good call on the coffee reduction; you'll excrete less mag in urine. (bienvenue a TMI-land lol)
- The effect of dietary caffeine on urinary excretion of calcium, magnesium, sodium and potassium in healthy young females
https://www.sciencedirect.com/science/a ... 1784801323
"increased output of magnesium appeared to be due to the combination of both a slightly increased urinary magnesium concentration and volume."
good call as well re the cod liver oil for d3. as for your prescribed 2000 IU vitamin d3 daily dose, that is a reasonable input and while it does not raise red flags re excess, it may not be as effective as quickly as you might like without any cofactors in the mix.
the addition of magnesium from all sources (foods, fluids, transdermal, supplemental) can be expected to improve your d3 dose-response. especially given your starting d3 level. we need lots of magnesium on a daily basis - probably more than the current RDIs for mag (they are under review). most people get about half of the existing low recommended mag amount.
you've already seen above some recommendations re dose, chemical form and timing in relation to d3 intake. try to maximize your mag input from food and if you enjoy them, epsom salts baths. if you were to choose a supplement and then experienced an excessive laxative effect, you would likely need to lower the dose or choose a higher quality product (eg switch from mag oxide which is a good laxative, to mag glycinate which modifies mag oxide with glycine and is better absorbed into body tissue).
as with most things, it is possible to overdo magnesium. i currently take up to 2 per day of a 200 mg magnesium glycinate product that says 1 per day on the label. that's in addition to the bit of mag in my multi vit/min and that total is ok; i know i probably need more like 600mg per day altogether. you just have to not be ridiculous with it

at times when my diet has been high in mag, i will start to feel side effects from a second mag glycinate pill in a day. specifically, sluggish muscles and so it's not as easy to climb the stairs.
edit: i had meant to comment on the iron supplement prescription as well. related:
- Iron and zinc interactions in humans
https://academic.oup.com/ajcn/article/68/2/442S/4648664
...a total dose of >25 mg Fe may produce a measurable effect on zinc absorption. This could occur if iron supplements are taken with a meal, and iron experts recommend that iron supplements be taken between meals...
- Competitive Interaction of Iron and Zinc in the Diet: Consequences for Human Nutrition
https://academic.oup.com/jn/article-abs ... 27/4779824
...The interaction of iron and zinc and competitive inhibition of zinc uptake by excess iron in ratios of 2:1 or greater, when the total amount of ionic species is greater than 25 mg, appear to have a measurable effect on human zinc nutriture...
- Iron, copper, and zinc status: response to supplementation with zinc or zinc and iron in adult females
https://academic.oup.com/ajcn/article-a ... 45/4716268
...Supplementation with Zn poses a risk to Fe and Cu status. Inclusion of Fe with Zn ameliorates the effect on Fe but not on Cu status...
i can't find the exact study i wanted to but the idea is that it's a balancing act. in your case to balance iron intake you can supplement zinc. also smart to take zinc between meals. the zinc level is highest naturally mid-morning so if you took it first thing that would probably make the most sense to your body. which would mean iron could go in later in the day. iron tends to be shall we say, binding. so if you need a laxative, magnesium oxide is your friend lol. can't hurt to have a couple different forms handy for different purposes.
the daily upper limit for zinc from supplements is 40 mg. if you go above 50mg per day you need to watch for copper depletion. anecdotally, others here have noticed reduced copper status on lower zinc doses but as long as the ratio of the two is ok in serum, ie copper level doesn't sink *too* much lower than zinc, it should not become an issue. i get 10mg zn in my multi plus an additional 30mg in a zinc picolinate supplement (best absorption per the available research). i take it 5 days per week and take the weekend off. if you experience nausea after taking zinc between meals, you can take less at one time. you can also add food but that can reduce zn absorption.
the weekly chowder would be good for long term maintenance once you know your levles for both zinc and ferritin are in good shape. eg around 18 umol/l for serum zinc (noting also that around 17 umol/l copper is good in ratio terms) and 80 ug/l for ferritin.
ok back to the original post:
if one person's anecdote is any consolation, there's no-one in my family with ms on either side.
as for prevention for kids sake, research suggests that keeping vit d3 status in good shape would be smart. i would add, nourish the immune system in general and avoid lifestyle contributors to inflammation.
links to help make the case for serum mag and serum zinc testing are coming your way soon
