DHA Recommendations Follow-Up

After I published my last post, DHA Recommendations Updated (A Bit), I received comments from a reader saying that there is no evidence that vegans need to supplement with DHA. So, I went digging for the evidence.

The first bit comes from the experience of Joel Fuhrman, MD, which I blogged about in November of 2010 in the post DHA Supplements: A Good Idea, Especially for Older Vegan Men, in which Dr. Fuhrman said that he has been seeing numerous elderly vegans with severe DHA deficiency, and he believes it may have exacerbated Parkinson’s disease and tremors in some of his patients.

Is there any evidence for a connection here? I’m not an expert on the literature regarding DHA and the brain, but here is an excerpt from a 2005 study that indicates it’s plausible:

“Docosahexaenoic acid (DHA), a dietary essential omega-3 fatty acid concentrated in membrane phospholipids at synapses and in retinal photoreceptors is decreased in [the Alzheimer disease] brain. This deficiency may be due to enhanced free radical–mediated lipid peroxidation, decreased dietary intake, and/or impaired liver DHA shuttling to the brain. Decreased DHA serum content correlates with cognitive impairment. Moreover, epidemiologic studies suggest neuroprotective consequences of diets enriched in omega-3 fatty acids (1).”

Note the part, “impaired liver DHA shuttling to the brain.” I would assume, then, that an important way that DHA gets to the brain is by being produced by the liver (or eaten) and shuttled via the blood. So if vegans have low blood levels of DHA (as they do, without supplementation), that could mean they are not getting enough to the brain.

The second bit is less strong, but comes from the paper, Mortality in British Vegetarians, a 2002 report showing that vegetarians in the Oxford Vegetarian Study had twice the risk of dying from a mental or neurological disease as did non-vegetarians (see Disease Rates of Vegetarians and Vegans). A different report, from the Adventist Health Study, found the opposite: vegans and lacto-ovo vegetarians had half the risk of dementia (2).

I tend to think the culprit in these disparate findings is vitamin B12 (not DHA), as Seventh-day Adventists have traditionally known to supplement with vitamin B12 whereas other populations of vegans have neglected it. But I would not completely rule out DHA at this time.

My sense is that kids who are raised vegan are rarely supplemented with DHA and to our knowledge most of them develop normally. This would indicate that dietary DHA is not necessary for optimal health. But none of these children have made it to old age (that I am aware of) to know if the situation changes as they get older. It could be that people born without a source of DHA past infancy become highly efficient at converting ALA to DHA, an ability that might not be developed in people who become vegetarian as adults.

While I would love nothing more than to dispense with the entire DHA/omega-3 issue, I just don’t believe we can do that unless future research proves there is nothing to be concerned about.

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References

1. Lukiw WJ, Cui JG, Marcheselli VL, Bodker M, Botkjaer A, Gotlinger K, Serhan CN, Bazan NG. A role for docosahexaenoic acid-derived neuroprotectin D1 in neural cell survival and Alzheimer disease. J Clin Invest. 2005 Oct;115(10):2774-83. | link

2. Giem P, Beeson WL, Fraser GE. The incidence of dementia and intake of animal products: preliminary findings from the Adventist Health Study. Neuroepidemiology. 1993;12(1):28-36. | link

21 Responses to “DHA Recommendations Follow-Up”

  1. Nadine Says:

    I always like to err on the side of caution especially when it comes to brain health! We buy DHA supplements online twice a year and have them shipped to Canada. We take them 2-3 times a week or so, but not all of the time. We also limit our oil consumption to flax, coconut and olive all in small amounts. I noticed the local health food store now has several brands of vegan DHA on the shelves since Dr. Oz went on about them and the price point is even cheaper.
    Also, what do you think about the omega lab tests? I saw the local blood place advertising them, but they are not covered by our provincial health care. Would it be worthwhile?

  2. Jack Norris RD Says:

    Nadine,

    > Also, what do you think about the omega lab tests? I saw the local blood place advertising them, but they are not covered by our provincial health care. Would it be worthwhile?

    Hard for me to say. I haven’t bothered getting mine tested, but I can’t fault someone who does. I think it’s probably akin to B12 in that you should just make sure you’re taking the DHA and in absence of any problems, assume you’re covered.

  3. Nadine Says:

    Thanks for the insight. B12 is covered here too so I get it done every few years. Last time it was beyond the reference range and they recommended I take less supplements.

  4. Andrea Says:

    “Dr. Fuhrman said that he has been seeing numerous elderly vegans with severe DHA deficiency, and he believes it may have exacerbated Parkinson’s disease and tremors in some of his patients.”

    These are signs of dopamine dysregulation which is the result of porn/Internet/video games/alcohol/drugs addiction. Having an addiction will lead the individual in neglecting their diet by not eating enough ALA in the first place however I doubt DHA fixes all types of tremors. DHA does fix hand-writting tremors however it doesn’t fix the dopamine dysregulation tremors that require giving up the addiction in the first place.

    Alzheimer disease is caused by inflammation; such as air pollution, smoking, etc… A deficiency of DHA is secondary.

    The science I linked on my comment here(http://jacknorrisrd.com/omega-3s-in-vegetarian-diets/#comments) indicates that Retinoic Acid(Vitamin A) upregulates the enzymes required for the conversion of ALA into EPA/DHA.

    Interesting video which proves that we should be getting our Omega 3’s from raw leafy greens: http://www.youtube.com/watch?v=VhjTtNw6Tk4

  5. Bertrand Russell Says:

    I think it comes down to: Do we want vegans to have the best chance at good health (so people don’t quit http://bit.ly/qPEmSv), or do we want to believe something that makes us feel good (“a vegan diet is natural and doesn’t need supplements!”)?

    If we want more people to be vegan, better to err on the side of caution regarding nutrition.

  6. Dan Says:

    I have also seen plenty of observational studies suggesting DHA levels are linked with better health. However, this could simply suggest that measured DHA concentration in humans is correlated with other underlying factors such as socioeconomic status, fewer adverse health habits, higher intake of fish (which again correlates with many good health habits), a general approach to supplementation for health, or more health-conscious behavior in general. It does not prove that higher DHA is responsible for better health outcomes. We have seen this pattern with many surrogate markers that in the past have not panned out well in randomized controlled trials.

    I feel somewhat conflicted on the DHA issue. I certainly do not want to deprive myself of a potentially important nutrient that I otherwise would have no access to as a vegan. But on the other hand, the level of evidence is not high enough to warrant supplementation (as with B12). Are there even case reports of DHA deficiency disease in the published literature?

  7. Jack Norris RD Says:

    > Are there even case reports of DHA deficiency disease in the published literature?

    I’m not aware of any, but a nutrient doesn’t need to have severe deficiency symptoms in order to be important for long-term health. In the paper I reference in the post above, Lukiw is suggesting that some dementia is from a DHA deficiency. It’s certainly possible that the only problem that ever arises from DHA deficiency is dementia in old age, or depression.

    > that measured DHA concentration in humans is correlated with other underlying factors

    Researchers try to weed these out. It’s such a consistent finding that it’s hard to believe it is simply masking some unknown factor that almost always occurs in people with higher DHA intakes or blood levels.

  8. Dan Says:

    You have more faith in epidemiology than I do. DHA in the blood is certainly a marker of fish intake, but fish contain numerous other molecules and fish intake itself may simply reflect healthier lifestyles (just as we vegans tend to exercise more and smoke less than fast-food eating carnivores). Measured confounding probably accounts for <10% of all confounding (measured + hidden/unmeasured/residual). There are just too many lifestyle traits that can be properly measured, or that change over time, or can't be shrunk into binary or quantitative statistical variables in these models.

    As someone else recently pointed out, the latest meta-analyses of omega-3 PUFA have been negative, and I've counted three recent such meta-analyses in my reading. I can see both sides of this issue as I pointed out that these meta-analyses typically enrolled sick patients and many carnivores, with probably very few vegans amongst them.

    A nice question might be, what is in 2 servings of oily fish per week? That is what the AHA currently recommends in their heart-healthy dietary recommendations (and this guideline dates back to 2002). Certainly there is DHA and EPA are in there, but so are alot of other things too.

  9. unethical_vegan Says:

    Jack, As someone with over a dozen years of post-doctoral experience in neuroscience I have comments on the hypothesized link between DHA and cognitive disorders. But there is no point in writing these out if you are going to delete them.

  10. Jack Norris RD Says:

    unethical vegan,

    Go ahead. I’m not sure why you would suggest that I’d delete them.

    The only comments I delete, besides spam, are vitriol and someone who can’t stop repeating themselves with no new info. And it’s been a long time since that’s happened.

  11. Dan Says:

    Jack, re: the new Option A, “If you want your DHA levels to be the same as non-vegetarians, supplementing with 300 mg per day will likely accomplish that.”

    Most of the trials I cited (and you know of) used much higher doses than that. The single (and well-done) abstract that used 200 mg per day in vegan men stated: “Plasma DHA concentrations increased by 50% on DHA treatment but still did not achieve the concentrations seen in omnivores.”

    Therefore, it is confusing how you derived the estimate of 300 mg/d as the option that will most likely accomplish moving DHA into the ‘omnivore’ range in vegans.

    (as an aside, even lacto-ovo-vegetarians are likely to be DHA-deficient)

    I am not stating that DHA is necessary for vegan health – I think the jury is still out. But it behooves one if providing dietary advice to furnish the correct doses. Either decide that DHA is important and provide a sufficient dose (without the qualifier that if you want to get some DHA in your system, you can take it every 2-3 days), and employ the correction supplementation strength as shown in the studies, or drop the recommendation altogether. I think you are trying to have it both ways by hedging your bet! 😉

  12. Jack Norris RD Says:

    Dan,

    Did you miss this?

    “200 mg per day raised vegan DHA levels .6%. 300 mg can then be expected to raise vegans’ DHA levels .9%, taking them from an average of 1.1% to 2.0%. It thus seems reasonable to recommend 300 mg per day for the average vegan to match the same level as the average omnivores. But since it is not clear that vegans need DHA levels equal to omnivores, taking 200-300 mg every 2 to 3 days could be adequate insurance while not costing nearly as much.”

    > Most of the trials I cited (and you know of) used much higher doses than that.

    Yes, and they raised levels much higher than what most omnivores typically have.

    > The single (and well-done) abstract that used 200 mg per day in vegan men stated: “Plasma DHA concentrations increased by 50% on DHA treatment but still did not achieve the concentrations seen in omnivores.”

    That’s why I recommend a additional 100 mg (for a total of 300 mg) per day if you want the same levels as omnivores.

    > and employ the correction supplementation strength as shown in the studies, or drop the recommendation altogether.

    It’s not a game to me – I’m not out to win some sort of argument. I think it is quite possible that vegans can benefit from a modest DHA supplement, but I don’t know it for sure.

    And I’m still waiting on “unethical vegan” to show why vegans don’t need DHA. If someone can prove to me that vegans don’t need DHA, I will be ecstatic at the news.

  13. unethical_vegan Says:

    “And I’m still waiting on “unethical vegan” to show why vegans don’t need DHA. If someone can prove to me that vegans don’t need DHA, I will be ecstatic at the news.”

    Many large human populations do not consume fish or visceral organ meats in significant quantities and yet there is no evidence of developmental issues associated with DHA deficiency in these populations. Morerover, the miniscule amounts of DHA and EPA present in non-aquatic foods strongly suggests that DHA levels in the adult brain are largely derived from endogenous synthesis and/or recycling.

    This is born out by analysis of the Epic cohort (and other epidemiological data):

    DHA consumption
    fish eaters: 0.19 ± 0.22
    meat eaters: 0.02 ± 0.02
    vegetarians: 0.0007 ± 0.004
    vegans: 0 ± 0

    Plasma DHA:
    fish eaters: 239.7 ± 106.2
    meat eaters: 215.6 ± 96.4
    vegetarians222.2 ± 138.4
    vegans: 195.0 ± 58.8

    http://ajcn.nutrition.org/content/92/5/1040.long

    Meta-analyses of the current literature also find little evidence that n-3 pufa supplementation affects developmental outcomes:

    http://ajcn.nutrition.org/content/92/4/857.short
    http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8586704
    http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD000375.pub4/abstract
    http://www.ncbi.nlm.nih.gov/pubmed/19881391

    (Note the Cochrane meta-analysis.)

    And the only *well-powered* study for pregnant women found absolutely zilch:
    http://jama.jamanetwork.com/article.aspx?articleid=186750

    And now the neuroscience: Long-term feeding studies find that even low levels of dietary n-3 pufas are sufficient for normal cognitive function in rodents. Significant cognitive deficits arose only when animals were fed diets completely devoid of n-3 pufas for extended periods of time. Interestingly, in adult animals n-6 DPA can completely replace neuronal DHA in adult animals without loss of viability (and only mild to moderate cognitive defects).

  14. Jack Norris RD Says:

    unethical vegan,

    Okay, between you and Dan, you’re starting to convince me. When I get some time I’ll look at these links and the studies Dan’s been sending me more closely. My main concern has been what Joel Fuhrman has reported from his practice of elderly vegans with very low DHA levels, cognitive problems, and who are B12 replete.

    What I would really like to see is a measurement of the cognitive function of people, especially people 50 and older, with DHA levels similar to vegans compared to the cognitive function of people with more normal DHA levels. But this info you sent might be enough to sit in for that.

  15. Jack Norris RD Says:

    Dan and unethical vegan,

    How ironic — this just out:

    http://onlinelibrary.wiley.com/doi/10.1111/nure.12071/abstract

    The beneficial effects of consuming omega-3 polyunsaturated fatty acids (n-3 PUFAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on cardiovascular health have been studied extensively. To date, there is no dietary reference intake (DRI) for EPA and DHA, although many international authorities and expert groups have issued dietary recommendations for them. Given the substantial new evidence published since the last Institute of Medicine (IOM) report on energy and macronutrients, released in 2002, there is a pressing need to establish a DRI for EPA and DHA. In order to set a DRI, however, more information is needed to define the intakes of EPA and DHA required to reduce the burden of chronic disease. Information about potential gender- or race-based differences in requirements is also needed. Given the many health benefits of EPA and DHA that have been described since the 2002 IOM report, there is now a strong justification for establishing a DRI for these fatty acids.

  16. Brandon Becker Says:

    I found this interesting message board post critical of Dr Fuhrman’s recommendations for DHA supplements (among others), claiming that he is misrepresenting the data and points out how his articles often conclude with links to the various supplements he sells: http://www.drmcdougall.com/forums/viewtopic.php?f=1&t=31586

  17. Mary Calabria Says:

    This attack from Dr. McDougall and his corroborators against Dr. Fuhrman is disgusting. It looks like it must have taken many months of planning and joint collaboration to put this character assignation together.

    And the hypocrisy of McDougall after this being posted on his public site, to promote it with e-blasts and then acting like the peacemaker to want the fighting to end. The low-fat vegan contingency gangs up against Fuhrman because has a more scientific and effective program and tells it like it is. Instead of debating the issues they had to attack his character. I don’t even think the point is for Fuhrman to defend himself against this disgusting behavior. It speaks to the pettiness and ego of those launching it. They also attack Dr. Gregor for agreeing with scientific issue that Dr. Fuhrman and him agree on. It is utterly repulsive, maybe even libelous.

    As a member of Dr. Fuhrman’s website, I tried to post a correction of statements there, and have had multiple correspondence with others too who have tried to go on Dr. McDougalls boards and defend Fuhrman, or set the record straight on some of the distortions, but those were always immediately deleted.

  18. Brandon Becker Says:

    I wouldn’t call it an attack but rather a debate about what the science says.

    I don’t know why you say that you and others’ posts were deleted when defending Dr Fuhrman, since Dr Fuhrman himself responded in this thread:
    http://www.drmcdougall.com/forums/viewtopic.php?f=1&t=31925&p=320695

    My view is to follow the science, whether that means McDougall is right or Fuhrman is right or neither are right. Debate is a good thing, especially since studies can often be conflicting and some studies are better science than others.

  19. Jack Norris RD Says:

    I’m probably not going to put any further comments through about this debate about Dr. McDougall and Dr. Fuhrman unless they mention actual studies and are discussing scientific arguments.

  20. Joe Says:

    Jack,

    I would like to try taking a 100 mg DHA supplement (in liquid drops form) per day to have some insurance of adequate DHA levels. Do you know of any reason why this wouldn’t be as effective as taking 200-300 mg every 2 to 3 days per “Option B” of your DHA Supplement recommendations? The reason for my 100 mg/day preference is that I seemed to get a strange reaction when I tried taking a 200 mg dose all at once — it felt like the fat in that dose was too much for my body to handle and made me feel fat.

    Thanks,

    Joe

  21. Jack Norris RD Says:

    Joe,

    The amount of fat in a DHA supplement is almost nothing – it won’t make you fat. That said, if you’re uncomfortable taking it, then taking less sounds like a decent plan.

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