Omega-3 is a long-term star of the supplements market. Naturally present in marine algae and oily fish, it is known to have extensive benefits across many aspects of human health. It’s no wonder that the global market size is expected to more than double within the next ten years, from $8.67bn to $17.86bn.
From a consumer perspective, the draw is simple. Omega-3 is associated with better heart health, better brain health, and better eye health to name a few. People who eat regular servings of seafood are less likely to die of heart disease, while omega-3 supplements have been shown to reduce symptoms of rheumatoid arthritis. And although the research base is relatively new, the ‘medicinal’ properties of fish oil have been proclaimed as early as the Roman era.
Omega-3, then, is well-entrenched in the popular psyche. What’s less well known is the plethora of other omega fatty acids – 5, 6, 7, 9 and 11 – which were long neglected by scientists as well as the general public.
“It’s important to realise that we’ve spent the last 50 years investigating omega-3s, but we have spent very little time understanding the other fatty acids,” says Dr Nils Hoem, chief scientist at Aker BioMarine. “Nutritional science is only now beginning its investigations into the deeper biological effects of food.”
The alpha and the omega
So what actually is omega-3 and how does it compare with the other members of the omega family? Well, its reputation for being ‘essential’ is not unjustified – omega-3 fatty acids form a critical part of our cell membranes, especially within the eyes and brain. However, since our bodies cannot make these fats, we have to obtain them from dietary sources. There are three main subtypes of omega-3: DHA and EPA (found in seafood and certain microalgae) and ALA (found in plants).
Omega-6, perhaps the best-known aside from omega-3, is ‘essential’ too, in the sense that the body can’t make it. However, supplementing this fat is generally unnecessary for those consuming a typical Western diet. Present in oils, nuts, cereals, bread and many animal products, omega-6 is very healthy if consumed in appropriate quantities. The problem emerges when the ratio of omega-3 to omega-6 becomes unbalanced.
Historically, this ratio stood at 1:4 or less, but modern Western diets provide a ratio closer to 1:20. This ratio is associated with an inflammatory state within the body and ultimately a range of diseases.
“Since omega-6s tend to be more inflammatory, and omega-3s tend to be less inflammatory, you need them both in the right ratio,” says Hoem. “Unfortunately since World War Two, the ratio has gone in the favour of omega 6, meaning most people in the Western world today have an over-eager early immune response.”
Another fatty acid common in supplements is omega-9, although the need for its inclusion is debatable. For one thing, the body can produce omega-9 without outside help; for another thing, this fat is easily obtained from dietary sources such as olive oil and avocado.
If the numeration system seems confusing (where are omegas 1, 2, 4 and 8?) we can chalk that up to a fusion of ancient Greek and modern chemistry. ‘Omega’ is the last letter of the Greek alphabet, and is used in chemistry to refer to the end of a long chain. In the case of omega-3, we are talking about a chain of carbon atoms with a double bond three notches away from the end. Omega-6 would have the bond in the sixth position, omega-11 in the eleventh, and so on.
A lesser-known member of the omega family – though one that is starting to rise in prominence – is omega-7. A non-essential fatty acid (one the body can synthesise), omega-7 is present in foods such as salmon, macadamia nuts, full-fat dairy, eggs and olive oil. It is also abundant within the sea buckthorn, which was used in Traditional Chinese medicine as an anti-inflammatory and is now used to make omega-7 supplements.
As Hoem explains, omega-7 is particularly interesting from a chemical perspective. Whereas most healthy fatty acids are ‘cis’ fatty acids – meaning their hydrogen bonds are on the same side – that doesn’t apply to a type of omega-7 called vaccenic acid. This is a trans-fat, in which the hydrogen bonds are found on opposite sides of the carbon atoms.
“In trans fatty acids, the double bonds point in a different direction, which can be dangerous as they can rupture the structure of the cell membrane and interact with the enzymes in unproductive ways,” says Hoem. “Vaccenic acid is a natural trans fatty acid, but because it’s a fatty acid we’re all used to, it doesn’t seem to do us any harm.”
Metabolic markers
There are several other types of omega-7 too, including palmitoleic acid (found especially in macadamia plants) and paullinic acids (found in a variety of plant sources). Because these fats can be synthesised by the human body, they didn’t attract much research attention until recently.
In 2008, however, a research paper was published showing that palmitoleic acid might have an important role to play in the metabolism. Specifically, it serves as a ‘lipokine’ (a fatcontrolling hormone) that is released from fatty tissue and travels to the muscles and liver. Here, it exerts a beneficial metabolic effect, as well as suppressing inflammation.
“Since then, awareness of the possible health benefits of omega-7 palmitoleic acid has dramatically increased,” says Dr Zhihong “Chiffon” Yang, a research fellow at the National Heart, Lung, and Blood Institute (NHLBI). “More research groups, including ours, have conducted studies to evaluate whether exogenous [dietary] omega-7 palmitoleic acid has beneficial effects on metabolism.”
In 2019, Yang’s team conducted an animal study with a striking finding – dietary omega-7 had cardiovascular benefits in mice. Rodents given palmitoleate concentrate saw a significant reduction in atherosclerosis (the furring of the arteries) compared with a control group, and another group that was given olive oil. They also saw improvements in their fat and glucose metabolism.
“Atherosclerosis is the underlying cause of about half of all deaths in westernised society, and our animal data suggest that dietary omega-7 palmitoleic acid may help improve atherosclerosis and overall cardiometabolic health,” says Yang. “In addition, it is known that not all polyunsaturated fatty acids are the same. Our results showed that not all monounsaturated fatty acids are the same, and palmitoleic acid showed unique metabolic benefits.”
Since their study was published, the team has gone on to initiate a clinical trial on omega-7 in humans. This trial – which is randomised and double-blinded – will investigate how healthy adults respond to concentrated oil enriched with palmitoleic acid. In particular, it will be looking to find out whether there is any impact on lipoprotein metabolism and satiety.
A growing buzz
Other studies (not associated with Yang’s team) have found possible benefits to the skin and mucous membranes. A recent Korean study found that 7-Mega (an omega-7 supplement derived from fish oil) enhances skin function and appearance in women over 40. There is also evidence to suggest these supplements may improve dry eyes and vaginal dryness during menopause.
However, Yang points out that more research is needed before we can make health claims with any confidence. “Compared to other monounsaturated fatty acids, palmitoleic acid stands out for its possible cardiometabolic benefits,” she says. “Nevertheless, more clinical studies are needed to verify its impact.”
Currently, little is known about the appropriate dosage of palmitoleic acid, which varies significantly from one study to the next. Meanwhile, the mechanism underlying its metabolic benefits remains poorly understood. In a more general sense, Yang thinks the research community needs to broaden its focus beyond just omega-3 and consider the ways that other fatty acids might boost our health. Her own team have also been looking at omega-11 fatty acids, which appear to have a similar benefit on cardiovascular disease risk factors.
“Increasing evidence has hinted at the importance of various dietary fatty acids with different double bound position and carbon chain length,” she says. “Most dietary fatty acid supplements contain various fatty acids, and careful studies are necessary to test the efficacy of these supplements with various fatty acid profiles.”
Hoem agrees, explaining that Aker BioMarine is pursuing a range of different research avenues. While pointing out that omega-3 is a nutrient, not a drug, he is nonetheless interested in what happens pharmacologically when subjects take a larger dose.
“It clearly has an effect when it comes to alleviating osteoarthritis pain,” he says. “We are also looking into sports medicine, and we are looking into a fatty acid called lysophosphatidylcholine for alleviating neuronal damage. We are looking briefly at omega-7s and omega-11s, and of course, we also support standard omega-3 research.”
Although it’s early days for this field of research, the buzz around the subject is growing. “My prediction is that over the next 10 years or so, there will be a host of new information about the biological effects of fats,” says Hoem. This is sure to be reflected in the fatty acid supplements market, which could move in some interesting directions over the years ahead.
