Never take supplements with coffee, avoid statins with grapefruit juice, and turbo-charge your painkillers with vitamin C
- New research shows mixing herbal remedies with prescription drugs can lead to bleeding if it’s a risky combination
- Here, Dr Sarah Brewer, a family physician and nutritionist, explains what combinations to look out for
Millions of us pop a supplement of some kind on a daily basis, in a bid to boost our health.
On top of that, many of us are also taking prescribed medication – often for conditions such as diabetes or high blood pressure – or swallowing over-the-counter remedies such as painkillers on a regular basis.
But have you ever stopped to check if your herb and drug combinations are safe?
While supplements can certainly boost your health in many ways, there are times when mixing them with prescribed medication – or vice versa – could be dangerous.
Just this week, researchers at the University of Hertfordshire warned that mixing some herbal remedies with prescription medication can increase the risk of bleeding, raise blood sugar levels or stop medications from working effectively.
While many interactions are theoretical, based on limited evidence, or only occur at high doses, it is really important to check before you mix tablets and supplements.
There are many drug and supplement combinations that can actually work well together but many that are risky. Here, Dr Sarah Brewer breaks down the combinations to be aware of
Not only that, but many people taking tablets or supplements often have no idea that in many cases, the foods and drinks taken alongside them could dramatically increase how the body absorbs them, or render them effectively useless.
But it’s not all bad news. At the other end of the scale, there are many drug and supplement combinations that can actually work well together – sometimes dramatically boosting the effectiveness of one or both ingredients.
Chris Etheridge, Chair of the British Herbal Medicine Association advises: ‘As with all medicines, whether pharmaceutical or herbal, patients should always seek the advice of a healthcare practitioner if they are taking other medicines.’
For example, if you have diabetes, you also need to check whether or not the supplement will affect your glucose control.
If you are taking a blood thinning medicine, it’s vital to check for interactions to prevent over or under thinning the blood.
And, if you have high blood pressure, it’s important to check whether or not a supplement or herb might affect your blood pressure control.
If you are taking medicines, check the in-pack patient information leaflet for known interactions, which are listed.
Although many herbs and supplements have not been tested for interactions with other herbs, supplements, drugs or foods, those that are licensed under Traditional Herbal Registration (THR) legislations have been assessed and the information is provided in pack.
Unfortunately, many healthcare professionals feel unable to provide advice on interactions.
The best freely available interactions checker I have found is on www.drugs.com and includes most commonly used herbal medicines, food supplements and prescribed medicines.
WHAT HAPPENS TO CAUSE A DRUG, SUPPLEMENT OR FOOD INTERACTION?
Herbal medicines and food supplements can interact with drugs in several ways, to increase or reduce their:
• absorption into the body
• effects inside cells
• break down in the liver
• speed of departure from the body via the liver, kidneys or intestines.
The effects of an interaction can range from the drug simply not working, to it working too well.
POTENTIALLY HARMFUL INTERACTIONS
All drugs have the potential for food, herb or supplement interactions. The most likely culprits, however, are anticoagulants (blood thinners such as warfarin or aspirin), sedatives, antidepressants and medicines prescribed to treat heart problems, high blood pressure and epilepsy.
1. WARFARIN AND GREEN VEG
Warfarin blocks the effects of vitamin K, which is needed to produce blood clotting proteins in the liver. Foods containing vitamin K include cauliflower (richest source), broccoli, spinach, Brussels sprouts, asparagus, lettuce and avocado. This is why you need to maintain a fairly constant intake of these foods to ensure your blood clotting control remains stable – it is significant changes in intake, rather than total intake, that causes problems with warfarin control.
2. PARACETAMOL/ACETAMINOPHEN AND WARFARIN
Less well known is that paracetamol (acetaminophen) also increases the blood thinning effect of warfarin. Those with the highest intake of paracetamol (9g per week, or more) while on warfarin have a 10-fold increased risk of over-anticoagulation, which could lead to haemorrhage such as a potentially fatal stroke.
3. ST JOHN’S WORT WITH THE PILL OR HRT
A traditional herbal medicinal product used to relieve the symptoms of slightly low mood and mild anxiety, St John’s Wort has one of the longest lists of potential drug interactions.
This is because it affects the liver’s system of enzymes that break down many drugs in the body.
St John’s Wort increases the production of liver enzymes that breakdown medicines and has been found to lower blood levels of contraceptive hormones by around 15 percent
As a result, taking St John’s Wort may cause blood levels of some drugs (including but not limited to oral contraceptive pills and HRT, antidepressants, blood thinning medicines, statins and drugs used to treat high blood pressure, migraine, HIV and cancer) to increase (causing side effects) or decrease (reducing their effectiveness).
An important potential interaction is with the oral contraceptive pill, which may increase the risk of unplanned pregnancy. This is because St John’s Wort increases the production of liver enzymes that breakdown medicines and has been found to lower blood levels of contraceptive hormones by around 15 percent – enough to cause breakthrough bleeding or ovulation and unplanned pregnancy.
HOW TO TAKE THE MOST POPULAR SUPPLEMENTS
1. CBD (cannabidiol) oil
GOOD FOR: relaxation, anxiety, stress, inflammation and pain.
DON’T TAKE IF: You are on any prescribed medicines without first checking for interactions – CBD can inhibit liver enzymes involved in metabolizing some medicines, and may result in increased drug levels that could cause side effects.
2. Valerian
GOOD FOR: Temporary sleep disturbance.
DON’T TAKE IF: You are taking sleeping tablets, buprenorphine or other medications that make you feel drowsy. Avoid excess alcohol.
3. Black Cohosh
GOOD FOR: The relief of symptoms of the menopause, such as hot flushes, night sweats, and temporary changes in mood (such as nervous irritability and restlessness).
DON’T TAKE IF: You have a history of liver disease or if you have, or have had, an oestrogen dependent tumour such as breast or ovarian cancer. Avoid alcohol and other drugs known to affect the liver.
4. Devil’s Claw
GOOD FOR: A traditional herbal medicinal product with good evidence for its painkilling and anti-inflammatory properties which help to reduce back and joint pain – and reliance on conventional painkillers.
DON’T TAKE IF: You have a history of stomach or duodenal ulcers or are on warfarin. Devil’s Claw can usually be taken alongside conventional painkillers but check with your doctor first.
CBD can inhibit liver enzymes involved in metabolizing some medicines, and may result in increased drug levels that could cause side effects
WHEN MIXING IS GOOD AND HAS A BENEFICIAL EFFECT
While you do have to be careful with drug and supplement interactions, it’s not all bad news.
Indeed, some supplements actually boost the effects of prescription medicines, or replenish the nutrients they deplete
1. SSRIs and Ginkgo
Antidepressant SSRIs (serotonin re-uptake inhibitors) can cause sexual side effects such as lowered libido, erectile dysfunction and difficulty reaching orgasm. Ginkgo biloba extracts have been successfully used together with SSRI drugs (fluoxetine and sertraline) to overcome these sexual problems. One trial published in the Journal of Sex & Marital Therapy found that Ginkgo biloba was 84 per cent effective in treating antidepressant-induced sexual dysfunction, with women responding better than men (91 per cent versus 76 per cent).
However, another study found that while there were some ‘spectacular’ individual responses in those taking Ginkgo biloba to treat sexual dysfunction caused by antidepressants, overall there were no statistically significant differences. The research was published in the journal Human Psychopharmacology.
2. Painkillers and vitamin C
Vitamin C boosts the effects of painkillers such as paracetamol, aspirin, and opiate drugs such as morphine. This effect may result from the anti-inflammatory effect of vitamin C, which also helps to protect the liver and kidneys from paracetamol-induced damage.
Not only that, but taking vitamin C may help you spread doses of painkillers further apart so you need less painkillers overall.
A study published in the Canadian Journal of Anesthesia involving 80 people who had their gallbladder removed showed that patients taking 2g vitamin C before having their gallbladder removed used significantly less morphine during the post-operative period than those given a placebo before surgery, for example.
3. Paracetamol and Milk Thistle
Paracetamol lowers levels of a liver chemical called glutathione, which is one of the ways in which paracetamol can damage the liver. Milk thistle extracts raise glutathione levels, to protect liver cells from toxins, including the effects of paracetamol (and alcohol). A typical dose of Milk Thistle in Traditional Herbal Remedy (THR) products is 193mg-261mg.
4. Statins and Co-enzyme Q10
Statins lower cholesterol levels by inhibiting the liver enzyme, HMG-CoA reductase. This enzyme is also needed to make co-enzyme Q10 for energy production in cells. Statins can halve blood levels of Co-enzyme Q10 within two weeks, which may contribute to the muscle aches and weakness that often occur in people taking a statin drug. Taking coenzyme Q10 (either a 100mg dose in ubiquinol form or 200mg in ubiquinone form) may help to overcome this. Vitamins D and E are also lowered by statin therapy, so a multivitamin may be a good idea.
5. Blood pressure drugs (ACE inhibitors) and Zinc
ACE inhibitors used to treat high blood pressure or heart failure can lead to a zinc deficiency, especially when used together with a diuretic (water tablets). Lack of zinc can lead to changes in taste sensation and reduced immunity. A multivitamin and mineral supplement that includes zinc is therefore a good idea.
6. Anti-fungal creams and Echinacea
Echinacea boosts immunity against infections. One study, published in the journal Therapiewoche, found that using Echinacea tablets together with econazole anti-fungal cream reduced the rate of recurrence of Candida yeast infections such as thrush compared with using the cream alone.
7. Corticosteroids, calcium and vitamin D
People taking long-term oral corticosteroids (e.g. for severe respiratory disease or for autoimmune conditions such as lupus) are at increased risk of osteoporosis. Good intakes of calcium and vitamin D are vital to help maintain bone density and are often prescribed together with these medications.
8. Antibiotics and probiotics
As well as killing harmful bacteria, many types of antibiotic can wipe out beneficial bacteria in the gut. This can lead to diarrhoea and has been linked with the development of irritable-bowel syndrome. Taking a probiotic supplement providing at least 5 million bacteria, and at least 3 strains, during and for at least a week after a course of antibiotics helps to replenish these beneficial bacteria to reduce intestinal side effects.
9. Antibiotics and vitamin K
Long-term use of antibiotics (e.g. for acne) can suppress the production of vitamin K dependent clotting factors in the liver, as well as killing probiotic bacteria that produce additional vitamin K for you. Eating more vitamin K rich foods, and taking a multivitamin supplement that includes vitamin K is therefore a good idea (as well as a probiotic).
10. Antibiotics and Bromelain
Bromelain, a pineapple enzyme, increases blood levels of the penicillin drug, amoxicillin, and improves its ability to penetrate tissues when treating sinusitis, bronchitis and abscess. You can buy bromelain as a supplement.
WATCH WHAT YOU SWALLOW YOUR PILLS WITH!
1. ALWAYS wash them down with water or orange juice:
Supplements are best taken with water or orange juice. Iron, in particular, is much better absorbed by the body when taken with orange juice. This is rich in vitamin C, which increases absorption by converting ferric iron to ferrous iron, which has a more efficient uptake mechanism.
2. NEVER mix with tea, coffee or grapefruit juice
Never take supplements with coffee or tea, as the tannins and compounds in the drinks can interfere with the absorption of some minerals.
Not only that, but in the case of probiotics, the heat from these drinks can destroy the live microorganisms – i.e. the ‘good’ bacteria – effectively rendering the supplement useless.
Coffee can affect the absorption of some minerals in supplements
Also, don’t take supplements or medicines with grapefruit juice. It contains compounds that can affect the way some drugs and herbal medicines are broken down by the body.
This interaction was discovered by accident when researchers looked at the effects of combining alcohol with a blood pressure medicine.
Grapefruit juice was used as the mixer and was found to greatly increased blood levels of the medication. The same effect is now known to occur with some other drugs, including statins used to lower cholesterol.
Taking one particular statin, lovastatin, with a glass of grapefruit juice was found to produce the same blood levels of the drug as when taking 12 tablets with water.
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