We need fats in our diet to survive, but how much is an area of debate and how much of which types of fat is an even bigger debate. There’s a lot of evidence that the inclusion of oily fish - or even fish oil supplements - will have beneficial effects in respect of disease prevention. But how true is this and do we need fish oils in our diet?
There are two completely essential fatty acids (EFAs) that humans require from food: linoleic acid (LA – an omega-6 fatty acid) and alpha linolenic acid (ALA – an omega-3). Although not essential, there are four other fatty acids that may be beneficial by reducing the requirement for LA and ALA: arachidonic acid (AA), gamma linolenic acid (GLNA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). If you’re not including much of these four in your diet, then you’ll need to compensate by consuming more LA and ALA.
EPA and DHA are the ones we’re going to focus on in this discussion. These are both, like ALA, omega-3 fatty acids and both can only be obtained from oily fish, marine algae or supplements based on either of the aforementioned. EPA and DHA are not essential in our diet as they can be synthesised by enzymes from ALA.
Why we need EPA and DHA
The amounts of EPA and DHA in the blood are reflective of both biological processes and dietary intake (1) and insufficient levels of them in our blood has been shown, through numerous studies, to give an increased risk of cardiovascular disease (2) through increased platelet aggregation, i.e. increased risk of excessive clotting (3). Having a sufficient level of DHA in the blood can also reduce serum triglycerides which is another risk factor for cardiovascular disease (3). Insufficient levels of DHA have also been linked to having negative neurological effects (4). Indeed, many conditions where there are an inflammatory process involved in the aetiology, links with inadequate levels of EPA and DHA have been demonstrated (2). It is important to note though, that a number of the studies have been done on fish oil intake rather than specifically EPA and DHA intakes, and the actual amounts of these two fatty acids in fish oils can vary.
Although ALA is considered the only essential omega-3 fatty acid because it cannot be synthesised by humans, evidence that human conversion of ALA to EPA and, particularly more so, DHA is relatively inefficient. Thus EPA and DHA may be considered conditionally essential nutrients and should dietary intake of both be poor, you can only be assured of sufficient blood levels of either if there is a sufficient ALA intake. In short: if you’re not consuming EPA and DHA, then you need to have a considerably higher ALA intake.
There is much discussion and conflicting information regarding how much dietary ALA can be converted into EPA and DHA. The process is via enzymes which facilitate the conversion. However, for optimal conversion these enzymes need to be acting efficiently and unfortunately, many aspects of Western eating habits interfere with the conversion to the nutritional disadvantage of people who follow typical modern Western diets. Indeed, it’s been indicated that maybe as many as 75% of the US population have insufficient levels of EPA and DHA through poor food choices (5,6).
Factors that affect the conversion of ALA to EPA and DHA include:
Although there are mixed reviews on the level of conversion, it’s well accepted that there is a higher conversion in women than in men. This appears to be related to the effects of the hormone oestrogen which may potentiate conversion rates (7,8). This is one reason that may explain why women have a lower heart disease risk than men. Two studies with the same lead author and published at the same time, looked at conversion rates in men and women. One looked at ALA metabolism in males and indicated that approximately 8% of dietary ALA is converted to EPA and 4% is converted to DHA (9). Another looked at women: approximately 21% of dietary ALA is converted to EPA and 9% is converted to DHA (10).
Diets with a saturated fat intake have been shown to have lower conversion rates (5,6); it’s not clear why this is as there are different enzymes involved in the metabolism of saturated fats and omega-3s. Diets high in omega-6 fats have also been shown to have lower conversion rates (5,6). This is much easier to explain: LA, the other completely essential fatty acid, competes with ALA for the same enzymes in its conversion to the conditionally essential fatty acid AA (5,6,11). Therefore a diet rich in omega-6 fatty acids, increases the demand for ALA in the absence of EPA and DHA.
It’s also been indicated that the less EPA and DHA you consume, the higher the conversion will be as the demand is higher (11,12,13).
In the absence of any dietary EPA and DHA, the crucial question is how much dietary ALA do our tissues convert into EPA and DHA?
Some papers have cited that human conversion of ALA into EPA ranges from 8% to 20% and conversion of ALA to DHA ranges from 1% to 9% (11). One study indicated that ALA conversion is about 6% for EPA and 3.8% for DHA (14). The factors mentioned above are the reason for these huge variations of rates.
As Huel doesn't contain any EPA and DHA, we've ensured it contains sufficient ALA for there to be adequate conversion to EPA and DHA.
Here’s how we justify this statement...
The total amount of omega-3s in Huel Version 2.3 is 15.8g based on a 2,000kcal intake. We don’t know the exact amount of ALA in Huel as the ALA present comes from the natural ingredients, but we do know that it is the predominant omega-3 fatty acid in flaxseed and therefore we know that there’s at least 14g of ALA per 2,000kcal Huel, i.e. a majority of the omega-3 content. Therefore Huel should be regarded as a very high source of ALA and provides more than the majority of people’s intakes.
Huel does contain a reasonable amount of saturated fat, but this is mostly in the form of medium chain triglycerides (MCTs) from the coconut oil. The evidence that saturated fat restricts conversion of ALA to EPA and DHA is based on intakes of diets high in long chain triglycerides (LCTs) and, seeing that MCTs are metabolised more efficiently than LCTs, their effects are likely to be very different. Huel is also rich in essential omega-6 polyunsaturates, which, as discussed above, can limit ALA conversion to EPA and DHA. However, the amount of omega-6s actually ingested are at levels a lot lower than the normal Western diet to which the studies cited above have been based on.
As it’s hard to get 100% reliable conversion rates and there is conflicting information, we need to be really conservative and look at the most unfavourable scenarios to assure regular consumers of Huel. Therefore, let’s say there’s as little as a 6% conversion to EPA and 3.8% to DHA. Based on 14g of ALA per 2,000 kcal, the conversion of ALA would yield 840mg of EPA and 532mg of DHA; a total of 1,372mg.
Guidelines vary and suggest that intakes of 500mg to 1,250mg combined DHA and EPA per day are more than sufficient (14,15), so conversion rate requirements are easily met based on a 2,000 kcal daily intake of Huel.
These figures are looking at ‘worst case scenario’ and demonstrate that the amount of ALA Huel provides is more than sufficient to convert to adequate amounts of EPA and DHA to maintain optimal health. In practice conversion rates are likely to be higher as Huel’s nutritional profile is far from indicative of a typical modern Western diet. This conservative level also ignores the favourable saturated fat and omega-6 profiles of Huel, that there’s adequate niacin, vitamin B6, vitamin C, zinc and magnesium to act as enzyme cofactors and that Huel contains no trans fat. Moreover, as there’s no EPA and DHA in Huel, the conversion will be at an increased rate. As you can see, there are numerous factors that potentially increase the conversion rates of ALA to EPA and DHA in Huel to a level notably higher than the already more than adequate conservative figure of 1,372mg.
Some women - females have lower energy requirements than males - will require a calorie intake of Huel lower than 2,000kcal, but seeing as women have marked higher conversion rates than men, they’ll still be getting enough.
Of course, this claim is based on an intake of Huel of over 2,000kcal per day and individuals who are consuming a daily amount of Huel considerably lower than this will need to ensure they are consuming either foods or supplements containing EPA and DHA or ALA at a reasonably high intake.
About the author: James Collier BSc (Hons), Registered Nutritionist. James has over 25 years of experience working in nutrition and dietetics, including 7 years as a Clinical Dietician in the NHS. Covering an array of clinical areas, he worked with people with a wide range of ailments and food intolerances. He also has an Honours Degree in Nutrition with Dietetics.
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