DLM: Elevated Triglycerides and Omega-3 Fatty Acids (2007)
Age 18-70 years old with hypertriglyceridaemia (TG > 200 mg/dL) or mixed hyperlipidaemia ( TC > 200 mg/dL and TG >200 mg/dL)
Researchers used 40 sequential patients attending an atherosclerosis Out Pt Clinic. This was a double blind study where the first 4 weeks of the study were designated as a dietary or wash-out phase followed by a 2 month therapy period. After the 4 week dietary or wash-out phase, participants were randomly assigned to 2 groups. First group recieve 12 capsules/day (4 capsules TID) of fish oil (12g/day, 3.6 gm/day omega-3, 60% EPA and 40% DHA). The second group received 12 capsules/day of soya oil (12g/day).
Statistical Analysis
Data was evaluated using StatView 512+. Statistical significance was assessed with paired t test (2-tail) and with 2-factor ANOVA for repeated measures. Correlations were calculated with Spearman Rank Correlation Coefficient on untransformed data. Because triglycerides were not normally distributed, they were log transformed before statistical analysis.
Clinical examanation and analysis took place at weeks -4, 0, +4, and +8. During exams data was collected on BMI, BP, and the average numbers of meals with fish per week. Total cholesterol and triglycerides were determine by enzymatic methods on an automated analyzer. HDL-C and LDL-C were determined on an automated analyzer. Apoprotein A-I and B100 were determined by rate of nephelometry. Laboratory safety tests consisted of hematolgy and blood chemistries: glucose, creatinine, CK, ALT, AST, and alkaline phosphate.
Participants were considered hypertensive with systolic > or = 160 and/or diastolic BP > or = 95 mmHg or those taking hypertensive drugs.Data was also collected on tobacco and alcohol use.
The trial ran out of the the Atherosclerosis Out-Patient Clinic of the Univeristy Hospital of Ciombra, Portugal. 35 participants (n=35) completed the trial (25 female, 10 males).
5 (4 males, 1 female) abandoned the study secondary to adverse effects of the drug (all were in the Soya Group).
Age of patients completing the study ranged from 30-70 years.
On average, participants in the Fish oil group consumed 11.5 caps/day, and 11.4 caps/day were consumed with the Soya oil Group.
| Fish Oil | Soya Oil | |
| Patients (no) | 20 | 15* |
| Male, Female | 17,3 | 8,7 |
| Age | 50.6 +/- 2.8 | 56.1 =/- 2.7 |
| BMI | 28.9 +/-0.8 | 30.6+/-0.9 |
|
Fish consumption No. meals/week |
5.0 +/-0.5 | 4.7+/-0.6 |
| Hypertension | 10 | 11 |
| NIDD Diabetes Mellitus | 4 | 2 |
* Represents the 15 participants who completed the study
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|
Fish Oil (n=15) |
Soya Oil (=20) |
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| Baseline | Week 8 | Baseline | Week 8 | ||||||||||||||
|
Total Cholesterol (mg/dL) |
253 +/-15 |
249 +/-12 |
291+/- 15 |
305 +/- 16 |
|
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|
Triglycerides* |
431 +/- 114 |
331 +/-55 |
391 +/- 46 |
469 +/- 64 |
|
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| HDL-cholesterol | 33.6 +/- 2.2 | 33.5 +/-1.5 | 37.4 +/- 3.1 | 37.1 +/- 3.4 | |||||||||||||
| LDL-chesterol** | 117 +/-11 | 126 +/-9 | 151 +/- 17 | 137 +/- 14 | |||||||||||||
| apoA-I | 159 +/-8.0 | 131 +/-6.5 | 184 +/- 8.9 | 151 +/- 9.2 | |||||||||||||
| apoBI00 | 188 +/-10 | 185 +/-9.4 | 222+/- 11 | 217 +/- 14 | |||||||||||||
Participants taking the fish oil supplement presented with a decrease in TG and LDL-C as compared to those taking Soya oil supplements (P= 0.0867* and P= 0.0872** ANOVA 2-factor repeated measures). There was no change in TG in either group compared to baseline.
To further study the effectiveness of fish consumption on lowering triglyceride levels, the participants were divided into tertiles according to the number of meals with fish consumed per week (tertile 1, 1-4 x/week; tertile 2, 5-6 x/week; tertile 3, 7-9 x/week). Fish oil supplementation lowered TG 35.5% in those in tertile 1 (n=7) vs baseline, P=0.0132 and combining tertile 1 and 2 (eating fish 1-6 times/week, n=13), lowered TG 44.4% (P=0.0622) vs baseline. In individuals consuming fish more than 6 times per week had no effects on trigylceride levels.
Of interest, there was a significant increase in glucose levels both in diabetics (n=4) and non-diabetics (n=15) with both oils (fish oil 11% increase P=0.0047).
The authors concluded that moderate doses of fish oils can improve the lipid profiles in the average fish consumer with greater impact for those consuming fish three to four times per week. The average reduction of triglycerids is dose related with the minimal effective dose of omega-3 fatty acids being about 1 gram daily and a plateau being reached between 5 and 10 grams. There was no change in HDL-C and a slight increase (not significant) with LDL-C with both oils. Both fish and soya oil showed a decrease in apo-A-I. ApoB100 did not change with either oil
Authors noted that a limitation to the study (and lack of statistically significant change on triglycerides with fish oils) could be due to the fact that the Portuguese diet is rich in fiber (which may interfere with fat digestibility and absorption) as well as the participants being high fish consumers; this may have decreased the lowering effect of fish oils.
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Quality Criteria Checklist: Primary Research
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| Relevance Questions | |||
| 1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | Yes | |
| 2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
| 3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
| 4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
| Validity Questions | |||
| 1. | Was the research question clearly stated? | Yes | |
| 1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
| 1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
| 1.3. | Were the target population and setting specified? | Yes | |
| 2. | Was the selection of study subjects/patients free from bias? | Yes | |
| 2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | Yes | |
| 2.2. | Were criteria applied equally to all study groups? | Yes | |
| 2.3. | Were health, demographics, and other characteristics of subjects described? | Yes | |
| 2.4. | Were the subjects/patients a representative sample of the relevant population? | No | |
| 3. | Were study groups comparable? | Yes | |
| 3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | No | |
| 3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
| 3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
| 3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | N/A | |
| 3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | N/A | |
| 3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
| 4. | Was method of handling withdrawals described? | Yes | |
| 4.1. | Were follow-up methods described and the same for all groups? | Yes | |
| 4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | Yes | |
| 4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
| 4.4. | Were reasons for withdrawals similar across groups? | No | |
| 4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
| 5. | Was blinding used to prevent introduction of bias? | Yes | |
| 5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | Yes | |
| 5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | Yes | |
| 5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | N/A | |
| 5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
| 5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
| 6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | Yes | |
| 6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | Yes | |
| 6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
| 6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
| 6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
| 6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | N/A | |
| 6.6. | Were extra or unplanned treatments described? | N/A | |
| 6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | Yes | |
| 6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
| 7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
| 7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
| 7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
| 7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
| 7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
| 7.5. | Was the measurement of effect at an appropriate level of precision? | ??? | |
| 7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
| 7.7. | Were the measurements conducted consistently across groups? | Yes | |
| 8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
| 8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
| 8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
| 8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
| 8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | No | |
| 8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | No | |
| 8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
| 8.7. | If negative findings, was a power calculation reported to address type 2 error? | ??? | |
| 9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
| 9.1. | Is there a discussion of findings? | Yes | |
| 9.2. | Are biases and study limitations identified and discussed? | Yes | |
| 10. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
| 10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
| 10.2. | Was the study free from apparent conflict of interest? | Yes | |