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 In so many other words, he implied that the new 600 IU/day recommendation paid too much respect to an old, outdated and arbitrary recommendation.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.