Mono- ja polüküllastumata rasvhapped on aga ülekaalus enamikus taimset päritolu rasvades, näiteks rapsiõlis. Kaht polüküllastumata rasvhapet (asendamatud rasvhapped), linool- (oomega-6-rasvhape) ja linoleenhapet (oomega-3-rasvhape) ei ole inimorganism võimeline iseseisvalt tootma, mistõttu peab neid saama toiduga.
Essential fatty acids cannot be made in the body; they must be obtained from foods such as nuts, oilseeds and their products (e.g. sunflower oil and other vegetable oils), and oil-rich fish. They are used as the raw material for several compounds, such as prostaglandins and leukotrienes, which help to control blood pressure and other vital bodily activities. Lack of essential fatty acid may result in hyperactivity, reduced growth, and even death.
