Supplement ratio oddity

Factual Questions
1

Per doctor’s instructions, I’m taking a calcium / vitamin D supplement.

Weirdly, the supplement contains 125% of my vitamin D requirement (1000 IU) - but only HALF of my calcium requirement.

Why wouldn’t they try to provide similar percentages of each?

I was concerned over the excess vitamin D, but have found some cites that suggest that even 2000 IU is safe - despite it being a fat-soluble vitamin.

Annoyingly, my instructions are to take 1200 MG of calcium (twice what is in the supplement) and 1000 IU of vitamin D, exactly what is in the supplement. I guess I just need to chew on a few oyster shells a day, or something.

2

Because the manufacturers of the supplement assume you consume other sources of calcium that contribute to your daily intake. Calcium is present in a lot of types of food, in particular in dairy, which the average Western diet is very rich in.

3

Plus, your calcium requirement is probably high enough to make a single capsule hard to swallow. Vitamin D is much more compact.

4

It’s not just your supplement, I think it’s all of them.

I just now went to Amazon, to look at the first random bottle of Centrum that it would come up with. You can read the label here.

It has just 2% of the DV of phosphorus, but 40% of selenium, 149% of the DV for chromium, and 2083% of something else.

I have no idea why someone would need those particular amounts of those nutrients. My guess is that they don’t put 22 mcg of pure selenium and 20 mg of pure phosphorus into the tablet. More likely, there is some sort of raw material where they get the selenium, and it happens to have that much phosphorus.

In other words, they aren’t aiming for specific dosages. They’re aiming for a product that is easy and cheap to make, and has broad appeal to the customers.

5

Also I think it may be easier to overdose on calcium than overdose on vitamin D.

6

FWIW, after testing my levels, my doctor had me taking 5000 IU of Vitamin D for a few months, then dropped me to 2000 IU as an ongoing recommendation.

7

There was a guy who was in the news recently with severe kidney damage from Vitamin D overconsumption and websites talked about it as a “cautionary tale” against the culture of popping supplements.

That may or may not be a noble goal, but the guy was consuming 150,000 IU of Vitamin D every day for months before he developed this problem from it. That’s hilariously more than any supplement pusher or manufacturer would ever recommend, let alone a doctor.

8

This is best achieved by standing under a cliff until a bloody great rock of limestone falls on your head.

LD50 for Calcium 6,450 mg/kg
LD50 for Vitamin D 37 mg/kg
LD50 for Sodium chloride 3,000 mg/kg

9

Hah - I think I read that same article. Also, someone here on the SDMB posted, about 12 years back, about being told to take an insane amount of vitamin D (typo in a message from the doctor, IIRC).

Amusingly enough, now that I need this supplementation, and I need to supplement with iron, AND there’s that pesky Welchol… each of which risks interfering with absorption of things, I’m basically popping something every 2 hours.

At least I can chalk (hah - pun intended) a daily dose of ice cream as medically necessary.

10

But the daily recommended dose for calcium in 1000 mg while for vitimin D is only 10-20 mcg

So the for Calcium the LD50 is about 6daily dose/kg
For vitamin D the LD50 is about 2000daily dose/kg

Of course LD50 may not be the best measure of toxicity, since more minor negative health effects (e.g. Diarrhea) will come at much lower doses.

11

Take the supplements for a while and then get tested to see if you have remaining vitamin/nutrient deficiencies. Supplements may work fine, need to be upgraded or downgraded, or even be totally ineffective. For various reasons some people can’t absorb particular substances and may need to take them in a different form, and occasionally some more serious underlying problem is exposed.

12

Calcium blocks the absorption of other vitamins, especially iron, zinc, and magnesium. That’s why it often has low concentrations in multivitamins. However vitamin D is required to absorb calcium, so those tend to be paired with one another in higher concentrations. So if there’s wildly high or low percentages on some vitamins it’s likely because that’s counteracting or assisting with another one that’s considered a priority.

13

Interesting. So I’d have to take about 1200 tablets (daily being 2 tablets) a day for the calcium to kill me, and 4000 for the Vitamin D to kill me quickly (assuming 100 kg weight, to simplify the math).

I assume that’s a single bolus, not taking the daily dose 200 (or 4000) over that number of days! Plus of course lesser issues like the fellow who wrecked his kidneys.

When I broke my foot a few months back, the ortho gave me an 8 week course of vitamin D - 50,000 IU weekly. 50 times the daily requirement. Luckily still well short of that 2000 times.

Oh, absolutely! The calcium and vitamin D and iron are all taken under doctors’ advice; I expect the calcium will be a lifetime thing. I’m hoping the iron will not, though I’ve now managed to educate three different doctors as to why I need it (long story short: I have restless legs syndrome, and it’s recommended that we get our ferritin levels well above the minimum “normal” range).

Without going into too much TMI detail: iron supplements have one well-known annoying side effect. Which in my case is a benefit.