SUPPLEMENTS can help to keep us healthy.
Vitamin A helps fight off infections, calcium is vital for bones and teeth, and fish oil supports the heart, lungs and blood vessels, for example.
But taking too much of any supplement can have serious consequences, experts warn.
Not only can overdosing cause nausea and vomiting, it’s also been linked to an increased risk of stroke and organ damage.
Writing in The Conversation, Dipa Kamdar, senior lecturer in pharmacy practice at Kingston University, said: “Around half of UK adults currently take a food supplement.
“But vitamins and minerals are usually only needed in small amounts and too much of a good thing can be bad for you.”
Here are all the benefits and potential life-threatening risks of some of the most common vitamins and minerals.
Vitamin A
Vitamin A helps your body fight infection, as well as boost your vision in dim light and maintain healthy skin.
It’s found in cheese, eggs, oily fish, milk and liver, but over-the-counter supplements are also widely available.
Men aged 19 to 64 need 700 micrograms (mg or µg) a day, while women need 600mg.
Some research suggests that taking more than 1,500mg of vitamin A every day for many years could make your bones more likely to fracture as you age.
“In older people, this can lead to fractures as they are more likely to get osteoporosis,” Ms Kamda said. “In severe cases, people may experience irreversible liver damage.”
[bc_video account_id=”5067014667001″ application_id=”” aspect_ratio=”16:9″ autoplay=”” caption=”Dr Hilary says vitamin D supplements may boost immune systems and prevent coronavirus” embed=”in-page” experience_id=”” height=”100%” language_detection=”” max_height=”360px” max_width=”640px” min_width=”0px” mute=”” padding_top=”56%” picture_in_picture=”” player_id=”default” playlist_id=”” playsinline=”” sizing=”responsive” video_id=”6165153259001″ video_ids=”” width=”640px”]Those who eat liver or liver pâté more than once a week may also be getting too much vitamin A.
And be careful if you take other supplements like fish liver oil, as these are also high in vitamin A.
If you’re pregnant, you should avoid vitamin A supplements and liver products altogether.
Research published in the journal Nutrients found vitamin A could cause birth defects and miscarriage when taken in excess.
Vitamin B6
If you don’t eat enough pork, poultry, peanuts, soya beans, oats or bananas, you may not be getting enough vitamin B6.
This could cause fatigue, skin rashes, cracked lips, a swollen tongue and even mood changes.
Dr Harry Jarrett, head of science and research at supplement brand Heights, previously told The Sun: “Low vitamin B6 levels have been linked to a greater risk of cardiovascular disease, certain cancers and depression and anxiety.”
But be careful not to take too much either.
“Taking 200mg or more a day of vitamin B6 can lead to a loss of feeling in the arms and legs known as peripheral neuropathy,” the NHS says.
“This will usually improve once you stop taking the supplements, but in a few cases when people have taken large amounts of vitamin B6, particularly for more than a few months, the effect can be permanent.”
Vitamin B6 helps the body to use and store energy from protein and carbohydrates in food, and the body form haemoglobin, the substance in red blood cells that carries oxygen around the body.
Men aged 19 to 64 need 1.4mg per day, while women need 1.2mg.
Vitamin C
Taking too much vitamin C can cause stomach pain, diarrhoea and farting, according to the NHS.
It can also cause problems for people with hemochromatosis, or too much iron, as vitamin C is known to enhance iron absorption.
“This may lead to iron overload, which can cause serious damage to your heart, liver, pancreas, thyroid and central nervous system,” Healthline says.
Consuming too much vitamin C can also increase the amount of oxalate (waste product) in your urine, which hikes your risk of kidney stones.
In a study by the University of Texas Southwestern Medical Center, adults who took a 1,000mg supplement twice a day for six days increased their oxalate excretion by 20 per cent.
It’s therefore recommended adults consume no more than 40mg a day.
Vitamin C is found in citrus fruits, peppers, strawberries, broccoli and potatoes.
Vitamin D and calcium
Vitamin D helps to regulate the amount of calcium and phosphate in the body.
These nutrients are needed to keep bones, teeth and muscles healthy, according to the NHS.
The body creates vitamin D from direct sunlight on the skin when outdoors, and during the spring and summer, most people should be able to make all the vitamin D they need naturally.
However, the NHS recommends taking a 10mg supplement between October and March, when daylight hours are shorter.
Adults and children over the age of one need 10mg of vitamin D a day. Babies under 12 months need 8.5 to 10mg.
Not getting enough vitamin D puts you at risk of bone deformities such as rickets, and bone pain known as osteomalacia.
But taking too much vitamin D over long periods can cause kidney failure and irregular heartbeats, scientists say.
A study by the University of Calgary also suggested that high doses could weaken bones.
“Do not take more than 100mg of vitamin D a day as it could be harmful,” the NHS says.
Vitamin D is found in a small number of foods, including oily fish, red meat, liver, egg yolks, and some fortified products like cereals.
Vitamin E
Avoid vitamin E toxicity by keeping your intake to 4mg for men and 3mg for women.
“There is not enough evidence to know what the effects might be of taking high doses of vitamin E supplements each day, but it could be harmful,” the NHS says.
Some studies have suggested excessive intake could cause blood thinning, clotting and potentially fatal bleeding.
It has also been linked to an increased risk of a stroke caused by bleeding in the brain.
Most people should be able to get all the vitamin E they need from their diet.
Good sources include olive oil, nuts and seeds, and wheatgerm.
Fish oil
Fish is packed full of vitamins and minerals, which is why the NHS recommends we eat at least two portions of the stuff every week.
Oily fish specifically – like herring, salmon and sardines – contains long-chain omega-3 fatty acids, which are said to help to prevent heart disease.
But research published in BMJ Medicine found taking fish oil supplements could actually increase your risk of heart issues like stroke or atrial fibrillation (an irregular heartbeat).
The benefits of fish oil seem to be best in people with existing heart problems.
Folic acid
Folic acid is the synthetic version of the vitamin folate, also known as vitamin B9.
It helps the body to make healthy red blood cells and is found in foods like leafy green vegetables, chickpeas and fortified cereals.
Supplements (400mg) are usually recommended before pregnancy and during the first 12 weeks to prevent defects like spina bifida, when a baby’s spine and spinal cord does not develop properly in the womb.
Higher doses are not thought to be harmful, but taking more than 1,000mg “can mask symptoms of vitamin B12 deficiency, such as tiredness, tingling hands and feet, sore tongue and muscle weakness,” Ms Kamdar says.
Headaches, indigestion, weakness and heart palpitations are also symptoms, and some people also experience depression, anxiety, problems with balance and coordination.
The NHS says: “It’s important for vitamin B12 or folate deficiency anaemia to be diagnosed and treated as soon as possible.
“The longer the condition goes untreated, the higher the chance of permanent damage.”
Ms Kamdar says a B12 problem “could lead to brain damage if left untreated“.
Iodine
Taking high doses of iodine for long periods could change the way your thyroid gland works.
This can have several knock-on effects, including weight gain.
Limit your intake to 140mg a day, in line with NHS recommendations.
Most people should be able to get all the iodine they need by eating a varied and balanced diet.
Good sources include dairy, eggs, fish and some fortified plant-based drinks.
Iron
How much iron you need will depend on several factors.
But generally the NHS recommends 8.7mg a day for men aged 19 and over, 8.7mg for women 50 and over, and 14.8mg for women 19 to 49.
Sticking to these guidelines helps make red blood cells, which carry oxygen around the body.
But taking iron in high doses (over 20mg) can trigger constipation, nausea, vomiting, stomach pain and potentially liver failure, the NHS and NIH warn.
“Very high doses of iron can be fatal, particularly if taken by children, so always keep iron supplements out of the reach of children,” the health service adds.
Ms Kamdar says prolonged consumption of more than 20mg of iron “can cause organ damage such as liver failure” because it “builds up in the organs and interferes with normal cell function”.