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Should You Be Taking Supplements?

People often take vitamin supplements to get enough nutrients to maintain or improve their health.

There is a general belief that everyone should have one-a-day multivitamins within their diet. Yet, there is an argument to say otherwise when looking at the evidence.

86% of Americans have reported taking supplements or vitamins, yet only 21% have a confirmed deficiency. This guide shares why supplements are popular and aren’t always safe.

Why do people take supplements?

There are a few reasons why people take supplements:

  • Prevention of diseases, i.e. vitamin D for its anti-inflammatory purposes, vitamin C as an antioxidant, and omega-3 to prevent heart disease.
  • Confirmed deficiencies.
  • It is an 'insurance policy' to ensure they get all the nutrients they need.
  • It was recommended by friends/family.
  • Google suggests that such vitamins benefit your personal needs.

There is a lot to say about whether or not we should all be taking supplements, and what is on the internet can be confusing and conflicting. But here are a few things you should know.


Deficiencies are usually caused by inadequate intake or absorption of specific nutrients. However, some people may be at a higher risk than others due to various factors such as lifestyle, health conditions or certain medications.


A meatless diet would not necessarily be classed as 'unhealthy', but this group is advised to be mindful of the nutrients they could be missing. Veganism is associated with vitamin b12, zinc, calcium and selenium deficiencies. Though not all will cause health implications, it is crucial to consider having bloodwork or taking supplements.


There are hundreds of medicines that can cause nutrient deficiencies. Therefore, it is essential to do your research or ask your doctor when having medication prescribed, but here are a few examples:

Proton pump inhibitors (i.e. lansoprazole and omeprazole) increase the risk of having nutrient deficiencies. This risk can be minimal for most but possibly significant in elderly or malnourished people. There are currently no guidelines to suggest extra monitoring for this, instead to reduce the overutilization of PPIs.

Metformin can deplete vitamin b12 and folic acid.

Diuretics deplete vitamins as it increases urine flow rate, specifically vitamin b1 (thiamin).


Smoking is known to lower vitamin C and B-carotene levels in plasma. This is because the body's antioxidants are used more quickly to combat the oxidants introduced by smoking. Although the best solution is to stop smoking, having a nutrient-rich diet or supplement can help. A study in 2017 found that having a diet rich in vitamin C can reduce the risk of lung cancer in females by 26%.

Although symptoms can vary, common signs include:

  • Fatigue
  • Dizziness
  • Muscle weakness
  • Headaches
  • Forgetful
  • Confusion
  • Lethargy

Condition-specific supplements

People with certain conditions are advised to take supplements. These include:

  • Folic acid and pregnancy - Taking iron and folic acid supplements as soon as possible during pregnancy has been scientifically proven to reduce the risks of low birth weight and maternal anaemia. Maternal anaemia has been linked to maternal and perinatal mortality, premature birth, and low birth weight.
  • Gastric surgery - All gastric procedures change the anatomy and physiology of the gastrointestinal tract, increasing the risk of developing nutritional complications such as anaemia, osteoporosis or protein malnutrition. It is advised that all patients use supplements based on what they need through life-long monitoring.
  • Autoimmune diseases - Vitamin D and Omega-3 are primarily known for their anti-inflammatory properties. A study in 2022 found that taking vitamin D over five years had reduced autoimmune rate by 22%, whereas only 15% for omega 3.
  • Vitamin D - Promotes and strengthens bone health. Evidence suggests that sufficient vitamin D levels can be impossible without adequate sunlight. The Institute of Medicine recommends that everyone aged 1-70 take 600iu daily and those 70+, 800iu.

Supplements are not always safe

The World Health Organisation (WHO) has advised that vitamins and minerals in excess can be toxic to the body and cause serious long-term problems—particularly fat-soluble as they are stored in tissue.

Specific vitamins to look out for include:

  • Vitamin A - Hair loss, cracked lips, and rough skin may signify that you are taking excess vitamin A. Later symptoms include headaches and generalised weakness. If taken in excess long-term, it can cause comas and sometimes death.
  • Vitamin D - Excess vitamin D may present as weakness, nausea, and vomiting. Toxic calcium and vitamin D levels can affect the cardiovascular system, causing hypertension and an irregular heartbeat.
  • Vitamin E - Although rare, too much vitamin E can increase the risk of bleeding, increasing the risk for those already taking anticoagulants. Replacing with vitamin K can reverse these effects.

Overdosing on water-soluble supplements is much less common as they are excreted in the urine. However, vitamin C, niacin, pyridoxine, and folate can also have undesired side effects if taken in excess.

So what about a multivitamin?

A multivitamin is a pill which contains several vitamins often used to fill nutritional gaps, usually to be taken once a day.

Pros of multivitamins

  • Multivitamins can help fill the nutritional gaps if you've had a hectic day.
  • They are convenient and can prevent fatigue in between meals.
  • They can be used to replace electrolytes after exercise.

Cons of multivitamins

  • They cannot replace a balanced diet.
  • Vitamins should be taken specific to personal needs so that you are not taking anything unnecessarily.
  • There is no significant evidence that a multivitamin will help to prevent conditions such as cardiovascular disease or cancer.


Supplements are not to be used instead of a balanced diet. But they can benefit some, especially those at a higher risk or who have confirmed deficiencies. For the majority, over-the-counter supplements will not be harmful if taken as directed, but you might want to consider if they will be of any benefit either.

About the author

Rebecca Barnsley

Hey, my name is Rebecca. I’m an RNA and freelance health content writer! I focus mainly on chronic health conditions, women’s health, mental health and well-being.