Can certain foods reduce the risk of dementia?
A controversial new book claims that a change of diet can prevent Alzheimer's disease. Our reporter meets the author
It's the condition that terrifies us more than any other: dementia robs a person of not only their memory, but also their identity and independence. According to the HSE, half a million Irish people live in families affected by dementia. Each year more than 4,000 people develop dementia in Ireland - over 11 people a day. All are living with a brain condition that deeply affects their lives and the lives of people who love them. This number is expected to treble in a generation.
Rates are soaring because we are living longer - based on census figures there are currently 55,000 people living with the condition in Ireland and this number is expected to increase significantly in the coming years; rising to 68,216 people by 2021 and to 132,000 people by 2041. Meanwhile, developments in treatments are dragging.
But is the condition really an inevitable price we must pay for long life? In a remarkable new book, a leading researcher in ageing argues not. Dr Preston Estep, director of gerontology at Harvard Medical School, believes the high rates of dementia in countries such as Ireland and the UK are strongly linked to our diets.
Alzheimer's is by far the most common form of dementia, and by studying countries with low rates, Dr Estep has devised an eating plan that he claims promotes not just quantity of years, but quality - maintaining one's mental faculties well into old age.
In 'The Mindspan Diet', Dr Estep investigates the diets of an elite group of regions of the world where people enjoy both long life and low rates of cognitive decline. Chief among these is Japan, and close behind are what he refers to as the Mediterranean rivieras - coastal areas of southern Europe, such as Liguria and Sardinia in Italy, and the Provence-Alpes-Côte d'Azur region of France, and certain areas of north and western Spain.
What is there to suggest that it's the diets of these countries that are keeping their inhabitants' brains young, and not a genetic history, or some other aspect of their lifestyle? Dr Estep points to the fact that obesity and diseases including heart disease and dementia are growing in countries such as Japan and Italy as their traditional diets are replaced with more modern, processed foods - but older people in rural parts of these countries, which haven't been so exposed to Western influences, seem to remain as healthy as ever.
The cuisines of these countries might not seem to have a lot in common, but Dr Estep has identified one vital component - and it's not, as you might expect, olive oil or even oily fish. Instead he believes these populations' low rates of dementia come down to something they don't eat, and that's red meat or, more specifically, iron.
Some research suggests that iron reacts with oxygen to cause "rusting" in the body, leading to the deposit of waste products, such as the plaques in brain cells seen in people with dementia.
"We always hear about antioxidants, whose job is to counter the work of 'pro-oxidants' in the body," says Dr Estep. "Iron is the most abundant and potent pro-oxidant in the body, and the more we have of it in our bodies, the more oxidative stress and damage.
"Iron, from red meat and iron-enriched grain products, is the reason we see high levels of Alzheimer's in countries such as the US and northern Europe."
Dr Estep says that he is not advocating cutting out meat altogether - iron is an important nutrient, particularly for younger women, many of whom are deficient in the mineral because of menstruation. "We should keep it in a range I generally describe as sufficient but low," he says. "I eat a little bit, but not much.
"Individuals are going to vary in how their bodies process iron, so they should have their levels tested rather than using a one-size-fits-all dietary recommendation.
"I certainly wouldn't recommend that anyone with iron-deficient anaemia avoid meat, or other sources of iron," he adds.
Another surprising finding Dr Estep made when studying "Mindspan elite" countries was that their inhabitants ate high levels of carbohydrates - the white, refined carbohydrates we're so often told to avoid.
"We've been repeatedly told by nutritionists over the years to eat wholegrains such as brown rice and pasta, but I've always known that the Japanese don't eat brown rice; they eat white rice," he says.
Dr Estep says carbohydrates provide a smooth, steady release of glucose - the best fuel for the brain "and for the longest-living Mediterraneans, the primary source of energy isn't olive oil - it's actually refined carbohydrates, bread and pasta. They are the very foundations of these cuisines".
For years, we've been told that omega-3, from oily fish such as salmon or mackerel, is the best thing to eat for brain health. Dr Estep says: "Fish is important, but you don't need a lot of it.
"We have this impression that the Mediterraneans eat a huge amount of fish, but the Med is very poor in fish stocks. They do eat it routinely, but only a small amount.
"I eat a small amount every day - a couple of pieces of pickled herring, perhaps.
"Carbs - by which I mean vegetables and grains - are really the base of the Mediterranean and Japanese diet."
Portion size is also crucial to the Mindspan diet: "The Japanese and the Mediterraneans are eating less food, and they're thinner than other developed countries, but the people I interviewed never said they were going hungry.
"The foods they eat give a slow, long-lasting release of energy into the system: one recent study done in Italy found the more pasta you eat, the thinner you are likely to be."
It will be music to the ears of many: according to this leading expert in ageing, pasta, bread and wine are all back on the menu.
So could a diet really keep your brain young?
Dr Emer Begley, policy and research manager at The Alzheimer Society of Ireland, says: "Eating a Mediterranean diet high in fish, nuts and vegetables is good for you, however, further evidence is required to identify the protective effect of this diet on reducing the risk of dementia.
"Our current best evidence for reducing dementia risk is eating a healthy balanced diet, keeping physically and mentally active, brain training, not smoking, drinking in moderation, maintaining a healthy weight and keeping cholesterol and blood pressure in check are all things we can do to reduce our risk. In this way it is very close to cardiovascular health."