DLM: Trans-fatty Acids (2005)
To understand the effect of trans fatty acids/hydrogentated fat on HDL-C levels and metabolism.
Inclusion Criteria:
--LDL-C > 130mg/dL in the greater Boston area
--normal fasting glucose
--no lipid lowering medications
--non-smoker
--no HRT for post-menopausal women
--normal kidney, liver, thyroid, and cardiac function
Exclusion Criteria:
--treated HTN with beta blockers--Latin square design: 6 experimental diets with varying amounts of soybean-oil derived spread or butter for 35 days each
--both subjects and investigators were blinded to the diet phase
--reported results only from 3 phases: 2 margarines with greatest differential in trans fatty acids, PUFA, and butter
--fasting blood for lipid and apolipoprotein determinations 3 times after day 28 of every diet phase
--mean value of measurements at 3 time points were used for analysis
--Diet: 15% kcals from protein
55% kcals from CHO
30% kcals from fat
--2/3 of fat from semiliquid margarine in squeeze bottles
--traditional margarine: sticks or butter
--3 day meal cycle for every phase
--36 subjects:
18 women (age 57-73 years)
18 men (age 52-73 years)
--women tended to have higher mean HDL-C and lower mean total chol/HDL-C ratios than men in this study
--mean caloric intake: 2114 +/- 320 kcals from women (mean +/- SD); 2792 +/- 518 kcals for men
--Eating a diet rich in semiliquid margarine led to a 19 mmol/L decrease in total cholesterol (p<0.05), 5 mmol/L decrease in HDL-C (p<0.05), and 0.11 increase in TC/HDL-C ratio (p<0.05)
--Eating a diet rich in stick margarine (trans fatty acids) led to a 2 mmol/L decrease in total cholesterol (p<0.05), 6 mmol/L decrease in HDL-C (p<0.05), and 0.67 increase in TC/HDL-C ratio (p<0.05)
--Eating a diet rich in butter led to a 6 mmol/L increase in total cholesterol (p<0.05), 3 mmol/L decrease in HDL-C (p<0.05), and 0.49 increase in TC/HDL-C ratio (p<0.05)
Statistically Significant:
--highest total and LDL-C after consumption of butter diet (p<0.05)
--lowest total and LDL-C after consumption of semiliquid margarine diet (p<0.05)
--HDL-C decreased 7% after stick margarine diet than after using butter (p<0.05)
--difference in HDL-C between stick margarine and butter diets was 11% in female subjects and nill in male subjects
--intake of stick margarine and butter resulted in highest, least favorable total chol/HDL-C ratio
--semiliquid margarine resulted in most favorable, lowest total chol/HDL-C ratio
--differences in HDL-C primarily due to changes in HDL2-C rather than HDL3-C
(differences in HDL2-C levels between stick margarine and butter was 27% in group as a whole and 31% in female subjects and not significant in male subjects)
--apoA-1 levels were lowest after subjects consumed stick margarine diet and highest after consumption of butter diet (7%, stick margarine vs butter, p<0.05); only statistically significant in women (10%, stick margarine vs butter)
--ApoA-1 in LpA-1 lower after consumption of stick margarine compared to butter (p<0.05); differences for entire group statistically significant only for females
Not statistically significant:
--differences in apoA-1 in LpA-1/A-11
--intake of hydrogenated fat/trans fatty acids and saturated fatty acids associated with changes in LDL-C and HDL-C levels consistent with risk for CVD
--magnitude of difference in HDL-C from consumption of lightly or heavily hydrogenated margarine-enriched diets not significant
--small effect on HDL-C and HDL subfractions with two types of margarines
--large effects on total and LDL-C levels and therefore, the total/HDL-C ratio
--HDL-C levels significantly higher after consumption of butter than 2 margarine diets, with largest difference noted after stick margarine diet
--suggests that major determinant of HDL-C levels is the SFA content of diet rather than either the trans-fatty acids to diets high in either oleic or SFA
--consumption of diets low in SFA and minimally hydrogenated fatty acids results in most favorable lipoprotein profile with respect to CVD
--difference in SFA rather than the trans or PUFA content of diets was the major determinant of HDL-C levels
--results from this study are consistent with the recommendations to restrict both saturated and hydrogenated fats
Government: | NIH,US Dept. of Agriculture, | ||
Not-for-profit |
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--small sample size
--What about confounders such as physical activity?
--investigators were not able to formulate diets to a single fatty acid, however there is practicality in the sense that they chose products that were commercially available
--there are major problems in table 3 where they attemped to show significant differences among the variables . For instance, using the S.E.M values (not SD), the differences shown for LDL- cholesterol between semiliquid and stick margarine do not appear significant
Examples;
LDL cholesterol
Semiliquid 155 + 6.36* = 161.36
Stick 168 – 7.07* = 160.93
Butter 177 – 7.54* = 169.46
* S.E.M
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 | |
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 | |
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 | |
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 | |
4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
Validity Questions | |||
1. | Was the research question clearly stated? | Yes | |
1. | Was the research question clearly stated? | Yes | |
1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
1.1. | 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 | |
1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | 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 | |
2.1. | 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 | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
2.3. | Were health, demographics, and other characteristics of subjects described? | 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? | Yes | |
2.4. | Were the subjects/patients a representative sample of the relevant population? | Yes | |
3. | Were study groups comparable? | Yes | |
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 | |
3.1. | 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? | Yes | |
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.) | 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 | |
3.4. | 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 | |
3.5. | 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 | |
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. | Was method of handling withdrawals described? | Yes | |
4.1. | Were follow-up methods described and the same for all groups? | 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%.) | N/A | |
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 | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
4.4. | Were reasons for withdrawals similar across groups? | N/A | |
4.4. | 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 | |
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. | 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 | |
5.1. | 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 | |
5.2. | 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 | |
5.3. | 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 | |
5.4. | 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 | |
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. | 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 | |
6.1. | 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 | |
6.2. | 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? | No | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | No | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | N/A | |
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 | |
6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | N/A | |
6.6. | Were extra or unplanned treatments 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 | |
6.7. | 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 | |
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. | 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 | |
7.1. | 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 | |
7.2. | 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 | |
7.3. | 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 | |
7.4. | 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 | |
7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | No | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | No | |
7.7. | Were the measurements conducted consistently across groups? | 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. | 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 | |
8.1. | 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 | |
8.2. | 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 | |
8.3. | 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)? | N/A | |
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)? | N/A | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | Yes | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | Yes | |
8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
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 | |
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. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | 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. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |