Saturday, January 28, 2012

Feature Article: Multivitamins: Healthy Or Deadly?

A controversial study by Mursu, et al was published recently in the Archives of Internal Medicine showing that women who took a multivitamin each day had an increased risk of mortality when compared to women who did not.  The results of this investigation ignited a media firestorm, to say the least.  Since then, I have been getting a ton of questions from my clients on whether or not it is safe to take a multivitamin.  I thought I’d use this blog post to examine the study and give a general, research based recommendation regarding multivitamin use.

The Study
The study in question took a look at risk of multivitamin use and mortality in 38,772 women from the Iowa Women’s Health Study (1).  Women were asked via questionnaire if they were using any supplements and if they were to describe what they were taking and how often.  This question was asked 3 different times over a mean follow-up of 19 years.  This was done to reflect changes in supplement use over the years.  Women taking a multivitamin had a 6% increased risk of mortality when compared to women who did not take a multivitamin.  Here are some of the other interesting findings of this investigation:

B6 supplements were associated with a 10% increased risk of death.
Folic acid supplements were associated with a 15% increased risk of death.
Iron supplements were associated with a 10% increased risk of death.
Magnesium supplements were associated with an 8% increased risk of death.
Zinc supplements were associated with an 8% increased risk of death.
Copper supplements were associated with a 45% increased risk of death.

Calcium supplements were associated with an 8% decreased risk of death.

Was this study methodologically sound?
Overall, this study had a sound methodology.  There was a very large sample size, updated measures of supplement use to reflect changes over time, an adequate follow-up and good control of potential confounders.   However, this study had one major flaw: the researchers didn’t exclude sick women.  This is a major problem because someone who gets diagnosed with a serious medical condition is much more likely to initiate multivitamin use.  God forbid you were diagnosed with cancer today; wouldn’t you want to load up on vitamins and supplements to help treat your disease? 

This oversight is problematic because many of those who are diagnosed with these serious diseases will die from them.  This makes it look like people who are supplementing are dying at a higher rate when in fact, they were sicker from the start.  You can eliminate this problem by excluding people who sick at the beginning of your study.

Previous Research
There are a number of well designed studies in recent years that have shown a benefit with multivitamin supplementation.  These studies show that multivitamins help reduce the risk of coronary heart disease, colon cancer and breast cancer.  Vitamin D supplementation is showing a lot of promise and folate supplementation has done much to reduce the incidence of neural tube defect in pregnant women.  We can’t forget these positive outcomes when assessing the benefits and risks of multivitamin supplementation.

So What’s The Bottom Line?
There has been a good amount of research that shows a benefit to multivitamin supplementation and just a few studies that show potential harm.  Considering that there were methodological flaws in some of the research that showed harm, I feel that the benefits of multivitamin supplementation outweigh the risks for most people.  However, to hedge your bets, I recommend taking a good multivitamin (which includes vitamin D) every other day.  This way you are minimizing the risk while retaining the benefit. This is what I do myself and what I recommend to my clients.  Always keep in mind that any kind of supplement will never replace a healthy diet.

1) Mursu J, Robien K, Harnack LJ, et at. Dietary supplements and mortality rate in older women.  Archives of Internal Medicine 2011; 171(18):1625-1633.

Saturday, January 14, 2012

Research Update: Sugar Consumption And Heart Disease

Low to moderate sugar-sweetened beverage consumption impairs glucose and lipid metabolism and promotes inflammation in healthy young men: A randomized controlled trial. The American Journal of Clinical Nutrition 2011; 94:479-85.

Objective: To examine the association between low to moderate sugar consumption and risk factors for coronary heart disease in 29 healthy young men.

Methods:  This investigation was a crossover trial.  What this means is that the 29 men in this study were put through 6 separate 3 week interventions.  During each 3 week intervention, a 600 ml soft drink beverage was consumed daily with varying sugar content.  Here are the soft drink interventions:

Intervention 1- 40 grams of fructose per day (moderate fructose)

Intervention 2- 80 grams of fructose per day (high fructose)

Intervention 3- 40 grams of glucose per day (moderate glucose)

Intervention 4- 80 grams of glucose per day (high glucose)

Intervention 5- 80 grams of sucrose per day (high sucrose)

Intervention 6- dietary advice to strictly limit fructose.

After each intervention a variety of blood tests were taken, including LDL particle size, LDL subclass, fasting glucose and high sensitivity C-reactive protein.

Results: The results of this investigation were fascinating:

1) LDL particle size was significantly reduced after both the high fructose and high sucrose intervention.  The smaller the LDL particle, the more likely it is to promote atherosclerosis, which in turn increases the risk of heart disease.

2) A more atherogenic LDL subclass distribution was seen with all of the fructose interventions.  This means that the LDL particles became more likely to promote heart disease.

3) Fasting glucose and high sensitivity C-reactive protein increased significantly after all interventions.  C-reactive protein is a measure of body wide inflammation and has been associated with a variety of diseases, including heart disease.

Discussion:  This is an amazing paper that shows that even a moderate consumption of sugar has the potential to increase risk of heart disease.  LDL particle size, subclass distribution, fasting glucose and high sensitivity C-reactive protein all changed for the worse when consuming even moderate amounts of sugar consistently for only 3 weeks.  These are powerful markers for risk of heart disease.

Take Home Message: Drinking sugar sweetened beverages like soda is not a good idea.  It has been known for years that they provide nothing but empty calories and promote weight gain.  Now the research is beginning to mount that they can cause disease as well.  Sugar sweetened beverages are the largest contributor of sugar in the American diet.  Giving them up entirely is a good first step to improving your health.

If you work with me privately or have read my book, you know how I feel about sugar.  After trans fat, I believe it is the most harmful thing one can eat.  It is a difficult concept to accept, but at the end of the day, humans were never designed to eat sugar.  Cutting down on it, or better yet, eliminating sugar entirely, will cause far reaching and dramatic positive changes in your life that I guarantee will surprise you.