EPA, DHA and Short-chain polyunsaturated fatty acids
Maintaining sufficient levels of ‘good fats’ in the diet has been associated with a plethora of health benefits, from reduced cardiovascular disease, healthy brain function and balanced mood, to reduced rates of cancer and even enhanced longevity. It’s no wonder that so much attention has been drawn to the benefits of increasing certain types of these fats in the diet. Along with the increasing scientific evidence, numerous ways of enhancing omega-3 intake now fill the shelves. Quite apart from increasing oily fish intake (a very valid solution as long as you restrict this to two portions of oily fish weekly), aisles are now filled with foods fortified with omega-3 such as yoghurts and bread, and there are numerous different types of omega supplements. When we say numerous, we mean products containing active ingredients (EPA/DHA) ranging from 10% to 90% – no wonder, therefore, that consumers have a mixed impression about omega-3 fatty acids and the health benefits these fats are purported to offer. We hope that the information below will clarify the science behind the biological roles that these fats play.
1. Short-chain fatty acids
Short-chain fatty acids are commonly labelled ‘essential fatty acids’ (EFAs) because they are parent fatty acids (ALA at the top of the omega-3 family and LA at the top of the omega-6 family) and cannot be manufactured by the body – hence we must obtain them from our diet. It is from these two parent EFAs that the long-chain omega-3 and omega-6 fatty acids are derived, through enzyme elongation reactions in the body. Most health benefits are derived from the long-chain fatty acids such as EPA, important for neurological function, as well as byproducts of EPA called eicosanoids – important anti-inflammatory substances including prostaglandins and leukotrienes. The majority of short-chain fatty acids are utilised as fuel and some go on to be metabolised to long-chain fatty acids (which are the precursors to eicosanoids). It is now well-known that these conversions are not very efficient in many people and the actual amounts of long-chain fats derived from short-chain fats tend to be very low. This is due to changes in the modern lifestyle and diet – for example, only a very small percentage of the parent omega-3 fatty acid ALA consumed in the diet is converted to the more important long-chain fatty acids such as EPA, DHA, and ultimately to the anti-inflammatory eicosanoids. You can overcome this poor conversion rate by ensuring your diet is rich in long-chain fatty acids, effectively by-passing the ‘blocks’ posed by viruses, nutrient deficiencies, trans fats, alcohol and other inhibiting factors such as stress. Short-chain fatty acids are plant based fats, the benefits of which are quite different from long-chain fats typically derived from fish, despite often being grouped together on the shelves with fish oils. Plant-based oils such as flaxseed tend to much cheaper than fish oils, which can also lead to a misconception about ‘value for money’. Plant oils are rich in ALA (the parent omega-3 fatty) acid, which does make them suitable for vegetarians, but the body still has to undertake a series of lengthy conversions before they become the more useful long-chain fatty acids such as EPA and DHA. Because humans aren’t efficient at converting short-chain fatty acids to long-chain fatty acids, plant oils cannot offer the same health benefits as fish oils – so, unless you are vegetarian it is advisable to seek out a purified and concentrated EPA supplement with the ‘active’ fatty acid already in its bioavailable form. Most foods fortified with omega-3 tend to be those containing plant-based omega-3 fats and, for the same reasons as discussed above, will not provide brain-boosting and heart-protecting benefits associated with fish oils. For vegetarians, vegans and those allergic to fish seeking to boost their EPA omega-3 levels, a newly available source of vegetarian omega-3 provides a more effective precursor to EPA than the commonly available flaxseed oil, containing the parent omega-3 ALA (which must be converted through a series of enzyme reactions before reaching EPA in the body). Echium Seed Oil found in Echiomega, unlike flaxseed oil, contains SDA – a closer relative to EPA, which converts more efficiently to EPA and its anti-inflammatory derivatives.
2. Cod liver oil
Cod store the majority of their omega-3 in their livers and relatively little in their flesh. Originally a by-product of the fishing industry, cod were first of all filleted before the liver was pressed for its oil, known to be rich in omega-3. The liver, however, is also the site of storage of vitamin A, though important for new cell growth, healthy skin, hair, and tissues, vitamin A is toxic in high doses. The liver also functions to neutralise toxic substances and so can act as a reservoir for contaminants such as methylmercury, dioxins and PCBs. Due to its high vitamin A content and, more recently (through contamination of the oceans), pollutants, cod liver oil is less safe now than when it was consumed by our grandparents! Seemingly cost-effective, the low amounts of EPA found in cod liver oil precludes this widely available product from offering the heart and brain health benefits that omega-3s are famed for.
3. Generic fish oil
This refers to oil that has been extracted from the flesh of fish and filtered to remove contaminants to legal limits, but not molecularly distilled or concentrated. They tend to be easy to spot on the shelves, as they typically contain 180mg EPA and 120mg DHA per 1000mg of fish oil and are relatively cheap to buy. In other words they amount to about 18% and 12% of EPA and DHA, compared with our concentrated EPA in PHARMEPA rTG-EPA 90, which contains over 90% concentration EPA.
4. Pharmaceutical-grade oil
These oils undergo rigorous molecular distillation and/or concentration. Molecular distillation ensures that the oil is free from contamination and from vitamin A. By concentrating the EPA, the amount of physiologically active EPA in the final product is increased and uptake in the body is enhanced. PHARMEPA rTG-EPA 90 for example, comprises 90% rTG EPA concentrate, in a pure, safe and well tolerated format for clinical dosing of 1-2 g daily.
KNOW YOUR FISH OIL AND COMPARE SUPPLEMENTS
Important considerations when choosing a fatty acid supplement:
RESTORE Omega 3
Vegetarian Omega 3-6-9
Bone & Joint Formula