Omega-3 fatty acids - do they increase or decrease prostate cancer risk?
A recent study produced confusing results. It found that a higher blood concentration of omega-3 fatty acids was associated with increased risk of high-grade prostate cancer, and a higher concentration of trans-fats was associated with decreased risk.1 These men were not supplementing with liquid fish oil, so it can be assumed that the blood levels represented fish intake. So should men still take omega-3 supplements? We know that DHA is good for the heart and the brain, but is it really bad for the prostate? What about trans-fats – how could more of this unhealthy fat possibly be beneficial for the prostate?
When we look more closely, we can see that this one study should not dictate major changes in our view of a cancer-preventive lifestyle. Read the entire article on DrFuhrman.com.
High fish consumption/blood omega-3s increase risk in some studies, decrease risk in others
- In a 2010 meta-analysis of 31 studies, the risks of prostate cancer diagnosis calculated for high fish consumption ranged from a 61% decrease in risk to a 77% increase in risk, and several showed no significant differences in risk at all.
- In the same meta-analysis, pooled data from four studies on fish consumption and death from prostate cancer (rather than diagnosis of prostate cancer) found a 63% decrease in risk for high fish consumption. 2
- A recent meta-analysis of studies on ALA intake (the omega-3 in plant foods like flax, hemp, chia, and walnuts, and small amounts in leafy greens) concluded that there was a small but significant decrease in risk (5%) for men consuming more than 1.5 grams of ALA per day.3
- At least 15 studies (the current study included), have used blood concentrations of omega-3 fatty acids as a measure of omega-3 intake. Some studies reported increased risk, some decreased risk, and some no effect.
Remember when looking at fish intake, we are not looking at omega-3 intake alone.
Fish are rich in omega-3s, but they also contain a significant amount of animal protein and accumulated environmental pollutants, both of which have been linked to prostate cancer. 4-7 Sufficient research has not been done on omega-3 supplements and prostate cancer to make any conclusions.
If we were to conclude anything from all the studies available on this subject it would be that fish and omega-3 fats in general do not have a major impact on this disease, but the inconsistency and widely differing results suggest regional variation in pollutant levels in the fish consumed.
Trans-fats and blood levels; more confusion in the midst.
Before you start eating Twinkies and French Fries fried in trans fat for their prostate cancer protection, let’s consider the possibility that after consuming trans fats (trans fats are man-made fat, already linked with cancer in multiple studies), those inflammatory fats are either burned, removed or stored in the body. Their levels may fluctuate abnormally because of having cancer. Therefore the high omega-3 and low trans fat blood levels in this study could be early signs of developing cancer, not the cause of it. Also, three previous studies on either trans-fat intake or blood trans-fats have found increased risk of prostate cancer.8-10
Should men still take omega-3 supplements?
Remember that omega-3s are essential fatty acids – the body cannot make them if we don’t get them from our diet. A deficiency of nutrients the body requires is never favorable for health, but more than needed may not be better when it comes to omega-3 fatty acids. I still recommend omega-3 sufficiency, which can be achieved with 100-200 mg/day of DHA plus 1 tbsp. of ground flaxseed for ALA. Almost all nutrients can be harmful in deficiency or excess.
1. Brasky TM, Till C, White E, et al: Serum Phospholipid Fatty Acids and Prostate Cancer Risk: Results From the Prostate Cancer Prevention Trial. Am J Epidemiol 2011.
2. Szymanski KM, Wheeler DC, Mucci LA: Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr 2010;92:1223-1233.
3. Carayol M, Grosclaude P, Delpierre C: Prospective studies of dietary alpha-linolenic acid intake and prostate cancer risk: a meta-analysis. Cancer Causes Control 2010;21:347-355.
4. Giovannucci E, Pollak M, Liu Y, et al: Nutritional predictors of insulin-like growth factor I and their relationships to cancer in men. Cancer Epidemiol Biomarkers Prev 2003;12:84-89.
5. Rowlands MA, Gunnell D, Harris R, et al: Circulating insulin-like growth factor peptides and prostate cancer risk: a systematic review and meta-analysis. Int J Cancer 2009;124:2416-2429.
6. Hardell L, Andersson SO, Carlberg M, et al: Adipose tissue concentrations of persistent organic pollutants and the risk of prostate cancer. J Occup Environ Med 2006;48:700-707.
7. Van Maele-Fabry G, Libotte V, Willems J, et al: Review and meta-analysis of risk estimates for prostate cancer in pesticide manufacturing workers. Cancer Causes Control 2006;17:353-373.
8. Hu J, La Vecchia C, Gibbons L, et al: Nutrients and risk of prostate cancer. Nutr Cancer 2010;62:710-718.
9. King IB, Kristal AR, Schaffer S, et al: Serum trans-fatty acids are associated with risk of prostate cancer in beta-Carotene and Retinol Efficacy Trial. Cancer Epidemiol Biomarkers Prev 2005;14:988-992.
10. Chavarro JE, Stampfer MJ, Campos H, et al: A prospective study of trans-fatty acid levels in blood and risk of prostate cancer. Cancer Epidemiol Biomarkers Prev 2008;17:95-101.