How many vitamins can you take a day?
If you are one of the many adults in the UK who takes one or more supplements daily, you may wonder if it's possible to take too many vitamins.
How many vitamins you can take in a day depends on the supplement and how much of the vitamin you already get in your diet. Combining too many supplements or taking more than the recommended dosage can increase the risk of overdose.
What to know about supplements
Supplements come in many forms, such as capsules, gummies, powders, and tablets. Some categories of ultra-processed foods will be “fortified with vitamins.” And some manufacturers add nutrients to drinks and energy drinks.
You might need supplements if you cannot meet your daily intake goals of certain minerals and vitamins through your diet alone. Choosing a vegan diet, for instance, may require the likes of vitamin B12 (in particular), vitamin D, iron, iodine and omega-3. Still, many people can get enough minerals and vitamins from a nutrient-rich diet.
There's a lack of evidence showing whether supplements help prevent or treat health conditions. For example, a study published in 2018 found that regular supplement use has no net effect on heart health or the risk of early death. The research team's findings were consistent for multivitamins, calcium, and vitamins C and D, all of which people have touted for heart health.
The 2018 study only looked at heart problems and early death. Some supplements might benefit your bone, eye, and skin health. For example, calcium and vitamin D help prevent bone loss, especially in people with a high risk of osteoporosis. Pregnant people benefit from taking folic acid, which helps minimise the risk of birth defects.
Vitamins with potential for overdose
You might develop adverse effects—as well as spend too much money—if you take too many supplements. Some minerals and vitamins can build up in your blood over time and raise your risk of an overdose. An overdose might happen by accident. Some manufacturers fortify foods and drinks with nutrients, so you may not realise how much you consume.
Any one nutrient can be toxic in excess amounts, though B vitamins and vitamin K do not usually cause toxicity. Some of the most severe risks of an overdose come from calcium and iron supplements. For example, too much calcium in your blood or urine might increase your risk of heart disease and prostate cancer. An iron overdose might cause coma or low blood pressure and damage your intestines and liver.
Other vitamins with a potential for overdose include:
Vitamin A: Taking too much vitamin A might lead to coma and death in severe cases and harm pregnant and breastfeeding people. Excess vitamin A may also harm the foetus during pregnancy and cause abnormal development of the eyes, heart, lungs, and skull.
Vitamin D: Vitamin D boosts how much calcium your gut absorbs. As a result, you might have too much calcium in your blood or urine.
Vitamin E: Excess vitamin E might increase the risk of haemorrhagic stroke, or sudden bleeding in the brain.
Symptoms of overdose
Multivitamin overdose generally causes symptoms that might include:
Bone, joint, or muscle pain
Cloudy urine
Diarrhoea
Dry, cracked lips or skin
Headache
Irregular or rapid heartbeat
Mood changes (e.g., irritability)
Nausea and vomiting
Seizures
Stomach pain
Some minerals and vitamins might cause specific symptoms. For example, an iron overdose might cause bloody, dark diarrhoea and weakness, while a vitamin A overdose can lead to blurry vision and dizziness. Excess calcium in your blood, which may result from taking too much calcium or vitamin D, may cause a lack of appetite, kidney stones, and muscle weakness.
Supplement safety tips
Always consult your GP or pharmacist before taking a new supplement. They can tell you whether a supplement might help prevent or treat a health condition or pose safety risks. Make sure you ask what dosage is best for you and when it's best to take the supplement. Dosage and timing recommendations might vary between people.
Tell a healthcare provider if you are:
About to have surgery
Breastfeeding
Pregnant
Keep in mind the supplements might interact with any medications you are taking. For example, vitamin A may decrease the function of warfarin, a blood thinner. Vitamin E might reduce the efficacy of some chemotherapies.
To lower your risk of an overdose, try looking for a multivitamin with no more than 100% of the daily value for any one nutrient to avoid an overdose.
In any case, it's essential to focus on getting your nutrients from food first rather than supplements. Supplements are not a substitute for a good diet: plant-based, fruit, vegetables, whole grains, nuts, and seeds. These are packed with what you need.
Extracts taken from Amanda MacMillan from www.health.com