There’s not a lot of stuff in the health, fitness, and nutrition world that get the seal of approval across the board from anybody and everybody in the industry.
Fish oil, however, has almost reached that level of prominence; from being hailed by many as the next best thing to help ward off strokes to being said to improve fat burning during exercise, there’s not a lot fish oil hasn’t been said to benefit.
One of the most pervasive beliefs is that supplementing with fish oil will protect you from cardiovascular disease, and ultimately add years to your lifespan.
In fact, it’s somewhat dogma these days that fish oil is some sort of wonder supplement for heart health and like many, I fully bought into this notion when I started to take my health and nutrition seriously a few years back.
After fishing into the research on the oil, my beliefs started to change though (awful pun, I know).
My skepticism began after my sister, a neuroscientist, grilled me for evidence to suggest that supplementing with fish oil had beneficial effects on cognition and the brain.
In all honesty, my bias got the better of me and after a quick browse of inconclusive and mixed evidence found on pubmed and google scholar, I decided to hold on to my preexisting beliefs than fish oil was on the top of the supplement pile as far as its efficacy goes.
Recently my skepticism has been renewed though, and today I’ll be revealing the truth behind fish oil:
- Does it really reduce your risk of cardiovascular disease and add years to your life?
- Should you go and chuck out all your fish oil caps?
- And what recommendations are actually supported by the science?
But first we need to quickly cover the science behind what fish oil actually is:
Not all fat is created equal; there are different types and they have very different effects on your body and health.
In short, dietary fats can be separated into 3 broad categories:
- Saturated fat
- Monounsaturated fat
- Polyunsaturated fat
This categorization comes down to the chemical structure of the fats, with polyunsaturated fats having multiple double bonds in their carbon chain, monounsaturated fats just having one, and saturated fats having none. To be honest, you don’t really need to know that though; just remember that there are different forms of fat and the chemical structure dictates the form.
Now, in the world of nutrition, some nutrients are classed as essential. This simply means that our bodies cannot make the nutrients itself like it can do with other non-essential nutrients. As a result, you have to consume these nutrients through your diet or via supplementation.
Assuming you, the person behind the screen, are human, there are 2 fats that are classed as essential to your body:
- Alpha-linolenic acid (which I’ll be referring to as ALA because it’s a pain in the arse to type out the whole time).
- Linoleic acid (we’ll call it LA).
Both of these guys are POLYunsaturated fats, which is one of the reasons why polyunsaturated fats are so often bigged up as healthy fats in the nutrition, health, and fitness world.
Now, going a little deeper, LA is known as an omega 6 fat. Again, this comes down to its chemical make-up. LA is pretty avid in regular western diets, being found in chicken fat, vegetable oil, and many highly processed foods for example. So it’s safe to say that most of us are getting enough of the stuff in. In fact, lots of us are likely consuming too much of it, but more on that in a sec.
On the flipside, ALA is an omega 3 fat which are harder to come by in standard westernized diets (ie: diets packed with highly processed foods and little in the way of nuts and seeds). Sources of ALA include chia seeds, flaxseeds, and walnuts (3).
Alpha-linolenic acid is essential, but it’s the fats that it’s converted into that all the fuss is about.
Whilst ALA is technically essential, its health promoting effects are largely down to two of the fats it’s converted into: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
EPA and DHA are responsible for lots of the beneficial effects of ALA as they’re much more potent.ALA:
- They have anti-inflammatory properties and may therefore reduce the risk of many health conditions such as inflammatory bowel disease, Alzheimer’s, and cardiovascular disease (4,5).
- They’re important for optimal brain function and are required to maintain cognitive capacity, with 12-16% of the fatty acids in grey matter being DHA (5)
- They have been associated with a decrease in blood pressure, and improved blood triglyceride and cholesterol profiles (6-9).
To emphasise the potential for these fats to aid health, a big ass study recruiting thousands of heart attack survivors gave some a daily EPA/DHA supplement, whereas others weren’t given anything. After 3.5 years taking their respective treatments, death from any cause was reduced by 20% in the EPA/DHA group, and sudden deaths were 45% lower too (10).
And this is where fish oil comes in.
You see, the process of converting ALA to EPA and DHA is pretty sucky and inefficient. In fact, only 5-10% is converted to EPA, and just 2-5% is converted to DHA (3). That means you would have to consume around 10g of ALA (equivalent to half a kilo of walnuts) to get in what the American Heart Association deem sufficient amounts of EPA and DHA for healthy individuals (around 500 mg of EPA/DHA per day) (1).
In fact, studies that have looked at the long term effects of ALA supplementation haven’t shown as beneficial effects as supplementing with EPA and DHA (1).
So it makes sense to bypass this sucky conversion process by making sure you get EPA and DHA in directly.
Care to take a guess at what the best sources of these fats are?
Yup, you got it: fish and other sea foods. EPA and DHA are actually found almost exclusively in seafood (1).
Fish oil may improve health markers associated with cardiovascular diseases, but that doesn’t necessarily equal less risk of cardiovascular events or early death
Now, it’s true that these omega 3 fats play many important roles in the body and may impact a number of risk factors associated with cardiovascular health. For example, research suggests that the omega 3 fats found in fish may help:
- Lower plasma triglycerides.
- Reduce resting heart rate (HR) and systolic and diastolic blood pressure.
- Improve the health and function of blood vessels.
- Improve the efficiency of the heart.
- Decrease levels of inflammation.
- increase brain blood flow.
In theory, all these effects should reduce the risk of cardiovascular issues and ultimately death. The thing is, if you’re already getting in sufficient omega 3 fats from your diet, then adding more on top in the form of a supplement won’t provide you with any more benefits. Because dietary intakes of omega 3 has actually increased in recent years, that means fewer of us will gain from additional supplementation.
Besides, whilst the potentially positive effects of fish oil (eg: their anti-inflammatory effects) are great, when it comes to actual end points like rates of heart attacks, strokes, and death, the evidence gets a little messy and isn’t as clear cut as you might think.
- Two large meta-analysis (big arse studies collating the results of previous research) by Marik and Varon (2009), and Zhao et al., (2009), have demonstrated that fish oil supplementation significantly reduces the risk of cardiovascular deaths, sudden cardiac death, all-cause mortality, and nonfatal cardiovascular events.
- Contrastingly to the two studies mentioned above, a meta-analysis on 29 studies by Filion et al., (2010) found that omega-3 fatty acids were not associated with a statistically significant reduction in all-cause mortality or restenosis (narrowing of blood vessels). Again, this study looked at high risk populations only rather than healthy people, and Despite the non-significant findings, the authors stated that the probability of a modest benefit of fish oil remains considerable.
- A more recent meta-analysis by Rizos et al., (2012) also found that upping fish oil intake wasn’t as beneficial as it’s often made out to be. They identified that increasing fish oil intake didn’t significantly decrease rates of all-cause mortality, sudden death, myocardial infarction, and stroke (although most showed a trend towards a benefit of fish oil*). Rates of cardiac death, on the other hand, were slightly lower in those taking fish oil though One problem here is that the 20 studies included in the analysis were an older and at-risk populations (ie: 49-79 yo), so we can’t extrapolate the findings to younger and healthier populations. What’s more is that the average fish oil dose was quite low and the study didn’t look at the effects of different dosages on the end points.
- Similarly, in an equally large meta-analysis on 29 studies, Filion et al., (2010) found that omega-3 fatty acids were not associated with a statistically significant reduction in all-cause mortality or restenosis. Again, this study looked at high risk populations only rather than healthy people, and despite the non-significant findings, the authors stated that the probability of a modest benefit of fish oil remains considerable.
- In contrast to the above, research by Marik and Varon (2009), and Zhao et al., (2009), has demonstrated that fish oil supplementation significantly reduces the risk of cardiovascular deaths, sudden cardiac death, all-cause mortality, and nonfatal cardiovascular events. Again, these findings can’t be taken as gospel due to study limitations like .
*a significant affect means that it’s highly unlikely that the results of an analysis were due to chance. When the data shows a non-significant trend towards a given outcome, it just means that we’re less certain whether the trend towards the outcome was due to chance or not. In this example, rates of all-cause mortality, sudden death, and myocardial infarction all showed a slight trend suggesting fish oil was beneficial, but the trends weren’t significant.
So there is research that suggests fish oil does reduce the risk of various cardiovascular end points and death, BUT there is also plenty of evidence indicating that it doesn’t. So on the whole, a mixed bag of results which making definitive conclusions over fish oil impossible to make – not exactly the conclusive evidence many will have you believe.
The evidence isn’t clear cut because of factors such as interindividual variability, differences in study designs, and the source of the fish oil in question.
Whilst the recent evidence above seems to downplay the positive effects of fish oil, there are a few things to consider before throwing out your fish oil supplements for good.
1. A lot of research can’t be directly applied to healthy people
First off, the majority of existing research has been conducted on high risk populations. By that I mean most study participants have already suffered from a cardiovascular event and/or have risk factors associated with cardiovascular conditions. This means that a lot of the research can’t be applied to healthy populations as they might not respond to fish oil in the same way. This lack of research on healthy people is highlighted in a statement by epidemiologist JoAnn Manson:
“The jury is still out on whether omega-3 supplements can prevent a first cardiovascular event in people at usual risk”
2. Not all sources of fish oil are created equal.
It should go without saying that getting your omega 3 fats in from real fish itself trumps the pills. This is because in its natural fishy form, the fats come packaged up with many other nutrients required for optimal health. I’m talking nutrients like protein, antioxidants, and vitamins/minerals. Not only do these nutrients have their own benefits from a health perspective, but they might act synergistically with the fat in fish, influencing the effects of fish oil.
In much of the early research on fish oil, it was fish consumption itself that was studied and shown to have promising health and heart effects. In fact, in the DART study where around 1,000 British heart patients were advised to eat two servings of oily fish a week, 29% fewer people had died in the “fish advice” group after two years than in a group that weren’t told to eat more fish.
Because of this, government guidelines and experts in the field suggest that fish oil consumed as fish is likely to have a more profound effect on health than in its supplemental form (1, Omega-3 Fatty Acids and Cardiovascular Disease) potentially due to synergistic effects of nutrients in fish meat when consumed together. So you can’t really compare fish oil consumed as a result of fish intake vs a fish oil supplement, and this might help explain conflicting findings.
3. The dose and brand of fish oil varies from study to study
The dosage of omega 3 fats consumed in studies varies a great deal too. For example, the average dose in the meta-analysis by Rizos et al., (2012) was relatively low at 1.51g per day. Seeing as higher fish oil intake of around 2-4g per day may be required to lower plasma triglycerides and meaningfully impact other health markers in patients with known coronary heart disease (1), 1.51g per day may have been too low to have much of an effect. In the study by Marik and Varon (2016) where the positive effects of fish oil supplementation were statistically significant, the average dose was higher (1.8g per day), which may be one explanation for some of the muddled findings, and indicates that higher doses than 1.51g per day might be needed.
What’s more is that the ratio of the two primary fats found in fish oil (EPA and DHA) may impact the effect that fish oil has on heart disease and death (1). Seeing as different studies use different brands of fish oil and therefore different ratios of these fats, this might impact study results.
3. The benefits of fish oil might be very dependent on the individual taking it.
Finally, as with almost everything in the health and fitness world, there can be very large interindividual variability. When it comes to fish oil supplementation, the benefit someone gains from it may be down to, amongst other things, their background diet and habitual intake of other nutrients such as LA (an omega 6 fat – remember I mentioned this a minute ago?).
You see, it might be the ratio between omega 6 intake and omega 3 intake that has the greatest bearing on health, not the absolute intake of omega 3s. As I mentioned earlier, in the western world, many of us consume too much omega 6 fats, meaning that our omega 6 to omega 3 ratio sits at around 15:1, whereas it’s been posited that a ratio closer to 4:1 is more conductive to prime health and protect against multiple illnesses (). Because of this variation in the omega 6:3 ratio, some people may benefit more so from taking a fish oil supplement than others, which might partially explain the mixed bag of study results and confusing messages in the media.
What this all means is that the positive effects of taking a fish oil supplement may not be experienced by everyone and some people may benefi
In fact, whilst recent evidence has somewhat questioned fish oil supplementation for cardiovascular health and death, …
Rates of cardiac death, on the other hand, were slightly lower in those taking fish oil though.
Despite the non-significant findings, the authors stated that the probability of a modest benefit of fish oil remains considerable.
So should you take a fish oil supplement or not then?
In an ideal world, we should all be following government guidelines and striving to get in at least two 3.5-oz servings of oily fish per week. As mentioned above, the fish itself packs in a tonne of nutrients that are vital to solid health and is a prime source of omega 3 fats.
When it comes to fish oil supplements though, despite the mixed bag of research, you shouldn’t necessarily go throwing out your pills just yet.
You see, even though the research by Rizos et al., (2012) showed no significant benefit of fish oil for a number of end points, there was still a trend towards less mortality and myocardial infarctions. Plus, the fact that there was a statistically significant 10% reduction of cardiac death is nothing to brush under the carpet.
Also, in their study that also suggested fish oil doesn’t reduce mortality or restenosis, Filion et al., (2010) stated that the probability of a modest benefit of fish oil remains considerable.
Along with other existing research suggesting a potential benefit of taking fish oil, it would seem that if your intake is low supplementing with roughly 500mg-2g of the stuff daily could at best help prevent various health conditions, and at worst, have no effect.
So it’s far from the nail in the coffin for fish oil. You just need to consider your own personal situation and decide whether it’s worth your while investing in a supplement.
- Are you like me and consume little or no oily fish in your diet?
- Are you an “at risk” individual, having suffered from heart issues in the past?
- And do you have the cash available to buy yourself the supplements in the first place?
If you find yourself nodding along to one or more of those questions above, then it might be worth considering a fish oil supplement.
But what should you look out for when parting with your hard earnt cash?
3 fish oil recommendations backed by science
1.Too much fish oil has the potential to cause side effects, so don’t overdo the stuff.
As with everything, it’s not sensible to over consume EPA and DHA in the form of fish oil. In fact, high intakes of these omega 3 fats may increase the risk of bleeding, gastrointestinal upsets, and worsening of some health markers (2).
The American Heart Association advise that for those of us not getting in the recommended two or more portions of oily fish per week, 500mg of EPA/DHA per day is a good baseline supplement to be taking. Depending on your circumstances, a higher dose may be a good shout with some experts recommending 1-2g per day for athletes/regular exercisers (14), and similar dosages being recommended for those with coronary heart disease (1).
2. The composition of the fats in fish oil supplements might impact their efficacy. Go for one with an even balance of EPA and DHA.
In terms of specific quantities of either EPA and DHA, it is unclear what the optimal dose is and this could even vary depending on the reason you’re taking it. We just don’t know at this stage.
With that said, experts in the field recommend going for a supplement with a 2:1 to 1:2 ratio of EPA:DHA (1,14). That might mean 300mg of EPA and 200mg of DHA for example.
3. The chemical properties of omega 3 fats make them fragile, so don’t expose your oil to too much heat or light and store it in the fridge
You know I rambled on about all that sciency chemistry stuff earlier?
Well it was for a good reason. You see, the chemical composition of fats is what gives them their individual properties. Because polyunsaturated fats, like the omega 3s in fish oil, have lots of double bonds in their structure, they’re less stable than saturated and monounsaturated fat.
What this means is fish oil is fragile and particularly prone to damage. This damage spoils the fats and pretty much reverses their healthful effects. It’s also why cooking with oils that are high in polyunsaturated fat is a bad idea (eg: vegetable and sunflower oil).
So when selecting your fish oil, pick on that’s being stored in a fridge, and ideally one that has been packaged away in a dark/opaque tub. It’s also best to go for the tub with the longest expiration date, which means the discount shelf where supplements with a short shelf life are bargained off is best avoided.
What about krill oil?
In recent years, krill oil has come onto the scene as a new player in the omega 3 game, with some claiming it’s the new number one source of the vital fats many of us supplement with fish oil for.
Other than being the primary dish on the almighty blue whale’s dinner menu, like fish, krill is a source of EPA and DHA. Their overall composition of fat is actually very similar to the fat found in fish (11).
There is a very important factor distinguishing the fats found in fish and krill though: in fish, biochemically the fatty acid chains are stored in groups of three as molecules called triglycerides.
In krill, 30–65% of the fatty acid chains are in twos as phospholipids though. (12,13).
Again, understanding what this means from a biochemical perspective isn’t important. Just be aware that in a practical sense it may influence the absorption of the fats and their effects on your body.
For example, a study by Ulven et al., (2011) found that krill oil had virtually identical effects on various health markers when stacked up again fish oil. However, the dosage of the krill oil was lower, meaning that for less oil, you may get equal benefits (13).
What’s more is krill contains relatively high amounts of astaxanthin; an antioxidant that gives krill it’s pinky/red color. Other than brightening up the shrimp like crustacean, this antioxidant may improve health markers such as cholesterol profile. In research on animals, it has also reduced the risk of diseases including diabetes, heart disease, and certain cancers (12).
With the above said, it’s still early days for krill oil and more research needs to be done on humans before we can all go raving on about its potential health benefits above and beyond that of fish oil.
So whilst krill oil might be an exciting prospect for the future, at this stage I wouldn’t dish out any more cash on the stuff than I would on a quality fish oil supplement.
Refs and reading
1. Fish oil supplementation- Evidence for health benefits
2. Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease
4. Wall, Rebecca, et al. (2010) Fatty acids from fish: the anti‐inflammatory potential of long‐chain omega‐3 fatty acids. Nutrition reviews 68.5: 280-289.
5. Pettit, Lauren K., et al. (2013) Modulating the inflammatory properties of activated microglia with Docosahexaenoic acid and Aspirin. Lipids Health Dis 12: 16.
6. Berry, Elliot M., and Jules Hirsch. (1986) Does dietary linolenic acid influence blood pressure? The American journal of clinical nutrition 44.3: 336-340.
7. Morris, Martha Clare, Frank Sacks, and Bernard Rosner. (1993) Does fish oil lower blood pressure? A meta-analysis of controlled trials. Circulation 88.2: 523-533.
8. Simopoulos, Artemis P. (2002) Omega-3 fatty acids and cardiovascular disease: The epidemiological evidence. Environmental health and preventive medicine 6.4: 203-209.
9. Simopoulos, Artemis P. (1999) Essential fatty acids in health and chronic disease.The American Journal of Clinical Nutrition 70.3: 560s-569s.
10. GISSI- Prevention study – http://circ.ahajournals.org/content/circulationaha/105/16/1897.full.pdf
11. A Brief Review of Krill Oil History, Research, and the Commercial Market
12. Krill oil – Krill for Human Consumption-Nutritional Value and Potential Health Benefits
13. Metabolic Effects of Krill Oil are Essentially Similar to Those of Fish Oil but at Lower Dose of EPA and DHA, in Healthy Volunteers