DFA: EPA/DHA and Cognitive Health (2011)
Fontani G, Corradeschi F, Felici A, et al. Cognitive and physiological effects of omega-3 polyunsaturated fatty acid supplementation in health subjects. Eur J Clin Invest. 2005; 35(11): 691-699.
PubMed ID: 16269019
To examine the effects of Omega-3 fatty acid supplementation on some cognitive and physiological parameters in healthy subjects.
- Males and females
- Healthy subjects
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Only subjects in good health, free of drugs and medications and with negative psychiatric and endocrine histories were enrolled in the experiment. Moreover, they must have performed non-competitive athletic activities for four hours weekly (aerobic activity, range three to six hours).
- Heavy smoking (more than eight cigarettes per day)
- Drinking (more than two glasses of spirits per day)
- Caffeine consumption (more than two cups of coffee per day).
Recruitment
- Subjects were recruited from members of the local non-competitive athletic associations
- The experiment was carried out on 33 healthy voluntary subjects comprising 13 males and 20 females in the age group 22 to 51 years (mean 33±7 years).
Design
- The subjects were randomly assigned to either the Omega-3 or P groups and consumed Omega-3 or P in a blind manner.The subjects were all tested and received a daily supplementation of Omega-3 for 35 days. Omega-3 group consumed eight capsules (4g) of fish oil (FO; 2.8g of Omega-3 PUFAs, EPA + DHA in a ratio of 2.1 and 1.60g of EPA, 0.80g of DHA, 0.40g of other types of Omega-3 PUFAs: Alpha linolenic, stearidonic, eicosatetraenoic and docosapentaenoic acid), while the 16 subjects of P group consumed eight capsules (4g) of olive oil (P) per day.
- Similarly, a group of 16 subjects (four males and 12 females, mean age 33±3 years) was tested with the same experimental procedure and received a daily a supplementation of olive oil, considered as placebo (P), for 35 days
- Subjects were tested at the beginning of the experiment and after 35 days
- Blood samples were taken on day one and day 35 to analyze the specific parameters: Arachidonic acid/eicosapentaenoic acid ratio (AA/EPA), cholesterol, triglycerides, high density lipoprotein (HDL), low density lipoprotein (LDL) and glycemia
- Tests involving different types of attention were used, i.e., Alert, Go/No-Go, Choice and Sustained Attention
- The subjects filled in a diary card to record their psychological and mood state and other general information
- For each test, the reaction time, the event-related potentials by electroencephalogram (EEG) and the electromyography (EMG) of the forefinger flexor muscle were recorded. The subjects then completed the Profile of Mood States (POMS) questionnaire and performed a series of attentional tests with concomitant recording of physiological activities, i.e., electroencephalogram (EEG), electromyography (EMG) and electrocardiogram (ECG).
- The subjects filled in the Profile of Mood States (POMS) psychometric scale [46] to assess their psychological state. Mood states are temporary and subjects had to report the mood state of the last five days. The POMS consisted of five negative mood scales:
- Anger (lowest possible value, 40; highest possible value, 99)
- Anxiety (34 to 85)
- Fatigue (88 to 37)
- Confusion (32 to 92)
- Depression (41 to 91)
- One positive scale: Vigor (24 to 75).
Blinding Used
Blinding is used to randomize the subjects.
Statistical Analysis
- Daily supplementation of olive oil as placebo and omega-3 polyunsaturated fatty acids as active supplement for 35 days
- Omega-3 group consumed eight capsules (4g) of fish oil and subjects of placebo group consumed eight capsules (4g) of olive oil (P) per day
- Data from the various tests and biological measures were collected, averaged and then compared by a paired samples T-test for comparison within the same group and a T-test for independent values when comparing between different groups
- Descriptive statistical analyses were used to define the characteristics of the population studied
- The associations between the primary measures of interest and cofactors (age and gender) were addressed by ANOVA statistical model
- Correlations were measured by Pearson’s R-test.
Timing of Measurements
Baseline and at the end of 35 days.
Dependent Variables
Profile of Mood States (POMS); attention tests.
Independent Variables
Age and gender.
- Initial N: 33 healthy voluntary subjects comprising 13 males and 20 females
- Attrition (final N): 33
- Age: 22 to 51 years (mean 33±7 years)
- Ethnicity: Italians
- Other relevant demographics: Habits, health, diet, sleep, smoking, use of drugs, alcohol and caffeine, sport activity and work
- Location: Local non-competitive athletic associations, Italy.
Key Findings
- No association was found between the variables studied and age or gender of subjects. AA/EPA was strongly affected by Omega-3 treatment.
- The groups Omega-3 and P did not differ at day one (mean values: 16.39±8.32 vs. 16.17±10.63)
- Comparisons between day one and day 35 in each group, after P and after Omega-3 supplementation, revealed a strong decrease of AA/EPA after Omega-3 [mean values, before Omega-3 (14.26±8.87) and after Omega-3 (4.29±2.60) T=6.89; P<0.0001], while no significant differences were observed after P
- Other blood parameters did not show significant variations
- Supplementation with Omega-3 PUFAs was associated with a clear variation of the profile of mood state
- The POMS analysis showed an increase of vigor and a decrease of the other mood states (anger, anxiety, fatigue, depression, confusion)
- Vigor and the other mood states did not differ from the period preceding the olive oil supplementation
- The reaction time (RT) decreased only after Omega-3 supplementation. This reduction occurred in Go/No-Go and Sustained Attention test, but no significant effects were observed in the Alert and Choice tests.
- The effect was particularly evident in the Sustained Attention test and the reduction of RT appeared to have been distributed over the entire test period with a concomitant reduction of variability after Omega-3 supplementation
- There was also a significant reduction in the number of errors from a mean of four to two errors/test after Omega-3 (P<0.04)
- The decrease of RT after Omega-3 supplementation could have been owing to a reduction of the latency of EMG activation of the forefinger flexor muscle engaged in pressing the computer key (time from onset of the stimulus to beginning of EMG activation N= EMG latency), or to an increase in the speed of contraction of the same muscle (time from the beginning of EMG activation to RT).
- The latter measurement did not show any significant variation the EMG latency was reduced in Go/No-Go, Choice and Sustained Attention tests after Omega-3 supplementation
- The event-related potentials showed no significant variations during Alert, Choice and Sustained Attention tests, while a change in the wave amplitude occurred in the Go/No-Go test after Omega-3 supplementation
- There was an increase in amplitude for the negative wave preceding the stimulus (CNV) and for P3, the positive peak after the stimulus
- The negative peak of the pre-stimulus wave passed through -30μV to -60μV after Omega-3 (P<0.0003)
- The P3 positive peak recorded before and after Omega-3 supplementation showed an increase in the amplitude in both the Go trial [peak amplitude mean values: before Omega-3 (43.77±42.80μV) and after Omega-3 (84.27±75.23μV); T=2.46; P<0.02] and No-Go trial [peak amplitude mean values: before Omega-3 (37.40±35.23μV) and after Omega-3 (75.65±69.28μV); T=2.40; P<0.02]
- In particular, after Omega-3 the percentage of the beta-2 band decreased significantly in all the tests and in the relaxation period. Its reduction was accompanied by a concomitant increase of the theta and alpha bands.
- The analysis of possible relationships between the variation of frequency percentage and other physiological parameters revealed a positive correlation between the theta band percentage in the Sustained Attention test and the vigor state recorded in POMS
- The results of the POMS questionnaire showed an enhanced vigor state and a concomitant decrease of the negative mood states after Omega-3 supplementation.
- The results of this experiment revealed an influence of Omega-3 on the activity of the central nervous system
- This was shown by the improvement of reactivity, attention and cognitive performances in addition to the improvement of mood state and the modifications of some neuro-electrical parameters
- These results have been obtained from a small study group and need further confirmation in a wider group of subjects and in particular for the possible influences of age and gender
- The absence of association between the variable studied and age or gender, observed in the present experiment, may be owing to the limited number of subjects
- It may be assumed that the importance of these results is strengthened by the fact that they occur in subjects in good health and performing physical activity in whom Omega-3 fatty acids improve an already good condition of well-being.
Industry: |
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- A very small study and study duration is only 35 days
- It is not a double blind trial
- The pilot study results are showing positive impact of omega 3 fatty acids and an improvement of reactivity, attention and cognitive performances in addition to the improvement of mood state and the modifications of some neuro-electrical parameters in healthy subjects
- Further studies are required in a large population including EPA, DHA and the ratio of EPA/DHA and AA/EPA on mood state and other neuro-electrical parameters.
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? | N/A | |
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) | Yes | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | N/A | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | N/A | |
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? | No | |
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%.) | N/A | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
4.4. | Were reasons for withdrawals similar across groups? | N/A | |
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? | N/A | |
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.) | ??? | |
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? | ??? | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | N/A | |
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? | N/A | |
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? | ??? | |
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? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | N/A | |
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? | N/A | |
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? | N/A | |
10.1. | Were sources of funding and investigators' affiliations described? | N/A | |
10.2. | Was the study free from apparent conflict of interest? | N/A | |