The 7 times it’s dangerous to mix supplements – raising the risk of kidney stones, drowsiness and even death
THERE'S a supplement for pretty much everything these days.
And a huge number of Brits have hopped on the bandwagon, with research suggesting 38 per cent of us take vitamins, minerals or supplements daily.
To enhance the effectiveness of some of them, certain combinations are advised.
For example, to get the full effect of vitamin D we should also be taking calcium, and experts suggest taking turmeric and black pepper together.
However, according to a new guide by , there are some dangerous combinations to be aware of.
These involve either a vitamin combined with a specific medication, or certain vitamin pairings.
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If you’re taking any of the below, consider switching up your supplement regime today.
1. Vitamin K and blood-thinners
If you’re taking vitamin K supplements with medications such as warfarin, sold under the brand name Coumadin, then it’s important to stop as vitamin K could interfere with it.
"Vitamin K plays a crucial role in blood clotting and also supports bone and heart health," Rob Hobson, registered nutritionist and consultant at Healthspan, says.
"Warfarin, a blood thinner, works by reducing the activity of vitamin K to help prevent blood clots.
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"Taking vitamin K supplements can counteract the effect of warfarin, which is why they are generally not recommended for people on this medication.";
He adds: "Maintaining a consistent intake of vitamin K-rich foods, such as leafy greens, is fine because it allows your doctor to adjust your Warfarin dose accordingly.
"However, taking a vitamin K supplement can disrupt this balance."
Adults need about 1microgram of vitamin K (found in green leafy vegetables) a day for each kilogram of their body weight, according to the NHS.
2. Calcium and iron
We need both calcium and iron for good health.
Adults need more than 700mg of calcium a day, while men aged 19 and over and women 50-plus need about 8.7mg of iron a day and women aged 19 to 49 need about 14.8mg, according to the NHS.
"Calcium maintains bone density and strong teeth, helps muscles to contract, and it’s used for nerve function," says Rob.
"Meanwhile iron is used to make healthy red blood cells; it's a key part of haemoglobin, a protein in red blood cells that carries oxygen around the body.
"Without enough iron, there won’t be enough oxygen transported around the body."
However, research published in the found that calcium can inhibit iron absorption by up to 50 per cent.
To enhance absorption, it's best to take iron supplements on an empty stomach with vitamin C, and separate them from calcium supplements by at least two hours, Rob says.
Do I need to take supplements?
IF you're being bombarded with adverts about supplements making big claims, you might be wondering if you should start taking any.
In short, most people don't need to.
Leading independent pharmacist and clinician Michael Sam-York said: "If you are relatively fit and healthy, you do not need any supplements.
"But if you are not getting your five a day, if you have a hectic lifestyle or have a restrictive diet like veganism, then your body may not be getting what it needs.
"Taking a supplement may be the quick fix you need."
Certain groups are advised to take supplements.
For example, pregnant women should take folic acid to reduce the risk of spina bifida in babies.
Vitamin D is the supplement most often prescribed by GPs.
Even though our bodies make vitamin D from sunlight, the NHS recommends everyone should consider taking a supplement during autumn and winter and children aged one to four all year round.
It is vital for keeping bones, teeth and muscles healthy.
Overall, there is actually limited evidence that most supplements and vitamins work, and most of it is anecdotal so beware of the placebo effect.
There is no harm in giving them a go but be honest with yourself about what happens when you do.
If you don’t notice a physical difference or improvement in symptoms, then don’t carry on taking it.
There is no point in wasting your money. Try it, but don’t expect miracles.
In general, the top 10 best nutrients for women are:
- Vitamin D: For healthy bones, teeth and muscles
- Omega-3: Boosts brain function
- Folic acid: For pregnant women, this reduces the risk of neural tube defects in babies
- Iron: One in four of us is thought to be low in iron. Can help with anaemia and heavy period sufferers
- Zinc: Healthy blood flow, wound-healing and good for eyesight
- Magnesium: For heart health, to regulate blood sugar and boost low mood
- B12: For extreme tiredness and boosting energy
- Turmeric: A great anti-inflammatory. Available as a supplement or just add the spice to food
- Evening primrose oil: Eases menopause symptoms
- Vitamin B6: Aids sleep
And for men:
- Omega-3: For a healthy brain and joints
- Vitamin D: Aids healthy bones, teeth and muscles
- B12: For energy levels
- Zinc: To boost sex life
- Turmeric: Anti-inflammatory
- Maca root: A herb that can boost a man’s fertility, energy levels and reduce stress
- Ginseng: Boosts energy levels
- Magnesium: Healthy heart and cholesterol levels
- Vitamin C: Muscle growth and immunity
- Thiamine: Helps energy levels and libido
3. St John’s Wort and antidepressants
St John’s Wort is a herbal, over-the-counter medicine that’s often used to treat mental health problems, like depression.
It contains many active substances, including hypericin and hyperforin, which are thought to affect mood, according to the charity Mind.
However, when taken with selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants commonly used to treat depression, it could lead to dangerously high levels of the feel-good hormone, serotonin.
In fact, suggests that this could be life-threatening.
To be safe, avoid combining the two.
SSRIs include drugs like citalopram, fluoxetine and sertraline.
4. Iron and zinc
The mineral zinc provides various benefits to our body.
"Zinc supports a healthy immune system and is important for male reproductive health," says Rob.
"It’s also good for wound healing and skin repair."
However, has found that iron can have a negative effect on zinc absorption if taken together in supplement form.
"If you are taking a supplement, there’s no need to go for one that contains more than 100 per cent of the recommended daily allowance (RDA)," Rob says.
The label on the back of your supplement should share the percentage of each nutrient that it provides.
While you can buy supplements, good food sources of iron include liver, red meat, kidney beans, nuts and dried fruit.
Meat, shellfish, dairy and bread are all high in zinc.
Men aged 19 to 64 need about 9.5mg of zinc a day, while woman need about 7mg, according to the NHS.
5. Zinc and copper
Copper is an essential mineral which helps with the absorption and utilisation of iron to produce haemoglobin, which carries oxygen around the body.
However, if you take copper and zinc together, you might not reap these benefits.
Rob explains: "Zinc and copper use the same protein transporters in the gut for absorption, so they’re competing for the same thing."
This can inhibit the absorption of copper over time.
A supplement that combines both minerals safely can help to avoid taking too much of either mineral.
But the NHS says you should be able to get all the copper you need (1.2mg a day for adults) from your daily diet.
6. Melatonin and other sedatives
The guide by Ben’s Natural Health reveals that melatonin, a hormone that plays a role in sleep, combined with other sedatives, such as valerian root and magnesium, can cause excessive drowsiness.
This could make it unsafe to drive or operate machinery due to the increased risk of accidents.
It’s recommended to avoid combining multiple sedatives; start with one to gauge the effect.
7. Vitamin D and high-dose calcium
The UK government recommends that everyone in the UK takes a daily vitamin D supplement from October to March containing 10micrograms, which is "enough for most people".
This is because the body creates vitamin D from direct sunlight on the skin when outdoors, but we don't make enough of it during the autumn and winter.
However, that taking more than 100micrograms of vitamin D a day could be harmful, potentially leading to confusion, pain, thirst and kidney stones.
High doses of calcium could also be dangerous, with finding that it could lead to hypercalcemia, where calcium levels in the blood become too high.
This can weaken bones and create kidney stones.
In the UK, it’s recommended that adults get 700mg of calcium each day.
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Rob says: "To put you at greater risk, you’d have to be taking very high doses of these nutrients regularly.
"There is no benefit to taking more than your body needs so stick to the recommended daily intake."