Diet as a risk factor for dementia

We hear so much from the media about what we should or should not eat. One day blueberries are the new so-called ‘superfood’ that will reduce our risk of developing dementia, the next it is the humble plum.

But what information can we rely on to be accurate? Can the food we eat really reduce our risk of developing dementia? If a person has dementia, can their diet or use of supplements influence how they experience dementia or its progression?

The brain requires a regular supply of nutrients in our diet to function and remain healthy. There is growing recognition that what we eat affects the way our brains work and our mental health, as well as our physical health.

Traditionally research undertaken to investigate the connection between diet, cognitive function and risk of dementia has primarily focused on the impact of individual nutrients on brain health. Those nutrients commonly researched include: vitamins B6, B12, C, E and folic acid, as well as omega 3 essential fatty acids. The outcome of such research has been inconclusive and thus guidelines to advise on specific nutrient intakes have not been developed. In this feature we’ll explore some of the ongoing research on this topic.

Healthy hearts mean healthy brains

We know that certain medical conditions such as high blood pressure, high cholesterol, diabetes and obesity can increase our risk of dementia. For some time these risk factors were commonly associated with vascular dementia. We now know that they are also associated with the development of Alzheimer’s disease.

Much of what we know now to be healthy for our heart is also healthy for our brain, so many of the dietary messages we have been encouraged to follow for a healthy heart will also apply to the health of our brains.

Salt

It is advisable to reduce our salt intake regardless of the type of dementia we are considering. A salt-rich diet can contribute to the risk of increasing our blood pressure, which in turn can increase the risk of stroke and vascular dementia.

About three-quarters of the salt we eat comes from processed foods such as bread, breakfast cereals, soup and sauces. So it is not just what you add yourself that makes the difference, but how the food itself is manufactured.

The Food Standards Agency recommends that we should aim to have no more than 6 grams of salt daily, which is approximately one level teaspoon.

Fats and oils

The significance of too much fat in the diet has been the topic of much conversation with regards to a healthy heart and vascular system. In particular saturated fat, commonly derived from animal fat (for example fat on meat, lard, butter or ghee) or trans fats (fats created during the hydrogenation of vegetable oils and often found in processed foods such as pastry or vegetable shortening) can elevate cholesterol levels in the body if eaten in significant quantities. A high saturated fat intake has also been implicated, along with other dietary factors, as increasing the risk of dementia.

Omega 3 and oily fish

Omega 3’s essential fatty acids have an important part to play in the structure of our brain cells, helping to maintain the health and functioning of our brain. Research undertaken as part of the Older People And n-3 Long-chain polyunsaturated fatty acid (OPAL) study supported the view that eating oily fish (or omega 3) is associated with better cognitive function in later life, but recommended further work to clarify the impact of these essential omega 3 oils on the brain.

We need omega 3 oils from food as they cannot be made efficiently by the body. Oily fish is a rich source of omega 3’s essential vitamins and minerals and it is recommended that we have at least one portion of oily fish a week. Guidelines vary though according to the individual – see the Food Standards Agency website, www.eatwell.gov.uk/healthydiet/fss/fats/ for further information. Omega 3 oils may also be found in vegetarian sources such as linseeds, rapeseed oil, walnuts and soya beans.

Antioxidants

Vitamins C and E, commonly found in fruit and vegetables, are examples of antioxidants – that is, substances that work against the negative effects of oxidation that occurs naturally in the body.

Vitamin E has been the subject of much research in relation to reducing the risk of dementia, with conflicting results. There are many other sources of antioxidants other than vitamins, for example in green tea, red wine and cocoa. Each of these has been the subject of studies and considered as a potential ‘superfood’ in protecting mind and body.

Research appears to demonstrate a link between antioxidants activity and dementia, but is not conclusive about which foods are guaranteed to help reduce the risk of dementia and how much we need.

It is generally considered that a diet rich in fruit and vegetables will provide us with a valuable source of antioxidants and be more beneficial than taking supplements alone. The Food Standards Agency recommends at least five portions of fruit and vegetables daily to help maintain a good intake of vital vitamins and antioxidants.

Folic acid, vitamin B6 and B12

Deficiencies in folic acid, vitamin B6 and vitamin B12 can cause an amino acid in our body, called homocysteine, to rise. Higher than normal levels are considered to be a risk factor for a number of disease states including cardiovascular disease and dementia, and are thought to contribute to poor cognition.

However, there are no guidelines to consuming supplements of B6, B12, or folic acid individually merely to reduce the risk of dementia (although these nutrients may be prescribed for actual deficiencies such as anaemia). Again the advice is to ensure that foods rich in B6, B12, and folate are present in the diet.

Can a Mediterranean-style diet help?

In recent years, research in the field of nutrition, cognitive function and dementia has built on what we know about the key nutrients involved in brain health. Subsequently this research has begun to focus more on dietary patterns or how combinations of specific nutrients can impact on cognitive function or reduce the risk of developing dementia, such as Alzheimer’s disease, and the process involved in developing this dementia.

The ‘Mediterranean-style diet’ has been popular for many years for helping to maintain a healthy heart and body. This style of eating is traditional to people living in the countries bordering the Mediterranean Sea. Generally such a diet is considered to be rich in fruits and vegetables, olive oil, cereals, legumes and fish, with small amounts of lean meat and moderate amounts of dairy foods. Overall this style of eating provides a diet rich in vitamins and antioxidants and low in saturated fats. This diet has been associated with reducing the risk of developing Alzheimer’s disease.

Conclusion

The impact of good nutrition on the health of our brains cannot be dismissed. We know that malnutrition affects physical and mental wellbeing: our brains need nutrients to work and remain healthy.

Diet and what we eat has an important role to play in adopting a healthy lifestyle which can help keep both our bodies and brains healthy. Eating a nutrient-rich diet, particularly one that has lots of fruits and vegetables, omega 3 oils, and low amounts of salt and saturated fats, will help to maintain the health of both our heart and brain.

Research in this field is ongoing and the hope is that this will provide us with more knowledge and understanding of how diet and nutrition impact on cognitive health and the risk of developing dementia.