Which Vitamins and Minerals Are Worth Taking? 

Emma Yasinski
Emma Yasinski Staff Writer

Lisa Torelli-Sauer, a 39-year-old vegetarian, used to be one tired woman. She put her two young sons to bed at 7:30pm, and says, “I could barely stay awake long enough to say goodnight to them.” Her most recent blood tests from her annual checkup had been normal, so her doctor hadn’t recommended she take any vitamins and minerals supplements. Yet, as her exhaustion persisted, she started taking a vitamin supplement that contains iron, magnesium, potassium, zinc and B vitamins.

“I’m amazed at how much better I feel,” she says. “I’m able to stay up hours longer in the evening and no longer feel tired in the afternoon.” 

Alison Acerra, MS, RDN, founder of the food-industry consultancy Strategic Nutrition Design, recommends talking with a nutrition expert before taking high-dose vitamin/mineral supplements. While one-a-day multivitamins are good insurance to fill nutrient gaps, she says, if you’re feeling fatigued, for example, “it’s really important to get to the root cause of that fatigue,” rather than guessing about supplements. However, she adds, many vegetarians and vegans are deficient in certain nutrients — especially iron and B vitamins.

Ideally, we would get all our nutrients from food. “I never want to give a false sense that supplementation is a miraculous cure-all, because there are so many benefits that we get from food that we just can’t get from isolated supplements,” says Acerra.

Some studies suggest that multivitamins aren’t helpful unless you’re experiencing a vitamin deficiency, and many supplements come with risks.

Another nutritionist, Mikayla Curti, a registered dietician, echoed the sentiment. “Start with food, because food is always medicine. . . it’s important not to just go willy-nilly.” 

Sometimes, because of dietary limitations, chronic conditions or other reasons outside of our control, like soil quality and access to sunlight, we aren’t able to get all the nutrients we need from food. That’s when supplements can be helpful.

The “standard American diet is not complete,” says Curti. “It usually lacks a certain list of nutrients.” Magnesium and vitamins D and B12, she says, are often missing from her clients’ diets. 

When do you need a Vitamins and Minerals supplement?

Talk with your doctor about taking these vitamin or mineral supplements if you are:

  • Planning on becoming pregnant within a month, folic acid reduces the risk of brain and spinal-cord abnormalities, called neural-tube birth defects, that can occur in the first month of pregnancy.
  • Pregnant folic acid to help protect against neural-tube defects and 800 IU of vitamin D to help prevent preeclampsia. Depending on risk, the doctor may recommend higher doses. Prenatal vitamins contain a range of vitamins and minerals, but new research casts doubt on their necessity for women who eat a nutritious diet.
  • A strict vegan who consumes no meat, fish, eggs or dairy, a B12 and iron supplement.
  • A person who rarely gets daily sunlight (either from lack of sun exposure or use of sunscreen), a daily vitamin D3 supplement.
  • Taking certain drugs, vitamin B12 and magnesium supplements may be needed if you regularly take heartburn drugs like lansoprazole (Prevacid and generic) or diabetes medication, such as metformin (Glucophage and generic).
  • Diagnosed with osteoporosis, vitamin D3 supplements and calcium from such calcium-rich foods as dairy products and green leafy vegetables, to slow bone loss.
  • Diagnosed with age-related macular degeneration, a blend of vitamins C and E, plus copper, lutein, zeaxanthin and zinc, known as AREDS (age-related eye-disease study), can slow the disease’s progression.
  • Diagnosed with gastrointestinal disorders, such as inflammatory bowel disease or celiac disease, or serious conditions like  cancer or HIV/AIDS. Talk with your doctor about nutritional supplement needs.

Fat-soluble versus water-soluble

The 13 essential vitamins reside in two different categories: fat-soluble and water-soluble. Fat-soluble vitamins are easier for your body to use when they’re ingested with fats. Water-soluble vitamins can be absorbed without fat. Once inside your body, fat-soluble vitamins are stored long-term in your fatty tissues, whereas water-soluble vitamins are excreted regularly through your urine. For this reason, it’s easier to ingest too much of a fat-soluble vitamin than a water-soluble one. However, it is also possible to consume toxic amounts of vitamins, even if they are water- soluble.

Fat-soluble vitamins:  A, E, D, K

Water-soluble vitamins:  C, B, thiamine, riboflavin, niacin, pantothenic acid, biotin, B6, B12 and folate

Personal trainer Chris Higgins used to take 2000 mgs of vitamin C per day — an amount he calls a “megadose.” As a result of taking so much vitamin C, he developed “extremely painful leg cramps,” followed by diarrhea and nausea. His physician suggested that he limit his vitamin C supplement intake to 100 mg per day. Now that his cramps and digestive symptoms have gone away, Higgins continues to take vitamins daily — including vitamin C — but he keeps the doses smaller. He is no longer a “proponent for taking megadoses.” 


Physician’s assistant Ben Tanner takes magnesium supplements, which makes him  feel “more relaxed and less anxious.”

Research suggests that magnesium may aid in lowering anxiety and blood pressure and promoting restful sleep. It can also help protect bones and may prevent type 2 diabetes and migraines.

Foods that contain this nutrient

Pumpkin seeds

Chia seeds




Black beans





Potential Side Effects: Gastrointestinal events like nausea and diarrhea may signal that you’ve ingested too much magnesium. This side effect is more common in patients with kidney issues than with others. 

Vitamin D

Andreas Grant, who lives in Sweden where there is very little winter sunlight, says he takes vitamin D supplements from October to March. “I feel a lot better and have more energy when I take it. But I only take it during the darkest months.”

While some foods contain vitamin D, most of the vitamin D we take in comes from sunlight. Wearing sunscreen, which is crucial to preventing skin cancer, can keep us from absorbing as much vitamin D as we need. People with darker skin also tend to absorb less vitamin D from the sun, because melanin, the molecule responsible for skin pigmentation, prevents its synthesis. 

Vitamin D is also known to be involved in immune function, and studies have shown it plays an important role in fighting respiratory infections. Research has also suggested that vitamin D deficiency is associated with worse COVID19 outcomes. However, other studies have revealed no association between the two.

The Institute of Functional Medicine issued a protocol recommending vitamin D supplements to help prevent severe COVID19.

Foods that contain this nutrient

Fortified milk

Fortified cereal

Fatty fish, such as salmon and canned tuna

Side Effects: Curti urges that the amount of vitamin D found in supplements is unlikely to hurt you, but having too much can cause nausea, weakness, kidney stones, irregular heartbeat and even death. The vitamin is fat-soluble.

Vitamin B12

Vitamin B12 is important to the functioning of our brain and blood cells. A deficiency can lead to anemia, muscle weakness, nerve damage, mood disorders and intestinal issues.

Deficiency is most common among vegans and vegetarians, people over 50 and those who have had gastrointestinal surgery or alcohol use disorders. Certain medications, like metformin, or drugs that treat acid reflux, such as proton pump inhibitors and H2 receptor antagonists, interfere with your body’s ability to absorb vitamin B12.

Foods that contain this nutrient

Red meat


Fatty fish like tuna, salmon and sardines

Lean fish like haddock


Fortified cereals


Fortified nutritional yeast 

Side Effects: It’s unlikely that you’ll take enough vitamin B12 to cause any toxicities or side effects, according to the NIH (National Institutes of Health). The vitamin is water-soluble.


Iodine deficiency is rare, but it’s the most common among vegans and vegetarians. In pregnant women, iodine deficiency can harm the developing fetus, causing miscarriages, low intellect and birth defects. Eating large amounts of soy and cruciferous vegetables can interfere with your body’s ability to absorb iodine. Deficiency can cause the thyroid gland in your neck to swell. If untreated, it can lead to hypothyroidism, potentially causing obesity, joint pain, infertility and heart disease. 

Foods that contain this nutrient

Iodized salt


Fish such as cod and tuna

Seafood including seaweed and shrimp

Side Effects: Ingesting too much iodine can cause similar symptoms to deficiency,  including a swollen thyroid gland. Symptoms can also mimic hyperthyroidism with an increased heart rate and unexplained weight loss. If you experience burning of the mouth, throat or stomach, a weak pulse or gastrointestinal symptoms, you may have iodine poisoning and should seek emergency medical attention. 

Some drugs can interact with iodine, including thyroid medications, ACE inhibitors and certain diuretics. 


Iron deficiency is another common lack among vegans and vegetarians. It also tends to be more common in menstruating women and those with gastrointestinal disorders.

Symptoms of iron deficiency include fatigue, weakness, impaired cognitive function and difficulty regulating body temperature. 

Some foods that have large amounts of iron, like spinach, also contain polyphenols, which can make that iron more difficult for your body to use. Foods with vitamin C can help your body absorb iron.

Foods that contain this nutrient

Red meat

Fatty fish like tuna and sardines

Enriched pastas and cereals

White beans

Dark chocolate



Side Effects: Iron supplements often cause nausea. Taking the pills with food can help. Ingesting too much iron can lead to more intense gastric issues like diarrhea, pain and vomiting. In the worst cases, it can cause convulsions, coma and even death.

Why MedShadow Suggests Caution with Vitamins and Minerals Supplements

Because supplements are usually sold over the counter and subject to different, less-stringent regulations than drugs, it’s important to know what to look for — and what not to look for.

Curti says it’s best to purchase from a manufacturer you know and trust. “Look into the quality and reputation of the company that makes it. Look for a product that has a description that really tells you that the ingredients are pure and [of] good quality.”

Not only have some supplements been found to contain allergens and impurities, but some don’t even include any of the vitamins or minerals they advertise. Others, especially those that claim to help build muscles, have been found to contain drugs and illicit substances, like selective androgen receptor modulators (SARMs). Twenty-two out of 25 melatonin supplements tested actually contained significantly higher or lower doses than their labels advertised, according to a 2023 study. One had nearly 3.5 times as much as the dose on the label. 

“Risky substances [can] find their way into a supplement, such as heavy metals, pesticides, harmful microbes or drugs,” says Michael Hull, MSc senior research manager at examine.com. “These contaminants may slip in inadvertently, due to poor quality control practices, or deliberately, such as a manufacturer adding Viagra (sildenafil) to better ensure [that] their “all-natural” sexual enhancement supplement “works.” Hull adds that the supplements most likely to be tainted are herbal and ones that promise to promote weight loss or sexual function.

Even if they are pure, many can interact adversely with prescription drugs. St. John’s wort, for example, can interact with such drugs as antidepressants, antipsychotics, antiepileptics, anxiolytics, anesthetics and analgesics. 

Hull says that proprietary blends can be particularly difficult to evaluate. “With a proprietary blend, a company doesn’t have to disclose the individual amount of each ingredient (although it could). Blends are used to help prevent the competition from knowing what the specific formulation is. But it can also hide the fact that very little of an active ingredient may be in the bottle.” If the bottle doesn’t tell you specific amounts of each ingredient, it’s best to buy another one that does.

How to Choose a  Vitamins and Minerals Supplement

If you do need a supplement, your healthcare providers won’t prescribe the vitamins and brands like they would a drug, but they can help direct you. Patients should “do their research, but they should also ask practitioners more than Google,” says Curti.

One sign it is a higher quality supplement is third-party certification. Groups like the National Science Foundation (NSF) or the United States Pharmacopeia (USP) test supplements to confirm that they contain the products listed on the label and don’t have unsafe levels of contaminants. An NSF certification, says Acerra, “is a good indication that it’s a high-quality product.” 

These certifications, however, do not prove that the supplements work. For example, the certification confirms that a vitamin E supplement contains vitamin E, not that it will  make your hair grow.


See also: Popular Supplements, Claims for Them and Alternative Approaches


DISCLAIMER: MedShadow provides information and resources related to medications, their effects, and potential side effects. However, it is important to note that we are not a substitute for professional medical advice, diagnosis, or treatment. The content on our site is intended for educational and informational purposes only. Individuals dealing with medical conditions or symptoms should seek guidance from a licensed healthcare professional, such as a physician or pharmacist, who can provide personalized medical advice tailored to their specific circumstances.

While we strive to ensure the accuracy and reliability of the information presented on MedShadow, we cannot guarantee its completeness or suitability for any particular individual's medical needs. Therefore, we strongly encourage users to consult with qualified healthcare professionals regarding any health-related concerns or decisions. By accessing and using MedShadow, you acknowledge and agree that the information provided on the site is not a substitute for professional medical advice and that you should always consult with a qualified healthcare provider for any medical concerns.

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Rhonda Añn Godwin

So appreciate the highly informative and lifesaving (in my case)) articles on medshadow. Thank you from the bottom of my heart!

Mina Hox

Mikayla Curti’s point about starting with food is essential. I advise my clients to prioritize natural sources of nutrients. But for athletes and active individuals, targeted supplements like my B complex bridge the gap and enhance performance.

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