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Home » Nutrition

WARNING: 6 Supplements Not To Take Without Testing

Modified: Aug 6, 2025 · Published: Nov 15, 2017 by Catherine Crow, NTP · Medical Disclaimer · This Post Contains Affiliate Links 15 Comments

4 Supplements Not To Take Without Testing | Butter NutritionSupplements seem like the smart fix for gaps in your diet - but in these six situations, they can do more harm than good.

Before you take calcium, vitamin D3, iron, vitamin A, or folic acid… read this first.

1) Before you take vitamin D...

While research has suggested that taking Vitamin D3 can have a positive impact on health if one is found to have low levels, the risks of too much vitamin D aren't commonly addressed. Vitamin D is now taken by the masses, often without proper testing to indicate a deficiency, and without proper monitoring.

According to Chris Kresser, "Furthermore, in most studies, taking vitamin D supplements does not decrease risk of death, cardiovascular disease, or other conditions. Based on an exhaustive review of over 1,000 studies in 2011, the Institute of Medicine recommends a much more conservative range of 20 to 50 ng/mL" [3]

Researchers even believe low vitamin D is actually a CONSEQUENCE of chronic inflammation and NOT a cause:

"Research points to a bacterial etiology pathogenesis for an inflammatory disease process which results in high 1,25(OH)2D and low 25(OH)D. Immunotherapy, directed at eradicating persistent intracellular pathogens, corrects dysregulated vitamin D metabolism and resolves inflammatory symptoms."[5]

Not to mention the impact nutrients like magnesium, vitamin C, and boron can have on vitamin D levels. [6,7,8,9]

So is it really a vitamin D deficiency OR is it chronic inflammation from infections, and mineral/vitamin deficiencies?

From running hundreds of hair analyses worldwide, it's clear: excess vitamin D3 from supplements has a strong negative impact on mineral balance - typically raising calcium, and lowering both potassium[2] and boron. This resulting mineral pattern can make one feel pretty sluggish. Symptoms such as brain fog, fatigue, slow-moving digestion, and blood sugar issues are common.

The main reason for this is your calcium to potassium level represents your thyroid ratio in hair analysis. The thyroid ratio affects how you actually feel.

So if you're taking vitamin D3, which raises calcium levels and lowers potassium, you're moving these minerals in the opposite direction of what supports thyroid health.

Don't worry, once you know your levels with hair analysis, you can reverse this mineral pattern with targeted nutrition and supplementation.

Some vitamin D is good. More is not always better. Testing before taking high dosages is smart.

2) Before you take folic acid...

You must know if you have a MTHFR deficiency.

Multivitamins often contain folic acid (the synthetic form of folate or vitamin B9) which can be harmful if you have a genetic mutation such as MTHFR. Methyl-tetra-hydro-folate reductase (MTHFR) is an enzyme that your body uses to convert folate (B9) into the active form of folate used by the body. This process is methylation.

Additionally, if you have a certain kind of MTHFR genetic mutation, even folate will not be enough, rendering the folate or folic acid as pretty useless for you. Here's some of the most common versions of the MTHFR genetic mutation, and how much it influences your body's ability to convert folate from food and supplements into methylfolate, the form that is useable by the body:

  • MTHFR C677T = heterozygous mutation (one mutation) estimated up to 40% loss of function
  • MTHFR T677T = homozygous mutation (two mutations) estimated up to 70% loss of function
  • MTHFR A1298C = heterozygous mutation (one mutation) estimated up to 20% loss of function (limited research and controversy here)
  • MTHFR C1298C = homozygous mutation (two mutations) estimated up to 40% loss of function

You can find out if you have one of the MTHFR genetic mutations by asking your doctor for the lab test or running your own by getting an ancestry test done and interpreting your raw genetic data with tools online. Note: They are constantly updating what these kinds of DNA tests show, so be sure to confirm that what you want out of it is still included before you order.

3) Before you take calcium...

You must know your calcium level (I prefer hair analysis testing for this). Excess calcium is a real problem, and is more common than calcium deficiency (in my office at least).

Typically calcium levels won't get too high on their own from food alone (unless intake is excessive). It's when a calcium-rich diet is paired with calcium supplements and/or vitamin D3 supplements that calcium levels start creeping up. Soaring calcium levels can lead to calcification - stiffness, back pain, joint problems, and even osteoporosis in the long term.[1]

A better bet for strong bones? Get some food-sourced calcium in your diet along with magnesium and boron (if you know you're low in these). And don't forget about the benefits of weight-bearing exercise for maintaining bone health.

4) Before you take iron or iron-containing supplements...

You must know your iron status. Too little iron and too much iron can both cause serious problems for your health, so supplementing blindly is never a good call.

If you're taking liver capsules or a multivitamin containing iron, make sure that you need it, and know that you're not at risk of iron overload (a situation where you absorb more iron from your food than normal). Find out more about your risk for iron overload here.

Iron testing used to be a normal part of blood work up until about 1997, so it's not out of line for you to ask your doctor for an iron panel that includes ferritin (iron stores).

5) Before you take vitamin A/beta carotene-containing supplements...

Know that vitamin A deficiency is rare in developed countries and that vitamin A toxicity is a real thing. Vitamin A has been long touted as a nutritional superstar, although it's found in almost all foods but most abundantly in a whole foods diet. By policy, it was added to low-fat milk products in 1970's. It's also found in multivitamins, supplements, skin creams (especially anti-aging creams), sunscreen, pharmaceutical drugs (like Accutane), and increases in the body if you're on the birth control pill. Research suggests toxicity may occur at lower levels than most official guidelines state - especially if you're unknowingly stacking multiple sources.[4]

If you suspect you've taken too much vitamin A from supplemental sources or what I call supplement stacking (ie. taking multiple supplements that make you double up on certain nutrients), there are a few things you can do right away. First, take a look at all your multivitamins, other supplements, lotions, prescription drug history, and beauty products to assess your intake. If there is excess, consider eliminating it.

6) Before you take copper-containing supplements

Getting too much copper in your diet (from food and/or supplements) or too much relative to your zinc levels can present in a wide variety of mental health symptoms.

Copper is pretty easy to find in the diet, especially for those who are on paleo-type diets that are avoiding grains and instead loading up on large amounts of nuts, seeds and chocolate.

Read more about the symptoms of copper overload to be aware of.

Testing over guessing: the smarter supplement strategy

You wouldn't wear a one-size-fits-all dress-so why take one-size-fits-all supplements?

Before you 'stack' another pill, test your actual levels.

Your body isn't guessing. Neither should you.

Take the Nutrient Excess Quiz now → and start making decisions based on real data, not hype.

https://bnmedia.s3.us-west-2.amazonaws.com/Tiktok+vids/Snaptik.app_7157841995644341547.mp4

So tell me, do you take any of these supplements? How do they make you feel? Please share in the comments!

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4 Supplements Not To Take Without Testing | Butter Nutrition

4 Supplements Not To Take Without Testing | Butter Nutrition
4 Supplements Not To Take Without Testing | Butter Nutrition

References:
[1] https://academic.oup.com/cardiovascres/article/36/3/293/298591/Hypercalcemia-and-metastatic-calcification
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC291035/pdf/jcinvest00315-0040.pdf
[3] https://chriskresser.com/vitamin-d-more-is-not-better/
[4] https://www.ncbi.nlm.nih.gov/pubmed/16469975
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4160567/
[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4712861/
[7] https://www.ncbi.nlm.nih.gov/pubmed/2170601
[8] https://www.sciencedaily.com/releases/2018/12/181214093837.htm
[9] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3765911/

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About Catherine Crow, NTP

Hi there! I’m Catherine Crow. Seattle-based Functional Nutritional Therapy Practitioner (FNTP), Educator, Diet Investigator, and Coconut Milk Ice Cream Enthusiast. My goal is to help guide you to improve your nutrition through strategic eating (not dieting) and without expensive supplements. Because when you know better, you can feel better! Read more...

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Reader Interactions

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  1. Nicole

    November 26, 2017 at 10:03 am

    Hi Catherine

    I am interested in the hair analysis but would like to know how you test the hair, where it is tested?

    Many thanks

    Reply
    • Catherine

      November 26, 2017 at 1:04 pm

      Hi Nicole,

      I send the sample into a lab here in the U.S. and they send me back the report to interpret.

      Abundantly,
      Catherine

      Reply
  2. Autumn

    November 26, 2017 at 10:23 am

    I was told to take d supplements but they failed to mention this can lower potassium! Argh!!!

    Reply
  3. Penelope

    November 26, 2017 at 1:54 pm

    I have the MTHFR defect ( c777t and 1298c
    But when I took the correct form of b vitamins my body had a complete breakdown. I got these Insane migraines and then panic attacks. Things that I dont suffer from. I just decided that it was harmful to take the correct form without better knowledge and care.
    I just made sure my diet contains the natural form of vitamins but guess It may not be perfect. I also have low iron ...... should I supplement or just try to add that to my diet and do it slowly . ( iron is around 18)

    Reply
  4. Dori

    November 28, 2017 at 10:41 am

    I have heard/read that 23andme is no longer providing this info that can tell us about MTHFR.
    Can you confirm if this is true or not?

    Reply
    • Catherine

      November 28, 2017 at 1:49 pm

      Hi Dori,

      No, I can't confirm because they are constantly changing what SNPs are included with each update. I called them once and had a very hard time getting out of them the information that I wanted, so I recommend calling them and asking them about the specific SNPs you want to know about, because otherwise there is no guarantee.

      Abundantly,
      Catherine

      Reply
  5. Mfon Amana

    December 04, 2017 at 9:19 am

    Personally from observation, I've noticed people don't understand why someone who had a high hair calcium would be supplemented calcium and some other things. High hair calcium is indicative that there is biounavailable calcium and you're also deficient as your body is removing calcium in bones to maintain concentration in blood. (This is important) (as calcium is mainly stored in bones).
    To remove excess biounavailable calcium, one has to improve adrenal and thyroid activity. Once your adrenals and thyroid improves, it still doesn't stop the fact that you're not getting enough calcium. So as a result, calcium is supplemented to prevent calcium leaching out of the bones, as well as Vitamin D (the only problem here is that they don't supplement Vit A and Vit K2 as well because it'll send calcium to the bones where it can displace toxic metals like lead and so forth as a placeholder..

    Reply
  6. Daniel Riverso

    February 26, 2018 at 9:45 am

    Hi, Great blog! You've inspired me to get my hair tested (results are back tomorrow) as I battle hair loss.

    If you should not be taking vitamin D supplements, how do you ensure you are getting enough if you live in a cold climate, such as Canada.

    Best,

    Dan

    Reply
  7. Tania

    November 05, 2018 at 6:54 pm

    Hi Catherine,
    such an amazing blog you have!
    Do you the reliable test to check vit. A and Iodine levels?
    Thanks,
    Tania.

    Reply
    • Catherine

      November 09, 2018 at 1:26 pm

      No. Unfortunately, I don't!

      Abundantly,
      Catherine

      Reply
      • john caluda

        November 20, 2018 at 2:20 pm

        a

        Reply
  8. craig eiswirth

    November 20, 2018 at 2:06 pm

    Hi Catherine just recieved this article in my email. I am not a doctor but have studied supplements/herbs about 30 years now. listen to doctors and nutritioniss who use and recommend them. I don't agree with some of this article.first i have learned most people are low in D3,magnesium and iodine according to the doctors i listen to. 20 ng/ml is too low. 50 is minimum with 80 preferable. extreme high doses for too long can cause problems. my level is around 100ng/ml. no problems. i do also take potassium and calcium so no depletion there. now you are right folic acid is synthetic and usually the form used in most multi's. i get folate separately to get natural form. now calcium i do not take everyday. magnesium is the mineral i use. but i do take k2 and A also. Bone-up is good because along with calcium has co-nutrients. A i don't take everyday. have to use some caution if doing high doses. beta carotene from what i understand is safe because the body will only convert to A what is necessary. iron is not recommended for men and i believe women who no longer go through menstration. but as a whole i feel safe using supplements and have done for decades. craig

    Reply
  9. Susan

    December 09, 2019 at 12:13 am

    I have just bought zinc,probiotic,and magnesium,my doctor has now said don’t take anything unless prescribed by him, l don’t want to take drugs,what do you think.

    Reply
    • Catherine

      December 09, 2019 at 10:51 am

      Hi Susan,

      Your doctor knows your health history and I do not, so I can't comment.

      Abundantly,
      Catherine

      Reply
  10. Fitoru Keto

    May 25, 2020 at 5:12 am

    Wow! Definitely learned a lot from this. Thank you so much for posting!

    Reply

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Hi, I'm Catherine! As a nutritional therapist, my passion is education. My goal is to help guide you to improve your nutrition through strategic eating (not dieting) and without expensive supplements! Because when you know better, you can feel better! More about me →

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