Supplements 101: What to Know Before You Start Taking Daily Vitamins

Mallory Creveling
Medically Reviewed
May 11, 2021

If your experience with supplements begins and ends at Flintstone’s multi-vitamins, this daily vitamin guide is for you. Supplement brands and options for what to take have expanded exponentially over the years. Now, you can find supplements everywhere from Urban Outfitters and Ulta to your local juice shop or your facialist’s studio. You’ve likely gotten ads for personalized packs (based on an online questionnaire) and individual vitamins and minerals, all wrapped up in a pill, powder, or gel capsule.

Maybe you’re thinking of adding a few to your routine, or maybe your doctor has recommended them based on your health goals. Before you start a daily vitamin routine, read up on all you need to know on how they can affect your health. Starting here…

What are supplements?

“Supplements include any number of ingredients, including vitamins, minerals, herbs , amino acids, enzymes, or even organ tissues,” says Ivy Carson , a nurse practitioner at Parsley Health. “They’re available in many forms, too, like capsules, tablets, powders, liquids, and soft gels.” While supplements can come from a range of ingredients, Carson says some common ones include magnesium, vitamin B , C, D, and fish oil. Many people also take multi-vitamins (a combo of a few essentials) and probiotics .

Supplements versus vitamins

This might get a little confusing—what’s the difference between a supplement and a vitamin? In truth, there’s overlap, Carson says. Vitamins, in particular, are those that are essential for normal cell function, growth, and development (think A, D, E, K, and B). Supplements, on the other hand, encapsulate a broader range of nutritional additives and can go beyond just the vitamins your body needs. “All vitamins are supplements, but not all supplements are vitamins,” Carson explains. So, whether you’re thinking about starting a routine of daily vitamins or daily supplements, they may look similar.

Why might someone take supplements?

Many people take supplements to address issues like fatigue , to support their hair, nails, skin, or immune system , or for hormone balance or sleep assistance. Vegan or vegetarians might also look into taking supplements for things like B vitamins or iron, which are commonly found in animal products. If you have certain conditions, like anemia, thyroid issues , or are looking to reduce inflammation in the body , you might also benefit from a daily supplement routine.

Another category of supplements, known as antimicrobial supplements, might help someone manage an overgrowth of microorganisms, Carson says, which includes yeast, fungi, or bacteria. SIBO, or small intestine bacterial overgrowth , for example, is one of the most common conditions these supplements might work to address—and a condition Parsley treats regularly. Individuals will typically take antimicrobial supplements until symptoms improve (based on lab work), so they’re a more short-term treatment.

How do doctors determine the supplements you need?

Before you start taking any supplements, it’s a smart idea to see a medical professional . The provider will ask you lots of questions about your medical history and any symptoms you’re experiencing or want to address. Then, the most important step for determining what supplements you might need are lab tests, Carson says. Standard blood work, as well as more in-depth vitamin, mineral, amino acid, and fatty acid level tests , might reveal where your deficiencies lie and the daily supplements that could help. FYI, the standard lab test will look at everything from B and D vitamins, iron, zinc, copper, and magnesium, and it’s a good place for your clinician to start looking at your body’s needs, Carson says. “It will answer, does the body have the nutrients it needs to do its job at a foundational level?” she says.

But beyond that basic blood test, you can also get more into the nitty-gritty of what your body needs to function optimally. One additional test Carson may use with her patients, for instance, involves a blood and urine sample and tests your nutrition from a few different angles, plus it offers a more in-depth look at what you need or where you’re lacking certain nutrients, she explains. For those with digestive issues , doctors will also examine a stool sample, which can help them determine, among other things, if you need a probiotic or prebiotic supplement and the appropriate strains of bacteria to recommend.

Carson adds that sometimes there’s a major difference between the minimum amount of vitamins someone needs and the amount one needs for optimal health, so doctors will keep that in mind when prescribing supplements. Keep in mind, too, that while doctors might suggest lab tests to give you a full assessment of what supplements might lead you toward optimal health, Carson says these tests and subsequent supplement suggestions will depend on both an individual’s needs and their budget. At Parsley Health , providers work within each patient’s means.

What to know before buying (or taking) supplements

Examine quality

While the FDA requires supplement manufacturers to adhere to certain practices to ensure quality and safety, compliance isn’t always enforced, Carson explains. That’s why you want to look for supplements with third-party testing (you’ll find stamps of approval from companies like NSF, USP, or Consumer Lab), to make sure what you’re taking is free from harmful contaminants, like heavy metals, that there are no undeclared ingredients, and that you’re getting what the label says. When looking for quality, you might want to skip those supplements sold in a grocery store , and opt for pharma-grade options.

Be aware of daily vitamin dosage

It’s smart to follow the dosage on your supplement’s label, but your doctor will know if you should take more or less, Carson says. Some vitamins (like the fat-soluble, A, D, E, and K) can build up in the system, causing toxicity—just one example of those you want to make sure you’re not overconsuming. Also, you may be able to reduce your dosage over time. Getting regular lab work done through your provider will help them determine you’re on the right dose and ensure sure your body is absorbing or responding to the supplement.

Consider timing

You should take some supplements, like zinc, with food, so you don’t get an upset stomach, Carson says. Check the label to see if your supplement suggests a meal with consumption or ask your doctor for a recommendation. If you’re taking several daily vitamins or supplements, your provider will likely have a specific order and timing they recommend to make sure you get the most out of them.

Note side-effects

If you’re feeling any negative effects, like extreme fatigue, headaches, or digestive issues when you start taking daily supplements, definitely mention it to your doctor to see if you should cut back. Those on antimicrobial supplements may experience something called a die-off reaction, Carson says, which happens when microorganisms (like bacteria and fungi) die and the body releases endotoxins. Your immune system then responds, causing reactions like irritability, diarrhea, or nausea. While it can be unpleasant, it’s usually a normal reaction, but your provider may have solutions for easing symptoms. FYI, those on B vitamins might have bright yellow urine , which is nothing to worry about but can cause concern the first time it happens, Carson says.

Know your contraindications

Some supplements may interact with certain medications. For example, herbal supplements with St. John’s wort, which people may take for depression or menopausal symptoms, can interact with meds taken for migraines, antifungal pills, blood thinners, or even some contraceptives, Carson explains. Supplements won’t give these warnings, but a medical professional will be able to help you identify any contraindications.

Consider working with a pro

In addition to talking about dosage and medication interactions, your provider will also know the different forms available of certain nutrients, like magnesium, iron, and B vitamins. Certain formulas react differently in the body, and your provider should tell you what’s best for you, individually, Carson says. Also, if you’re pregnant, breastfeeding, or want to become pregnant, it’s also smart to talk to your doctor before taking any supplements.

Supplements: The bottom line

Supplements can definitely support and promote optimal health, but quality is key, and working with a medical professional to determine what you need (and where to get it) will serve you best. “Just because something is sold over-the-counter doesn’t mean it couldn’t have dangerous side effects,” Carson says. That’s why it’s so important to talk to your doctor about taking supplements and discuss what will work best for your body. Finally, keep in mind that supplements aren’t a substitute for overall healthy habits—they’re just a solid complement.

Mallory Creveling

Mallory, a New York City-based freelance writer, has been covering health, fitness, and nutrition for more than a decade. Her work has appeared in publications like Women's Health, Men's Journal, Self, Runner's World, Health, and Shape, where she previously held a staff role. She also worked as an editor at Daily Burn and Family Circle magazine. Mallory, a certified personal trainer, also works with private fitness clients in Manhattan and at a strength studio in Brooklyn. Originally from Allentown, PA, she graduated from Syracuse University's S.I. Newhouse School of Public Communications.

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