As populations age, dementia is a problem across the developed world. Might nutrients or vitamins provide a solution?  

Unfortunately there is no drug treatment available to prevent dementia or bring about lasting improvements. So are there any supplements we can take or diets we can follow to prevent or delay a decline in our memory and reasoning as we get older?  

Can vitamins help?  

A review of the evidence for B vitamins, and Vitamins E and C was published in 2018. It found either no convincing evidence or that the evidence was of a low quality.

A review of the evidence for a wider range of supplements was also published in 2018. It examined studies into the effects of soy, ginkgo biloba, B vitamins, vitamin D plus calcium, vitamin C and β-carotene. The review concluded that few studies examined the effects on clinical Alzheimer-type dementia or mild cognitive impairment (MCI) and those that did suggested no benefit. It went on to conclude, ‘Evidence is insufficient to recommend any (over the counter) OTC supplement for cognitive protection in adults with normal cognition or MCI’

What about Vitamin D? 

Researchers at Oxford University have noted an association between lower levels of Vitamin D and increased risk of Alzheimer’s and cognitive impairment. However, the association could be a coincidence or it could be that one of the effects of Alzheimer’s is to reduce Vitamin D levels in the body. An association doesn’t necessarily prove that taking Vitamin D would prevent Alzheimer’s. This may explain why the researchers also observe, ‘findings from interventional studies have produced mixed results on the benefits of vitamin D supplementation on dementia and cognitive outcome.’

However, because there is an association, this looks to be an area worth researching further.

To avoid Vitamin D deficiency:  

  • Try to take advantage of 20 minutes or so of sunshine per day (a little less if you are fair skinned, a little more if you have darker skin) from April to October in the UK.
  • Make sure you include foods which provide vitamin D in your diet (like oily fish, eggs and fortified breakfast cereals).
  • Alternatively take a Vitamin D supplement as recommended by the UK NHS for the over 65s (up to - but no more than - 25ug/day).  

Might there be evidence for gingko biloba?

One of the reviews mentioned earlier found no clear evidence for the value of gingko biloba in reducing the risk of dementia. However, an overview review of the evidence, published in 2017, suggested a possibly more positive picture. The conclusion was that Ginkgo biloba extract (GbE) has potentially beneficial effects for people with dementia when it is administered at doses greater than 200mg/day for at least 5 months – although, given the low quality of some of the evidence, more rigorous further research is needed. 

WebMD advises that Ginkgo leaf extract is probably safe for most people when taken by mouth in appropriate doses but notes it can cause some minor side effects such as stomach upset, headache, dizziness, constipation, forceful heartbeat, and allergic skin reactions.

Is a healthy diet best?  

There is increasing evidence that a healthy diet is good for both the heart and the brain, including reducing the risk of Alzheimer’s. For example, a 2018 review article noted, ‘healthy dietary patterns, characterized by high intake of plant-based foods, probiotics, antioxidants, soy beans, nuts, and omega-3 polyunsaturated fatty acids a low intake of saturated fats, animal-derived proteins, and refined sugars, have been shown to decrease the risk of neurocognitive impairments and eventually the onset of AD (Alzheimer’s)’. 

The review recommends a number of diets as being helpful here i.e.

Another 2018 review of the evidence reached a similar conclusion i.e. ‘Higher adherence to the Mediterranean dietary pattern has been associated with decreased cognitive decline and incident AD. Another dietary pattern with neuroprotective actions is the Dietary Approach to Stop Hypertension (DASH). The combination of these two dietary patterns has been associated with slower rates of cognitive decline and significant reduction in incident AD.’

The review describes the evidence as ‘moderately convincing.’ This isn’t an overwhelming endorsement. However, given the existing evidence for the overall health benefits of both the Mediterranean and the DASH diets and the lack of obvious harmful side effects for most people, it seems worthwhile to recommend healthy diets as action we can take as individuals that may help to reduce the risk of Alzheimer’s.


  • There doesn’t seem to be convincing evidence that over the counter vitamin supplements can reduce the risk of dementias such as Alzheimer’s.
  • However, subject to further research, Vitamin D and ginkgo biloba may have some potential to reduce risk.
  • A healthy diet is currently the nutritional option most likely to help reduce risk – in particular a combination of the Mediterranean Diet and the DASH diet.
  • More research is needed into healthy diets as a potential means to reduce the risk of dementia – but we consider it worth recommending the Mediterranean and DASH diets for the range of health benefits they provide and (unlike some vitamin supplements) the absence of harmful side effects for most people.  

Reviewed by Richard Franklin March 2020, next Review February 2024.