RD&T contributor, Dr. Joel Furhman, discusses the need for DHA by vegans and near-vegans in this article. From examining Blue Zones to addressing concerns about links between DHA and prostate cancer, he explains the potential benefits of conservative use of supplements.
Blue Zones and Nutrition
According to Healthline: “‘Blue Zone’ is a non-scientific term given to geographic regions that are home to some of the world’s oldest people.”
Blue Zones: Not Examples to Emulate
Some long-lived societies generally eat more plants and less animal products than other modern regions. However, most of them (except a minority of Adventists) still eat some natural animal products or seafood and are not vegan. Protective factors in their diets have been noted (such as high vegetable and legume intake, no processed foods, low meat intake); however, these societies do not represent the ideal human diet. They eat foods that are grown locally, which of course is a good thing in one sense, but has the shortcoming of not taking advantage of the wide varieties of foods that are available to us today. These populations don’t have the opportunity to use the advances in nutritional science to construct a dietary portfolio of the healthiest foods in the world. We have an opportunity to do much better than the Blue Zones.
The percent of centenarians in Okinawa is 6/10,000.1 Overall, in the Blue Zones, less than 10 percent live past 90.2 The life expectancy (after survival to 65) for Adventists in Loma Linda, CA, is 85 in men and 87.5 in women.3 These societies live longer than the average Westerner, but that does not mean they have maximized health and longevity.
A Nutritarian diet, along with my supplemental recommendations, does not attempt to duplicate a Blue Zone. Rather, it significantly surpasses the diets of the Blue Zones by incorporating the most current research, such as what foods enhance later-life brain function and stem cell and telomere maintenance.
It slows aging by utilizing the protective substances in leafy greens and other nutrient-rich foods. The Nutritarian diet takes advantage of the latest findings in nutritional science; we do not attempt to replicate primitive diets or regional diets that do somewhat better than typical Americans – but rather extract the most lifespan-enhancing practices based on scientific studies, with the goal of consistently and predictably extending human lifespan considerably further. Since this diet enables people to live well into their nineties, I have the responsibility to protect and enhance brain health until 100. No one wants to live to be 100 and not have a fully functioning brain. It’s interesting to note that the younger the average age of death, the less likely dementia will occur, and as such, may not be as much of an issue.
Does DHA Cause Prostate Cancer?
Though deficiencies of nutrients can accelerate aging as well as stem cell and telomere decay – and even promote cancer – it is true that nutritional excess or overdosing with many otherwise important and health-supporting nutrients can also increase the risk of cancer. Using the link between nutritional excess of a substance and cancer is never a logical argument to allow deficiencies to exist. For example, excess vitamin D supplementation may increase mortality risk, but so may deficiency.4-6
The link between fish oil and/or excess fish intake and prostate cancer has been suspected for years, and I reported comprehensively about the risks of excessive fish intake and taking inappropriate dosages of fish oil in my book, The End of Heart Disease (pp 120 -126, published 2016).
Raising further questions
We still have to question these studies because other studies have shown the opposite. A meta-analysis reviewing all the studies evaluating this question showed that even though some studies show benefit and some studies show harm, it was so random that they could not find such a relationship between DHA, fish oil and prostate cancer.7 If DHA and prostate cancer have any association, it is small and insignificant. However, regardless of whether high-dose fish oils or high fish intake increases prostate cancer or not,8 it is not a reason to avoid a small amount of DHA to prevent a fatty acid deficiency and protect against dementia. Especially in those eating a healthy (cancer-protective) plant-based diet.
Fish oil capsules supply about 1000 mg of oil per capsule (with about half of that EPA and DHA), with many people taking multiple capsules a day. Algae-based DHA-EPA is typically given in the 200-250 mg dose, not as a pharmacologic intervention to lower triglycerides or as an anti-inflammatory, but merely to prevent deficiency.
High-dose fish oil is not only suspected to increase risk of prostate cancer but also the DART 2 study showed that those with heart disease had a 26 percent of increased risk of cardiac death and increased risk of sudden cardiac death in the group that used supplements containing 3 grams/day of fish oil.9
These excessive doses can cause problems, as acknowledged by the Institute of Medicine: “high doses of DHA and/or EPA (900 mg/day of EPA plus 600 mg/day DHA or more for several weeks) might reduce immune function due to suppression of inflammatory responses.” The negative outcomes or lack of cardiovascular benefits from fish oil capsules10 demonstrate that fish oil has no benefit in populations already eating fish, and cannot mitigate the high risk of Standard American Diet (SAD) eating.
Public health authorities and mainstream nutritional researchers give opinions on supplements based on the general results shown in such large populations studies that generally show no benefits to taking fish oils in populations that regularly eat fish and other animal products. Stating that blood tests are not needed or useful may be true when discussing omnivores and fish-consuming populations, but not when considering vegans, whose blood levels of DHA and EPA are more likely to be low and can even be very, very, low. I have had some patients whose DHA levels were undetectable.
The fact also remains that DHA and EPA are essential components of brain cell membranes, with roles in membrane structure and function, cell signaling, neuron survival, brain development and repair, and production of anti-inflammatory lipid mediators.11,12
These fatty acids are considered “conditionally essential.” Because conversion of the essential fatty acid ALA to EPA and then to DHA is limited, consuming pre-formed DHA and EPA may be necessary to have adequate stores of these important fatty acids, according to the Institute of Medicine, which states, “consuming EPA and DHA directly from foods and/or dietary supplements is the only practical way to increase levels of these fatty acids in the body.”
Supplements for nutritional adequacy
My goal in recommending supplementation with a conservative dose is to ensure people have enough even if their conversion rate is somewhat low. The goal is not to treat a disease; it is not magic – it just assures nutritional adequacy.
Although DHA and EPA are considered conditionally essential, there is not yet an official recommended intake level or definition of deficiency based on blood levels of these fats. However, the omega-3 index, a measurement of the percent DHA + EPA to total fatty acids in red blood cell membranes, is a useful indicator. Estimates based on large population studies on heart disease risk have established that a high risk of heart disease is associated with an omega-3 index less than four percent and low risk of heart disease when the percent of DHA + EPA to fatty acids is greater than eight percent. These levels can be used as surrogates for insufficiency and sufficiency.13 I doubt a level of eight is necessary for excellent health, but one thing we know for sure is that levels under four are dangerous and associated with brain shrinkage.
DHA deficiency study
A study supported by the Nutritional Research Foundation, in attempt to discover how common DHA deficiency was in vegans, analyzed diets and omega-3 blood tests on 166 vegans who were not supplementing with EPA and DHA, finding an omega-3 index of <4% in 64 percent of vegans and the index <3% in 27 percent of vegans; the majority were in the range considered insufficient.14 These omega-3 index levels are consistent with those that have been associated with low brain volume in the elderly.15 The findings agreed with previous studies showing low DHA and EPA levels in vegetarians and vegans compared to omnivores.16
Average ALA intake by vegans in this study was double the adequate intake set by the Institute of Medicine (3.4 grams/day), and higher ALA intake was not correlated with higher omega-3 index, suggesting that genetically determined conversion efficiency from ALA to DHA and EPA is a more important determinant of DHA and EPA blood levels than ALA intake.14 A previous study reported similar findings.17
Generalized statements about the value of DHA/EPA supplements have no application when considering vegans. Since the Blue Zones are generally not vegan, they cannot be relied on to determine vegans’ nutrient intake and needs.
- Poulain M. Exceptional longevity in Okinawa: A plea for in-depth validation Demographic Research 2011, 25.
- 2Rosero-Bixby L. The exceptionally high life expectancy of Costa Rican nonagenarians. Demography 2008, 45:673-691.
- Fraser GE, Shavlik DJ. Ten years of life: Is it a matter of choice? Arch Intern Med 2001, 161:1645-1652.
- Durup D, Jorgensen HL, Christensen J, Schwarz P, Heegaard AM, Lind B. A reverse J-shaped association of all-cause mortality with serum 25-hydroxyvitamin D in general practice: the CopD study. J Clin Endocrinol Metab 2012, 97:2644-2652.
- Durup D, Jorgensen HL, Christensen J, Tjonneland A, Olsen A, Halkjaer J, Lind B, Heegaard AM, Schwarz P. A reverse J-shaped association between serum 25-hydroxyvitamin D and cardiovascular disease mortality – the CopD-study. J Clin Endocrinol Metab 2015:jc20144551.
- Sempos CT, Durazo-Arvizu RA, Dawson-Hughes B, Yetley EA, Looker AC, Schleicher RL, Cao G, Burt V, Kramer H, Bailey RL, et al. Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. nationally representative NHANES. J Clin Endocrinol Metab 2013, 98:3001-3009.
- Dinwiddie MT, Terry PD, Whelan J, Patzer RE. Omega-3 Fatty Acid Consumption and Prostate Cancer: A Review of Exposure Measures and Results of Epidemiological Studies. J Am Coll Nutr 2016, 35:452-468.
- Crowe FL, Appleby PN, Travis RC, Barnett M, Brasky TM, Bueno-de-Mesquita HB, Chajes V, Chavarro JE, Chirlaque MD, English DR, et al. Circulating fatty acids and prostate cancer risk: individual participant meta-analysis of prospective studies. J Natl Cancer Inst 2014, 106.
- Burr ML, Ashfield-Watt PA, Dunstan FD, Fehily AM, Breay P, Ashton T, Zotos PC, Haboubi NA, Elwood PC. Lack of benefit of dietary advice to men with angina: results of a controlled trial. Eur J Clin Nutr 2003, 57:193-200.
- Abdelhamid AS, Brown TJ, Brainard JS, Biswas P, Thorpe GC, Moore HJ, Deane KH, AlAbdulghafoor FK, Summerbell CD, Worthington HV, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev 2018, 11:CD003177.
- Dyall SC. Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA. Front Aging Neurosci 2015, 7:52.
- Lukiw WJ, Bazan NG. Docosahexaenoic acid and the aging brain. J Nutr 2008, 138:2510-2514.
- Harris WS, Del Gobbo L, Tintle NL. The Omega-3 Index and relative risk for coronary heart disease mortality: Estimation from 10 cohort studies. Atherosclerosis 2017, 262:51-54.
- Sarter B, Kelsey KS, Schwartz TA, Harris WS. Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega-3 fatty acid supplement. Clin Nutr 2014.
- Pottala JV, Yaffe K, Robinson JG, Espeland MA, Wallace R, Harris WS. Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes: WHIMS-MRI study. Neurology 2014, 82:435-442.
- Sanders TA. DHA status of vegetarians. Prostaglandins Leukot Essent Fatty Acids 2009, 81:137-141.
- Fokkema MR, Brouwer DA, Hasperhoven MB, Martini IA, Muskiet FA. Short-term supplementation of low-dose gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), or GLA plus ALA does not augment LCP omega 3 status of Dutch vegans to an appreciable extent. Prostaglandins Leukot Essent Fatty Acids 2000, 63:287-292.
This is Part One of a three-part series.