One in two Americans are now expected to develop dementia in their lifetime, with the number of new cases soaring at an alarming rate.  

Many of us already know that making simple healthy choices such as eating well and staying active can help stave off the disease. 

But research shows there are also supplements available that might assist prevention of the disease, and others that could have the opposite effect.

Three doctors have now provided exclusive analysis of these studies to the Daily Mail to help compile a list of five supplements that could impact your risk of developing Alzheimer’s.

‘Exercise is the most important supplement someone can take to reduce their risk of developing Alzheimer’s,’ said Dr. Cory Goldberg, a plastic surgeon and wellness program founder based in Toronto, Canada.

‘But there are also a number of other supplements that may help or, at the least, won’t hurt when it comes to the disease.’

From fish oils to multivitamins, here are the supplements that may help boost brain health, and those that have been linked to a build up of damaging proteins thought to cause the neurodegenerative disease.

Just be sure to always check with your physician before you stop or start taking any new supplement.

Omega-3 fatty acids

Omega-3 fatty acids, commonly found in fish oils, have a long list of health benefits.

Fish oil supplements, for example, are sold for just a few cents a pill and claim to help slash the risk of heart disease.

But doctors said they could also reduce the risk of Alzheimer’s as they are a crucial component of neurons, meaning they could aid brain health.

Small scale studies have suggested that people taking omega-3 supplements experienced improved cognition compared to those taking a placebo.

‘If you’re not eating fish twice a week, I would highly recommend taking an omega-3 supplement,” said Shelley Balls, a registered dietitian nutritionist based in Wyoming.

‘In fact,’ she adds, ‘intake of omega-3 fatty acids could lower your risk of all-cause dementia or cognitive decline by approximately 20 percent.’

However, this theory is yet to be backed up by large clinical trials.

A 2020 review of 38 trials involving nearly 50,000 people who took omega-3 found the supplements had ‘little or no effect’ on cognitive health.

Furthermore, A 2012 review by Cochrane Institute involving 3,500 older people found that the supplements had no benefit on cognitive function. 

And a third paper by the same institute, this time from 2016, found ‘no convincing evidence’ that the supplements reduced symptoms in patients with mild-to-moderate Alzheimer’s.

Dr. Cameron Sepah, a clinical psychologist in California, told the Daily Mail that although these results did not prove omega-3 supplements would prevent Alzheimer’s, it was unlikely that taking them would do any harm.

‘Different studies have shown that omega-3 with high DHA content maintains brain function, fights inflammation and prevents cognitive decline,’ he added.

The Alzheimer’s Association also states that ‘Experts agree that more research is needed, and there is not yet sufficient evidence to recommend omega-3 fatty acids to treat or prevent Alzheimer’s disease.’

Roughly one fifth of adults in their 60s already take the supplement, according to Harvard Health. But doctors warned that people should be careful to check that any mercury – which can be present in fish – has been removed from the supplement as it can harm the brain.

Multi-vitamins

About 30 percent of Americans take a multivitamin every day to boost their overall health.

But scientists now say these pills could also prevent Alzheimer’s by ensuring people have an adequate supply of nutrients for cells to function normally. 

A 2023 study from Columbia University that followed 3,500 adults over 60 years old, found those who took a multivitamin for a year performed better on cognitive tests compared to those who took a placebo.

And in January last year, researchers at Mass General Brigham who gave 573 people a multivitamin containing at least 20 different nutrients for two years also found participants scored higher on the tests.

Dr. Goldberg called the results ‘encouraging’ but ‘controversial.’

‘The strength of these studies is not great enough to really conclusively prove a benefit because of the number of different confounding variables — like diet and exercise — and variation in the population,’ he explained.

He added that, overall, it wouldn’t hurt to take multi-vitamins because it is difficult to prove or disprove the benefit. But, he warned that people should only purchase the supplement from a reputable brand – consult your doctor before deciding which to buy.

Previous studies have shown that multivitamins can be contaminated with heavy metals like lead and arsenic, which can also impact cognitive health. Additionally, people should remember that some gummy-style vitamins can be packed with sugar. 

B Vitamins

Some researchers suggest that taking B vitamins – such as B12 and folic acid – could help reduce the risk of developing Alzheimer’s disease.

A 2022 meta-analysis of 95 studies that lasted for 12 months or more, with 46,175 participants, found evidence that the supplements did slow cognitive decline.

The reviewers also said that a higher intake of folate, but not B12 or B6, was associated with a reduced incidence of dementia.

However, not everyone agrees. 

A 2018 Cochrane review of five trials involving 879 people found ‘no evidence’ that supplementing B vitamins for six to 24 months boosted cognition.

Despite this, Dr. Goldberg said B vitamins are ‘very important’ for brain health, and that he was aware of studies suggesting they could protect against Alzheimer’s.

‘I think it has good health benefits in general,’ he said. ‘But particularly for people on a plant based diet who are in need of vitamin B12.’

According to the NIH, up to 15 percent of Americans may be deficient in vitamin B12 — which is essential for the functioning of neurons.

The CDC said less than one percent of Americans are deficient in folate, but about 10 percent are deficient in vitamin B6.

Signs of deficiency include regular fatigue, weakness, shortness of breath, headaches, and dizziness.

Dr. Sepah added that B vitamins are helpful for breaking down homocysteine, an amino acid in the blood that has been associated with mental decline when at high levels.

Melatonin

Many studies have warned that sleeping aids raise the risk of Alzheimer’s because they ‘knock someone out’ rather than helping them drift off to sleep.

The evidence is less clear-cut when it comes melatonin, but scientists told the Daily Mail that long term use could raise the risk of the disease.

Melatonin is sold over the counter in the US for about 20 cents a pill, but in other countries – including parts of Europe and the UK – it is only available with a prescription.

Melatonin imitates a hormone that makes people feel tired, boosting the hormone’s levels in the brain and helping to send someone to sleep.

Some studies have suggested that melatonin reduces the time it takes to fall asleep and improves sleep quality, which could theoretically reduce the risk of Alzheimer’s.

But Dr. Goldberg said he was ‘on the fence’ about its benefits, describing melatonin as a ‘blunt tool’ being used on the body’s complex hormone system. He said this could have adverse effects.

‘If you take something that regulates the sleep-wake cycle and align it to your own, that could be a benefit, but there is also the risk that it interferes with the system,’ he said.

‘I would say rather than being for or against melatonin as a supplement, I would encourage people to address sleep issues and try to maximize quality and quantity of sleep to try to prevent Alzheimer’s.’

‘In effect, with melatonin, you are tinkering with one of your hormones in a very complex system,’ he continued. ‘It definitely has the potential for negative consequences.’

A 2014 review analyzing dozens of studies on melatonin found the evidence was too weak to recommend it to the general population. 

‘While melatonin is well-known as a sleep supplement, long-term use at high doses could impact cognitive ability,’ says Dr. Sepah.

‘Certain studies suggest it can interfere with circadian rhythm-based brain detoxification and, therefore, potentially impact beta-amyloid removal (a key component of Alzheimer’s).’

Iron supplements

Roughly 14 to 18 percent of Americans take iron supplements to combat a deficiency and avoid anemia – where the body has too few healthy red blood cells.

These patients tend to be women who are menstruating and those who have recently lost a lot of blood due to an accident.

However, scientists have warned that regularly taking iron could raise the risk of developing Alzheimer’s.

They said that high levels of iron in the blood had been linked to inflammation and the formation of protein clumps in the brain, which have been linked to Alzheimer’s.

‘It’s very uncommon to consume too much iron via diet alone, but when supplements are involved there is a chance you can overdo it,’ Balls told the Daily Mail.

‘Focus on consuming iron-rich foods such as red meat, seafood, poultry and eggs, dark greens, beans, peas, nuts, and seeds rather than taking a supplement to help prevent an imbalance.’

Dr. Sepah says that ‘While iron is crucial for health, too much of it can result in oxidative stress and neurodegeneration.’

‘Increased brain iron has been associated with Alzheimer’s plaques, particularly in those with genetic susceptibilities,’ he adds. 

A 2017 review of 34 studies on the impact of high iron levels in animals found it had adverse effects.

It is recommended people speak to a doctor before discontinuing taking iron, especially if it has been prescribed.

The iron blood level considered to be normal is around 50 to 150 micrograms per deciliter (mcg/dL).

Women under the age of 50 need about 18 milligrams of iron per day, while women over 50 – and men – need only eight milligrams.