What supplements (and what amounts) should I be taking with Vitamin D?
February 17, 2021 7:23 AM   Subscribe

It seems like Vitamin D is a link to overall better health, and with work from home and winter, I've been getting 0 sunlight. I'm taking 250 mcg (10K IU) / Day of vitamin D. Someone mentioned taking vitamin K or magnesium with it. What's your reco?

I'm not looking for someone to judge my choice of taking 10K IU/day of D3, while it's above generally recommended amounts, it's shown to be safe. I'm 6'1 and 180lbs.

What I AM looking for is any tips or general recommendations on what, if anything, I should also be taking with the vitamin D. I've seen lots of quips about magnesium, calcium, iron, and vitamin K, but none have really laid it out in a clear way where I can just start eating the pills.

Are any of these pills anything more than placebo? Hard to say. But I appreciate your advice!
posted by bbqturtle to Health & Fitness (14 answers total) 9 users marked this as a favorite
Take it with some fat to increase absorption: if you do fish oil or any fatty supplements, take them together, or take it with a meal that has some decent fat.

For that reason you also might get better uptake with two smaller doses per day than one large.
posted by SaltySalticid at 7:35 AM on February 17, 2021 [1 favorite]

I have a relative who used to do research for a big pharma company and is a massive proponent of Vitamin D. They recommend magnesium in addition to Vitamin D, especially to relatives who drink alcohol. I can't remember the exact reasoning (I was already taking magnesium at night to help with sleep), but I think the magnesium was supposed to help with Vitamin D absorption or your body's ability to use it.
posted by ghost phoneme at 7:48 AM on February 17, 2021

D3 and K2 support bone health, which is why they are recommended together. There are supplements that have both in one. I take that in liquid form.

Taking it with some fat does help increase absorption because D3 is fat-soluble.

Magnesium supports the enzymes that metabolize D3, which is why you see some recommendations to take them together.
posted by bedhead at 7:58 AM on February 17, 2021 [1 favorite]

I've seen recommendations not to take vitamin d at night because it might interfere with sleep.
For what it's worth, I was diagnosed with very low vitamin D levels. I've also been struggling with severe anxiety for about a year. I started taking vitamin D about 2 months ago and (I have no idea if it's related) my anxiety symptoms have been getting gradually more manageable, to the point that I feel able to do a lot of things I could not before. So there's that. I'd love to know if it's placebo or coincidence, or the vitamin D.
posted by Zumbador at 8:24 AM on February 17, 2021 [2 favorites]

Hi there. I'm a toxicologist who has worked in regulatory enforcement around supplements. I am not your doctor, but vitamins D and B12 are the only vitamins I take routinely, and in my opinion taking any other vitamin or supplement is pointless at best and potentially harmful over time unless you've been directed to do so by your physician in response to a confirmed deficiency or other medical condition.

Taking vitamin D with a meal is a good idea, as noted above for fat solubility, but there's no need to supplement your diet with commercially available extracted or purified oils. Literally any meal you eat will have some fatty component, whether it's from beans or veg or nuts or what have you (even a single serving of 100g of celery has 0.2g fat). I say this because commercial supplements, like fish oil, are largely unregulated and end up the subject of enforcement actions over identity or purity (i.e. contamination) violations. You will never find a toxicologist who takes an over-the-counter fish oil, cod liver oil, etc.--whatever it's called, I ain't eating a patent medicine sold on an unregulated market.

Haha ok, end of little soap box moment.
posted by late afternoon dreaming hotel at 9:24 AM on February 17, 2021 [32 favorites]

Response by poster: @late afternoon dreaming hotel

Since you obviously think about this kind of thing a lot - how much Vit D do you take? Would you recommend B12 due to dietary reasons?
posted by bbqturtle at 10:10 AM on February 17, 2021 [1 favorite]

I'm not dreaming in the late afternoon, but: My serum vitD came up as 9 a few years back. Got the megadoses and I've been taking 5k IU daily ever since (which as you know is well higher than the 200 IU doses that the popular media discusses, which seem homeopathic to me). My vitD levels have never gone above the bottom range of normal in a half dozen tests since. So there's one data point for you. I'm in support of taking whatever you need to get your blood levels to the normal range.
posted by Dashy at 10:22 AM on February 17, 2021 [1 favorite]

My father's doctor told us that taking big doses is rough on one's kidneys because it's a big molecule and she said can do damage. She felt that geriatric patients (over 70) needed to be particularly mindful of this. I take 1000IU most days and 5K maybe 1x a week and I've been clinically low in the past - and am not geriatric.
posted by leslies at 10:41 AM on February 17, 2021

RN here. Please be careful with vitamin K. It is important in one of the body's blood clotting pathways; people who take Coumadin (warfarin is the generic name, sometimes called a "blood thinner" ) should definitely NOT take vitamin K without talking to their physician. Vitamin K will reverse the anti-clotting effect of warfarin! There are even dietary restrictions for those taking warfarin, to avoid foods high in natural vitamin K, so it doesn't take much to upset the clotting pathway, much less the higher doses found in supplements.

I know that vitamin K1 and K2 are somewhat different, but blood clotting - or not clotting, depending on your medical needs - is not something random internet strangers or GNC clerks should give you medical advice about. Please consult your doctor.
posted by citygirl at 2:08 PM on February 17, 2021 [8 favorites]

Some of the supplements you mention can be toxic in high doses. Vitamin D toxicity is uncommon, but too much magnesium will give you diarrhea and also make your kidneys unhappy.

Unless you've been told you are deficient in all those vitamins / minerals, in which case your doctor can guide you as to doses. Otherwise for the vast majority, you will absorb vitamins and minerals more efficiently from food than from pills.

I would particularly stay away from taking vitamin K without doctor's orders, for the reason citygirl outlines.
posted by basalganglia at 2:24 PM on February 17, 2021 [2 favorites]

I take a similarly large dose, and per the recommendation of doctors split it into two servings, morning and afternoon.

I don't take it at night, because I have experienced a correlation between that and not being able to sleep.
posted by jander03 at 7:29 PM on February 17, 2021

I had a lab test result for low vitamin D. My doctor prescribed 10000 iu's a day. I still take 5000 iu's a day.
posted by ohshenandoah at 12:00 PM on February 18, 2021 [1 favorite]

Apologies for just now noticing that you asked me a question.

Since you obviously think about this kind of thing a lot - how much Vit D do you take? Would you recommend B12 due to dietary reasons?

I take a small amount over the RDA for my age etc. simply because there's a commercially available supplier that makes an OTC capsule that's right at that sweet spot. There's some evidence that taking more can be beneficial, but I've never tested in the deficiency range so I don't think there's compelling evidence suggesting I need to take more. I wouldn't worry about taking a bit more than the RDA, but I would avoid taking megadoses in excess of the RDA (for any vitamin, mineral, supplement of any kind).

Prior to toxicology, I worked in cancer research, especially in molecular epidemiology. That had me paying a lot of attention to the tiny gene and protein switches in our bodies and what environmental factors twiddle the knobs. We in the modern, industrial era are expsoed to a surreal array of synthetic chemistries at extremely low/variable doses over our entire lives, and we're still a long way away from being able to understand exactly how all those substances interact with our biology. Big doses of anything (like vitamins) are a little more open to understanding in this way, but not much, and we know there's a real worry of "feeding the weeds," so to speak. Cancer cells are generally just cells that have the brakes removed, so they're better at gobbling up nutrients than their neighboring healthy cells. They don't discriminate whether the source is from a pill or not, if there's excess of some nutrient, they'll take it.
posted by late afternoon dreaming hotel at 9:52 AM on February 19, 2021 [1 favorite]

Nobody's mentioned iron so I'll guess I'll be the resident anemic. Iron is an amazing help if you're anemic (even mild/subclinical anemic), but don't bother with it if you're not. Even the gentle types have digestive side effects that are NOT worth it. It's also one of the more dangerous ones to overdo (keep it away from children!), so unless you have a strong suspicion you're anemic don't even worry about it.

Some weightlifters/sporty people I know take magnesium after tough workouts to prevent muscle cramps and tightness. It's also supposed to be good for sleep. FWIW I've tried it but didn't notice any difference.
posted by 100kb at 5:00 PM on February 21, 2021

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