B12 + Iron
Plant-based eaters
Cutting meat and dairy means cutting the main sources of these two. B12 especially, since there's no reliable plant source.
Health Guide
What Vitamins Do You Actually Need: Daily Guide
1
Test, don't guess
Ask for a blood panel before you buy anything.
2
Skip the megadose
Extra vitamin D past your needs just gets stored, not used.
3
Pair for absorption
Take iron with vitamin C, keep it away from coffee.
The vitamin aisle is built to make you panic buy. Twenty bottles, all claiming you're deficient in something. Here's what your body actually runs on every day, who genuinely needs to supplement, and where the rest is just packaging.
01 · The basics
The ones actually worth knowing
Out of everything on a supplement shelf, these are the vitamins and minerals people genuinely run low on. General adult daily targets below, your number shifts with age, sex, and pregnancy so don't treat these as gospel.
Vitamin D
The one everyone's low on
600–800 IU/day
Why it matters: bone health, immune function, mood. Get it from: sunlight, fatty fish, fortified milk. If you work indoor shifts and live somewhere with real winters, you're probably short on this one.
Vitamin B12
Only in animal products
2.4 mcg/day
Why it matters: nerve function and energy metabolism, the "why am I always tired" vitamin. Get it from: meat, eggs, dairy, fortified cereal. Not naturally in plant food, full stop.
Iron
The period tax
8–18 mg/day
Why it matters: carries oxygen in your blood, low iron means low energy and that gray, drained feeling. Get it from: red meat, beans, spinach, fortified grains. Anyone who menstruates needs roughly double what everyone else does.
Magnesium
The chill pill mineral
310–420 mg/day
Why it matters: muscle function, sleep quality, stress response. Get it from: nuts, seeds, dark chocolate, leafy greens. If magnesium supplements make you sleepy that's normal, not a side effect to worry about.
Calcium
Not just for milk drinkers
1000–1200 mg/day
Why it matters: bone density now sets up how your bones hold up at 50. Get it from: dairy, fortified plant milk, tofu, leafy greens. Works with vitamin D so pair the two.
Vitamin C
Not actually a cold cure
65–90 mg/day
Why it matters: immune support and collagen production, helps you absorb iron better. Get it from: citrus, bell peppers, strawberries. One orange covers your day, easily.
02 · Reality check
Who actually needs to supplement
Most people eating a decent variety of food don't need a pill for everything. These are the actual gaps worth paying attention to.
Vitamin D
Anyone working indoor shifts
Barista, retail, office, whatever. If sunlight is a lunch break at best, your D levels are probably not great, especially October through March.
Iron
Anyone who gets a period
Blood loss every month means your iron needs are roughly double the general adult recommendation. Fatigue that won't quit is worth a blood test, not just more coffee.
03 · Do this
Building a stack without wasting money
Skip the 25-ingredient gummy bottle. Do this instead.
1
Get real data
Ask your doctor for a basic panel: vitamin D, B12, ferritin (iron). Most primary care visits can add this for free or cheap.
Ask your doctor for a basic panel: vitamin D, B12, ferritin (iron). Most primary care visits can add this for free or cheap.
2
Fix the actual gap
Buy the one or two things you're actually low on. Not a multivitamin covering forty things you don't need.
Buy the one or two things you're actually low on. Not a multivitamin covering forty things you don't need.
3
Take it right
Fat-soluble vitamins (D, A, E, K) need food with fat to absorb. Iron wants vitamin C nearby and coffee far away.
Fat-soluble vitamins (D, A, E, K) need food with fat to absorb. Iron wants vitamin C nearby and coffee far away.
04 · Skip these
Common mistakes
Where people burn money and, occasionally, actually hurt themselves.
×
Buying a gummy multivitamin for everything
Doses are usually too low to matter and half the bottle is sugar.
Doses are usually too low to matter and half the bottle is sugar.
×
Taking iron with your morning coffee
Coffee and tea block iron absorption. Space them out by at least an hour.
Coffee and tea block iron absorption. Space them out by at least an hour.
×
Megadosing vitamin C to "prevent" a cold
Past a normal amount your body just excretes the extra. It doesn't stop you from getting sick.
Past a normal amount your body just excretes the extra. It doesn't stop you from getting sick.
×
Ignoring vitamin D in winter
Less sun means lower levels for basically everyone north of the sun belt, not just people who feel off.
Less sun means lower levels for basically everyone north of the sun belt, not just people who feel off.
×
Trusting a random influencer's supplement stack
Check for third-party testing (USP, NSF) before buying anything they're pushing. Your body isn't a content strategy.
Check for third-party testing (USP, NSF) before buying anything they're pushing. Your body isn't a content strategy.
Daily amounts reflect general adult recommendations from the NIH Office of Dietary Supplements, individual needs vary by age, sex, and health status, so talk to a doctor before starting any supplement. ods.od.nih.gov