An over-the-counter drink taken daily may help improve memory in people with very early stage Alzheimer's disease, research suggests.
The drink contains a special combination of nutrients which may have an impact on the part of the brain linked to memory, a study found.
Charity experts gave the news a cautious welcome but said more research was needed.
Final results from the LipiDiDiet clinical trial, which was funded by the EU, were presented at the Advances In Alzheimer's Therapy congress in Athens.
The trial involved more than 300 people with "prodromal" disease - memory problems that are not severe enough to be diagnosed as dementia.
Half were given a special daily drink with a combination of fatty acids, vitamins and other nutrients, for two years and the other half were given a control drink with equal calorie content but without the nutrients.
After two years, there was no difference in cognitive performance between the groups of people.
But when the participants were tested with a more sensitive test to look at factors such as past events, places and associated emotions, those who took the supplement performed better than the control group.
There was no difference between the groups on the likelihood of people progressing to full Alzheimer's disease.
Brain scans showed that those on the drink had reduced brain shrinkage in some areas, including the hippocampus which is involved in memory.
Dr James Pickett, head of research at the Alzheimer's Society, said the drink, which includes the Fortasyn Connect combination of nutrients, may bring improvements.
He said: "The results show that an over-the-counter nutritional supplement can bring memory improvements for people in the very early stages of Alzheimer's disease, providing some relief to one of the most common symptoms.
"However, the study wasn't considered an overall success as there were no wider improvements in cognition and there was no evidence that the drink can slow the progression of Alzheimer's disease.
"People worried about their memory should visit their GP for advice. If early Alzheimer's disease is suspected, this supplement is one option for people to try, along with taking regular exercise, avoiding smoking and eating a healthy, balanced diet to keep their memory sharp."
Dr Rosa Sancho, head of research at Alzheimer's Research UK, said: "We know that a healthy, balanced diet can be important for reducing the risk of dementia.
"This nutritional drink aims to supplement a person's intake of certain nutrients that could help keep connections between nerve cells in the brain healthy, but previous trials of this product in people with Alzheimer's have had mixed results.
"While the initial results seem to suggest those using the drink may have reduced brain shrinkage, the product didn't show an overall benefit on memory and thinking, which was the primary goal.
"These preliminary results are interesting, but we will need to see the full published trial data to gain a better understanding of the potential of this intervention."
Professor Peter Passmore, from Queen's University Belfast, said: "Today's news is very encouraging because now we have something that we know is safe and effective in helping to conserve the brains of people with early Alzheimer's.
"Also, this is the first time a nutritional intervention has shown favourable effects on memory and everyday tasks in this patient group - the everyday tasks are key as they have a big impact on people's daily lives."
Professor Hilkka Soininen, from the University of Eastern Finland, who led the trial, said: "Today's results are extremely valuable as they bring us closer to understanding the impact of nutritional interventions on very early AD (pre-dementia) which we are now better at diagnosing but unable to treat due to a lack of approved pharmaceutical options."