There are several reasons why it might be a bad idea for you to eat grapefruit, not including the fact they taste awful.
Sharp and unforgiving flavour aside, there are plenty of benefits you can get from the citrus fruit. It’s rich in vitamins A and C, contributing to stronger immunity and cardiovascular health.
Some evidence suggests it may help with weight loss too.
But many of us should steer clear, as a lot of people discovered upon seeing a grapefruit-themed meme.
The viral post from Tired Girl Apparel shared a photo of a t-shirt emblazoned with: “’You’re so funny!’ Thanks, I can’t have grapefruit.”
It was captioned: “If you know…”
The post drew a lot of confused commenters, with one asking: “Wait am I not supposed to eat grapefruit?”
Another chimed: “Well this is how I find out.”
“I Googled it because I didn't know it, and I’m on three of the meds that say to avoid grapefruit,” added another, giving it a clue as to why grapefruit might be a no-go for some people.
Another said: “Me being on Prozac and not knowing this.” Warmer.
It’s not just antidepressants users encountering a revelation, with one adding they ‘can’t have it on birth control pills either’.
Apparently, grapefruit can block an enzyme that’s essential for breaking down certain medicines within the body.
“If this enzyme is blocked, too much medication could remain and build up in your bloodstream, causing too-high levels,” explains John Hopkins Medicine.
A recent study in the Canadian Medical Association Journal reported that grapefruit can also significantly increase some drugs’ potency. The study said that a blood pressure drug called felodipine tripled its volume in a patient’s blood after they had a glass of grapefruit juice when compared with having a glass of water.
"One tablet with a glass of grapefruit juice can be like taking five or 10 tablets with a glass of water and people say ‘I don't believe it’, but I can show you that scientifically it is sound,” Dr David Bailey, one of the study’s researchers, told the BBC.
"So you can unintentionally go from a therapeutic level to a toxic level just by consuming grapefruit juice."
So, which common drugs come with a no-grapefruit warning? Let’s take a look.
Antidepressants
First up is the subject of the meme: antidepressants. Sertraline, a type of selective serotonin reuptake inhibitor (SSRI), is a particularly risky one. SSRIs increase the levels of serotonin in the brain, but it’s possible to have too much serotonin in your system.
This can result in serotonin syndrome, which is potentially a very serious condition that can cause seizures, among other things.
The NHS warns: “Do not drink grapefruit juice while you're taking this medicine.
“Grapefruit juice can increase the amount of sertraline in your body and increase the risk of side effects.”
Benzodiazepines, used to treat anxiety and insomnia, come with a similar warning.
Contraceptives
Contraceptive pills, particularly those containing oestrogen, can be negatively affected by grapefruit.
Birth control app Emme explains that it may increase their efficacy, but also increase the risk of side effects.
"The interaction is primarily due to compounds in grapefruit that inhibit the activity of an enzyme called cytochrome P450 3A4 (CYP3A4) in the small intestine,” it says.
“This enzyme is responsible for metabolizing many substances, including certain hormones found in birth control pills.
“When grapefruit or grapefruit juice is consumed, it can inhibit the function of CYP3A4, leading to a slower breakdown of estrogen. As a result, estrogen levels in the blood may increase.”
Potential side effects include: nausea, breast tenderness, headaches, and potentially an increased risk of blood clots.
Statins
These medicines lower low-density lipoprotein (LDL) cholesterol in the bloodstream, and they’re typically prescribed to people with a heightened risk of heart attacks and strokes.
“Grapefruit juice can affect some statins and increase your risk of side effects,” says the NHS.
“A doctor may advise you to avoid it completely or only consume small quantities.”
Antihistamines
If you’re dosing up on antihistamines to combat the pollen, or because you’re allergic to your cat, then grapefruit can heighten the chance of getting side effects.
Grapefruit juice isn’t alone with this one, with the NHS saying apple and orange juice should also be avoided.
Notable mentions
Grapefruit can also interact badly with blood pressure medication, immunosuppressants and corticosteroids used to treat Crohn’s disease.
“One pill might interact with grapefruit and another, similar medication for the same condition may not, so it’s always best to check with your doctor or pharmacist if you are in doubt,” said John Hopkins Medicine.
Featured Image Credit: Ekaterina Vasileva-Bagler/Getty ImagesTopics: Health
Rachael Davis