Know what you're putting in your body.

158 herbs, nutrients, and compounds. What the science says, what tradition knew, and what to watch for. Founding members keep this running.

$60 /year

Founding rate — locked for life. Regular price after launch: $96/year.

✓ Full access to all 158+ entries
✓ Print-ready reference card for every herb
✓ Monthly curated set — 5 herbs, one body system
✓ The Sunday Letter — weekly research digest
✓ Bookmarks synced across devices
✓ Founding rate locked forever

Become a founding member

Cancel any time. No questions asked.

BONE HEALTH & STRENGTH

Magnesium

Mg — Element #12

also known as Magnesium oxide, Magnesium citrate, Magnesium glycinate, Magnesium sulfate

An essential macromineral that acts as a cofactor in over 300 enzyme reactions. Most of the body's magnesium is stored in bone, with the rest distributed across muscle and soft tissue.

Role in the body Cofactor for ~300 enzymes including ATP production; structural in bone; regulates muscle, nerve, and cardiac function

Recommended daily intake

Adult Men 19 30 · 400 mg
Adult Men 31 Plus · 420 mg
Adult Women 19 30 · 310 mg
Adult Women 31 Plus · 320 mg
Pregnancy · 350-360 mg
Lactation · 310-320 mg

Upper intake limit

350 mg/day from supplements only — does not apply to magnesium from food

Signs of deficiency

Muscle cramps and twitching
Fatigue and weakness
Loss of appetite, nausea
Abnormal heart rhythms in severe cases
Numbness or tingling

Cofactor for over 300 enzymes, including those that produce ATP — the body's energy currency
Required for DNA, RNA, and protein synthesis
Supports normal muscle function and helps prevent cramps
Helps regulate blood pressure as a natural calcium channel antagonist
Involved in glucose metabolism and insulin sensitivity
Necessary for normal heart rhythm

Active in Mg²⁺ ion.

Doses above the supplemental upper limit can cause osmotic diarrhea, nausea, and abdominal cramping

Very high doses can cause hypermagnesemia — low blood pressure, lethargy, and in severe cases cardiac arrest

Reduces absorption of fluoroquinolone and tetracycline antibiotics, and bisphosphonates — separate doses by at least 2 hours

NIH ODS — Magnesium · MedlinePlus — Magnesium in diet · Britannica — Magnesium

Works with

Vitamin D Magnesium is a cofactor for enzymes that convert vitamin D to its active form (calcitriol); deficiency impairs vitamin D activation. Calcium Magnesium is required for parathyroid hormone secretion; without adequate magnesium, calcium metabolism is impaired regardless of intake.

You might also explore

The curious few.

50 founding spots left