Thread by @c0nc0rdance

Hopefully you know that grapefruit juice can inhibit liver enzymes that break down the active ingredients in certain therapeutic drugs, which can result in dangerous overdosing with certain drugs.

A few surprising insights (thread):

1. It was only discovered in 1991, and mostly by accident.

A Canadian team were studying the impact of alcohol consumption on a hypertension drug, Plendil, and needed a "mixer" base for the control (water) and treatment (alcohol) so they mixed both into grapefruit juice.

The bioavailability of Plendil was higher than expected in the study, in both arms, but lower in a water-only control group.

That study (conducted in 1989, to clarify) led to this 1991 Lancet paper, but it wasn't well publicized until after more study.
pubmed.ncbi.nlm.nih.gov/1671113/

2. Metabolism of almost every drug is affected to some degree.

The polyphenols in grapefruit juice can strongly interfere with Cytochrome P450 enzymes in your liver, the same enzymes that can either *activate* a "pro-drug" or deactivate active compounds over time.

Everything from Tylenol to Viagra to birth control to caffeine have different pharmacokinetics in individuals for up to three days after drinking a glass of grapefruit juice.

3. It's not just grapefruit juice.

All citrus plants can produce the types of furanocoumarin, and all citrus derives from genetic hybridization of three ancestral plant lineages. Grapefruit juice has the highest specific effect on certain enzyme, orange juice the lowest.

4. Grapefruit juice, indirectly, likely causes thousands of deaths every year in the US.

People continue to take their medications with grapefruit juice, especially among the elderly, and the result can be an effective dose 10-20 times safe levels.

cbsnews.com/news/drinking-…

Just raising awareness. Take a minute to check in on relatives who take daily medication or who you know like grapefruit juice and be sure they're aware of the risks.