In this remarkable paper called 'Liver Lover's Headache' by Selhorst, Jennings, and Corbett, IIH was seen in individuals who consumed a
shocking amount of liver in their diet (with estimated vitamin A intake of 60,000 to 340,000 IU!).
Sashank Prasad, MD
Chief of Neurology | Penn Presbyterian Medical Center
Professor of Clinical Neurology | University of Pennsylvania Perelman School of Medicine
Original Message:
Sent: 6/3/2025 10:59:00 AM
From: Scott Forman
Subject: RE: Vitamin A in oat milk
That was my mistake. I wrote 100,000 U and meant 10,000, although one dose of vitamin A above 10K units would not necessarily cause disk swelling and headaches.
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Scott Forman, MD
Senior Fellow North American Neuro-ophthalmology Society
Adult and Pediatric Neuro-ophthalmology
Comprehensive Ophthalmology
Functional Medicine
Original Message:
Sent: 6/3/2025 10:52:00 AM
From: Andrew Carey
Subject: RE: Vitamin A in oat milk
from OpenEvidence:
An oral dose of vitamin A is considered toxic when it exceeds 10,000 IU (3,000 μg retinol activity equivalents) per day for adults as a chronic intake, and acute toxicity can occur at single doses of 25,000 IU/kg or more. Chronic toxicity is associated with daily intakes above this threshold, leading to manifestations such as hepatotoxicity, reduced bone density, and increased intracranial pressure. The American Academy of Ophthalmology specifically notes that daily doses above 10,000 IU exceed the FDA-recommended tolerable upper intake level for adults, and chronic intakes above this level are associated with toxicity risks. The U.S. Food and Drug Administration also identifies acute toxicity at single oral doses of 25,000 IU/kg and chronic toxicity at daily intakes of 4,000 IU/kg for several months, with clinical symptoms including liver abnormalities and central nervous system effects.[1-2] Long-term supplementation studies in adults have shown that daily intakes below 25,000 IU are generally safe, but doses at or above this level are considered potentially toxic over the long term.[3] The risk of toxicity is higher in certain populations, such as children, the elderly, and those with liver disease or high alcohol intake.[1-2] In summary, chronic oral intake of vitamin A above 10,000 IU per day in adults is considered toxic, and acute toxicity can occur at much higher single doses.[1-3] 2.AQUASOL A. FDA Drug Label.Food and Drug Administration
Updated date: 2020-08-14
Original Message:
Sent: 6/3/2025 10:48:00 AM
From: Scott Forman
Subject: RE: Vitamin A in oat milk
Greater than 100,000 Units
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Scott Forman, MD
Senior Fellow North American Neuro-ophthalmology Society
Adult and Pediatric Neuro-ophthalmology
Comprehensive Ophthalmology
Functional Medicine