Multivitamins - do we need them?
Almost all of us have taken multivitamins, and many take them regularly, hoping they will help improve health, compensate for poor eating habits, and even reduce the risk of developing chronic diseases.
Unfortunately, in most cases, this is not the case.
Why is this so? That’s what this article is about.
What are multivitamins?
Multivitamins usually contain three categories of nutrients:
- Water-soluble vitamins – these do not usually accumulate in the body and also do not cause serious side effects if taken more than the body needs (e.g. B vitamins, vitamin C).
- Fat-soluble vitamins – these are accumulated in the body and, if taken in excess, can reach toxic levels and potentially cause devastating side effects (e.g. vitamins A, D, E and K).
- Minerals – inorganic elements that can accumulate in the body and, in some cases, can cause unwanted side effects if taken in excess (e.g. iron, iodine, zinc, copper and selenium).
Where is the problem?
Multivitamins are promoted as a means of reducing the risk of heart disease, cancer and other serious health problems, improving immunity, reducing fatigue, etc.
Research does not support these benefits, for example:
- A review of 84 studies involving nearly 700,000 people found that there is little or no evidence that vitamin and mineral supplements help prevent cancer, reduce the risk of cardiovascular diseases and prevent premature death.
- A study of the mental functioning and multivitamin use habits of 5947 men followed for 12 years found that multivitamins did not reduce the risk of mental decline, such as memory loss or slower thinking.
- Although there is evidence that vitamin C plays a crucial role in immune function, the impact of vitamin C supplementation on immunity is still a matter of debate. Some studies suggest that vitamin C may help reduce the duration and severity of colds, while others show limited or no effect. In other words, vitamin C is vital for the immune system, and if it is deficient in the body, supplementation will improve immunity. But if you eat a nutritious and balanced diet, no matter how much vitamin C you intake, there will be no improvement.
We need to take as much as our body needs, and excessive intake of some vitamins or minerals through supplementation/multivitamins can cause toxicity, leading to various health problems, for example:
- Vitamin A (retinol):
- Symptoms of toxicity: nausea, dizziness, blurred vision, bone pain and, in severe cases, liver damage.
- Sources of toxicity: High doses of vitamin A supplements and excessive consumption of animal liver.
- Vitamin D:
- Symptoms of toxicity: Hypercalcaemia (elevated blood calcium levels), nausea, weakness and, in severe cases, kidney damage.
- Sources of toxicity: Excessive use of supplements and use of supplements in combination with high consumption of foods rich in vitamin D (salmon, herring and sardines, cod liver oil, canned tuna, egg yolks, mushrooms, foods fortified with vitamin D).
- Symptoms of toxicity: Nausea, vomiting, abdominal pain and, in severe cases, organ failure.
- Sources of toxicity: Accidental intake of iron supplements (especially in children) and excessive use of iron supplements without a diagnosis of iron deficiency.
- Symptoms of toxicity: Constipation, kidney stones and impaired absorption of other minerals.
- Sources of toxicity: Excessive use of calcium supplements without regard to dietary calcium intake or health conditions.
- Symptoms of toxicity: Hair loss, nail damage, nausea and neurological disorders.
- Sources of toxicity: Excessive intake of selenium-containing supplements/multivitamins.
- Symptoms of toxicity: Nausea, vomiting and immune dysfunction.
- Sources of toxicity: Prolonged intake of high doses of zinc without medical supervision.
- Vitamin E:
- Symptoms of toxicity: Blood clotting disorders.
- Sources of toxicity: Excessive intake of vitamin E above recommended levels.
- Vitamin B6 (pyridoxine):
- Symptoms of toxicity: Nerve damage, numbness and walking difficulties.
- Sources of toxicity: Prolonged use of high doses of vitamin B6.
- Symptoms of toxicity: Nausea, vomiting and liver damage.
- Sources of toxicity: Excessive use of copper additives or consumption of copper-contaminated water.
- Symptoms of toxicity: Masking of symptoms of vitamin B12 deficiency, which may cause nerve damage.
- Sources of toxicity: Excessive folate intake without addressing underlying health problems in folate metabolism or use (e.g. celiac disease or inflammatory bowel disease may affect folate absorption, while kidney problems may make it difficult to excrete excess folate).
It is important to note here that nutrient toxicity is relatively rare.
These examples highlight situations where vitamins and minerals are taken in excess through supplementation/multivitamins.
In other words, all these vitamins and minerals are vital for the proper functioning of our bodies, but what is too much is too bad.
Who might need multivitamins or certain supplements?
Although taking multivitamins is, in most cases, a waste of money and, in some cases, even harmful, there are exceptions:
- Vitamin B12 absorption may decrease with age. Older adults may need to supplement vitamin B12 as well as vitamin D and calcium.
- As vitamin B12 is mainly found in animal products, vegans and vegetarians are at higher risk of vitamin B12 deficiency. Their bodies may also be deficient in calcium, zinc, iron, vitamin D and omega-3 fatty acids.
- Gastric reduction surgery can result in nutritional problems, which can be addressed with multivitamins and mineral supplements.
- Low-calorie diets or other forms of rapid weight loss may make it difficult to get all the nutrients your body needs from food.
- Some gastrointestinal conditions can cause poor absorption of nutrients, so your doctor may recommend taking multivitamins or specific vitamins.
- If you do not get enough sun, you may need to take extra vitamin D.
- If you have low levels of red blood cells in your blood (anaemia), your doctor may recommend taking iron supplements.
How much is too much?
Most of the mentioned side effects occur when a person consumes more nutrients than the current Tolerable Upper Levels (UL).
Each nutrient has a maximum level above which it becomes toxic. Exceeding the ULs can cause severe side effects such as liver damage and, in some cases, even death.
The table below shows both – the Recommended Dietary Allowance (RDA) and the Tolerable Upper Levels (UL) for vitamins and minerals that can cause problems in adults.
Recommended daily intake for men (RDA)
Recommended daily intake for women (RDA
Maximum tolerable daily intake (UL)
900 mcg Retinol activity equivalent (RAE)
700 mcg RAE
3,000 IU (International units)
Vitamin B3 (niacin)
16 mg Niacin equivalents (NE)
14 mg NE
Vitamin B6 (pyridoxine)
Vitamin B9 (folate)
400 mcg Dietary folate equivalents (DFE)
400 mcg DFE
No UL established
*Only applies to synthetic forms of nutritional supplements, foods fortified with them, or a combination of both.
Nutrient intake recommendations for infants and children vary considerably depending on their age. More information is available HERE.
Why is it hard for us to give up multivitamins?
Because contrary to most evidence, we believe that vitamins and other supplements will help us maintain or improve our health, give us extra energy, etc.
We also believe that foods fortified with vitamins and minerals are healthier (and therefore better) – after all, we’ve been told for almost a century that vitamins are healthy and natural.
In fact, taking a multivitamin is like a kind of guarantee that we are doing our best to take care of ourselves.
Unproven marketing claims for dietary supplements
Vitamins are very cheap to produce, so manufacturers can spend a lot of money on advertising.
In addition, food supplements are regulated as food products, not as prescription or over-the-counter medicines.
What is the difference?
Medicines are strictly regulated and can only be sold after the manufacturer has proven that they are effective, have no significant adverse side effects and that the benefits of taking them outweigh the risks.
Manufacturers of dietary supplements do not have to prove anything. They do not even have to prove that their marketing claims about the effects of supplements are true.
How does this play out in real life?
Manufacturers of dietary supplements cannot claim that their product, for example, “reduces the risk of heart disease” because that is a medical claim that needs to be proven.
They can say that it “promotes heart health” or “improves immunity” and make vague promises that their product reduces fatigue, increases energy levels, improves motivation, and so on.
Although almost all dietary supplements state somewhere in the fine print that they are not intended to diagnose, treat or prevent disease – this does not affect how people perceive marketing claims.
A healthy and balanced diet, rich in fruit and vegetables, provides our bodies with all the vitamins and minerals they need.
We only need supplements if our diet is deficient or if we suffer from a disease that affects the absorption or use of nutrients.
In most cases, multivitamins are not harmful, but the money people spend on them would be better invested in their health by buying healthy (nutrient-dense) foods.
Multivitamins contain many nutrients that you may not need. If you are deficient in a nutrient, it is better to take it on its own rather than in combination with substances you do not need.
In other words, if you need vitamin D and iron, take vitamin D and iron supplements rather than multivitamins, which contain the maximum number of different vitamins and many of the chemicals listed in Mendeleev’s table.
Eat healthy, eat balanced, exercise and – be healthy!
Help to maintain this site, create interesting articles and delicious low-calorie recipes!