Will A Multivitamin A Day Keep The Doctor Away?
Author: Dr. Stephen Chaney
Junk foods and convenience foods have become the American way. We are perhaps the most overfed and undernourished country on the planet. Even worse, we are exporting our unhealthy lifestyle to the rest of the world.
Because of the foods we eat experts estimate that only somewhere between 3% and 10% of us get the nutrients we need on a daily basis. For the vast majority of Americans who are undernourished, multivitamin use helps us fill the nutritional gaps in our diet.
But could multivitamin use do more than just fill nutritional gaps? Could it also help us protect our health? Could multivitamins reduce heart disease risk? Here things get a bit murky. We are confused by conflicting headlines. One day the headlines blare that multivitamins are placebos. They are useless. They are a waste of money. The next day the headlines claim that multivitamins are panaceas that can help protect us from heart disease, cancer, diabetes, and whatever else ails us.
In this week’s Health Tips From the Professor, I will review the latest study claiming that multivitamin use reduces heart disease risk and help you put that study into perspective.
Do Multivitamins Reduce Heart Disease Risk?
The current study (Rautianinen et al, Journal of Nutrition, doi: 10.3945/jn.115.227884, 2016) was a re-analysis of data collected in the first Physician’s Health Study between 1982 and 1995. That study was originally designed to test the effect of aspirin and/or beta-carotene on heart disease and cancer. It enrolled a total of 22,071 male physicians over the age of 40 and followed them for an average of 12.2 years. The conclusions of the initial study were that aspirin use decreased cardiovascular risk while beta-carotene had little effect on either heart disease or cancer.
However, the study also collected data on a wide range of lifestyle factors (including diet and supplement use) and clinical outcomes, so it has provided a valuable database for many subsequent studies, including this one.
This study analyzed a subset of the population (18,530 male physicians) that did not have any sign of heart disease or cancer at the beginning of the study and looked at the effect of multivitamin usage on several cardiovascular disease outcomes including:
- Non-fatal heart attacks
- Non-fatal strokes
- Death due to cardiovascular disease
- Total cardiovascular events (the sum total of the previous three events)
Here were the results of the study:
- When the authors simply asked whether the participants were using multivitamins or not at the beginning of the study, multivitamin use had no effect on any of the cardiovascular disease outcomes listed above. These results are similar to several similar studies.
- However, when the authors compared those who had been using multivitamins for 20 years or more at the beginning of the study to non-users, long term multivitamin use was associated with a statistically significant 44% decrease in total cardiovascular events.
- When the authors looked at each of the individual cardiovascular disease outcomes (heart attack, stroke, and death due to cardiovascular disease) there was a similar percentage decrease when comparing 20+ year multivitamin users with non-users, but there were not enough people in each of these individual categories for the differences to be statistically significant.
The authors concluded that their study suggests that “multivitamin use over a long duration may be associated with a lower risk of major cardiovascular events” but that further studies are needed because of the low number of long-term multivitamin users in the study.
Putting This Study Into Perspective
There are several clinical studies looking at the effect of multivitamin use on cardiovascular outcomes that have come up empty handed. However, there are an equal number of clinical studies that have shown a positive effect of multivitamin use on cardiovascular outcomes, at least under certain conditions and with certain population groups. For example:
- The Physician’s Health Study II (Sesso et al, JAMA 308: 1751-1760, 2012) showed no overall effect of multivitamin use on cardiovascular disease. However:
- For those physicians who had a prior history of heart disease, multivitamin use was associated with a 44% reduction in the risk of heart attack. So, in this case multivitamins were shown to reduce heart disease risk.
- There was a significant effect of age, with physicians who were 70 or older showing a stronger effect of multivitamin use on the reduction of overall cardiovascular disease.
- This study did not ask how long the participants had been using multivitamins prior to the study so it could not assess the effects of long term multivitamin use.
- Other studies suggest that long-term multivitamin use could also reduce heart disease risk in women. For example:
- The Washington State study (Pocobelli et al, American Journal of Epidemiology, 170: 472-483, 2009) found that 10 years of multivitamin use was associated with a 16% decrease in cardiovascular mortality among women.
In short, the available data suggest that the benefits of multivitamin use are most likely to be apparent with those who are at highest risk of having a heart attack because of age or pre-existing disease as well as those who have been using multivitamins for decades, not just a few years.
Multivitamins And Heart Disease Risk: Placebo Or Panacea?
If you just read the headlines you have every right to be confused. Some headlines claim that multivitamins are just placebos. They are a waste of money. Other headlines seem to suggest that multivitamins are panaceas that will prevent everything from heart disease to cancer and diabetes. As usual, the truth lies somewhere in between.
Let’s start with the obvious. If you are in great health, have a heart healthy diet and lifestyle, and do not have a genetic predisposition to heart disease, your chances of having a heart attack, stroke or other forms cardiovascular disease are very low. A multivitamin might benefit you in other ways, but it is unlikely to significantly reduce your already low risk of heart disease. Many of the subjects in previous studies fall into this category, which is why many of those studies come up empty handed.
The people who are most likely to benefit from multivitamin use are those who have a poor diet, or are at increased risk of heart disease because of genetic predisposition, pre-existing disease or age. None of the studies to date have looked at groups with poor diets or genetic predisposition to see whether multivitamin use did reduce heart disease risk. The one study that did look at groups who were older or had pre-existing disease found a beneficial effect of multivitamin use in those groups.
The recent study, along with several other studies, also suggests that it may require decades of multivitamin use to significantly impact heart disease risk. That makes sense. Heart disease doesn’t just happen overnight. It takes decades to develop, so it is only logical that it might also require many years of multivitamin use to significantly impact heart disease risk.
If so, this highlights a very serious flaw in those studies reporting no effect of multivitamin use on heart disease risk. Most of the negative studies only inquired about multivitamin use at the beginning of the study. They did not ask how long those people had been using multivitamins. If you ignore the long term multivitamin users, you are very likely to get a negative result.
The study featured in this article (Rautianinen et al, Journal of Nutrition, doi: 10.3945/jn.115.227884, 2016) is a perfect example. The group who had been using multivitamins for 20+ years had a 44% decrease in heart disease risk. However, this group represented only 5% of the multivitamins users. The size of this group was not large enough to influence the overall results. Consequently, when the authors of the study looked at multivitamin users as a whole, there was no significant effect of multivitamin use on heart disease risk.
The Bottom Line
The question of whether multivitamin use could reduce heart disease risk has been contentious in recent years, with some studies claiming that multivitamin use has no effect, and other studies suggesting that multivitamin use significantly reduces heart disease risk. A recent study helps provide a better understanding of why previous studies have reported such conflicting results.
- This study found that when you just asked whether people were using multivitamins or not at the beginning of the study, there was no significant effect of multivitamin use on heart disease risk – in agreement with all of the previous negative studies. That is because those studies did not take into account the length of multivitamin use.
- However, when the authors of the study looked at the subgroup who had used multivitamins for 20 years or more, they had a 44% decreased risk of heart disease compared to non-users. It turns out that most of the previous studies reporting a beneficial effect of multivitamin use on heart disease risk also focused on long term multivitamin users.
- Previous studies have also suggested that multivitamin use may significantly decrease heart disease risk for people at increased risk of heart attack, either due to age or pre-existing heart disease.
- Taken together these studies suggest that long term multivitamin use may reduce your risk of heart disease. Even short term multivitamin use may be beneficial if you are at increased risk of heart disease.
- Of course, multivitamin use is just one piece of the heart health puzzle. For the NIH’s recommendation for a heart healthy lifestyle, click a heart healthy lifestyle.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.