long-term exclusive use of flax oil can result in w6 deficiency symptoms, because flax oil contains four times more w3s than w6s. One can expect w6 deficiency symptoms from exclusive use of flax oil within 16 months to 2 years.
Over the long term, what ratios would be healthy? W6:w3 ratios found in diets varies from 1:2.5 (Inuit diets), through 6:1 (other traditional diets), to 20:1 (contemporary safflower and corn oil diets). Inuit are relatively healthy, but many of them suffer strokes, probably due to deficiency of vitamins C and E, and osteoporosis due to high protein intake, which leaches calcium from bones. Other traditional diets keep users free of degenerative diseases. Contemporary diets cause degenerative conditions.
The w6:w3 ratio in the brain is about 1:1. The ratio in our fat tissue is about 5:1. Other tissues are about 4:1. Our enzymes convert w6s only one-fourth as quickly as they convert w3s. To get equal conversion then, the ratio in foods should be 4:1, but because w6s mediate degenerative conditions, the ratio should favor w3s.
Such ratios can be developed by blending w3-rich oils with w6-rich ones to arrive at the appropriate ratio. Hemp oil, which contains three w6s (LA) for each w3 (ALA) and also 1.7% GLA, giving w6 conversion a head start in making beneficial PG1 prostaglandins, could be used in such blends, along with flax and other w6-rich oils.
As you may know, hemp is marijuana. The oil is legal, as are the steamed (un-sproutable) seeds. Eating hemp seeds or drinking hemp seed oil will not produce any intoxicating effects, since both oil and seeds contain very little THC (tetrahydrocannabinol, which causes the intoxication, but traces of THC may be present, enough to show up in urine drug screens, leading to the loss of jobs).