4 Sneaky Signs You Might Need a Multivitamin

Registered dietitians explain the signs of nutrient deficiency and when it may be time to start taking a daily multivitamin.

Eating a healthy diet is one of the best ways to support your overall health. A well-balanced diet based on whole foods will provide the vitamins, minerals and other essential nutrients that support your well-being. Still, Americans are missing out on several nutrients, including calcium, potassium, fiber and vitamin D, all considered nutrients of concern by the Dietary Guidelines for Americans. This may explain why daily multivitamin supplements (and multivitamin-mineral supplements or MVMs) are the most common dietary supplements used by all age groups in the U.S. to fill nutritional gaps, according to the Centers for Disease Control and Prevention.

"Multivitamins can be useful for people who have difficulty eating a balanced diet, have nutritional needs higher than what they can eat or have difficulty absorbing nutrients," says Kelsey Kunik, RDN, nutrition advisor for Zenmaster Wellness.

But how do you know when you need to take a multivitamin? Are they safe to take daily? What are the signs of nutrient deficiencies? Here, we dive into the science behind multivitamins and MVMs, plus five sneaky signs you might need to take them.

What Is a Multivitamin and Is It Good for You?

Multivitamins and MVMs are dietary supplements that help people satisfy their body's requirements for vitamins, minerals and micronutrients vital for good health. "Multivitamins are meant to be taken regularly to correct any nutrient deficiencies or to help ensure you're getting all the micronutrients your body needs," explains registered dietitian Brittany Lubeck, M.S, RD. "Typically, they're taken orally as a gummy, capsule, tablet, chewable or powder." Essentially, taking a multivitamin serves as a nutritional insurance policy.

However, the dietary supplements industry is largely unregulated in the U.S., since the Food and Drug Administration isn't legally required to approve dietary supplements for safety before consumption. That means there are no standards for what's inside your multivitamin. Fortunately, many brands seek voluntary approval through third-party agencies like USP and NSF International. "With a seal from these and other third-party agencies, you know that the supplement contains what it claims," says Lubeck.

4 Signs You Might Need a Multivitamin

Nutrient deficiencies can be tough to spot. But these are some under-the-radar clues that may suggest you need a multivitamin.

You May Have Poor Nail Health

The National Institutes of Health explains that iron is essential for producing hemoglobin, a protein in red blood cells that carries oxygen throughout your body for energy. Falling short of iron can lead to several health issues, including a nail abnormality called koilonychia. Signs of koilonychia are thin, brittle, spoon-shaped nails. If you have spooning of the nails (raised edges that are scooped outward like a spoon), you be among the 25% of people globally who have anemia, half of which is caused by iron deficiency, per StatPearls.

You May Have Impaired Night Vision

Night blindness and cloudy vision are potential signs of a vitamin A deficiency. Vitamin A plays a crucial role in your vision, allowing you to view the full spectrum of light, reports the American Academy of Opthalmology. Without adequate vitamin A, your eyes cannot produce the pigments required for proper retinal function, leading to night blindness and impaired vision. Additionally, vitamin A is essential for helping your eyes produce enough moisture to keep them lubricated and healthy. Vitamin A deficiency in the United States is rare; however, according to the NIH, children and adults with gastrointestinal disorders, such as irritable bowel disease, and those with cystic fibrosis or pancreatic insufficiency may be at risk for inadequacy.

You May Have Cracked Corners Around Your Mouth

Angular cheilitis, a condition characterized by painful cracks at the corners of the mouth, is associated with several nutrient deficiencies, according to 2023 information from StatPearls. These deficiencies include iron, zinc and B vitamins such as folate, riboflavin and B12. Luckily, proper oral or topical antibiotic treatment improves angular cheilitis within a few days, with full healing in two weeks. Of course, you'll also need to correct any nutrient deficiencies at the root of the problem.

You May Bruise Easily

Have you noticed you bruise easily and that the bruises take a long time to heal? If so, you may lack vitamins C and K, says the NIH. Vitamin C deficiency can cause weak blood vessels due to insufficient collagen production, resulting in easy bruising, per StatPearls. Vitamin K is essential for blood coagulation and clotting after injury. According to the Merck Manual, inadequate vitamin K levels can lead to easy bruising.

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Frequently Asked Questions

Is it OK to take a multivitamin every day?

While it's generally safe to take a daily multivitamin to ensure nutritional adequacy, most people who eat a healthy, balanced diet don't need them. Before starting any new supplement, "always check with your doctor, especially if you have nutrient deficiencies or any medical conditions that may affect how you absorb and store nutrients," Kunik advises.

Should a healthy person take a multivitamin?

If you're healthy and eating a nutritious, well-balanced diet, don't stress about taking a multivitamin. "Some people like to use multivitamins to help fill nutritional gaps in their diet. If you don't have any nutrient deficiencies, then whether you take a multivitamin is a personal choice," says Lubeck.

Are multivitamins better than individual vitamin supplements?

Depending on your needs, you may need to take individual supplements instead of a multivitamin. Individual supplements often supply more of a specific nutrient than in a multivitamin. For example, you may opt for a vitamin D supplement during the winter when there's less sunlight. Another example is that many people following a vegan or vegetarian diet may require vitamin B12 supplementation, as it's a nutrient most commonly found in animal products.

How do you know if your multivitamin is working?

The best way to know if your multivitamin works is to get bloodwork done to examine the levels of various vitamins and minerals in your body. "You should be able to tell if your multivitamin is working based on whether any physical signs of nutrient deficiencies have resolved," says Lubeck. "If you continue to experience signs of a deficiency after using a multivitamin for some time, it may not work," she says.

The Bottom Line

Recognizing the signs and symptoms of nutrient deficiencies is critical for knowing when to take a multivitamin. While these dietary supplements are generally safe and can help ensure adequate nutrition, they are not necessary for everyone. A daily multivitamin will offer little benefit if you eat a healthy, balanced diet centered around whole foods. Speak with your doctor or registered dietitian about taking dietary supplements if you have digestive issues, food allergies, a lack of appetite or are pregnant.

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