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Recap: The 15th Vitamin D Workshop

Posted on: June 26, 2012   by  Kate Saley

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This past week was the 15thVitamin D Workshop in Houston, TX. The Vitamin D Council team flew out on Tuesday morning to begin the festivities.

Wednesday through Friday from 8 to 5 researchers presented studies ranging from the detailed molecular function of vitamin D to epidemiological studies. There were some great speakers and presenters who introduced intriguing findings.

David Feldman and colleagues out of Stanford University definitely caught the attention of a number of researchers in the room. He presented his study in which mice with and without prostate cancer were given different amounts of vitamin D3. The control mice (with no tumors) received 1,000 IU/kg while the mice with cancer received 5,000 IU/kg. The researchers found that the mice with tumors who received 5,000 IU/kg supplementation “exhibited significant tumor shrinkage (>50%).”

Another highlight of the workshop was the vitamin D discussion/ debate on Friday afternoon. The discussion panel consisted of Drs Daniel Bikle, Robert Heaney, Reinhold Vieth, Edward Giovannucci, Roger Bouillon, and Christopher Gallagher. Drs Gallagher and Bouillon both felt that for now, 600 IU/day was the correct recommendation and they wanted to see larger, population wide controlled trials at higher doses before we can recommend higher doses to the public. They also pointed out the logistical challenges in recommending a radically new daily allowance.

On the other side of the debate were Drs Vieth, Heaney and Giovannucci. Heaney felt that in nutrition, an evidence-based approach needs more emphasis on physiology and that not enough respect was being given to the vitamin D levels of nomadic peoples who get plenty of sun exposure.

Vieth emphasized that the traditional 400 IU/day recommendation was an arbitrary figure, not based on evidence, but what they historically put in cod liver oil. In so many other words, he implied that the new 600 IU/day recommendation paid too much respect to an old, outdated and arbitrary recommendation. Furthermore, he pointed out that public recommendations affect Canada much more greatly than the United States with much more stringent laws in healthcare.

Giovannucci called attention to the fact that many important public health recommendations have been made based on our biological knowledge as well as observational data, with limited RCT research, including – tobacco control, body weight, seat belt use, sun avoidance, and alcohol use. He acknowledged the need for RCTs, but also pointed out that RCTs will not give a perfect picture, especially for diseases that take many years to develop. Like Heaney, he questioned if the evidence-based approach used to assess drugs was perfectly fit for nutrition. His argument was an extension of an earlier talk he gave titled, “Vitamin D and health: Are randomized controlled trials the final arbitrator?”

Next year, the workshop takes place in San Francisco. Until then, we’re looking forward to more research and seeing the debate continue on.

5 Responses to Recap: The 15th Vitamin D Workshop

  1. Mary Pittaway

    Hi Kate, There are a growing number of health care providers working in Developmental Medicine, who are interested in communicating about Vit. D issues related to people with cognitive disabilities. How would you suggest we go about organizing such a discussion group? Thanks, Mary Pittaway

  2. Kate Saley

    Hi Mary,
    What are you looking to get out of this sort of discussion group? Spreading awareness, education, advocacy? Thanks.

  3. Jim Larsen

    There are a very large methodological problems in many of these food fights. Folks love to form up into tribes and fight, but the question they’re fighting over is basically the wrong question.

    Imagine arguing whether 3 mg of penicillin 1x/day was good or bad. Or whether such a dose for x weeks would cure cancer.

    Researchers by definition ask very concrete, very limited questions. The results are often framed as Relative Risk or Hazard Ratios. Folks then attempt to say that those limited findings mean we’ve found the Magic Bullet.

    Look at the USPSTF recommendation:”The USPSTF recommends against daily supplementation with ≤400 IU of vitamin D3 and 1,000 mg of calcium carbonate for the primary prevention of fractures in noninstitutionalized postmenopausal women.” Headlines:”D and calcium are no good.”

    Given the 6 fold variability in dose-response relationship with D (Dr. Heaney), it seems ineffective to argue dose X is the Magic Bullet. Like other interventions, we could rationally discuss 75iu/kg/day (better) or serum levels (50 ng/ml)(best).

    Ideally, we’d always place variable X in context with the other contributing variables. Yes, D decreases fall and fractures (relatively), but optimally strong/healthy bones need D in context with 20 other nutrients AND impact exercise. Bones are more than meat hangers.

    This simply highlights the difference between the researcher (isolate one variable) and the clinician (treat the whole person). Or the ethical issues in giving advice to everybody. Does anyone seriously believe that 400 iu and 1,000 mg calcium carbonate will solve all problems without sufficient serum D/calcium levels, B, K, magnesium, impact exercise, etc.?

    Therefore, shouldn’t we all add those caveats to the dialogue?

  4. JBG

    The mouse/prostate cancer study will be of interest when it is published. 5,000 IU/kg implies 350,000 IU for a 154-pound man. That’s a lotta vitamin D (assuming the dose is taken every day). But if it shrinks prostate tumors, that’s a pretty big deal.

    Any idea why mice without cancer were given a different dose? Was it to see if the effect of some cancer-inducing agent could be countered by (a smaller amount of) vitamin D? The human equivalent of even the 1k IU/kg is 70,000 IU for a 154-pound person.

  5. Brant Cebulla

    JBG, I think they used a smaller dose on non-tumor mice because they postulated beforehand that the mice with tumors would use more vitamin D, and they were correct.

    Amazingly, the tumor infested mice who were fed 5,000 IU/kg had the same 25(OH)D level that the 1,000 IU/kg non-tumor mice had, implying that (a) the tumor knew it was being fed vitamin D and (b) it used the vitamin D and catabolized the vitamin D much more rapidly. That being said, Feldman did not offer even a guess at the mechanism going on here.

    I am sure he will be investigating into the mechanism here for the next couple years.

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