Blood Level Omega 3 Fatty Acids as Risk Determinant Molecular Biomarker for Prostate Cancer
Blood Level Omega 3 Fatty Acids as Risk Determinant Molecular Biomarker for Prostate Cancer
Year: 2013
Authors: Sorongon-Legaspi, M.K. Chua, M. Sio, M.C. Morales Jr., M.
Publication Name: Prostate Cancer
Publication Details: doi: 10.1155/2013/875615
Abstract:
Previous researches involving dietary methods have shown conflicting findings. Authors sought to assess the association of prostate cancer risk with blood levels of omega3 polyunsaturated fatty acids (n3 PUFA) through a meta analysis of human epidemiological studies in available online databases (July, 2012). After critical appraisal by two independent reviewers, Newcastle-Ottawa Quality Assessment Scale (NOQAS) was used to grade the studies. Six case control and six nested case control studies were included. Results showed nonsignificant association of overall effect estimates with total or advanced prostate cancer or high-grade tumor. High blood level of alphalinolenic acid (ALA) had nonsignificant positive association with total prostate cancer risk. High blood level of docosapentaenoic acid (DPA) had significant negative association with total prostate cancer risk. Specific n3 PUFA in fish oil, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) had positive association with high-grade prostate tumor risk only after adjustment of interstudy variability. There is evidence that high blood level of DPA that is linked with reduced total prostate cancer risk and elevated blood levels of fish oils, EPA, and DHA is associated with high grade prostate tumor, but careful interpretation is needed due to intricate details involved in prostate carcinogenesis and N3 PUFA metabolism. (Authors abstract)
Prostate cancer in the recent decades has been shown to cause remarkable morbidity and mortality among males. Dietary components such as omega 3 polyunsaturated fatty acids (n 3PUFA) are of interest due to their established cardiovascular benefit, neuro protectiveness, and anti-inflammatory effects. Studies involving dietary intake of n 3 PUFA have yielded conflicting and non conclusive results. A recent metaanalysis, for instance, has attributed the inconclusive results to pooled diverse study design, presence of confounding variables,and presence of biases. Thus, recall bias when using dietary questionnaires can significantly affect results. In this meta analysis, results showed a positive association, though not significant, between high blood levels of ALA and prostate cancer risk. This finding does not coincide with the results of previous meta analyses which have suggested a protective effect of high dietary intake of this short chain n 3 PUFA on prostate cancer development. A protective effect of dietary ALA supplementation might be linked to the bioconversion of ALA to EPA and DPA, which are potent anti inflammatory mediators, producing a subclinical inflammation marker, matrix metalloproteinase 9 (MMP 9) that inhibits synthesis and release of cytokines. Possibly, high blood levels of ALA may suggest a genetic variation that no longer produces the positive effects brought about by ALA metabolism and bioconversion. When the association of blood level DHA and EPA with prostate cancer and high-grade prostate cancer was determined, heterogeneity was noted. The source was found to be mostly the nested case cohort of the Physician’s Health Study, possibly due to the selection of subjects and minimal adjustment of confounding variables. Currently, studies still report inconsistent findings regarding the role of long chain n 3 PUFA, such as EPA and DHA, in the development of prostate cancer. The present meta analysis employed a rigorous standard to assess methodological quality of the studies included in the analysis. Although heterogeneity was noted, the study design and sources of inter variability were assessed and adjusted to assure homogeneity of pooled data. Publication bias was not noted to be present among the included studies. The studies included in the present analysis were carried out in western countries, where diets are generally not healthy; thus the results extracted can only be generally applied to the western population. Additional studies with multiethnic or eastern populations are recommended to cover a more representative sample of the total population of human males. More research are recommended in order to elucidate the possible influence of genotypic variants, since few studies have been conducted. The contribution of environmental toxins to prostate cancer development also needs further research. In conclusion, this meta analysis provided evidence that elevated blood levels of DPA are associated with decreased risk of developing prostate cancer. Elevated blood levels of EPA and DHA in combination are associated with increased risk of high grade prostate tumor. Cautious interpretation of these results must be done, since prostate carcinogenesis is multifactorial, and the body’s metabolism of n 3 PUFA is complex. (Editors comments)
Prostate cancer in the recent decades has been shown to cause remarkable morbidity and mortality among males. Dietary components such as omega 3 polyunsaturated fatty acids (n 3PUFA) are of interest due to their established cardiovascular benefit, neuro protectiveness, and anti-inflammatory effects. Studies involving dietary intake of n 3 PUFA have yielded conflicting and non conclusive results. A recent metaanalysis, for instance, has attributed the inconclusive results to pooled diverse study design, presence of confounding variables,and presence of biases. Thus, recall bias when using dietary questionnaires can significantly affect results. In this meta analysis, results showed a positive association, though not significant, between high blood levels of ALA and prostate cancer risk. This finding does not coincide with the results of previous meta analyses which have suggested a protective effect of high dietary intake of this short chain n 3 PUFA on prostate cancer development. A protective effect of dietary ALA supplementation might be linked to the bioconversion of ALA to EPA and DPA, which are potent anti inflammatory mediators, producing a subclinical inflammation marker, matrix metalloproteinase 9 (MMP 9) that inhibits synthesis and release of cytokines. Possibly, high blood levels of ALA may suggest a genetic variation that no longer produces the positive effects brought about by ALA metabolism and bioconversion. When the association of blood level DHA and EPA with prostate cancer and high-grade prostate cancer was determined, heterogeneity was noted. The source was found to be mostly the nested case cohort of the Physician’s Health Study, possibly due to the selection of subjects and minimal adjustment of confounding variables. Currently, studies still report inconsistent findings regarding the role of long chain n 3 PUFA, such as EPA and DHA, in the development of prostate cancer. The present meta analysis employed a rigorous standard to assess methodological quality of the studies included in the analysis. Although heterogeneity was noted, the study design and sources of inter variability were assessed and adjusted to assure homogeneity of pooled data. Publication bias was not noted to be present among the included studies. The studies included in the present analysis were carried out in western countries, where diets are generally not healthy; thus the results extracted can only be generally applied to the western population. Additional studies with multiethnic or eastern populations are recommended to cover a more representative sample of the total population of human males. More research are recommended in order to elucidate the possible influence of genotypic variants, since few studies have been conducted. The contribution of environmental toxins to prostate cancer development also needs further research. In conclusion, this meta analysis provided evidence that elevated blood levels of DPA are associated with decreased risk of developing prostate cancer. Elevated blood levels of EPA and DHA in combination are associated with increased risk of high grade prostate tumor. Cautious interpretation of these results must be done, since prostate carcinogenesis is multifactorial, and the body’s metabolism of n 3 PUFA is complex. (Editors comments)
