Half of dementia patients suffer from malnutrition, according to a new report published by Alzheimer's Disease International (ADI).
The London-based non-profit organisation found that a low intake of fluids is common for people with the cognitive condition in all parts of the world.
The study, which was conducted by the Global Observatory for Ageing and Dementia Care at King’s College London claims that 10 per cent of dementia patients living at home are undernourished.
For those in residential care, the rate is 30 per cent while in hospitals it is 70 per cent.
Malnutrition can cause reduce mobility, frailty and increase the risk of fractures from falls. The experts warned that it can also exacerbate other health conditions and increase mortality.
According to the researchers, side-effects from dementia treatments could be playing a part in the figures as they are believed to suppress a person's appetite, but they said more research needs to conducted before that can be stated as a fact.
The study adds to research conducted in France which found that around 45 per cent of people with mild to moderate Alzheimer's disease lost significant amounts of weight.
George McNamara, head of policy for the Alzheimer's Society, told the Daily Telegraph that healthcare professionals can help malnutrition to be avoided by monitoring weight and food intake.
"We also need to educate caregivers and care home staff, as dementia training can be the difference between someone starving and living well with the condition," he added.
The report added that there is no evidence to suggest that taking nutritional supplements lowers the risk of dementia, but it did say that those which consume a Mediterranean-style diet tended to be more healthy in later life.
Some 820,000 have a form of dementia in the UK at present and the number is set to rise to 1.7 million by 2051.