EAL

Cardiovascular Disease and Micronutrients

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To identify and assess the evidence for the efficacy of three antioxidants (vitamin E, vitamin C, and coenzyme Q₁₀) for the prevention and treatment of cardiovascular disease (CVD) or modification of known risk factors for CVD.

Inclusion Criteria:

Reports that focused on one of the three identified antioxidants alone or in combination and with the disease states of CVD which included stroke, heart failure and PVD
Reports were included if they affected known risk factors for CVD such as blood lipids or HTN
Language of publication was not a barrier to inclusion
Only human studies were included.

Exclusion Criteria:

Not described.

Description of Study Protocol:

15 databases were used with search terms antioxidant, vitamin E, vitamin C, and coenzyme Q₁₀and all pharmacologic synonyms in combination with the MeSH term cardiovascular disease
Search was confined to controlled trials
Search of bibliographies of review articles
Consultation with experts in cardiology, clinical trials, antioxidants, pharmacology and nutrition for their articles.

Data Collection Summary:

Each article was independently reviewed by two physicians who abstracted data
Information was collected regarding trial design and quality, number and characteristics of patients, details on the intervention, and time between intervention and outcome measurement
Data was synthesized quantitatively and qualitatively as appropriate
Pooled analyses were performed of the effects of vitamin E alone and in combination with other antioxidants on death, MI and blood lipid levels
The vitamin C and coenzyme Q₁₀ studies were not similar enough to justify pooling.

Description of Actual Data Sample:

1,339 articles identified in literature search
1,127 articles were found
528 were selected for screening
From these, 156 articles were identified that represented results from 159 reports on 144 unique trials (those that reported data that was not duplicated in another publication). One-third of the 144 were judged to be of high quality using the Jadad method.

Summary of Results:

The range of vitamin C supplementation among the studies was 120mg to 2,000mg per day
The range of vitamin E supplementation among the studies was 30mg to 1,000mg per day or 100 IU to 3,200 IU per day, depending on the method used in the study to measure vitamin E
The available evidence did not generally support any positive benefits of using vitamin E alone or in combinations to test for the prevention of all-cause death or cardiovascular death
There was little evidence that vitamin E supplementation results in a reduction in cardiovascular mortality
Supplementation with vitamin E alone and in combinations in doses ranging from 100 IU to 1,200 IU did not demonstrate a statistically significant effect on serum lipids after at least eight weeks and no more than 24 weeks of treatment
The value of coenzyme Q₁₀ supplementation in patients with CVD is still an open question with no convincing evidence supporting or refuting evidence of benefit or harm
Vitamin C has not been shown to have any substantial effect on cardiovascular disease outcomes.

Author Conclusion:

The pooled analysis shows no evidence for the use of vitamin E alone or in combination on all-cause mortality, cardiovascular mortality, fatal or non-fatal MI or blood lipid levels
The large clinical trials not included in the pooled analysis were substantially in agreement with this conclusion
Large studies of vitamin C in combination with other antioxidants for the prevention of cardiovascular disease reported no favorable outcomes
There is no evidence to support or refute the value of coenzyme Q₁₀ in cardiovascular disease.

Funding Source:

Government:

US Dept. Health and Human Services

Reviewer Comments:

Quality Criteria Checklist: Review Articles
Relevance Questions
	1.	Will the answer if true, have a direct bearing on the health of patients?	Yes
	2.	Is the outcome or topic something that patients/clients/population groups would care about?	Yes
	3.	Is the problem addressed in the review one that is relevant to dietetics practice?	Yes
	4.	Will the information, if true, require a change in practice?	Yes

Validity Questions
	1.	Was the question for the review clearly focused and appropriate?	Yes
	2.	Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?	Yes
	3.	Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?	Yes
	4.	Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible?	Yes
	5.	Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?	Yes
	6.	Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?	Yes
	7.	Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?	Yes
	8.	Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included?	Yes
	9.	Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed?	Yes
	10.	Was bias due to the review's funding or sponsorship unlikely?	Yes