A cross-sectional survey of adults in the U.S. and Germany, published in Nutrients, found that although participants were aware of food sources of long-chain omega-3 fatty acids (LC N-3 FA) and of the benefits of these healthy fats, 99% of them fell into the intermediate or high-risk omega-3 status category for cardiovascular disease.
Mean omega-3 index (N3I) was 4.3% in U.S. participants, found the researchers from Purdue University, West Lafayette, Indiana who led the study. In Germany, average N3I was 5.5%. The Ludwig Maximilians University, Munich conducted research in five German cities in collaboration with the Purdue University team.
Perceived omega-3 status was also disconnected from actual status. Omega-3 status varied very little between those who thought they were consuming adequate LC N-3 FA and those who believed their intake as inadequate.
“Even among those who thought they were getting enough, they still had low omega 3 and they didn't differ from people who knew they were not getting enough,” commented study leader Dr. Regan Bailey, Associate Professor, Department of Nutrition Science at Purdue University.
“I think that most people know that nutrition is important and they think that having a healthy diet is important. In this particular study, they even knew the food they ate, so they correctly identified fish as the primary source. But there was still this disconnect with their omega-3 status,” she added.
Perceived omega-3 status
Bailey suggested there could be a number of reasons why the omega-3 status of people who perceived themselves to be sufficient was no better than those who saw themselves as deficient.
“People could be eating fish that is low in omega-3. They could be eating a lot of walnuts and flax and plant-based sources and not efficiently converting those to omega-3. We really don't know the reasons why for disconnect we can really only speculate,” she speculated.
“The omega-3 content of fish really depends on what the fish eat. If the fish are eating a lot of algae it will have more omega-3 than a farm-raised fish that has a corn based diet for example. So there's a lot of variability even if you're eating fish.”
Omega-3 index, a biomarker and risk factor
Omega-3 status is assessed using the omega-3 index (N3I), which is the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content in the red blood cell (RBC) membranes.
N3I has been validated as a biomarker that reflects long-term intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It has also been established as a risk factor for coronary heart disease (CHD) mortality. Optimum status for minimising risk is ≥8%, whilst the range, 4–8% is considered an intermediate risk and N3I of ≤4% is regarded as high risk.
Nevertheless, public awareness of N3I as a status measure is almost totally lacking, while guidelines on intake of fish required to achieve optimum status have never been verified with studies that measure the dose response.
“The recommendation is two fatty fish meals per week. Ideally that should put you in a more optimal range,” explained Bailey. However, “There has never been a real dosing study on this”
“The Japanese have [an N-3-I] of about 9 1-%. They are high fish consumers,” she continued.
Many doctors may also be unaware of the relevance of N-3-I as a risk factor for heart disease and coronary events.
“Most physicians aren't trained in preventative medicine, its more treating more treatment and prevention,” suggested Bailey as a possible explanation for this.
She also explained that raising awareness on such issues was part of the reason why she helped form Global Health and Nutrition Alliance (GNHA) together with a number of academic scientists and physicians.
“That's really why GNHA came together, because we wanted to educate both consumers and health care practitioners on the importance of omega-3.”
GNHA are hoping to achieve their aims through participating in outreach media events. They are also planning to promote understanding of the importance of vitamin D, and eventually other key nutrients.
“We're a group of academic scientists and physicians who came together to talk about important nutrition issues. When we met we didn't really have an agenda. We sat around a table and figured out what we thought were the most important or pressing nutritional issues,” said Bailey.
“Our first focus has been omega-3. We're also working on vitamin D. Then we will reconvene and hopefully have other issues that we can help address. We really want to get the word out about what's going on in these areas. There's a lot of consumer confusion. So we want to create tailored messaging to help consumers increase their intake of omega-3s and vitamin D.”
Food or supplements?
Bailey recommended that optimum omega-3 status should ideally be reached through foods primarily.
However, she acknowledged, “That's not practical for everyone. There are people who either for food allergies or for preferences like vegetarianism or veganism don't want to eat fish. There are algae based sources of omega-3s in both supplements and some fortified foods.”
For those who do intend to source their omega-3 through supplements, Bailey had one further piece of advice.
“I try to encourage people if they are taking an omega-3 supplement, to take that with a meal. Don't take it on an empty stomach because you need dietary fat to absorb the fat in the supplement”
Volume 9, issue 9, 930 DOI: 10.3390/nu9090930
"Discrepancy between Knowledge and Perceptions of Dietary Omega-3 Fatty Acid Intake Compared with the Omega-3 Index”
Authors: Sowmyanarayanan V. Thuppal, Regan L. Bailey et al