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The Great Multivitamin Debate

Posted Oct 14 2011 12:52am


If you have been watching the news, talking to colleagues, or reading blogs you have likely heard the news: Multivitamins are apparently going to kill you.  Reports such as this are exactly why I began to write this blog years ago.  A study is released, the abstract is read, and conclusions are glorified.  But one thing all good health journalists should know is that you always read the study in it’s entirety, and not just the abstract.  Or if you do read the entire study, try not to scare everyone with sensationalized headings to grab attention.


Before I go further let me say that I am always in favor of food before supplements.  There are those who can obtain nearly all the nutrients they need from a healthy diet.  But there are also those who need supplementation in cases of deficiency, certain disease states or stages of life when absorption of nutrients is interrupted or decreased. 


I read the study ( and you can too by clicking here ) to learn a bit more about the science behind the headlines.  This research has several good things going for it: 1) It is published in a well-respected peer- reviewed journal and 2) The sample is a well known cohort (or group) that has been followed for a long period of time.


The study looked at self-reported vitamin and mineral supplementation in relation to mortality in participants (majority white women) of the Iowa Women’s Health Study.  Over a period of almost 20 years women filled out questionnaires three times regarding demographics, food intake, and supplement use.  From this data the researchers found that the use of multivitamins, B6, folic acid, iron, and copper were associated with an increased risk of death.  This was especially true for iron for which a dose-response was observed (meaning more iron meant higher risks).  There was also an associated decreased risk of death for those who took calcium supplements.


After reading the above information you are likely ready to throw-out your vitamins but before you do so, read on.  The big weakness of making rash judgments from these conclusions is that this research stems from what is known as an “observational study”.  What does this mean?  Unlike a clinical trial where the environment, dietary intake etc. is controlled by the researcher, the multi-vitamin study conclusions are all based off of self-reported data with no way to control the lives of the participants.  And while the researchers did attempt to control for big differences such as age, education level, existing co-morbid conditions, think of all the potential differences between these women ( see David Katz’s piece for the Huffington Post for more on this ).  Because this is an observational study we cannot make cause-and-effect statements (like multi-vitamins cause death) but we can suggest an “association”. 


For example, in the concluding comments the researchers stated: “We cannot rule out the possibility that the increase in total mortality rate was caused by illnesses for which use of increased iron supplements is indicated” and “An intermediate event such as CVD or Cancer, can induce a change in supplement use and confound the exposure-outcome association”.  Or in other words we don’t know if the women got sick with an illness such as cancer or heart disease during the years of this research and as a result began taking a supplement.


The other item of note is that the actual increased risk observed was a 2% greater risk over 18 years.  Not very high.  And the average age at the beginning of the study was 61 years. 


Observational research is interesting and important.  It opens the door to further research where we may be able to see cause and effect.  Also, some of our great public health campaigns have been implemented after findings from observational research so we should pay attention to these findings and see what further research can tell us.  If only the media would present all sides to the findings we wouldn’t have a general public that gets thrown around with the latest nutrition news. 


Now onto local news.




Last weekend we spent the day picnicking  in Tomalas Bay/Point Reyes for my father-in-law’s birthday.  The rain let up just in time for the perfect beach day.


We found a little cove at Millerton Point






Along with the bread, cheese, and prosecco, I made a simple caprese salad with tomatoes, fresh basil, skim mozzarella and topped with olive oil and balsamic vinegar.




But the real star of the show were these beauties:




We picked up fresh, raw oysters from Hog Island Oyster Co . on our way.  From the Hog Island website:

Location is key to growing delicious, healthy oysters.  Forty-nine miles north of San Francisco, Tomales Bay is a pristine estuary where coastal rivers flow into the Pacific Ocean. Extreme tides and cold, clean, brackish waters create an oyster’s paradise.

Today, Hog Island Oyster Farm leases 160 acres in Tomales Bay where we raise over 3 million Pacific, Kumamoto and Atlantic oysters per year as well as Manila clams and mussels.

As advocates for the oceans and environment, we are proud that Hog Island oysters and shellfish are on the super Green List of sustainable seafoods: good for you and good for the oceans!”


Raw oysters have been a relatively new addition to my life but our relationship has blossomed.  When ordering at a restaurant I love to eat oysters with the classic mignonette so I made some to bring to our picnic.  I had to adjust the recipe to fit ingredients that I had but it was perfect:


Caitlin’s Mignonette

1/4 cup red wine vinegar
1/4 cup white wine vinegar
1 shallot, peeled and finely diced
cracked black pepper to taste




We used make-shift shucking tools (flat-headed screw drivers) and while there were a few injuries (nothing that couldn’t be solved with a band-aid) the combination of sunshine and company (and an generous dose of raw oysters) was the ideal way to celebrate a birthday and the warmth of an autumn afternoon.


Do you take multivitamins?  How do you feel about this study?  Do you like oysters?

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