Am I overdosing on these vitamins/minerals?
March 18, 2023 12:11 PM   Subscribe

YANMD. My doc has me on a very high fiber diet (because reasons), and has suggested fiber supplements as a way to help me get my daily total higher. She okays the fact that I go beyond the manufacturer's recommended dosage, but I have a question about all the *other* things that are in my fiber supplements beyond just the fiber.

So, for example, I use a particular brand of fiber gummies. The manufacturer says "2 per day" but I usually take 6 per day, with my doc's okay. I want the fiber they're providing, but I just did the math and realized that if I take 6 per day, I also get:

200% of the USDA daily recommended allowance of niacin
300% of B6
250% of folate
1500% of B12
750% of biotin
600% of pantothenic acid

I really know nothing about these, and I don't know if these numbers are problematic at all. Advice, please? If any of this is problematic, I absolutely have different fiber supplements I could switch to. However, I actually prefer these gummies because they are easily portable, don't need to be mixed in a beverage, etc. I'd like to continue using them if I can.
posted by BlahLaLa to Health & Fitness (14 answers total)
I find that an excess of B6 and B12 will eventually make me jumpy.
posted by Thella at 12:37 PM on March 18 [1 favorite]

In terms of vitamins the ones that are most worrisome in excess are the fat-soluble vitamins, since the body doesn't have a good mechanism to excrete the excess. Vitamins A and E are fat soluble, and I know a person who took enormously high amounts of Vite A supplements, insisting that as long as the supplement was "natural" it could not possibly be harmful. He became jaundiced, and in fact he had severe liver damage on liver biopsy, and was on his way to liver failure.

Every item you list is a B vitamin. B vitamins are water soluble - they notoriously turn your pee bright yellow, and excess will be peed out. This is probably why your doctor is not concerned about your large intake.
posted by citygirl at 1:10 PM on March 18 [7 favorites]

IANAD, TINLA. I take a B12 supplement weekly (I'm vegan so I only get B12 from fortification/supplementation) that's roughly 200,000% of the daily recommended dosage and my last blood levels were smack dab in the middle of normal. B12 is poorly absorbed in the first place and is further inhibited by drugs such as Metformin or Prilosec, both of which are very common. I wouldn't get too excited about 1500% of B12 daily myself but it might be worth it to ask for a level on your next blood test if you're worried.

I don't know anything about niacin, B6, folate, or pantothenic acid, but I have recently read a few articles suggesting people stop taking skin, hair, and nail vitamins (biotin) because high levels can interfere with *measurement* of thyroid function. I wouldn't personally be overly concerned about that (I have no thyroid anyway) but if I did suspect I was having thyroid issues I would probably mention the biotin to my doctor.
posted by MagnificentVacuum at 1:16 PM on March 18

I'm a doctor, not your doctor, this is not medical advice. There's a little more nuance to the "B vitamins are water soluble and therefore cannot cause toxicity" conventional wisdom. Niacin (vitamin B3) is known to cause adverse effects starting at doses as low as 2-3x the RDA (depending on your age and sex).
posted by telegraph at 1:20 PM on March 18 [4 favorites]

I stopped taking biotin supplements because biotin can cause false low readings on the blood test for heart attack, leading to misdiagnosis which has killed at least one person. If you feel confident that you'll be taken seriously in the ER or are confident in your overall heart health you may feel differently.
posted by Frowner at 1:27 PM on March 18

I’m a toxicologist. I cannot help but sneer at this kind of shit. Your doctor is trying to make you feel like you’re being given medical attention by telling you to take unreasonable doses of active ingredients that are poorly regulated. That’s it. That’s the punchline. These things aren’t helping you unless you have a clear, diagnosed deficiency and if your doctor is telling you otherwise then they are a charlatan.
posted by late afternoon dreaming hotel at 4:15 PM on March 18 [2 favorites]

You can easily find fiber gummies that don’t have micronutrient supplements, so why risk it?
posted by goingonit at 4:19 PM on March 18 [2 favorites]

I overheard a supplements person at the grocery store telling someone that over the past couple decades, she's come to think it's best to minimize excess supplements as much as possible so as to go easy on the kidney.
posted by aniola at 4:19 PM on March 18

Response by poster: To be clear, my doc is not telling me to take these B vitamins. My doctor is telling me to have a very large amount of fiber in my diet, a number that can be hard to hit without adding some kind of fiber supplement. I happen to have found a tasty fiber supplement...that happens to have B vitamins added in.
posted by BlahLaLa at 5:18 PM on March 18 [1 favorite]

I take psyllium husk capsules, which are ground psyllium husks in gelatin capsules. If I want pro- or prebiotics, which I do, I eat fermented foods like kimchi or sauerkraut and leafy greens.
posted by theora55 at 6:35 PM on March 18 [2 favorites]

You're better off finding a tasty fiber supplement...that doesn't happen to have added vitamins beyond what you need.
posted by aniola at 6:35 PM on March 18 [1 favorite]

Which isn't to say that some people don't need large amounts of these vitamins. Some people do. But if you're not one of them, don't make your body do the extra work.
posted by aniola at 6:38 PM on March 18

Hypervitaminosis B6 is a rare cause of neuropathy. I've only seen it in people who are massively megadosing (even more than your list here).
posted by basalganglia at 7:35 PM on March 18

My instinct is there's no worry here, but more relevantly I'd add that the NIH seems to have data on some or all of these that include upper limits.

I stopped at two (both seem completely safe), but you could run through the other ones and compare to your dose to see if you're anywhere close to the warning limit:

Vitamin B6: You are taking around 5 mg/day, the upper limit is set to 100 mg/day (and that includes a safety margin.)

Pantothenic Acid: They were unable to set an upper limit because they've never had a report pantothenic acid toxicity in humans.
posted by mark k at 10:32 AM on March 19 [1 favorite]

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