Can Multivitamins Cause More Harm Than Good?

By Samantha Gilbert, FNC, CHNP, CNC     Last updated on December 26th, 2021

Everywhere we look, we see doctors, nutritionists, health coaches, and even your “healthy” neighbors touting the importance of multivitamins. They worry that you’re not getting enough nutrients from your food, no matter how healthily you’re eating. 

We tend to look to authority figures (or those who present themselves as such) when wondering what we should do, but even a doctor — when unfamiliar with your personal biochemistry — could give you the wrong advice. 

What if recommending daily multivitamins to everyone is actually creating serious health problems?

What Are Vitamins?

Vitamins are organic nutrients required for biochemical reactions that ensure growth, survival, and reproduction. Some are unable to be synthesized by the body, and must therefore be ingested alone or through your diet.

What Are Multivitamins?

Multivitamins may include herbs, vitamins, and/or minerals, and are usually sold over the counter. They’re not regulated by the government like medications are, so they may or may not be effective, and no list of side effects is required. Additionally, multivitamins that do not undergo rigorous, third-party testing, provide no guarantee they contain the level of ingredients stated on the label — there could be more or there could be less. In fact, I often see this with kelp supplements that contain far higher iodine levels than reported, which can be detrimental in someone with a thyroid condition such as Hashimoto’s thyroiditis. Nutrient levels in some multivitamins can even exceed the suggested daily limits (which, due to individual biochemistry, aren’t relevant to everyone, anyway).

An estimated 200+ million Americans are taking mass-market (a.k.a. consumer-grade) supplements. The majority of them are useless at best, outright harmful at worst. This is due to the use of fillers, preservatives, excipients, antioxidants, glazes, sweeteners, artificial coloring, binders, and deodorizers. These additional ingredients are found in the world’s most heavily promoted and widely used brands, such as Centrum or One A Day. These ingredients are also found in laxatives, hair dyes, herbicides, fungicides, pesticides, fertilizers, cement, glues, and resins. Some of these substances are well-known carcinogens, irritants, allergens, and birth-defect-causing agents.

There are five major categories of supplements to choose from:

  • Consumer-Grade
  • Generic
  • “Natural”
  • Professional-Grade
  • Opportunistic (MLM)

In general, each successive category is more expensive than the previous one. To a large extent, higher prices reflect better quality but not always — there is plenty of expensive junk too. Professional-grade nutraceuticals are the only class of supplements I recommend to my clients due to their strict quality control standards and third-party testing.

You can find consumer-grade supplements on supermarket and drugstore shelves and on Amazon. They are labeled as Centrum, One A Day, Nature‘s Way, Theragran, and generics (Costco’s Kirkland and CVS, for example). The majority of high-end health food stores and specialty websites don’t resell consumer-grade supplements due to quality concerns. They are made from the cheapest, least efficient components to maximize profit. The entire daily “dose” is usually squeezed into one or two hard-pressed tablets and is optimized for extended shelf life. To mask oxidation, spoilage, odor, and discoloration common to all supplements, their manufacturers use artificial colorings, preservatives, and glazes that often cause a lot of allergic reactions and negative side effects.

Clients often report negative reactions to the supplements they are taking, but in many cases, I find it’s not the actual nutrient that is the problem, but rather, the quality of the product and all the additional toxic ingredients.

Buying supplements from Amazon or eBay comes with an even greater risk because many of them are either counterfeit and dangerous, useless and expired products that have been repackaged as new, or they are stolen products released on the black market without any quality control. And I’m sure you know by now that Amazon is more concerned about profit over quality control.

The Importance of Individual Biochemistry 

We are all biochemically unique; as humans, we exhibit great diversity in blood and brain chemistry. We each have our own individual chemistry, so we have our own unique responses and reactions to the same nutrient inputs. No two people will process vitamins and minerals in exactly the same way. 

Most people are deficient in several nutrients and overloaded in others due to their genetics. An individual assessment with lab testing is crucial to determine the appropriate vitamin and mineral recommendations for any given person. 

Are Multivitamins Dangerous?

Anything that is “one size fits all” can be dangerous. Because multivitamins assume that we all need the same specific nutrients in the same specific ratios, you could personally be getting too much or too little. 

Being consistently overloaded with vitamins and minerals can hurt you. Ingesting inappropriate doses becomes even more dangerous when you consume them every day. You could accumulate a buildup of vitamin C or zinc and experience nausea, diarrhea, or stomach cramps. You could get too much selenium and experience hair loss, GI issues, fatigue, or even mild nerve damage. Folic acid can also wreak havoc, especially if you already suffer from cancer, depression, anxiety, or other cognitive impairments. You can read more about that here.

Unfortunately, I still see many practitioners prescribing multivitamins based on faulty testing methods such as MTHFR, which will make a patient worse over time. Before I found my current doctors, my naturopath put me on a multivitamin as well as 5-HTP for depression and a B-vitamin complex. They all contained folic acid (the multivitamin contained both folic acid and copper). Since I was already undermethylated with copper overload, these nutrients made me feel worse. I spent another two years suffering from massive depression and oxidative stress due to this inappropriate prescription.

Please don’t assume that vitamins and minerals are safe simply because they’re “natural.” Your body isn’t like anyone else’s, and the supplements you choose must be calibrated for you, specifically, if you want to avoid negative effects.

Multivitamins and Heavy Metals

Many multivitamins also contain heavy metals (especially cheap, consumer-grade, and generic options from Costco and CVS), which can stay in your body and increase your likelihood of dementia or other issues. An accumulation of heavy metals over time from daily multivitamins could harm your organs and lead to numerous health complications, including:

  • Depression
  • Fatigue
  • Anxiety
  • Headaches
  • Nerve damage

Can Multivitamins Cause Depression? 

Daily use of multivitamins containing high levels of vitamin D over a period of several months is known to be toxic, resulting in symptoms such as depression, confusion, fatigue, and muscle weakness. Too little or too much vitamin A can lead to negative side effects, including depression from too much retinol (derived from Vitamin A). Multivitamins usually contain vitamin A in a combination of beta-carotene and retinol (preformed vitamin A).

Can Multivitamins Cause Headaches?

Some generic multivitamins include large amounts of fat-soluble vitamins, for which excess is stored in the body versus excreted in the urine. These can therefore build up inside the body through consistent multivitamin use over a period of time. The buildup of Vitamin A, for example, may cause headaches — along with dizziness, liver damage, and weakened bones. 

While Vitamin C is water-soluble, large doses over time can prevent it from being completely absorbed, overly deplete copper, and therefore result in a buildup in the intestinal tract. A buildup of Vitamin C (also included in multivitamins) can result in headaches and nausea.

Can Multivitamins Cause Anxiety?

B-complex vitamins (included in most generic multivitamins) are stimulating and have been known to cause anxiety and panic attacks for people whose dosage is too high for their individual needs. Folic acid can be over-activating to the body and brain, resulting in anxiety. The interaction of multivitamins with certain medications can also increase anxiety symptoms. All vitamins are “metabolic activators,” so if you’re prone to anxiety or manic episodes, take multivitamins with caution.

Can Multivitamins Cause Acne?

Many of today’s most popular multivitamins contain vitamins and minerals that, in excess, are known to cause acne. Vitamins B6 and B12, for example, may cause acne. B12 encourages inflammation-causing compounds and alters the gene expression of the skin, and multivitamins tend to contain excessive levels of it. Iodine can also cause acne on the face and upper trunk. Too much calcium, also included in most generic multivitamins, can prevent you from absorbing enough zinc to keep your skin clear.

How to Evaluate Your Multivitamins

  1. Take an inventory of all the supplements you are currently taking, including the brands.
  2. Ask yourself why you are taking each of them.
  3. Take note of any reactions (good or bad) you’re experiencing as a result of these supplements.

Do You Need a Multivitamin?

If you’re generally healthy, you most likely don’t need a generic multivitamin. In fact, more harm can be done by taking too much than by not taking anything at all. 

Keep in mind that nutrients from food and supplements can greatly influence the regulation of genes. I strongly encourage you to save your money and work with a practitioner that really understands biochemistry, and the importance of nutrient-specific protocols for your individual case. 

Do you take multivitamins? I’d love to know what your experience has been in the comments below!


45 thoughts on “Can Multivitamins Cause More Harm Than Good?”

  1. I have been suffering from symptoms of anxiety and depression for a month now. I came across this. I noticed that around the first time I felt “extremely sad”, was few days after I took a Women’s Daily Supplement from Healthy Options. It contains Folic Acid, which I wanted to take as I am planning to get pregnant. Is this related? Thank you.

  2. I suffer from insomnia and anxiety and depression. I can relate very much to being undermethylated and having a copper overload. Multivitamins do not do me good. However, protein rich food does help. I started to read about Ajurveda personality types and wanted to ask you if I can take the info from there to stabilize myself.

  3. I did a google search to try and find out what vitamins or supplements can make you moody. I’ve been extremely moody and lacking patience lately and wonder if it’s due to my new regime of taking vitamins. My list is this … garlic, DHEA, Vitamin B complex, turmeric cucurim, brain smart and multi collagen. Could any of these be causing this ?? Thank you !!

  4. hello mam actually i am non smoker now i quitted 1.5 yrs ago but from that i started anxiety and panic attacks it comes and goes in month to month after long time i checked that in blood test my homocyctien levels is raised up by 59.72 which is so much in consider my b12 is so low like 12 or 14 something even vit d deficiency my bones are cracking i am taking multv in good dose with 1.5mg of folic in it and b6 b12 and also some b in it with copper selenium iron magnese i am afraid cause i have anxiety so wen i took that capsules for 30 minutes my anxiety and puplitations raise but by time its subside a bit what should i do plz help i checked all of symptoms plz mail me

  5. Hi Samantha, how do you know if you’re taking too many supplements? I was recently methylated by my practitioner, and placed on 16 herbal supplements. I feel like I have the most energy I have had in a long time, but there are other things I’m experiencing that have me concerned I am taking too many. I have pains under my left arm, stomach aches, etc. so are these harmful or helpful?
    Thanks, Megan

    1. Hi Megan – thanks for sharing your experience. Unfortunately, I cannot advise you without consultation and testing. I’m not sure what you mean by “methylated by my practitioner.” Do you mean you were properly tested as undermethylated and your practitioner advised nutrients to bring methyl into your system?

  6. I am anemic due to being very stupid and skipping meals and running round after others.I had every symptom.fainted,erratic heartbeat.was diagnosed as being very anemic although I had started to improve due to starting to eat fruit,veg,meat normally again.I decided to help it along with multivitamins.I am now stopping taking them as they are having a negative effect on me.I’ve been told by my Dr its an overload as my weight has gone up through sensible eating etc etc.never again will I touch a multivitamin

  7. Last year January 2019 my Dr put me on Fusion Plus The B-12 shot (once every month) and Vitamin D tablets(1 every week). I started feeling bad having headaches mouth pain muscle pain & stomach pain. Oh yea also getting mouth sores on the inside of my mouth and rashes on my back.
    I went to a new doctor & she took me off the shot & vitamin D. She said my vitamin levels were dangerously high.
    But I’m still on the Fusion.
    Will my body ever get back to normal from all the stuff I was on??

  8. I am on Lexapro at 10 mg per day and have been for years. I’ve tried to phase out but have not been so successful but that is another story.
    I have MTHFR(two mutations) and take 400 mcg of folate and 50 mcg of methyl cobalamin 3 days per week (its a b complex) Can the combination of these cause over methylation? I take to help bring my homocysteine levels down too and also had an explained blood clot years ago which help me realize my MTHFR.

    It is very difficult to find the balance. I have upper body pain that I associate with osteoarthritis of the neck etc. Then again, I hear overmethylation can cause upper body pain too. Any thoughts on this? Rod 63

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