Experts reveal how your food intake can impact the effects of certain medications to your body


We all know that what we eat and drink can affect our health. But did you know that what you consume can also affect the way your medication works?

A new study published by the Medical College of Wisconsin in the U.S. has revealed that some artificial sweeteners impact the way the body metabolises certain medications.

The lab-based research showed that the rate of metabolisation of drugs like antibiotics, antidepressants and antivirals are different depending on the individual's intake level of artificial sweeteners.



It was said that the artificial sweeteners (the two tested were sucralose and acesulfame potassium) disrupted the function of a protein in the liver that helps remove toxins and drugs from the body.

The researchers stated that the study only serves as a preliminary work and "more research is needed".

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The food that you consume affects how your body metabolises certain medications. Credit: Shutterstock/fizkes.

However, it should be noted that the research was only one of the examples of studies showing how your diet can impact the effects of drugs in your body.

Another report suggested that while the potential for grapefruit and other citrus fruits to interfere with the absorption of prescription medications is well-known, the mechanism by which this occurs has only recently been understood.

Furanocoumarins are compounds found in citrus fruits that inhibit an enzyme in our body.

This enzyme is responsible for breaking down many different types of drugs, including statins, calcium channel blockers, and antidepressants.

When the enzyme is inhibited, the level of the drug in the bloodstream can increase to dangerously high levels.



This is why it is important for patients taking any of these medications to avoid grapefruit and other citrus fruits, according to Edinburgh University clinical pharmacology professor Simon Maxwell.

He explained: "Under normal conditions, this enzyme reduces the amount of the drug that enters your blood — and the quantities you are prescribed take into account this process."

"But if at the same time you drink grapefruit juice— or eat the fruit — the furanocoumarins stop this enzyme doing its job. This can be important for a number of widely prescribed drugs."

"This interaction partly occurs in the gut, enabling increased absorption, but also — significantly — in the liver, preventing it from progressively removing the drug in the hours after absorption."

"Together, this means that overall exposure to the drug can be significantly increased, resulting in toxic effects."

But the effect of food and drinks on medicine absorption is not always negative.

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A cup of espresso can maximise the effects of paracetamol to your body. Credit: Shutterstock/wsantina.

According to Aidan Goggins, a pharmacist based in London, the caffeine in a single espresso can actually enhance the effect of paracetamol. This is because the caffeine speeds up the absorption of the drug in the gut.

This effect can also be ‘bought’ in a pill, in the form of paracetamol combined with caffeine. These over-the-counter remedies are marketed as being for fast pain relief.

However, it is important to note that the research into how foods interact with medication is still in its infancy.

Many of the discoveries have only been found by accident or picked up much later once the medicine has become widely available.

"It is often only in the years after the drugs go on the market that clinically relevant interactions with other foods become uncovered, so they are frequently omitted from the drug packaging and the patient never gets informed about them," said Mr Goggins who expressed his belief that more researchers should look into adding more advice and warnings about food interactions in the packaging.

The experts also provided insights on which food affects certain medications.



Note: Always check with your GP before making adjustments to your diet to avoid health complications.

1. Citrus

Medicines affected: At least 85 different medicines — including midazolam (a benzodiazepine, used as an anaesthetic), sertraline (an antidepressant), statins (including simvastatin and atorvastatin), sildenafil (for erectile dysfunction) and calcium channel blockers (for high blood pressure).

What happens:

Mr Goggins explained: "Many medicines are metabolised in your gut and liver by an enzyme called CYP3A4, which normally reduces the amount of the drug that enters your bloodstream."

"Citrus fruits contain compounds called furanocoumarins that stop CYP3A4 from doing its job — and they’re more concentrated in juice than the fruit [because a glass of juice contains more of the fruit]."

The process leads to the body absorbing more of the drug and making it "more powerful" than intended.

"For example, a 240ml glass of grapefruit juice can increase blood levels by as much as 200 per cent, taking it from the therapeutic range to the potentially toxic range," he added.

Some side effects of the increased effects include: extreme muscle damage for statins; priapism (excessively long-lasting erections) for sildenafil; headaches, dizziness, fatigue and impaired sleep with sertraline; excessive sedation for midazolam; and excessive reduction in blood pressure, raised heart rate, dizziness, fatigue and blurred vision for those taking calcium channel blockers.

Advice:

Mr Goggins suggested: "Given the number of drugs affected in some way by this interaction, it’s safest to avoid drinking citrus fruit juice, particularly grapefruit, or eating the fruit for two hours before and four hours after taking any medicines."

"Some drugs — midazolam, sertraline, statins (apart from the newer one, Crestor, which is metabolised differently) and sildenafil — are so significantly affected by this interaction that it completely halts the action of CYP3A4 and the body needs to make a new supply, which can take up to 72 hours. If you take these medicines, you may be better off avoiding these fruits and juices, but speak to your doctor or pharmacist first."

2. Dairy

Medicines affected: Antibiotics

What happens:

Dairy products can reduce the absorption of common antibiotics used to treat many types of infection. Antibiotics such as tetracyclines (such as doxycycline) and fluoroquinolones (such as ciprofloxacin) are particularly affected by dairy products.

It is thought that the calcium in dairy products binds to the antibiotics, forming a substance that the body is unable to absorb. This can reduce the effectiveness of antibiotics by up to 42 per cent.

Advice:

Mr Goggins advised: "If you are taking antibiotics, it’s best to avoid dairy products for at least two hours before and after taking the medication."

3. Processed meat

Medicines affected: Antidepressants known as monoamine oxidase inhibitors.

What happens:

Prof Maxwell explained: "Processed meat (and other foods) has been reported to interact with some older antidepressant tablets known as monoamine oxidase inhibitors (MAOIs)."

"MAOIs work by reducing the activity of a key enzyme (monoamine oxidase), resulting in higher levels of “feelgood” brain chemicals including norepinephrine, serotonin and dopamine."

"But this enzyme also helps control levels of the amino acid tyramine, found in fermented foods, salami, mature cheese, pickled herring, Bovril, Marmite, (or similar meats or yeast extract), and some beers, lagers or wines."

"Raised levels of tyramine can cause high blood pressure, resulting in pounding headaches, blurred vision and, occasionally, bleeds on the brain."

Advice:

"Patients taking MAOI drugs should minimise their intakes of these types of foods to reduce the risk of this amino acid building up over time," Professor Maxwell said.

4. High-fibre foods

Medicines affected: Thyroid drug levothyroxine

What happens:

The underactive thyroid, or hypothyroidism, is a condition in which the body does not make enough of the hormone thyroid. One of the most common treatments for this condition is levothyroxine, which is a synthetic form of the hormone.

However, recent research has shown that eating foods high in fibre can make levothyroxine less effective. Fibre binds to the drug as it travels through the gut, reducing its absorption. (Levothyroxine also binds to foods containing calcium and iron, as well as coffee.)

This is a troubling finding, as many people with hypothyroidism rely on levothyroxine to manage their condition.

Aidan Goggins quipped: "Shockingly, this is something many people don’t know about."

"One study found that 20 per cent of patients take levothyroxine with a meal and another 20 per cent take it less than 30 minutes before the meal — despite it being known for years that food interacts with the absorption of this medicine."

Advice:

"Take levothyroxine on an empty stomach — and at least 60 minutes before a meal," Mr Goggins recommended.



5. Bananas

Medications affected: Drugs for high blood pressure and heart failure known as angiotensin-converting enzyme (ACE) inhibitors (e.g. lisinopril and ramipril) and angiotensin receptor blockers (ARBs, e.g. losartan and candesartan)

What happens:

Prof Maxwell quipped: "ACE inhibitors and ARBs tend to favour a retention of potassium in the kidneys."

"While most people adjust to this without a problem, some find that their potassium levels rise — particularly the elderly or people with kidney disease."

"For this group, eating large amounts of foods high in potassium, such as bananas or salt substitutes can raise these levels excessively, leading to weakness, fatigue and abnormal heart rhythm."

Advice:

Prof Maxwell advised: "Eating bananas and other high-potassium foods shouldn’t be a problem for most people."

"But you might not notice any symptoms in the early stages, so anyone taking these medicines should have their potassium level and kidney function checked by their doctor beforehand and in the weeks after starting."

7. Cereals

Medicines affected: Antibiotics.

What happens:

It was found that consuming foods rich in iron, zinc or magnesium can reduce the absorption of certain antibiotics. The research looked at the effects of these minerals on the absorption of tetracyclines and fluoroquinolones.

The study found that taking these antibiotics with food fortified with iron or minerals can reduce the absorption of the drug by up to 64 per cent. This is because the minerals can bind to the antibiotic in the gut and prevent it from being absorbed into the bloodstream.

8. Sugar-free mints

Medicines affected: Progesterone-only contraceptive pills, such as norethisterone and levonorgestrel.

What happens:

Aston Medical School Department of Diet and Nutrition lead Duane Mellor said: "Sugar-free mints that contain sorbitol (a type of sweetener) can have a laxative effect."

"This can cause diarrhoea, reducing the amount of time your medication has to be absorbed, which is particularly important for this type of mini-pill, and is why it has to be taken at the same time every day so enough of it is circulating for it to have its effect."

"This can mean that insufficient quantities of the hormones get into your body to act as a contraceptive."

"This is why on sugar-free mint packets it often says consume no more than 25g per day. The problem with this is that it’s not known how much diarrhoea caused by sorbitol is enough to stop the mini pill working."

Advice:

The nutrition expert said: "If you’re taking the older type of progesterone-only pills daily, it could be best to avoid foods containing sorbitol or to use another form of contraception."

"Note, this doesn’t affect newer progesterone-only pills containing desogestrel (such as Cerazette), as these are not so sensitive to small changes in the amount of drug absorbed."

So, there you have it, folks! We would like to reiterate that you should check with your GP first before making some adjustments to your diet.

What are your thoughts on this? Let us know in the comments below!
 
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