If you spend a week behind our counter, two questions come up more than any others: how much vitamin D should I be taking, and which magnesium is the right one? They're good questions, and the answers are less complicated than the internet makes them sound.
Here's what the federal nutrition data actually says about both, what the differences between forms mean in practice, and how we talk it through with people at our store in Saginaw.
Vitamin D: the one Texans assume they have covered
There's a running assumption in North Texas that nobody here could be short on vitamin D. We have sun nine months a year. But sun exposure and vitamin D status aren't the same thing, and the reasons are pretty mundane. From June through September most of us are moving from an air-conditioned house to an air-conditioned truck to an air-conditioned building. Sunscreen, which is a good idea, also reduces how much vitamin D the skin makes. And the shorter, lower-angle days from November through February produce far less of it than a July afternoon.
What the recommended amounts actually are
From the National Institutes of Health Office of Dietary Supplements:
- Birth to 12 months: 10 mcg (400 IU)
- Children and teens 1–18: 15 mcg (600 IU)
- Adults 19–70: 15 mcg (600 IU)
- Adults 71 and older: 20 mcg (800 IU)
- Pregnant and breastfeeding: 15 mcg (600 IU)
The upper limit for adults is 100 mcg (4,000 IU) a day from all sources combined, meaning food, fortified drinks and supplements together. Some people are told by their doctor to take more than that for a period of time based on bloodwork, and that's a conversation for the person who ordered the test, not for a shelf tag.
Why the labels say 2,000 and 5,000 IU
Walk our vitamin wall and you'll see 1,000, 2,000, 5,000 and 10,000 IU softgels sitting next to each other. Higher-dose products exist because vitamin D status varies enormously from person to person, and because doctors commonly recommend specific doses after a blood test. The honest answer to "which one should I take" is that a simple 25-hydroxyvitamin D test turns a guess into a number. Ask for it at your next physical.
D3, D2 and taking it with food
Vitamin D3 (cholecalciferol) is the form the body makes from sunlight and is generally the one we recommend people look for. D2 (ergocalciferol) is plant-derived and a reasonable option for strict vegans. Either way, vitamin D is fat-soluble, so it's absorbed better alongside a meal that contains some fat, which is a small habit change that costs nothing.
Who the NIH flags as more likely to fall short
Older adults, breastfed infants, people with darker skin, people who consistently stay out of the sun or cover up, people with conditions that affect fat absorption such as celiac or Crohn's disease, and people who have had gastric bypass surgery. If you're in one of those groups, it's worth raising with your provider rather than guessing.
Magnesium: the mineral, and then the maze of forms
Magnesium is involved in hundreds of enzyme reactions in the body, and it's one of the minerals Americans most reliably under-consume. The recommended daily amounts:
- Adult men: 400–420 mg
- Adult women: 310–320 mg
- Pregnancy: 350–360 mg
- Teen boys 14–18: 410 mg; teen girls 14–18: 360 mg
Food sources are ordinary and easy: pumpkin seeds, almonds, cashews, black beans, spinach, whole grains, yogurt. Most people who want more magnesium can move the needle at the grocery store before they ever open a bottle, and we'll say so.
The upper limit people misread
You'll see a 350 mg upper limit for adults quoted online next to a 420 mg recommended intake, which sounds like a contradiction. It isn't. The 350 mg limit applies only to magnesium from supplements and medications, not to magnesium from food, which healthy kidneys clear without trouble. The reason for the cap is straightforward: too much supplemental magnesium at once causes diarrhea, nausea and cramping.
Which form to buy
This is the real question, and it's why there are eight magnesium products on our shelf instead of one.
- Magnesium oxide. The cheapest and most common. It carries a lot of elemental magnesium by weight but is absorbed relatively poorly, and its laxative effect is the strongest of the group.
- Magnesium citrate. Better absorbed than oxide, widely available, still noticeable on the digestive end at higher doses.
- Magnesium glycinate. Magnesium bound to the amino acid glycine. The form most people ask us for when they're sensitive to the others.
- Magnesium chloride and lactate. Also among the better-absorbed forms per the NIH.
- Magnesium malate and threonate. Newer arrivals with smaller bodies of research behind them and higher price tags.
One more thing the label won't make obvious: what matters is elemental magnesium, not the total weight of the compound. A capsule listing 1,000 mg of magnesium citrate does not deliver 1,000 mg of magnesium. A good label states the elemental amount directly. Our guide to reading a supplement label walks through where to find it and what else on that panel is worth your attention.
Timing, food and the small stuff
Fat-soluble vitamins, meaning A, D, E and K, go down better with a meal. Magnesium is often taken in the evening, mostly because that's when it's easiest to remember and because the larger forms are gentler on a fuller stomach. Iron and calcium compete for absorption, so they're usually spaced apart. None of this is complicated, but it's the kind of thing that turns a supplement you take erratically into one you actually finish.
What we carry
Between the vitamin wall and the back shelves we stock vitamin D and magnesium from Nature's Sunshine, NOW Foods, Bluebonnet, Natural Factors, Nordic Naturals, Solaray, KAL, Trace Minerals Research, Natural Vitality, Garden of Life and Terry Naturally, among others, in capsules, softgels, liquids, powders and chewables. That range exists so that "I can't swallow pills," "I need it third-party tested" and "I want the gentlest form you have" all have an answer.
Our online store isn't live yet. Everything above is available in the store only for now, with full online ordering planned for later this year.
When to talk to your doctor first
Please do, particularly if you take prescription medication. Magnesium can interfere with the absorption of certain antibiotics and osteoporosis medications, and both magnesium and vitamin D are worth mentioning if you have kidney disease or take a diuretic. We're a supplement store, not a clinic, and we'd rather you hear "check with your physician" from us than not hear it at all.
Common questions
Can I take vitamin D and magnesium together?
Many people do, and there's no general reason to separate them. If you're taking other medications, ask your pharmacist about timing. That's a free conversation and pharmacists are good at it.
Is it better to get these from food?
Food first, always. Supplements are there to fill gaps that food isn't filling, which is exactly what the word "supplement" means.
How long before I notice anything?
Nutrients aren't medications and they don't work like one. Vitamin D levels in particular shift over weeks to months, which is another argument for testing rather than guessing.
Do I need a blood test before taking vitamin D?
Not for amounts at or near the recommended daily intake. For the higher-dose products, a test is the difference between a plan and a guess.
Which magnesium is best for a sensitive stomach?
Glycinate is the form most often requested for that reason, and it's the one we most often hand people who've had trouble with citrate or oxide. Come in and we'll compare the panels side by side.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is educational and is not medical advice. Talk with your healthcare provider before starting any supplement, especially if you take prescription medication, are pregnant or nursing, or are shopping for a child.
Sunshine Herbs is at 1205 N Saginaw Blvd, Suite H, Saginaw, TX 76179. Call (817) 232-4372, or just come by. The vitamin wall is easier to explain in person.