Multivitamins – Cheap Insurance or Expensive Urine?

“Supports Bone, Breast and Urinary Tract Health.”
-Jamieson Vitavim for Women

“Helps Maintain Immune Function.”
-Centrum for Men

From these claims on various multivitmains, it’s sounding like taking a multi may lower your risk of cancer and other diseases. Is this true? Are they worth taking to make up for what we don’t get from our diets?

THE RESEARCH: DISEASE RISK

Stroke and Heart Attack

• In the Physician’s Health Study II, they found no evidence overall that taking a multi for more than a decade prevented heart attacks or strokes more than taking a placebo. However, it didn’t increase risk either.
• In the U.S. Multiethnic Cohort Study and the U.S. Women’s Health Initiative cohort, people who said they took a multivitamin were no more or less likely to suffer a heart attack or stroke than those who said they didn’t take one. They also didn’t have a lower or higher risk of cancer.

Cancer

• The Physicians Health Study II found that men taking a multivitamin were 8% less likely than man taking a placebo to be diagnosed with cancer. However this should be interpreted with caution – the lower risk for cancer wasn’t statistically significant for any specific type of cancer. This may be because there may not have been enough cases or detect significant differences, but it’s also possible that the lower risk of cancer in multi takers was due to chance.

THE RESEARCH: FILLING IN THE GAPS

• In a 2000 study by Diane McKay and colleagues, they found a significant boost in blood levels of certain nutrients up to the levels that are associated with a lower risk of disease. Taking a multivitamin can be a pretty convenient way to fill in the gaps that may exist between what you need and what you’re actually consuming.
• According to Health Canada, many Canadians get too little calcium, magnesium, potassium, vitamins A and D and fibre. Other nutrients that some groups especially need include iron, vitamin B-12 and folic acid.

WHAT TO LOOK FOR IN A MULTI:
The following nutritients are difficult to get enough of through food alone for some individuals.

1. Iron: More than 15% of Canadian women are deficient in iron. Females 19-50 need 18 mg of iron daily. Non-meat eaters need 1.8 times this amount
2. Vitamin B-12: Adults 50 years + should get the RDA (2.4 mgs) from fortified foods or a supplement as some older adults don’t make enough stomach acid to separate B-12 from protein in foods. A supplemental form of B12 isn’t bound to protein. Vegans should also get B-12 from a multi or fortified foods because plant foods have no B-12. However B-12 is present in dairy products and eggs, along with meats.
3. Vitamin D: Our bodies ability to convert sunlight into active vitamin D declines as we get older. Also, in the winter sunlight lacks the UV rays that make vitamin D in northern climates. To add to this, there are few foods that are rich in Vitamin D, which means that many people have less than optimal blood levels of vitamin D. Most multis have at least 400 IU of vitamin D – it is recommended that adults < 70 consume 600 IU a day, while adults > 70 consume 800 IU a day.
4. Folic Acid: Women need 400 mcgs of this vitamin early in their pregnancy (and often before a women is pregnant) to reduce the risk of spina bifida and other neural tube defects. However, It is recommended not to consume more than 1000 mcgs of folic acid a day, as any more can mask a B12 deficiency. Most adults get 100-200 mcgs a day from folic acid fortified foods (bread, pasta) so look for a vitamin that provides no more than 400 mcg’s.

What to not look for in a multi: calcium, potassium or fibre are too bulky for a multi

Check this list out to see what a well-balanced multi should contain: 

adapted from Nutrition Action November 2013 Edition

BOTTOM LINE:

• It’s worth taking a multivitamin if it supplies nutrients that may be more difficult to get enough of through food – such as vitamin D or B12.
• Don’t count on a multi to ‘support’ your heart, breast, immune system, skin, colon, brain or anything else.

References:

JAMA 308: 1871, 2012.
AM, J. Epidemiol. 173: 906, 2011.
J. Am. Coll. Nutr. 19: 613, 2000.