Until now, the supply of the valuable unsaturated fatty acids DHA and especially EPA has not always been easy for vegans and vegetarians, because most plant sources contain no DHA and certainly no EPA.
In addition, due to a very low conversion rate, it is difficult to meet the requirement for omega-3 fatty acids with vegetable oils alone. Only special algae can be used as a direct vegan or non-animal source to obtain the valuable omega-3 fatty acids.
In addition to cold-water fish, another natural source also contains the valuable unsaturated fatty acids: the non-animal microalgae Schizochytrium sp. Since the algae is particularly rich in the omega-3 fatty acids DHA and EPA, it counts as a true substitute source from the sea. This makes it perfect for supporting the health of people who do not want to eat fish for personal reasons or who cannot eat fish due to allergies and intolerances.
It grows in sea regions that are close to the coast and it is also grown in algae farms. As phytoplankton, it is an essential component of the diet of sea fish – which then accumulate the valuable fatty acids in their bodies.
Omega-3 fatty acids from alpha-linolenic acid
The plant precursor of the long-chain, polyunsaturated omega-3 fatty acids DHA and EPA is alpha-linolenic acid (ALA). It is found in some green leafy vegetables and vegetable oils such as linseed, rapeseed, walnut and soybean oil. Walnuts, flaxseeds and chia seeds are also sources of alpha-linolenic acid. Alpha-linolenic acid is attractive for vegans and vegetarians, as it is only found in plant sources. Conversion into the long-chain forms is possible in the human body in principle, but the unsaturated fatty acid is only converted into DHA and EPA very slowly and to a small extent of 2 to 5% in the body.
Due to this severe quantitative restriction, vegetable oils alone cannot meet the demand for EPA and DHA and are therefore not a safe alternative for an adequate supply of DHA and EPA. However, they are a useful supplement because they help replace saturated fats.
Here's an overview of omega-3 fatty acid levels in various vegetable oils:
- Chia oil – up to approx. 64%
- Hemp oil – approx. 17% (gamma-linolenic acid (Omega 6) approx. 4%)
- Walnut oil – approx. 13%
- Rapeseed oil – approx. 9%
- Soybean oil – approx. 8%
In comparison: Algae oil and alpha-linolenic acid
For the two vegan sources of omega-3 (algae oil and alpha-linolenic acid), an example calculation best illustrates how much DHA and EPA reach the human body.
In the following example, we compare the amount of DHA and EPA that the body receives from algae oil and walnut oil:
Based on this example calculation, it becomes clear that you would have to consume about 80 ml walnut oil to get to 500 mg EPA/DHA.
In other words: 1 g algae oil provides as much EPA and DHA as is produced by the body from 80 mL walnut oil.
Alpha-linolenic acid is therefore not a bad supplier of DHA and EPA, but the body must first convert ALA to obtain the unsaturated fatty acids. Relative to the amount of oil consumed, only a comparatively small amount of DHA and EPA reaches the body. The situation is quite different with algae oil. The oil of the microalgae Schizochytrium sp. already contains a high proportion of DHA and EPA, and the conversion step is no longer necessary.
* The conversion rate of alpha-linolenic acid to EPA/DHA is 2–5% (the conversion rate depends on various factors, causing the variation). In this example 5% is assumed.