Vitamins and supplements: Medical myths uncovered

Longevity and a healthy lifespan result from a healthier and more active lifestyle. In recent years, vitamins and supplements have become more popular with the promise of longevity. However, are all claims of these supplements and vitamins factual and accurate? 

In the US alone, the market size value of the supplement industry is at USD 163.9 billion and is projected to increase to USD 327.4 billion by 2030! This equates to a compound annual growth rate of 8.9% [1]. In the UK, the market size of the vitamin and supplement industry will be £ 1.4bn in 2022. 

It is estimated that approximately 20 million people in the UK are taking vitamins and food supplements [2]. In the US, 86% or four of five people are taking vitamins, yet only 21% have confirmed vitamin deficiency [3]. 

Understandably, people want to live longer and stay healthier as more years are added to their lives. Hence, it is no surprise that supplements are growing popular if popping a pill could lead to better health and the prevention of long-term conditions. 

However, it is essential to note that supplements are necessary for specific individuals or patient groups. For example, the World Health Organization (WHO) [4] recommends that pregnant women should take 400 micrograms (0.4mg) of folic acid daily to prevent preterm birth or low birth weight and neural tube defects such as spina bifida. Similarly, the WHO recommends 30 to 60 mg of iron daily to prevent maternal anaemia. 

Vitamin D supplementation is recommended during the winter when people have little exposure to sunlight. This is highly recommended for people who live in polar or subpolar regions where long winter nights reduce exposure to the sun. 

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Generally, for adults who are living a healthy lifestyle, eating healthy foods, having sufficient sunlight exposure and exercising, the majority of the vitamins and supplements are not necessary. However, since multivitamins and accessories are backed up by Science and interspersed with creative marketing, it is no wonder that some misconceptions about supplements and vitamins exist. 

Here are some common misconceptions about multivitamins and supplements that you should be aware of: 

Myth 1: More vitamins are better for your health 

While vitamins are critical in our growth and development, larger doses can lead to serious adverse effects. 

Vitamin A toxicity 

Vitamin A or retinol is essential for better functioning of the photoreceptors in the retina of the eyes [4]. This vitamin helps in night vision and maintains the health of the skin, the lining of the urinary tract, the intestine and the lungs. It is also an essential vitamin since it protects the linings of the internal organs from infections. Some excellent sources of vitamin A include egg yolks, fish liver oils, cream, butter and fortified milk. 

Carotenoids, present as red, orange or yellow pigments in fruits and vegetables, are slowly converted by the body into vitamin A. Carotenoids are best absorbed when the vegetables or fruits are cooked with some oil. Some fruits and vegetables rich in carotenoids include orange, yellow and dark green fruits and vegetables. 

However, consuming excess vitamin A is not suitable for your health. Taking vitamin A at a dose ten times the recommended daily allowance (RDA) for months can cause toxicity. 

Taking high amounts of carotenoids from fruits and vegetables is not harmful since carotenoids such as beta-carotene are converted to vitamin A slowly. 

Consuming very high amounts of Vitamin A supplements can cause the following: 

  • Coarse hair 
  • Partial loss of hair, including the eyebrows
  • Dry, rough skin 
  • Cracked lipids 

In infants, chronic consumption of large doses of the vitamin results in liver damage and congenital disabilities in fetuses. 

In children, vitamin A toxicity manifests as the following: 

  • General weakness and severe headaches 
  • Bone and joint pain 
  • Fractures
  • Loss of appetite and abnormal growth 
  • Itching of skin 
  • Enlargement of liver and spleen 

Acute toxicity, which occurs when large amounts of vitamin A supplements are taken all at once, can cause the following: 

  • Irritability 
  • Nausea 
  • Headache
  • Nausea 
  • Drowsiness 
  • Vomiting within hours, followed by skin peeling
  • Increased pressure in the skull 
  • Coma and death may occur unless the consumption of vitamin A is stopped

In pregnant women, taking a vitamin A derivative called isotretinoin, which is used to treat severe acne, can cause a congenital disability. Hence, pregnant women must not take vitamin A above the safe upper limit of 3000 micrograms to prevent the risk of congenital disabilities.  

Too much vitamin C 

Vitamin C is crucial in strengthening the immune system and reducing the risk of contracting common colds and other diseases. This vitamin is vital since it is an antioxidant that protects cells against free radicals. An imbalance between antioxidants and free radicals can increase the risk of cancer, heart disease and autoimmune disorders. 

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The daily recommended allowance is 2000 mg per day. However, vitamin C from fruits and vegetables have not been shown to result in any signs and symptoms. 

However, excess vitamin C supplementation can result in the following: 

  • Nausea
  • Vomiting 
  • Diarrhoea 
  • Heartburn 
  • Stomach cramps 
  • Bloating 

Too much calcium 

Calcium is needed to build and strengthen bones in the body. However, excess calcium supplementation can result in the following: 

  • Hypercalcemia 
  • Nausea 
  • Vomiting 
  • Weakness 
  • Frequent urination 
  • Bone pain 
  • Kidney problems 
  • Formation of calcium stones 

Too much vitamin D

Vitamin D is necessary for calcium and phosphorus absorption and retention. Both calcium and phosphorus are essential in building bones. Vitamin D reduces the risk of inflammation and helps control infections.

Signs and symptoms of vitamin D toxicity are similar to calcium toxicity. 

Myth 2: Supplements labelled as ‘natural’ are always safe 

Supplements are made from plant extracts or active biological compounds extracted from plants, fruits or trees. However, dilution of the active compounds should be considered, as some supplements might only contain trace amounts. 

Myth 3: Taking supplements along with medications is always safe 

Supplements have active compounds that can treat or manage certain conditions. However, it is always best to consult your doctor when taking over-the-counter supplements since certain compounds in these supplements might interact with your medications. 

Drug-to-drug interactions might only worsen your health and result in delayed recovery or adverse events. 

Myth 4: Prebiotics and probiotics are wonder drugs and cure all diseases 

Prebiotics are supplements or foods with compounds that promote gut bacteria growth, while probiotics are living microorganisms that improve gut health. 

Probiotics improve gut health and have been shown to promote overall health by reducing the risk of hypertension, diabetes and depression. Probiotics also ease irritable bowel syndrome (IBS) symptoms. 

Although many benefits are associated with probiotics and prebiotics, studies in this area are still relatively young. Claiming that probiotics and prebiotics can cure all diseases still needs to be backed up by solid evidence from published studies. 


Vitamins and supplements are essential in promoting good health and have been well-documented in clinical trials to treat or manage certain diseases. Eating different types of fruits and vegetables could promote better gut health, reduce inflammation and improve overall health and well-being. It might also result in a healthy life span and longer lifespan. 

When planning to take supplements, always consult your doctor to ensure that these do not interact with the medications you are currently taking. 

Considering the myths presented in this article will help you decide the best supplement and vitamins. 

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The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.