ONC: Dietary Supplements and Medical Food Supplements Containing Fish Oil (2013)


Silva Jde A, Trindade EB, Fabre ME, Menegotto VM, Gevaerd S, Buss Zda S, Frode TS. Fish oil supplement alters markers of inflammatory and nutritional status in colorectal cancer patients. Nutr Cancer. 2012; 64(2): 267-273. Epub 2012 Feb 1.

PubMed ID: 22295891
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To determine whether there is a change in the markers of inflammation and nutritional status of patients with colorectal cancer undergoing chemotherapy that were supplemented with 2g fish oil, compared with non-supplemented ones.

Inclusion Criteria:
  • Diagnosis of colorectal cancer
  • Beginning chemotherapy
  • Older than18 years of age
  • Taking part in anthropometrics, dietary and biochemical assessment.
Exclusion Criteria:
  • Less than 18 years of age
  • Receiving palliative care or on parenteral nutrition
  • Allergy to fish and fish products
  • Autoimmune disease.
Description of Study Protocol:


Oncology Research Center.




Fish oil: Four capsules per day equal to 600mg EPA + DHA for nine weeks (SG) vs. no supplement (NSG).

Statistical Analysis

Fisher's exact test to test differences in SG and NSG according to dichotomous variables (sex, stage of disease, primary site and frequent consumption of fish). Test for continuous variables were performed with T-test (parametric variables) or Mann-Whitney test (non-parametric variables). Outcome variables between M0 and M9 were also tested with Wilcoxon test. The difference in CRP to albumin levels between SG and NSG was also compared with score values:

  • No risk: 0.4 or less
  • Low risk: 0.4 to 1.2
  • Medium risk: 1.2 to 2.0
  • High risk: 2.0 or more. 
Data Collection Summary:

Timing of Measurements

Assessment of inflammatory process and nutritional status before chemotherapy (M0) and after week nine (M9). Blood in week before start of chemotherapy (M0) and one or two days after the last chemotherapy session (M9). Questionnaires at M0.

Dependent Variables

  • Cytokines, CRP, albumin: Blood analysis
  • BMI: Height and weight on electronic balance with attached ruler.

Independent Variables

Fish oil: Four capsules per day equaling 600mg EPA + DHA for nine weeks (SG) vs. no supplement (NSG). Compliance ensured by a weekly phone contact and in-person on chemotherapy treatment days.

Control Variables

Chemotherapy treatment.

Description of Actual Data Sample:
  • Initial N: 23 (17 males, six females)
  • Attrition (final N): 18
  • Age: 52.3 years (range 40 to 70 years)
  • Other relevant demographics: No difference between groups in weekly fish frequency, primary location of cancer, stage of disease, CRP or serum albumin
  • Anthropometrics: No difference in body weight [BMI: 25.0 (SD 3.4) for NSG vs. 27.3 (SD 6.1) for SG, P=0.31]
  • Location: Brazil.
Summary of Results:


  • All reported weight loss after diagnosis: 52.2% lost more than 5% and 26.1% lost more than 10%
  • At M9, the only marker that showed lower levels in SG compared to NSG was CRP, with a borderline statistical association (P=0.09)
  • There was a reduction in body weight and BMI in NSG (P=0.09 and P=0.03, respectively) when M0 was subtracted from M9, whereas in SG neither factor varied between M0 and M9
  • Malnutrition was not found at baseline, nor at M9 in either group. There was no hypoalbuminemia in M1 or M2.
  • The difference between the ratio CRP:albumin between SG and NSG in M9 showed a borderline association (P=0.09). The change amid the moments in SG was statistically significant (P=0.05), though in NSG there were no changes between baseline and M9. Clinically, this is considered beneficial; in the SG, an improvement in the degree of risk of complication or death was found, an increase from 10% to 20% in the number of patients with no risk and a reduction from 27.4% to 10% in the higher risk group. In NSG, the individuals without risk decreased from 25% to 12.5%, while higher risk of complication or death increased from 41.7% to 62%.
Author Conclusion:

Low doses of fish oil supplement can positively modulate the nutritional status and the C-reactive protein:albumin ratio.

Funding Source:
University/Hospital: FUNPESQUISA-UFSC
In-Kind support reported by Industry: Yes
Reviewer Comments:
Quality Criteria Checklist: Primary Research
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? 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
  3.2. 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? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) 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
  5.5. 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? 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? 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
  7.6. 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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  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? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes