Multivitamins have been around for almost a century, and help fill the nutrition gaps many people experience in the 21st century. Before the invention of multivitamins (or any vitamin supplements) people would either rely on consuming vitamins through diet, or they would become malnourished. It was surprisingly easy to get your daily dose of vitamins and minerals in the 18thand 19thcenturies though, as industrial processing of foods was uncommon.
Carl Zimmer wrote an article in the New York Times where he described how the rise in processed rice led to a condition called Beriberi. A condition that is caused by a deficiency in thiamine. The processing of the rice was stripping the rice of its outer layer (which was a great source of vitamins) (1).
This is just one small example of how diet changed fairly rapidly from the mid 19thCentury to the 20thCentury.
Vitamins were first discovered by a Polish scientist called Casimir Funk, who was not only responsible for the name (vital-amine = vitamin) but also became the “father of vitamin therapy” in 1912 (2).
In the hundred years since, vitamin supplements have become a massive industry. In recent years, in a bid to earn even more revenue, multivitamins specifically aimed at men and women have now become popular.
Male multivitamins are supposedly designed to help increase testosterone levels, while female multivitamins are often marketed to help with fertility, more specifically pregnancy and breastfeeding.
Multivitamins may help to reduce infection in the malnourished or elderly.Many people take multivitamins because they believe that doing so will protect them from infection, but the evidence for this is surprisingly sparse. A 2003 study looked at whether a vitamin and mineral supplement could reduce (self reported) infection and improve well being in adults with Type II diabetes (3).
The study found a significant improvement in subjective reports on infection, and an reduction in absenteeism in people who took the multivitamin supplement compared to the placebo group. The study was performed on people with type II diabetes, who are often more likely to suffer from a micronutrient deficiency – often due to poor diet.
Whether the effects would be similar with people who did not have type II diabetes was something that the authors decided should be explored further in the future. Another study looked at the effect of multivitamins and fortified milk on children in India. The study was very interesting because it looked at both healthy children, and children who lived in poverty stricken parts of India (4).
It found that children who had grown up in relatively low-risk environments (in other words they were unlikely to be malnourished) were unaffected by multivitamin use.
However children, who had grown up in poverty saw a significant improvement in their ability to resist infection, and a big reduction in the severity of infection if they did catch something. This is a common trend with supplements, if you are deficient in a certain vitamin, mineral, or amino acid then supplementing can see a big improvement, but if you aren’t deficient, then you are not going to see any benefits.
A meta analysis in 2005 by El-Kadiki & Sutton looked into the effect of multivitamin supplementation on infection rates in elderly people (5).
It found a lot of conflicting results among journal articles. Some, such as a 1993 study which found that there was a reduction in infection rates (6).
While others found no such evidence (7).
The meta analysis concluded that “the evidence for routine use of multivitamin and mineral supplements to reduce infections in elderly people is weak and conflicting. Study results are heterogeneous, and this is partially confounded by outcome measure”.
The bottom line is that multivitamin use may reduce infection in people with a poor diet, but if your diet is healthy then there will be absolutely no effect on infection rate.
Multivitamins may improve memory.It may seem like an odd relationship but there have been many studies that have looked at the effect of multivitamins on memory. Multivitamin ingredients such as B12 have been shown to have a limited effect on memory and dementia and being deficient in B12 can increase your risk of Alzheimer’s and dementia (8, 9).
Vitamin K is another common multivitamin ingredient that may improve memory (10).
A 2012 study found that multivitamin use enhanced “immediate free recall memory but no other cognitive domains” (11).
In case you were wondering, free recall is where subjects are given a list of items to remember and then asked to repeat them back to the person running the study. The items do not have to be repeated in the same order as they were written down.
Another study in 2012 found that 16 weeks of multivitamin supplementation led to an improvement in working memory in elderly women at risk of cognitive decline (12).
After reviewing the evidence, it seems that certain types of memory (such as immediate/working memory) can be improved with multivitamin use. Though this only seems to be the case in elderly people who are at risk of dementia. Quite a few studies have posited that the cause of dementia in these people may be a deficiency in vitamin B12 or vitamin K.
As with the infection studies, if you are malnourished then you may see a benefit to your memory, but considering vitamin B12 and vitamin K are both quite easy to get through diet, very few people will see any changes to memory.
Multivitamin use may help prevent macular degeneration.Many children (particularly in the UK) were often told to eat their carrots as it can help them see in the dark. This was actually something that was made up during the second world war to disguise the fact that the British had developed radar technology. But there was actually some truth behind it.
Consuming a healthy diet has been continually linked with improved vision, or rather a prevention in loss of eye sight. One study found that reducing vitamin A deficiency can help to improve eye sight in children (15).
Studies on the elderly have found that multivitamin and mineral supplements can help reduce the risk of age-related cataracts (16).
A Cochrane Database System Review on antioxidant vitamin and mineral supplements found that there was sufficient evidence to state that vitamin E and beta-carotene can help prevent age related macular degeneration, but that vitamin C did not have enough evidence backing its effectiveness (17).
An update to the study in 2017 found that multivitamin use can delay the progression of age related macular degeneration, but that certain ingredients that are marketed at the elderly (lutein and zeaxanthin) are ineffective (18).
This backed up the findings of a 1994 study which found that carotenoids and antioxidant vitamins can “help retard some of the destructive processes in the retina and the retinal pigment epithelium that lead to age-related degeneration of the macula” (19).
Similar studies have found that increasing consumption of foods that are high in carotenoids may help reduce the risk of age related macular degeneration (20).
Other studies have found no evidence for multivitamins being effective at preventing macular degeneration and most reviews find that there just isn’t enough evidence to support this theory. The bottom line is that multivitamins mayhelp to slow down the inevitable, but the effect (if it exists) will be minimal. Following a diet with high levels of carotenoids may be more effective.
Multivitamins may help improve mood and reduce stress.A 2011 study on healthy older men found that a vitamin and mineral supplementation taken over 8 weeks led to improved alertness, and a reduction in negative morning moods compared to a placebo (21).
Another study in 2013 found that multivitamins led to reduced stress, fatigue, and anxiety in men taking at-home mobile-phone assessments of their mood (22).
However in men who took the assessments at work, there was a significant increase in stress ratings. Which makes it hard to draw a conclusion from.
A study in 2000 found that a multivitamin and mineral supplement produced a statistically significant improvement in mood compared to a placebo (23).
Another study in 2002 found a significant improvement in stress reduction when taking a probiotics multivitamin compound (24).
A study in 2004 found that taking a multivitamin supplement led to improved behaviour in children with mood and behavioural problems (25).
There seems to be sufficient evidence to say that multivitamins can improve mood, reduce stress, and perhaps even improve behaviour. It’s not clear whether mood, stress, and behaviour are negatively affected by a deficiency, or whether taking the multivitamin when not in a deficiency will improve them.
Multivitamins may help obese people lose weight.This last benefit is highly suspect, but worth mentioning anyway. A study in 2010 found that giving a multivitamin to obese women led to a statistically significant reduction in body weight and body fat by increasing energy expenditure and fat oxidation, it also improved serum lipid profiles (26).
The possible reason for this could be an improvement in gut health in obese people, a population group that often suffers from bad dieting practices and a deficiency in many micronutrients. But the evidence for multivitamins improving body weight and fat levels is relatively scarce.
For the most part, multivitamins are perfectly safe, and side effect free. The risk reward ratio is in favour of taking multivitamins. There can be some minor side effects, particularly when you take multivitamins alongside a diet that is alreadyhigh in vitamins. Too much vitamin C can lead to gastrointestinal distress, while consuming too much vitamin D (combined with calcium) could potentially lead to the formation of kidney stones (27, 28).
There may also be a more serious side effect, but it is quite complicated. Several studies have found a link between taking multivitamins and mortality. A 2005 study on men found that regular multivitamin use led to a small increase in prostate cancer death rates (29).
But there is no causal link to explain this, so we can assume that the relationship is due to correlation.
After reviewing the evidence, it is safe to say that taking multivitamin supplements is completely safe provided that you are not already over consuming foods that are high in vitamins such as vitamin C and vitamin D. As to the risk of prostate cancer? There just isn’t enough evidence to support this theory, and no explanation as to how it could increase risk.
The recommended dosage for a multivitamin would differ based on the particular product that you were taking. Multivitamins are a combination of different vitamins and minerals, and are often created so that each vitamin and mineral is at optimum levels. Instead, we are going to look at the vitamins and minerals individually to find their recommended dosages, we are using the NHS website guidelines (30).
Vitamin C (40mg per day), B1 (1mg per day), B2 (1.3mg per day), B3 (16.5mg per day), B5 (<200mg per day), B6 (1.4mg per day), B7 (no RDA), B9 Folic Acid (200mcg per day), B12 (1.5mcg per day), Vitamin A (0.6mg per day for men), Vitamin D (10mcg per day in winter), Vitamin E (4mg per day for men), Vitamin K (1mcg per kg of bodyweight).
The next ingredients are commonly added to multivitamins, again this information comes from the NHS guidelines.
Potassium (3,500mg per day), Selenium (0.075mg per day), Iodine (0.14mg per day), Zinc (9.5mg per day), Calcium (700mg per day), Iron (8.7mg per day), Manganese (<4mg per day), Magnesium (300mg per day for men).
Q: What vitamins can increase sperm count?
A: Vitamin C (2,000 to 6,000 milligrams daily) helps prevent sperm from clumping or sticking together, thus improving the chances for fertility. Zinc supplementation(100 to 200 mg daily) has been shown to increase testosterone levels, sperm count and sperm motility.
Q: Do multivitamins have side effects?
A: Many multivitamin products also contain minerals such as calcium, iron, magnesium, potassium, and zinc. Minerals (especially taken in large doses) can cause side effects such as tooth staining, increased urination, stomach bleeding, unevenheart rate, confusion, and muscle weakness or limp feeling.
Q: Do multivitamins make you gain weight?
A: No, however they can assist in weight loss by balancing the bodies minerals and ensuring a perfect environment to support weight loss efforts.
Q: How long does it take vitamins to kick in?
A: Any supplement is going to take a minimum of 2 to 4 weeks to begin to work before person feels them ‘kick in.’ If it’s a mineral, you’re looking at about 90 days before your deficiency is fully amended.
Q: Is it better to take a multivitamin in the morning or at night?
A: It’s better to take them in the morning, since taking multivitamins at night can interfere with a good night’s sleep due certain vitamins being more energetic in nature.
Q: Is it safe to double dose on multivitamins in a day?
A: One day will be fine. Every day might cause toxic levels of minerals to build up in the body. Stick to the RDA guidelines and you’ll be fine.
For a hundred years, the idea that multivitamin supplements were effective went unchallenged. In recent times this belief has come into question. For people who are malnourished, or deficient, taking a multivitamin is unquestionably useful. However, if you already consume a healthy diet which contains high levels of fruit and vegetables, not only is a multivitamin redundant, it may actually be harming your health.
The issue with multivitamins is that the populations who are most in need of them are also the populations least likely to take them. Whereas people who don’t need to take them, are much more likely to. If you are considering taking a multivitamin, then first you should look at your current diet. Is it already healthy? If so then you probably get more benefit from avoiding a multivitamin and perhaps topping up individual vitamins or minerals that you may be deficient in.
If your diet is not currently healthy, then consider whether it would be possible to improve it in any way, before jumping to the multivitamin. That does not mean that a multivitamin would not be beneficial, just that it should be seen as a last solution rather than a first line of defence.
What is interesting about a lot of the studies that have been mentioned in this article is the fact that results are often seen in people with poor diets, or in people who are overweight or infirm. The elderly may see quite a lot of benefits from taking multivitamins, partly because they are at higher risk of infection, or macular degeneration, but also because their diet and health may be sub optimal.
People who are relatively healthy are often not used in these studies, and when they are the study often fails to see a significant improvement in their health. For men specifically, there does not appear to be any real benefit to taking multivitamins unless 1) your diet is unhealthy and you are deficient in a number of vitamins and minerals, or 2) you have a health condition.