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What Vitamins Should You Be Taking? Your Guide to Essential Nutrients

Recommendations for diet and supplements.

Mairi Sutherland

Medically reviewed by


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Key takeaways
  • Age, sex, medical conditions and more may impact your need for additional vitamin supplementation.
  • Eating a balanced diet can provide a proper intake of many required nutrients.
  • Vitamin and mineral supplements are not monitored by the FDA and should be used with caution.

When it comes to keeping our bodies healthy, essential nutrients are just that, essential. These vitamins and minerals help our bodies perform crucial tasks like building healthy blood cells, supporting strong immune function and assisting energy production.1

To maintain adequate levels of these nutrients, many people turn to vitamin supplements — an estimated one-third of all adults in the U.S. take multivitamin supplements (MVMs). In 2020 alone, around $55.7 billion was spent on dietary supplements, $21.2 billion of which was spent just on MVMs.2

However, starting supplements can be overwhelming — if you've ever entered a supplement store, you can picture the daunting selection of herbal supplements, multivitamins, prenatal vitamins and specific vitamins for women or men that are readily available. So, how do you choose the right vitamins, and, more importantly, do you really need them?  

Recommended vitamin intake

Before choosing a supplement, learn your recommended daily allowance (RDA) per nutrient. Your daily intake should be close to your RDA unless otherwise advised by a healthcare professional to prevent vitamin deficiency or toxicity. 

Part of the reason there are so many specific supplements is that the RDA can vary based on sex, age group and health status. Breastfeeding and pregnant women, in particular, should recheck their RDAs as some levels increase to support the growth and development of a baby.  

Vitamin and mineral forms

You may notice that different MVMs have different ingredients; this is because there are many different types of micronutrients. Certain vitamins and minerals are categorized based on how our body processes them, which influences how much we need daily:

  • Water-soluble vitamins (vitamin C and all eight B vitamins): As the name suggests, these vitamins dissolve in water, pass through your body and cannot be stored easily. As a result, you must constantly replenish your body's supply. Since many foods contain these vitamins, a lack of water-soluble vitamins is rare in North America.3
  • Fat-soluble vitamins (A, D, E and K vitamins): Unlike water-soluble vitamins, these can be stored in your fatty tissue and liver.4 Fat-soluble vitamins are found in various high-fat foods, relying on your body's ability to absorb fats, so individuals with gastrointestinal conditions may struggle with malabsorption issues.5
  • Macrominerals (calcium, sodium, potassium, magnesium, chloride and phosphorus): These are considered the major minerals since your body requires large daily doses of each, ranging from 0.3 to 2.0 g.6
  • Microminerals (chromium, copper, fluorine, iodine, iron, manganese, molybdenum, selenium and zinc): Also called trace minerals or elements, your body only requires small (or trace) amounts of microminerals daily.7

Dietary sources of vitamins

Let's push aside the various containers of gummy vitamins, supplements and other daily vitamins for a moment — did you know that a balanced diet is actually an excellent source of many key nutrients? Being mindful of the different food groups and consuming a healthy variety of food sources is a natural way to reach your intake of essential nutrients.

According to the U.S. Department of Agriculture, here is a range of recommended daily amounts for each food group, though more exact amounts will vary by age:

  • Whole grain products: 3 to 4 oz-equivalents (women), 3 to 5 oz-equivalents (men)8
  • Fruits: 1.5 to 2 cups (women), 2 to 2.5 cups (men)9
  • Vegetables: 2 to 3 cups (women), 2.5 to 4 cups (men)10
  • Protein foods: 5 to 6.5 oz-equivalents (women), 5.5 to 7 oz-equivalents (men)11
  • Dairy products: 3 cups (women and men)12

Important vitamins

Now that we've established a baseline understanding, here are some important nutrients to pay attention to (complete with their RDAs and food source inspirations):

Vitamin D

Vitamin D is essential for bone health as it helps with phosphate and calcium absorption.13 It also assists your immune system, muscle function and nervous system.14 Understandably, vitamin D deficiency is linked to weak bone conditions like rickets, osteomalacia and osteoporosis.15 As such, older adults are often advised to take a vitamin D supplement because age increases the risk of bone weakness.16

RDA of vitamin D:17

  • Adults (19 to 70 years): 15 mcg (600 IU)
  • Adults (71+ years): 20 mcg (800 IU)

Dietary sources:18

  • Wild mushrooms 
  • Protein sources like oily fish, egg yolks and red meat
  • Vitamin D-fortified foods like milk, plant-based milk alternatives or breakfast cereal

Vitamin D is one nutrient that is difficult to obtain from food alone, so if you're concerned about your vitamin D levels, consider measuring them with imaware's at-home Vitamin D Monitoring Test. In the meantime, step into direct sunlight (with sun-safe precautions in mind) and let your body synthesize vitamin D3.19

Speaking of which, you can't get "too much" vitamin D from the sun because your skin limits the amount it makes. Very high levels of vitamin D (greater than 150 ng/mL) are almost always caused by consuming too much vitamin D from dietary supplements, so be sure to speak to your healthcare provider about dosages to avoid potentially harmful side effects. As a general rule of thumb, the daily upper limit for adult vitamin D intake is 100 mcg (4,000 IU).20


Iron is vital to your body's ability to produce healthy red blood cells and maintain hormone production.21 Studies have also linked iron deficiency and overload to bone fragility,22 so identifying the right amount for you is paramount for strong bones. Women generally need more iron, with individuals who are menstruating, pregnant or breastfeeding at a higher risk of anemia and often requiring additional iron supplementation.23

RDA of iron:24

  • Adult men (19 to 50 years): 8 mg
  • Adult women (19 to 50 years): 18 mg
  • Adults (51+ years): 8mg
  • Pregnant: 27 mg
  • Breastfeeding: 9 or 10mg

Dietary sources:25

  • Heme iron is in red meats, poultry, and fish
  • Non-heme iron is in eggs, beans, lentils, nuts and dark leafy greens (and if you prefer non-heme sources, consuming more vitamin C is recommended to help maximize your absorption)

While iron deficiency is more common, your bloodwork may indicate that your serum ferritin (iron-storing protein) levels are elevated, in which case excessive dietary intake and iron supplements might do more harm than good. The American Association for the Study of Liver Diseases, for example, recommends that treatment of hemochromatosis (excessive buildup of iron in the body) include avoiding both iron and vitamin C supplements.26


Calcium is one of the bone-supporting nutrients responsible for strong bones and teeth. It also helps your nervous system, muscles, hormones and blood vessels. Like vitamin D, calcium deficiency can lead to weak bones and conditions like osteoporosis. Postmenopausal women or women over 50 years of age are typically advised to have a higher calcium intake as the body seems to absorb and retain less calcium after menopause.27

RDA of calcium:28

  • Adults (19 to 50 years): 1,000 mg
  • Adult men (51+ years): 1,000 mg
  • Adult women (51+ years): 1,200 mg

Dietary sources:29

  • Milk, cheese, yogurt and lactose-free dairy products
  • Fortified plant-based milk alternatives
  • Products of fortified flour like bread
  • Dark green vegetables like spring greens, broccoli, and kale

Getting enough calcium between natural food sources and fortified products is easy without additional interventions. However, vegans and other individuals who do not consume dairy should know that fortified plant-based dairy alternatives do not carry as much calcium as regular dairy.

Conversely, too much of a good thing – like excessive calcium – poses some risks. Hypercalcemia (serum levels greater than 10.5 mg/dL) and hypercalciuria (urinary calcium levels higher than 250 mg/day in women and 275 mg/day in men) are rare in healthy people, but it is still a risk worth noting. Although not all studies confirm it, high calcium intake might also increase the risk of cardiovascular disease and prostate cancer.30


As the name suggests, there are three forms of omega-3s: alpha-linolenic acid (ALA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA).  

Omega-3 fatty acids are crucial for cellular health as they make parts of the membranes surrounding the cells in your body. They provide your body with energy and support your heart health, immune system, lungs and skin health, with DHA being particularly important for your brain and eye health.31 Common symptoms of low omega-3s are rough, scaly or itchy skin.32

RDA of *ALA:33

  • Adult men (19+ years): 1.6 g
  • Adult women (19+ years): 1.1 g

*Note: There are no established recommended amounts for EPA and DHA, though the U.S. Food and Drug Administration recommends consuming no more than 5g/day of EPA and DHA combined from dietary supplements.

Dietary sources:34

  • Fish and fish oil
  • Nuts and seeds like walnuts or flax seeds
  • Specially fortified brands of eggs, milk or bread

Adding fish to your weekly diet is a great way to increase your omega-3s (and avoid the unpleasant burps caused by fish oil capsules — we've all been there). 

Outside of food sources, more fish oil is not always better. Be sure you are familiar with the potential side effects of consuming excessive amounts of omega-3 fatty acids.35 If you experience any adverse symptoms from supplements, decrease your intake and discuss your dosage again with your healthcare provider. Ultimately, your goal should be to get most of your omega-3s from food sources for the best nutritional gain.

Vitamin B2

Vitamin B2, or riboflavin, is an essential nutrient that helps create cells and turns food into energy.36

A vitamin B2 deficiency can impact your ability to digest various essential micronutrients, but fortunately, it is rare in the United States.37 Those at higher risk of low B2 levels are vegetarians and vegans due to vitamin B2's primary presence in animal products.

RDA of vitamin B2:38

  • Adult men (19+ years): 1.3 mg
  • Adult women (19+ years): 1.1 mg

Dietary sources:39

  • Eggs, lean meats and livers
  • Milk, yogurt and cheese
  • Spinach and portabella mushrooms
  • Fortified products like breakfast cereals, oats and quinoa

Fortunately, you can typically get your daily intake of vitamin B2 with a strategically balanced diet. However, since vitamin B deficiencies are more common in older adults, vitamin B testing and supplementation may be advised if you are over 50.

Toxic levels have not been observed from food sources or supplements as your body generally excretes any excess via urine (though you may notice your urine turn bright yellow if you take B2 supplements).40

Are dietary supplements safe?

If you plan on consuming dietary supplements, remember to use them appropriately. As previously mentioned, taking too much or taking something that doesn't interact well with other medications are just some of the potential dangers.41

It's important to note that vitamins and supplements are unregulated by the FDA. Unlike other drugs, they aren't monitored for composition, quality control, safety or effectiveness. There are some private organizations, like, NSF International and U.S. Pharmacopeia (USP), that test certain supplement brands using submissions from manufacturers and spot checks from retail stores. But the onus is on consumers to understand what they're stocking in their medicine cabinet.

Before taking a supplement, consider measuring your nutrient levels to confirm your needs, researching the product using a verified source and talking to your healthcare provider about any health concerns. For example, your age or health status — like poor dietary intake, issues with malabsorption or inadequate synthesis of vitamin D — may determine whether you will benefit from supplementation of key vitamins. 

Everyone is different, and supplements, even specific categories like multivitamins for men or supplements for women, can affect people differently. A multivitamin might seem like the best way to cover all your bases, but each type contains a different combination of vitamins, minerals and amino acids that you may or may not need. 


If you're wondering what supplements to begin taking, remember that one of the best ways to maintain a healthy level of vitamins and minerals is to eat a balanced diet. Advanced age, pregnancy and chronic medical conditions may increase your recommended intake and need for supplementation. Certain nutrients, like vitamin D, may also require additional sources, but always be cautious when taking dietary supplements.

If you're worried about your intake of essential vitamins or think you have a nutrient deficiency, start by speaking to a healthcare professional.

Updated on
February 22, 2024
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  2. National Institutes of Health. Multivitamin/mineral Supplements - Health Professional. Accessed February 5, 2024.
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  40. Harvard T.H. Chan School of Public Health. Riboflavin - Vitamin B2. Accessed February 5, 2024.
  41. American Cancer Society. Are Dietary Supplements Safe? Accessed February 5, 2024.

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