Written by Karen Asp

They’re invisible to the naked eye, but vitamins play a major role in your body’s functions.[1] They provide the nutrients you need to stay healthy, fit, and strong.

Vitamins are so important, in fact, that being low in even one nutrient could have an impact on your health. That’s because your body’s ability to heal, repair, and defend itself from illness depends on a precise mix of vitamins. And even if you don’t get sick, a deficiency in one area (or multiple ones) can affect the way you feel.[1; 2; 3]

“In the patients I see, at least one vitamin deficiency is relatively common,”[3] says Eudene Harry, M.D., a medical lifestyle expert and medical director for Oasis Wellness and Rejuvenation Center in Orlando, Florida.[3; 4]

If you suspect you have a vitamin deficiency (we’ll get into that below), get tested sooner rather than later, either with an at-home test or by seeing your provider. In some cases, you may be prescribed medications or supplements to remedy the deficiency.[1; 2; 3]

Certain foods can also help boost your levels of various essential nutrients. So even if you don’t have a known or suspected deficiency in one or more vitamins, it’s a good practice to eat a diet rich in the five vitamins below.[1; 2; 3]

Here’s how to spot whether you have a vitamin deficiency, the foods that can potentially help, and ways to test your levels from the comfort of home with LetsGetChecked’s vitamin tests.

Related article: What I Learned by Taking a Home Vitamin Test

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Monitor vitamin levels to help identify nutritional deficiencies with our at-home test.

Essential Nutrient #1: Vitamin D

Why it’s important: Your body needs vitamin D to absorb calcium, which is critical to maintaining bone health and lessening your risk of osteoporosis. Vitamin D also plays a role in optimizing your immune function,[19] says Samantha Cassetty, RD,[20] an advisor to Performance Kitchen,[20; 21; 22] a Seattle-based meal service that specializes in frozen meals made from whole food ingredients inspired by the Mediterranean diet.[21; 22] Past studies have shown that people with low levels of vitamin D are more likely to catch a cold or the flu.[23]

How to spot a deficiency: Many people are unaware that they’re low in vitamin D,[25] largely because they haven’t been checked, Cassetty says.[20] This can now be done through a simple at-home vitamin D test. Clues include muscle weakness or bone pain or fatigue. You might also be susceptible to weak and brittle bones (and ultimately osteoporosis).[19; 20]

Foods that help fix it: Vitamin D is found in only a handful of foods, which is one reason it’s a common deficiency. Reach for fortified milk and orange juice, salmon and egg yolks, as well as mushrooms (of all kinds) that have been exposed to UV light.[19; 20; 25]

Your body also manufactures vitamin D when it’s exposed to sunlight, but lifestyle factors can interfere with this process, the National Institutes of Health notes. Living in a northern climate, wearing sunscreen (even though it’s advised to prevent skin cancer), and spending a lot of time indoors all limit your sunlight exposure.[19]

Getting the D you need through sunshine and food alone is very difficult,[19; 20; 25] so you may need to take a vitamin D supplement if your levels are low, Cassetty says.[20] A simple blood test can reveal this.

Check your vitamin D levels from home now.

Related article: What Foods Are High in Vitamin D?

Essential Nutrient #2: Vitamin B12

Why it’s important: This vitamin keeps your brain’s neurons as well as your nervous system well-nourished, and it helps healthy red blood cells to form. It also helps your body make DNA.[13]

How to spot a deficiency: Anemia, long-term dementia, confusion, and depression are just some of the symptoms of a B12 deficiency,[13] says Ojai, California–based Sharon Palmer,[14] RDN, author of California Vegan: Inspiration and Recipes from the People and Places of the Golden State.[14; 15; 16] It’s smart to do a B12 test at home, before you even experience symptoms.

Foods that help fix it: You can find B12 in animal-based foods as well as fortified foods like breakfast cereals, nutritional yeast, and plant-based products (think plant milk and veggie burgers).[13; 14] But because as you age your body doesn’t absorb B12 from foods very well,[13; 14] people over age 50 should ask their provider about taking a supplement, Palmer says.

If you’re a vegan or vegetarian, it’s also necessary to rely on a supplement or fortified foods for your B12 fix.

Check your vitamin B12 levels from home now.

Related article: Top Essential Vitamins and Minerals for Vegans

Essential Vitamin #3: Folate

Why it’s important: Folate, also known as vitamin B9, is important for the formation and repair of healthy red blood cells and DNA. One reason that pregnant women are often given folic acid supplements is to prevent birth defects in the growing fetus. Folate can also help keep your heart healthy.[3; 5; 6]

How to spot a deficiency: If you’re deficient in folate, you could develop anemia, which occurs when you don’t have enough red blood cells to carry oxygen and nutrients throughout your body, Dr. Harry says.[3] As a result, you might feel tired, weak, depressed, Or experience mouth ulcers.

Foods that help fix it: If your folate deficiency is pronounced, you may need to take a supplement or medication. But sometimes a folate deficiency can be improved with food, Dr. Harry says,[3; 5] so fill your plate with choices that are rich in folic acid. The list is long: green leafy vegetables (kale, spinach), brussels sprouts, broccoli, asparagus, edamame, lentils, oranges, beans, and avocados. And don’t forget enriched cereals, including Cheerios, Special K, and Corn Flakes.[3; 5] Dietary requirements call for 400 micrograms (mcg) for the average adult.[5] Spinach has about 260 mcg per cup cooked,[5] while edamame has about 450 mcg per cup.[7]

Related article: 5 Common Fertility Myths, Debunked

Essential Nutrient #4: Vitamin A

Why it’s important: Vitamin A plays a critical role in maintaining healthy eyes and mucosal surfaces[8] (mouth, nose, lungs, GI tract, urinary tract, and skin).[9] It can help smooth the skin so that it forms a stronger barrier against the environment.[10]

How to spot a deficiency: Some of the most common symptoms of a vitamin A deficiency include poor night vision and dry, gritty, excessively irritated eyes.[8] Left untreated, it can even contribute to corneal ulcers,[11] making vision difficult, Dr. Harry says.[3] Premature aging of the skin might also be apparent:[3; 8; 10] “You might look older than your [actual] age,” she adds.[3] Vitamin A also helps balance your immune system, so without enough of it on board, you might be prone to getting sick more often than people with normal vitamin A levels.[12]

Foods that help fix it: Vitamin A is found in plants as well as animal foods, Dr. Harry says.[3; 11] Sweet potatoes, carrots, spinach, butternut squash, and bell peppers are rich plant sources of vitamin A,[3; 8; 11] while good animal sources include liver, cod liver oil, salmon, and cheese.[3; 8; 11]. High levels of vitamin A can be harmful in pregnancy, so consult with your doctor if you’re expecting, before changing your diet.

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Buy an At-Home Vitamin Test

Monitor vitamin levels to help identify nutritional deficiencies with our at-home test.


  1. U.S. National Library of Medicine
    Medline Plus

  2. Cleveland Clinic
    8 Vitamins & Minerals You Need for a Healthy Immune System

  3. Eudene Harry

  4. Eudene Harry MD

  5. National Institutes of Health
    Office of Dietary Supplements

  6. Mayo Clinic
    Folate (folic acid)

7.U.S. Department of Agriculture
FoodData Central
Edamame, cooked

8.University of Rochester Medical Center
Health Encyclopedia
Vitamin A

  1. Britannica
    Mucous membrane

  2. Schagen SK, Zampeli VA, Makrantonaki E, Zouboulis CC.
    Discovering the link between nutrition and skin aging.
    Dermato-endocrinology 2012 Jul 1;4(3):298-307

  3. National Institutes of Health
    Office of Dietary Supplements
    Vitamin A

  4. Huang Z, Liu Y, Qi G, Brand D, Zheng SG.
    Role of Vitamin A in the Immune System.
    Journal of Clinical Medicine 2018 Sep 6;7(9):258

  5. National Institutes of Health
    Office of Dietary Supplements
    Vitamin B12

  6. Sharon Palmer

  7. Sharon Palmer

  8. Amazon
    California Vegan: Inspiration and Recipes from the People and Places of the Golden State

  9. Mayo Clinic
    TUESDAY Q & A: Vitamin B-12 deficiency more common with increasing age

  10. Today’s Dietitian
    Vitamin B12 and the Vegan Diet
    Sharon Palmer
    https://www.todaysdietitian.com/newarchives/0418p38.shtml#:~:text=All vegans should take 250,a few times per week.

  11. National Institutes of Health
    Office of Dietary Supplements
    Vitamin D

  12. Samantha Cassetty

  13. Performance Kitchen

  14. Performance Kitchen

  15. U.S. Department of Health and Human Services
    National Institutes of Health
    Research Matters
    Low Vitamin D Levels Associated with Colds and Flu

  16. Mayo Clinic
    Can vitamin D protect against the coronavirus disease 2019 (COVID-19)?

  17. Cleveland Clinic
    Vitamin D Deficiency

  18. National Institutes of Health
    Office of Dietary Supplements
    Vitamin K

  19. Merck Manual
    Consumer Version
    Vitamin K Deficiency

  20. U.S. National Library of Medicine
    National Center for Biotechnology Information
    Vitamin K Deficiency8https://www.ncbi.nlm.nih.gov/books/NBK536983/