Originally published April 9, 2015
Due to the growing prevalence of Alzheimer’s disease and limited efficacy of drugs for the associated memory-loss symptoms, scientists and non-scientists alike are interested in the potential for practical lifestyle changes such as diet to reduce the risk of developing Alzheimer’s disease and memory loss.
The food you eat can alter the chances you and your loved ones will develop diseases such as Alzheimer’s or dementia. Yet even if you’ve merely dipped your toe into the vast ocean of information on nutrition and Alzheimer’s disease, it’s easy to become confused about which foods or food-types you should add to or remove from your diet if you want to reduce your risk of developing Alzheimer’s disease.
Unlike the protective effect of some foods, such as leafy green vegetables, the role of fat and fatty foods in Alzheimer’s disease risk seems to be less understood, and controversial. What does seem to be clear is that it’s role in Alzheimer’s disease is a little complicated. Luckily, despite the present uncertainty about whether some types of fats or specific fatty foods are actually beneficial or harmful, the research on diets and Alzheimer’s disease risk does seem to coalesce around some common themes that can be translated into real-life changes. What seems most certain is that not all fats are created equal.
What fatty foods should I avoid? Red meat & Dairy.
Consumption of saturated fats – including those found in red meats and high fat dairy – has been linked to lower cognitive performance in healthy elderly people, as well as an increased risk of developing dementia or being diagnosed with Alzheimer’s disease.
Saturated fat intake may increase Alzheimer’s disease risk or exacerbate cognitive decline by degrading the integrity of the blood brain barrier (which usually protects the brain from potentially harmful agents in the blood), increasing inflammation in the brain, or decreasing the ability of brain regions important for memory to use glucose for energy.
Saturated fats also increase cholesterol, which is involved in the regulation of the beta-amyloid proteins that are thought to play a major role in driving the disease process. In short, you may want to hold off on the cheese burgers.
What fatty foods should I eat? Fatty Fish.
Several epidemiological studies have found that the more people report consuming fatty fish, the less likely they are to develop cognitive impairments and be diagnosed with Alzheimer’s disease or dementia.
The “fattiness” of the fish is likely key to the protective benefit, as the consumption of lean fish has been linked to an increased risk of developing dementia. It also seems likely that the particular fat itself found in fish, mainly polyunsaturated fats that are rich in Omega-3 Fatty Acids, may play a role in keeping the neurons in your brain healthy and communicating effectively.
Indeed, positive results from clinical trials with just Omega-3 Fatty Acid supplements corroborate the role of these fatty acids in improving cognition – or at least slowing cognitive decline in healthy elderly and Alzheimer’s disease patients. Studies in animals have found that Omega-3 Fatty Acids may also prevent Alzheimer’s disease by enabling the synthesis of Acetylcholine, a neurochemical important for attention and memory that is drastically reduced in the brains of Alzheimer’s disease patients. Omega-3 Fatty Acids may also promote the clearance of some of the pathological proteins (e.g. beta-amyloid) that likely drive the disease process.
However, the benefits of from eating fatty fish may go beyond their fattiness: Fatty fish are also a rich source of minerals that may protect against oxidative stress that occurs during aging and Alzheimer’s disease. For example, sardines contain high levels of Selenium, a mineral with antioxidant properties that is decreased in Alzheimer’s disease patients. To reap some of these promising benefits, pile your plate high with fatty fish such as salmon, sardines, and mackerel.
What fatty foods should I be cautious about? Coconut Oil.
Excitement over the health benefits of coconut oil seems to have taken the internet world by storm. It’s purported role in Alzheimer’s disease is largely driven by the testimony of one physician who reported that giving her husband coconut oil actually reversed his Alzheimer’s disease symptoms.
However, coconut oil specifically has not been linked to Alzheimer’s disease risk in epidemiological studies, and there seem to be no clinical trials that have systematically evaluated the effects of coconut oil.
In animal studies, some have found beneficial effects on cholesterol levels (e.g. less of the “bad” LDL cholesterol) and cognition, whereas others report harmful effects on cholesterol levels and cognition. There could be many reasons for these inconsistencies, but one possibility is that the optimal amount of dietary coconut oil to consume in order to ward off dementia lies within a narrow range.
Indeed, a mere tablespoon of coconut oil has 12g of saturated fat – which is over half of your recommended daily intake. So what is driving all the hype? The saturated fat in coconut oil mostly consists of medium-chain-triglycerides, which may not be as harmful as the long-chain-triglycerides found in cow milk, for example. In fact, medium-chain-triglycerides are converted into ketones, which serve as an alternative energy source for the neurons in your brain. This could be especially helpful in Alzheimer’s disease, as the neural and cognitive dysfunction may be partly due to the decreased ability of Alzheimer’s disease brains to properly metabolize and use the primary energy source of the brain, glucose.
Even more promising, some studies have also found that ketones may be able to protect neurons from beta-amyloid and its associated attacks on neuronal function. Nevertheless, you may want to restrain from dousing your food in coconut oil until scientifically-rigorous research has time to catch up to the enthusiastic anecdotes that can be found on the internet. In the meantime, coconut oil in low amounts is probably a good alternative to butter and margarine, but only in those recipes in which a rich source of Omega-3 Fatty Acids – such as olive oil – simply will not do.
An important caveat to remember is that your genetic background can play an important role in the efficacy of nutritional interventions. For example, many nutritional correlations or interventions show no effect or even an opposite effect in carriers of the APOε4 allele, a gene that codes for a protein involved in blood cholesterol transport. It may be worthwhile, then, to find out whether you or your loved one is a carrier before implementing any dietary change to lower your Alzheimer’s disease risk.
Another important thing to remember is that Alzheimer’s disease normally occurs late in life, when the nutritional status and dietary patterns reflect decades of habits of eating. Not to mention other lifestyle habits – such as physical activity levels or coping with stress – that may synergistically or antagonistically interact with your diet to affect your overall risk. That is, it may not be possible to reverse 70 years of cheeseburgers with 2 years of sardines.
All things considered, it is very unlikely that we will find a secret, super-diet that will protect us all from Alzheimer’s disease and dementia. If anything, dietary changes are more likely to delay the onset, decrease the speed of cognitive decline, or otherwise lessen the severity of Alzheimer’s disease in subtle ways.
However, given the limited treatment options for Alzheimer’s disease, incorporating a few relatively inexpensive and tasty diet changes is worthwhile. Especially when a particular diet or food has other known benefits – such as reducing your risk of developing diabetes and heart disease or promoting healthy weight loss – what do you have to lose?