Q: Hi Tracy, I’m interested in your thoughts about this headline I read: ”Fish oil increases the Risk of aggressive Prostate Cancer”. Is this true? There wasn’t enough data presented to really understand what the study showed, but headlines like that certainly get a guy’s attention. I am never quite sure what to say to a client who brings this kind of thing to my attention. Thanks!
A: Not surprisingly, about a dozen folks sent me a link to various newspaper headlines regarding this study. As you well know, news headlines are often phrased not by study authors but rather by journalists in an attempt to be particularly provocative or sensational. Unfortunately this headline is another example of an eye-grabbing claim that is not statistically backed up by what is actually in the study itself. As always, a study’s conclusions are only as valuable as the overall study design. In this particular case, I think there are a few issues – basic scientific ones – that all practitioners should understand about clinical studies showing this type of “association” between a nutrient or a behavior and a disease outcome. We have the unique opportunity to provide some sanity and balance in helping our clients to interpret what they read in the media.
1. Correlation is not causation. This was a correlation report. Correlation studies can help us to ask good questions – to shape useful hypotheses that can then be tested out in controlled studies that actually measure causality. There have been hundred of studies (literally) that have investigated fish oil – many of which in a gold-standard causality design methodology – and found significant anti-inflammatory benefits. There are actually also correlation studies showing that increased fish intake decreases the risk of prostate cancer substantially. While others show a correlation between lower incidence of prostate cancer with high levels of omega-3 fats in the blood. Clearly, our scientific investigations have not yet well isolated the true causality factor; this is the major reason why results of seemingly similar (or even identical) clinical studies can vary widely.
2. This study was not set up to even evaluate omega-3 intake at all – from fish or any other food, much less from fish oil supplements. Researchers did not even measure fish or fish oil intake. They just measured omega 3 blood levels – which for all nutrients generally reflects only recent consumption in the past few days. So it’s ridiculous (and scientifically false) to make a claim about fish or fish oil intake and ongoing use – when it wasn’t even measured in the study. This publication was based on a review of data collected in a study designed to asses the impact of synthetic vitamin E supplementation on prostate cancer incidence.
3. The omega-3 levels uncovered in this study are actually consistent with the lower side of normal for average male blood levels of Omega-3s in the general population (not those in the high end of the typical range, as you might expect from the headline claims). Across large population samples, we know that Omega-3 levels for the average man are approximately 4-5%. In this study, data showed that men without prostate cancer had an average levels of 3.52; those with prostate cancer had an average level of 3.66. Again, this overall data does not show evidence of a higher-than-typical intake of omega-3s from diet, much less concentrated consumption of fish or fish oil supplements.
4. Quality matters greatly. Since no fish or fish oil intake was measured, we have no information about the quality of the source of Omega-3 fats in these participants’ diet (e.g. chemical toxicity, especially from mercury, which is prevalent in some types of fish and is also present in low-end, poorly-processed fish oil supplements).
5. The best way to consume all nutrients is via whole, clean, unprocessed food. Of course. We know this intrinsically as wellness practitioners. When we consume unsaturated fats while they are still part of a food (vs. isolated as an oil), those fats are less vulnerable to oxidation. We should always try to maximize our clients’ nutritional intake via food. However, we also know that many of our clients are unwilling or unable to get all the nutrients their unique body needs via food. This is especially true for our clients struggling with inflammatory disorders and disease. It’s important that our suggestions for each unique client be customized to support that individual’s diet and health status.
6. Optimal nutrition is about balance. There is no single remedy or nutrient that will “fix” or prevent any disease. Omega-3 fats are called “essential” because they are necessary for life yet the body cannot manufacture them on its own. Thus, omega-3 fats must be consumed. Without them, we could not build membranes for new cells, as we generate billions of them daily. As with all polyunsaturated fats, Omega-3 fatty acids are vulnerable to oxidation and the generation of free radicals (aka oxidative stress) in the body. This is a normal, expected component of metabolism, and the body naturally protects itself from this type of oxidative damage through the use of antioxidant nutrients and protective mechanisms (e.g. Vitamin E). But in a body that already has a shortage of antioxidant protection, high intake of any polyunsaturated fats without supportive antioxidants could indeed hypothetically increase oxidative damage. This is why a varied diet high in a rich variety of nutrients, including antioxidants from vegetables and fruits, is so critical for biochemical balance. You also want to ensure any brand of Omega-3 oils you recommend includes antioxidants in the liquid or capsules themselves (e.g. mixed tocopherols). Check the ingredient list.
Supplements can do a great job boosting an individual’s intake of nutrients when they are lacking in the diet or are specifically identified as insufficient for their unique body. As with all nutrients, more is not necessarily better. And to ensure benefit, it is critical that supplements deliver nutrients in a form such as they are found in nature (e.g. folate vs. synthetic folic acid). Choose a fish oil that includes antioxidant support from mixed tocopherols (or take in daily via food naturally high in Vitamin E such as almonds or sunflower seeds). It’s also important that fish oil be molecularly-distilled and guaranteed to be chemical toxin free (not just a few hundred parts-per-million (PPM) level but zero!), or the toxins that come along with the essential fats may be a driver for negative outcomes. Don’t look for the cheapest brand available; read labels carefully to ensure safety. Indeed, we still have much to learn about the influence of many specific nutrient levels (not just omega-3s) on the etiology of various diseases! But we need to be careful about following speculative guidance (pro or con!) from correlation studies to avoid known-essential nutrients – especially without supportive evidence proving causation.
If you want to know more, this extensive write-up might be interesting to you: http://www.greenmedinfo.com/blog/how-selected-bad-study-became-big-news
I have written before about the value of Omega-3 supplements. Here are some more ideas to consider: https://schoolafm.com/ws_clinical_know/critical-omega-3-fat-facts/