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One labelled serving daily. Note that the two formats are not evidentially equal: most of the trial evidence used 4-6 capsules per day of an encapsulated juice concentrate, while modern scoopable blends deliver about 10-12 g and are the least-studied format. The gram figures below describe the common scoop serving, not a dose the trials validated

Any time · with food

A product that discloses per-ingredient amounts and carries third-party heavy-metal testing

1servings/day

With meals · with food

Capsule or softgel

• None absolute. If you take warfarin or another vitamin-K antagonist, do not start or stop a greens powder without telling your prescriber and monitoring INR
• Thyroid disease, for blends containing kelp or seaweed
• Chronic kidney disease or a history of calcium-oxalate stones

• Warfarin and other vitamin-K antagonists
• Levothyroxine and antithyroid drugs

• Hemochromatosis or iron overload disorders (avoid iron-containing formulations)
• Hypervitaminosis A (avoid high-dose vitamin A formulations)
• Hypercalcemia (caution with high-dose calcium-containing MVIs)

• Warfarin (Coumadin)
• Tetracycline antibiotics (doxycycline, minocycline)
• Quinolone antibiotics (ciprofloxacin, levofloxacin)