Are multivitamins really good for you? Here's what the experts say

New scientific research has suggested that a dietary supplement could prevent cognitive decline in people over the age of 65. Photo / Raimond Klavins, Unsplash

In the battle against dementia, there may be a simple weapon we've had in our armoury all along: taking a daily multivitamin. New scientific research has suggested that a dietary supplement could prevent cognitive decline in people over the age of 65, keeping their brain sharp for an extra two years.

The study of 2200 men and women found those who took a multivitamin every day slowed their ageing by 60 per cent, or 1.8 years. They had improved global cognition, episodic memory and executive function, compared to those taking a placebo. The multivitamins contain vitamins A, C, D, E, K and B, minerals including zinc, selenium and magnesium, as well as a couple of antioxidants.

"We knew these supplements could be beneficial for brain health, but no one had ever tested them in the way we were proposing," says the author of the study, Laura D. Baker, professor of internal medicine, neurology and public health sciences at Wake Forest University, North Carolina. "This amazing finding needs to be replicated in further studies, but if it's true, the treatment could be available to everybody on a worldwide basis. Multivitamins are inexpensive and accessible."

According to YouGov, around half of us already take a supplement once a week or more and the supplement market in the UK is growing - it's due to hit £559 million (NZ$1 billion) in 2025.

Yet for many years, debate has raged over the use and efficacy of supplements.

The only previous study of long-term multivitamin use, the Physicians Health Study II, which ran from 1997 to 2011, did not show any particular protection against cognitive decline. Earlier this year, an editorial in the Journal of the American Medical Association stated: "People are wasting money thinking there has to be a magic set of pills that will keep them healthy when we should all be following the evidence-based practices of eating healthy and exercising."

Most experts agree that you can't out-supplement a bad diet. Photo / Fernando Andrade, Unsplash

Right now, the only recommendation the NHS makes for adults generally is to take 10 micrograms of Vitamin D in autumn and winter. So why might these findings – published in Alzheimer's and Dementia, the journal of the Alzheimer's Association – change the approach of the medical community?

"The educated hypothesis is that the over-65s are at sub-optimum micronutrient status for a variety of reasons," says Baker. "We don't absorb nutrients in the same way as we age. Generally in the US, we eat a terrible diet of processed food, carbs and saturated fats but not many nutrient-rich foods."

The UK will face similar issues – not only is our diet increasingly processed, but we face the same issues as we age: declining chewing ability, loss of appetite, slower metabolism and a decline in production of stomach acid which helps break down food.

The research showed that multivitamins particularly led to improvements in people with cardiovascular disease. "Cardiovascular disease is always associated with faster cognitive decline," says Baker. "The disease itself may rob the body of micronutrients at a faster rate, so you need to consume more. Secondly, medication changes absorption of micronutrients.

"Our hypothesis is that taking a multivitamin on a regular basis has helped heart disease patients overcome some of their medical conditions."

However, Baker cautions that further research, with a larger and more diverse group of participants, is needed before we recommend all midlifers start taking supplements. "This study was made through a national recruitment drive by mail or advertising in the media and that tends to recruit a certain type of person. We want to make sure our sample is diverse in terms of sex, ethnicity, but also rural."

The multivitamin involved in the research was Centrum Silver, containing the aforementioned wide-spectrum mix of vitamins and minerals, as well as carotenoids lutein and lycopene – antioxidants which are thought to protect the skin and eyes. This specific combination was not present in the less-optimistic Physicians' Study, and there are studies which back up the efficacy of ingredients found in the formulation.

"There's enough evidence to say, with the heavy doses of the B vitamins and the addition of lutein and lycopene, that it's a pretty decent mix," says Baker. "You also have to consider the possibility it's not any single ingredient, it's the combination."

Ultimately, opinion is divided over whether we need to turn to supplements if we are otherwise healthy. Photo / Mark Timerlake, Unsplash

Nishtha Patel is a clinical nutritionist who believes the addition of B vitamins may be useful. "A lack of B12 – vital for keeping red blood cells and nerves healthy – can give symptoms of cognitive decline similar to dementia," she says. "And if you are taking medication, this makes a difference to how nutrients are assimilated." For example, drugs such as metformin, which are used to treat type 2 diabetes, deplete B12.

"B vitamins have been extensively researched for maintaining levels of the compound homocysteine," says public health nutritionist Dr Emma Derbyshire, from the Health & Food Supplements Information Service. Homocysteine is an amino acid and high levels are a risk factor for heart disease. "If levels of homocysteine rise too high, for example, this can impact on the health of the blood vessels in the brain, with a potential impact on blood flow," says Derbyshire. "Vitamins can also act as antioxidants in the brain and reduce the risk of inflammation, which can increase the risk of poor brain health."

However, cautions Derbyshire: "Multivitamins are not intended for treating disease, they are aimed to help bridge nutritional gaps in the diet. In this current study, the participants did not have dementia. It may be that micronutrient levels were low in these participants and topping up vitamins and minerals helped to improve brain health."

Ultimately, opinion is divided over whether we need to turn to supplements if we are otherwise healthy. "In general, eating a balanced and varied diet should provide sufficient amounts of the vitamins, minerals and other nutrients that we need, as well as important dietary components, such as fibre, without the need for supplements," says Dr Louise Durrant, nutrition communications manager at the British Nutrition Foundation. "Vitamin D is the exception to this."

Most experts agree that you can't out-supplement a bad diet. "I meet few people who are getting the nutrients they need or who eat enough fruit and veg in their diet," says registered nutritional therapist Alex Allan. "Sometimes people reach for a 'pill for an ill', but they should look at diet and lifestyle first, then supplements."

For those tempted by the research to reach for a multivitamin, some key advice. If you are on medication, you must seek advice from your GP first, as some supplements cannot be taken with specific medication.

"For instance if you are on blood thinners like warfarin, Vitamin K can be contraindicated, fish oils can be contraindicated," says Patel. "You need to know the quantities and how much you should be taking."

Secondly, generally speaking, multivitamins are preferable to single-dose supplements because they are formulated to work together and remove the risk of the individual accidentally taking too high doses of single vitamins.

"It's best to opt for a multivitamin," says Allan. "B vitamins tend to work as a complex, while some minerals like calcium and magnesium work in harmony."

Timing is important to get the most out of our supplements. "Take B vitamins in the morning as they can disrupt sleep, and Vitamin D with the heaviest meal," says Patel. "I prefer liquids and powders over tablets as they are better for absorption, but am not a fan of effervescent [varieties] due to sweeteners that are sometimes present in them."

The ideal is that we get our vitamins and minerals from the food we eat. Our diet is also providing other key components such as fibre, carbohydrate, protein and essential fats. Plus vitamins are easier to absorb in food and there is less risk of accidentally taking too high doses of single vitamins. As Durrant says: "It is important to remember that supplements should not be used as a substitute for a healthy diet." Food for thought.

Six warnings signs of possible dementia

1. Constantly forgetting things you were told recently and asking the same questions repeatedly.

2. Putting objects in unusual places – like your keys in the bathroom cabinet.

3. Frequent problems finding the right word, using substitute words ("that thing you sit on"), jumbling sentence structures, or, if English is your second language, going back to the language you spoke as a child.

4. Getting lost in a familiar place or somewhere easy to navigate such as a supermarket.

5. Having difficulty making sense of what you see – for example, judging distances on stairs, or mistaking patterns or reflections for other objects.

6. Regularly being unable to follow what someone is saying and finding it hard to take part in conversations.