Do Multivitamins Work and How Do You Know If You Need One?

My mother-in-law (a retired nurse and dietitian) used to say that in the U.S., we have some of the most expensive pee in the world. We’re taking so many vitamins and minerals to stay healthy and then urinating those pricey supplements right out.

In truth, the absorption of nutrients via a daily multivitamin depends on a host of factors, including the quality of the supplement, whether you have certain diseases that prevent the absorption of nutrients, and the type of vitamin and mineral.

The effectiveness of multivitamins is a topic of ongoing research and debate in the nutrition and medical communities. Whether multivitamins work depends on several factors, including an individual's dietary needs and health status. Here are some key considerations:

For individuals with specific nutrient deficiencies, multivitamins can be beneficial in replenishing those nutrients. They are particularly useful for people with dietary restrictions, certain health conditions, or those who have difficulty absorbing nutrients.

There's mixed evidence regarding the role of multivitamins in preventing chronic diseases. Some studies suggest a potential benefit, while others show minimal or no effect. For most people with a balanced diet, multivitamins might not provide significant health benefits.

Read More: Multivitamins Don't Work. Here's Why so Many People Still Take Them

According to the National Institutes of Health, an analysis found that about a third of the adult population reported taking a multivitamin in the past 30 days. Overall, women are about 6 percent more likely to take a multivitamin compared to men.

It’s understandable. We lead busy lives, and sometimes, it’s hard to know whether we eat the fruits and vegetables necessary to stay healthy. At the same time, it’s also questionable whether the vitamins and nutrients that we get in a pill, gummy, or gel cap are even absorbed in the body. And, more importantly, whether we needed to take them in the first place. 

Read More: Dietary Supplements Are No Substitute For a Healthy Lifestyle

According to the Harvard TH Chan School of Public Health, a number of diseases are caused by a lack of nutrients. Some result from not getting enough of certain nutrients, and some because the body is not absorbing those nutrients.

One of the most well-known is scurvy, a disorder caused by a lack of vitamin C. The illness can cause bleeding under the skin, infection, anemia, slow wound healing, changes in personality, and even death. Some of the earliest examples date back to 3800 BCE, in the damaged bones of a young Egyptian child.

Other nutrient deficiency diseases include rickets, caused by a lack of vitamin D, pellagra (low B-3), and peri peri (low B-1). However, these diseases are relatively uncommon in modern society due to the availability of healthy foods. Although there are still rare cases of rickets in malnourished children. 

Read More: What You Need to Know About Vitamin D and Supplements

If you’re pregnant, you should be taking a prenatal multivitamin because of the risk of nutrient deficiencies, the most important of which is folate. A folate deficiency can cause spina bifida or anencephaly in infants. If you’re breastfeeding, you should continue to take your prenatal multivitamin because breastfeeding can cause several nutrient deficiencies as your body tries to produce nutrient-rich milk for your baby.

Older individuals who take a number of medications that can impact the absorption of certain nutrients and can also have a reduced diet should consider taking a multivitamin. Those with Celiac disease may also have issues absorbing certain nutrients. This is also true of those with alcoholism, which hinders the absorption of vitamins B and C.

Generally speaking, if you’re committed to a healthy diet that includes the foods listed above, you don’t necessarily need a multivitamin. As my mother-in-law once said, it might just be adding dollars to your urine. Still, there are a number of cases where there’s no harm in taking one. And if you’re pregnant or thinking about getting pregnant, a good prenatal multivitamin is a necessity.

For the general population, research has shown that taking a multivitamin does not reduce the risk of heart disease, cancer, and cognitive decline, and they should not be used as a shortcut to good health.

Read More: What You Should Know About Magnesium Supplements

A multivitamin is not a good substitute for eating a healthy diet that’s loaded with ample produce (aim for 2-3 cups of fruits and vegetables daily), as well as legumes, whole grains, and fatty fish as a source of protein and omega 3 fatty acids. 

In some cases, yes, multivitamins can cause diarrhea. High doses of certain vitamins, like vitamin C or magnesium, can lead to diarrhea. Also, if the body is sensitive to certain ingredients in the multivitamin, it can make the gastrointestinal upset.

There's no one-size-fits-all answer, as it depends on individual nutritional needs and health goals. Some people may benefit from long-term use, while others might only need them for a short period to address specific deficiencies. It's best to consult with a healthcare provider for personalized advice.

Nausea can occur if multivitamins are taken on an empty stomach, or if they contain certain ingredients that irritate your stomach. Iron, in particular, is known to make the stomach upset in some individuals. Taking your multivitamin with food can often help reduce nausea.

Yes, it's possible to overdose on multivitamins, especially with vitamins A and D that can accumulate in the body. Overdosing can lead to a range of health issues, depending on which vitamin or mineral is consumed in excess.

The time it takes to notice effects from multivitamins can vary. Some people may feel a difference in energy levels or general well-being within a few days, while for others, it might take several weeks or months, especially if the multivitamin is addressing a specific deficiency.

There's limited evidence linking multivitamins and acne. However, certain ingredients in some supplements, like B12, can potentially affect skin health in susceptible individuals. It's not a common side effect and may depend on individual skin sensitivity and the composition of the multivitamin.

Read More: Your Guide to B12 Supplements: Everything You Need to Know About Them