A. It differs in several ways.
First, the sample types we typically use (red blood cells or dried blood spots versus whole plasma or plasma phospholipids). Each of these sample types has a unique fatty acid profile, so you cannot compare the EPA+DHA level in RBCs to the EPA+DHA level in plasma, or in plasma phospholipids – the numbers will be quite different, even from the same lab. So regardless of which lab you choose to work with, you should always order the same type of test if you want to be able to track trends in the same patient over time. We focus on RBC and whole blood (dried blood spot) analyses because from either one we can provide our branded metric, the HS-Omega-3 Index®, and because these provide the best reflection of tissue omega-3 fatty acid status. In addition, there is considerably more day-to-day variation in the plasma tests than in the RBC – (or whole blood) – based tests. However, for research purposes, OmegaQuant can and does analyze any sample type based on the client’s needs and sample types available.
B. The uniqueness of the specific method we use
Second, even if you order the RBC-based assay from two different labs, there is no guarantee whatever that you’ll get the same answer. That’s a big problem. The reason is that, unlike serum cholesterol or glucose or calcium, there is no standardized method (i.e., internationally recognized gold standard) to which all labs must peg their assays. There is no standard test material to which all labs are required to conform. So your EPA+DHA, for example, might be 6.7% in Lab A and 5.2% in Lab B. Which one is “right?” We don’t know what “right” is because there is no formal standard. At OmegaQuant, the specific method we use has more research behind it than any other commercially-available test and many more studies will be published in the coming years. A significant advantage of the HS-Omega-3 Index test is the ability to correlate it to clinical outcomes from major epidemiological and interventions studies (see below for “Research behind the test”)
C. The number of fatty acids reported in the profile
In addition to the HS-Omega-3 Index, we also provide, at no additional charge, a complete fatty acid profile including 4 omega-3 fatty acids, 7 omega-6 fatty acids, 4 monounsaturated fatty acids, 6 saturated fatty acids, 3 groups of trans fatty acids, 5 composites (group sums), and 2 ratios (see below). Other ratios or groups of fatty acids can be calculated from these. But beyond these 26 fatty acids, there are still others (very minor components) that can be detected in both RBCs and in whole blood, and some labs will report these as well. It is our view at OmegaQuant that it is possible to provide too much information, and hence we draw the line at these 26, and in many respects, even this is more than can practically be addressed. We provide them as a courtesy to those clients who want to know. Sometimes “less is more” and we believe that applies here.
D. The ratios included in the profile
As noted above, we provide two fatty acid ratios: the omega-6/omega-3 and AA/EPA. Although we include these values, we believe that the HS-Omega-3 Index is, by far, the single most important (and actionable) component of our report. These other fatty acids and ratios are provided as a courtesy and because some practitioners find them useful. We would suggest that for the dried blood spot assay, the omega-6/omega-3 ratio should be 4.6 or less, and the AA/EPA ratio should be 9 or less. For the red blood cell assay, the omega-6/omega-3 ratio should be 2.6 or less, and the AA/EPA ratio should be 15 or less.
E. The use of “reference” or “normal” ranges
Included with each the 5 classes of fatty acids are “reference ranges.” The reference range is provided simply to give an idea of how these values compared to a large number of others taken from a relatively healthy population. In the case of the RBC assay, the reference range was taken from approximately 11,000 individuals whose samples were submitted to the laboratory for analysis. In the case of the dried blood spot assay, the reference range was taken from approximately 27,000 individuals. No information regarding the state of health of any of these individuals is known. In both cases, the reference range encompasses 99% of the individuals in their respective populations. Although “average,” these are not necessarily “optimal” levels, i.e., target levels or levels that one should to attempt to achieve. The only result for which we feel justified in providing an actual target or optimal level is the HS-Omega-3 Index since it has received undergone the most research. As the research in this area matures, we will recommend new “target” values for other fatty acids or ratios when we believe that they have been adequately validated.
F. The provision of dietary recommendations to correct deviations from “normal”
As noted above, we provide reference ranges for general information only, not to suggest or guide changes in diet. We do not believe that the research has advanced to the point where we can tell people who have a below (or above) “average” level of any given fatty acid class that they should try to change it. First, since most fatty acid levels in the blood are not influenced by diet but are established by internal genetics and metabolism, even attempting to alter a fatty acid level by dietary change would be largely futile. Secondly, we don’t have the data at present to show that even if one could change fatty acid levels (again, except for the HS-Omega-3 Index and trans fatty acids), it would benefit them to do so. So until further research convincingly demonstrates that raising or lowering a certain fatty acid or class is beneficial or not, we will take the conservative approach of simply giving each client the numbers, and they can track them as they wish.
Clearly, we are very comfortable with recommending specific targets for the HS-Omega-3 Index® because the research supporting a target of 8% is strong, and we know that you can specifically raise the Index by eating more omega-3. We don’t, however, know exactly how much EPA+DHA any particular person should be told to take to achieve the 8% target. People differ, and so each person’s response to supplemental omega-3s will vary. Just like one cannot predict how much serum cholesterol will go down when a patient is placed on statins, we cannot accurately predict how the HS-Omega-3 Index® will respond to an increased intake; it must be individually tested. (See Question 2).
G. The research behind the test
Dr. Harris has been doing research in omega-3s for 30 years, and has over 80 published research papers in this field. He, along with his colleague Clemens von Schacky, MD, a cardiologist from Munich, was the first to propose the Omega-3 Index as an independent risk factor for heart disease. More importantly, currently Dr. Harris is the Principal Investigator for and is using the HS-Omega-3 Index test in two major epidemiological studies, both funded by the National Institutes of Health (NIH): the Framingham Heart Study and the Women’s Health Initiative’s Memory Study. In addition, he will be doing the blood analyses in the newly announced $20M, 20K-subject “VITAL” study testing omega-3 and vitamin D for CHD and cancer prevention. Dr. Harris is using the same method in at least 8 additional clinical studies being funded by the NIH.
H. The clinical applicability of the test
Because of the research foundation supporting the HS-Omega-3 Index, its clinical utility will continue to grow and mature as the results of these new studies are published. Health care providers and consumers alike want their results to be comparable to those published in the mainstream medical literature. If high or low risk for disease X is defined by a particular HS-Omega-3 Index value as derived from these research studies, then only by using this specific test can you be sure that yourlevel of risk is accurately predicted; a value from another lab may or may not give you a clinically-useful estimate of risk. It is for these reasons that the Cooper Aerobics Center (Dallas, TX) selected OmegaQuant as their sole provider for fatty acid testing.
At OmegaQuant, we offer the HS-Omega-3 Index test primarily for researchers and re-sellers. Healthcare providers wishing to use this test in patient care should contact Health Diagnostic Laboratory (HDL, located in Richmond, VA; customer service, 804-343-2718) to set up an account. HDL performs the same HS-Omega-3 Index test that was developed at OmegaQuant, and payment for services performed at HDL is sought from third party payers. For individuals wishing to have the test performed directly by OmegaQuant via a dried blood spot, the price is $199.95 and payment is required at the time of sample submission. Contact OmegaQuant Customer Service at 1-800-949-0632 or send an inquiry to firstname.lastname@example.org. Researchers, please contact Customer Service for a price quote for fatty acid analysis of any sample type.
No. There is no way to predict – for any given person – what his/her HS-Omega-3 Index will be just by knowing how much fish they eat or how many capsules they take. Individual differences in metabolism, absorption, and genetics make it impossible to predict with certainty how a given person will respond to supplements.
The only way is to directly measure the HS-Omega-3 Index®.
The target HS-Omega-3 Index is 8% and above, a level that current research indicates is associated with the lowest risk* for death from CHD. This is also a typical level in Japan, a country with one of the lowest rates of sudden cardiac death in the world. On the other hand, an Index of 4% or less (which is common in the US) indicates the highest risk*. At present, there is no reason to suggest that the target should be different for men vs. women, or for different age groups. Whether there is an upper limit of safety for the Index is not clear, but there is likely a value above which there is not likely to be any additional health benefit. Further research will help define this level.
*In this context, “risk” refers only to that associated with differing levels of omega-3 fatty acids. Risks associated with other factors such as cholesterol, blood pressure, diabetes, family history of CHD, smoking, or other cardiac conditions are completely independent of the Omega-3 Index. All risk factors – including the HS-Omega-3 Index—should be addressed as part of any global risk reduction strategy.
Increase your intake of EPA+DHA. The amount you would need to take in order to raise your HS-Omega-3 Index into the target range (>8%) depends in part on your starting level, but it cannot be predicted with certainty as described above. Nevertheless, if your HS-Omega-3 Index is between 4% and 8%, we would recommend that you increase your current EPA+DHA intake by ½ -1 gram (500 – 1000 mg) per day. This can be accomplished in two ways: eating more oily fish and/or taking fish oil supplements. On the other hand, if it is less than 4%, our recommendation would be that you raise your intake by 1-3 g (1000 – 3000 mg) per day. Although this can be accomplished by eating more oily fish, fish oil supplements are usually necessary to achieve this level of EPA+DHA intake.
In our experience, to increase the HS-Omega-3 Index by 4%, one would need to increase his/her intake by about 1 g of EPA+DHA per day for roughly 6 months. Alternatively, one could increase by 2 g/d and a 4% increase could be achieved more quickly. In other words, raising the Index is a function of both dose and time.
In North America, the test is performed by OmegaQuant® in Sioux Falls, SD (for researchers and resellers), and by Health Diagnostic Laboratory in Richmond, VA (for clinicians). In Europe, the test can be obtained from our sister laboratory, Omegametrix (Munich, Germany), and in Asia, at Omegaquant Asia (Seoul, Korea). As other labs around the world become licensed to offer the HS-Omega-3 Index test they will be listed on our website.
For private pay individuals submitting a dried blood spot for analysis, once the sample is received at OmegaQuant, the results will be available on-line within 3 working days. For researchers and resellers, contact Customer Service at email@example.com to discuss turn-around times.
You can learn more about saturated and trans fatty acids here.
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For the RBC Test (obtained directly from a blood tube) overnight fasting is not necessary. In general the same is true for the dried blood spot test, the only exception being the situation where an individual might take a fish oil supplement 2-6 hours before taking the blood test. In this case, the EPA+DHA value from the dried blood spot will be artificially inflated; therefore, the test should be done at least 12 hours after the last dose of fish oil.
Whole blood and RBCs are different starting materials and the EPA+DHA content of each is different, but highly correlated. Based on multiple experiments, we have derived a mathematical equation that converts the DBS EPA+DHA value into the corresponding RBC value (which is the HS-Omega-3 Index). Therefore, the sum of EPA and DHA in the DBS report will usually be slightly different from the HS-Omega-3 Index.
The OmegaQuant report now includes information on percentile ranks for not only the HS-Omega-3 Index, but also for each of the 5 major fatty acid groups and two ratios. The purpose of the percentile ranks it to give the client a perspective of where he or she falls within the normal range of the population. For example, an HS-Omega-3 Index of 5.5% would correspond to a percentile rank of 44%. This means that approximately 44% of the population has a lower HS-Omega-3 Index, and 56% a higher Index.
Since at OmegaQuant we perform both red blood cell-based tests and dried blood spot-based tests (which generate the same values for the HS-Omega-3 Index, but different values for the other fatty acids reported because of the different sample types), the “populations” used to make the percentile determinations are different. Percentiles on the red blood cell test were determined based on about 11,000 individuals who have had this test, and percentiles on the dried blood spot test were determined based on about 27,000 individuals.
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