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AGE RELATED BRAIN DECLINE: GOT FISH?
October 5, 2009
The primary cause of developing progressive neurological decline is the aging process. Determining ways to preserve brain function as the human body ages is of great importance to medicine and the general public. It is imperative that our senior citizens be able to lead productive, independent, and meaningful lives as they age. Nutritious diets have been established that reduce risk of many chronic conditions, such as heart disease, diabetes, obesity, and cancer; could a diet high in fatty fish achieve this goal of improving brain function at older ages?
The Brain and Aging
An inevitable event in the course of a human life is aging. There is no fountain of youth that we know of that can prevent the onset of aging. However, by understanding the aging process, one can formulate possible ways of slowing down the process and preventing the occurrence of certain health problems.
Though the aging process varies amongst individuals, as some people may live to be ninety with minimal health problems and others may die prematurely due to heart attacks, strokes, and other devastating diseases, there are certain characteristics concerning the brain that seem to be common in the elderly. The overall size of the brain tends to shrink with age, especially in the hippocampus and frontal lobe. (http://www.aarp.org/health/brain/aging/) Brain cell synapses, which allow for the interaction between neurons and other cells, decrease. Similarly, the neurotransmitters that are sent across these synapses from neurons to their target cells decline in numbers. Decreases in the amount of myelin, important in ensuring that a signal is sent completely across an axon, in the brain take place. These events lead to a decrease in memory ability and overall cognitive function. Further, the presence of free radicals in the body take a toll on cells, as these chemicals, when reacting with oxygen, will cause oxidative damage to the cells’ mitochondria. Mitochondria are important in providing the needed ATP, or energy, needed for cells to function. Though free radicals are necessary in certain processes of the mitochondria, exposed to wrong organelles they can wreak damage.
Also with age, risk of neurodegenerative disorders, possibly as a result of the previous mentioned consequences of aging, becomes increased. Parkinson’s disease and Alzheimer’s disease are two of the most prevalent diseases of the brain in the elderly population. In fact, 5.3 million people in the United States are living with Alzheimer’s, and 1 million in the U.S. have Parkinson’s.
The average life expectancy continues to increase, but because these damages and diseases to the brain are not lessening, the effects of aging on the brain will become even more significant as the number of elderly rises. Longevity can be seen as a great outcome of modern medicine, but if a large portion of those living over the age of 60 develop neurological problems that hinder them from enjoying their lives and prevent them from being able to perform basic tasks, the extra years added to their lives becomes almost meaningless. The future of medicine needs to focus on increasing the quality of these now lengthy lives. Currently new treatments and drugs are being researched, and lifestyle choices with their long-term consequences continue to be analyzed. One possible dietary supplement is claimed to have an impact on brain health and slowing of aging: omega-3 fatty acids.
Omega-3 Fatty Acids
When concerning diets, many advertise that people should keep from consuming fatty foods. Though true for some cases, we must be careful what fats we are talking about. The saturated fats found in greasy foods are the substances that give fats a bad name. However, omega-3 fatty acids are actually one type of fat that our bodies need. (http://www.webmd.com/diet/guide/good-fat-bad-fat-facts-about-omega-3)
Omega-3 fatty acids are a group of polyunsaturated fats, meaning they have more than two double bonds in their carbon chains. The two important ones to our health are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Alpha-linolenic acid (ALA) is another omega-3 fatty acid, but actually has limited benefit to our bodies; it must be converted to DHA or EPA to gain the health benefits. (http://www.omega3learning.purdue.edu/diet-health/view/consumers/articles/omega-3-fatty-acids-the-basics/) Because the human body cannot generate omega-3 fatty acids on its own, we must ingest these essential nutrients through food consumption. Cold-water fish, especially salmon, mackerel, herring, and anchovies, are high in omega-3 fatty acids, specifically DHA and EPA. (http://dhaomega3.org/index.php?category=overview&title=Dietary-Sources-of-Omega-3-Fatty-Acids) ALA can be found in certain vegetables and beans, but because ALA does not convert well to DHA or EPA, their dietary benefits are limited; however, diets that consist of a high intake of fatty fishes are a great source of these healthy fats.
Fatty Fish: “Miracle Food?”
There are many claims that omega-3 fatty acids are essential for optimal brain performance. Companies that make fish-oil supplements have made claims that these fatty acids are “the miracle food of the 21st century.” (http://www.omega-3.us/) Though business incentives must be taken into account when reading similar advertisements and slogans by companies, their statements may be based on factual evidence.
Websites created to promote public health have made similar claims about the health benefit of fatty fish oils in our diets. Today, many people turn to the Internet for facts about health improvement. WebMD takes knowledge from health professionals and quality literature to share information about illnesses, treatments, and preventative measures against disease and pain with public users. On the topic of omega-3 fatty acids and health, the website claims that these fatty acids may be protective barriers against many neurological problems. (http://www.webmd.com/diet/guide/good-fat-bad-fat-facts-about-omega-3) Research groups and consortiums formed to discuss health topics and share valuable information that they gather with the public have provided for many websites that discuss essential fatty acid consumption. The DHA/EPA Omega-3 Institute was created to inform the public that DHA and EPA can improve the health of those that consume enough of them. (http://dhaomega3.org/index.php) Another similar group, Omega-3 Learning for Health &Medicine, says their purpose is to “communicate, develop, disseminate and advance the understanding of the nutrition and health benefits of omega-3 fatty acids to the world.” (http://www.omega3learning.purdue.edu/about-us/) As the elderly population will be continually searching for ways to prevent future memory and brain function loss, websites like these provide public information that the elderly can resource. Thus it is important to determine whether or not these claims are true. Much research has gone into studying whether omega-3 fatty acids are truly beneficial to our brain function and overall health.
Though web pages have made claims about the health benefits that accrue with diets high in fatty fish consumption, it is important to analyze primary sources of actual research performed. The Italian Longitudinal Study on Aging was a study of 5632 people in Italy between the ages of 65 and 84 years. The main objective of the study was to observe health conditions that were prevalent in the elderly and to look for trends between those who acquired the condition and those that did not. A review of the study stated that in a population of elderly individuals, age-related cognitive decline was significantly reduced in people that had high consumption of unsaturated fatty acids, such as omega-3 (Solfrizzi V, et al 2008). The review goes on to state that omega-3 fatty acids may postpone or even prevent onset of dementia. Dementia is marked by the decrease in mental abilities that disallows one to perform their daily tasks. (http://www.mayoclinic.com/health/dementia/DS01131) Alzheimer’s disease is one cause of dementia.
The effects of DHA in improving memory after neurodegeneration due to cerebral ischemia, or decreased blood supply to the brain, was observed in a study using rats (Fernandes JS et al, 2008). Rats learned task behavior on a maze for 8 days and then were subject to cerebral ischemia. Rats that were fed diets rich in fish oil showed significant improvements in memory, though such diets did not prevent the degradation of brain cells. Thus the fatty acids were able to improve memory despite the depleted portion of the brain. This shows that just because the human brain tends to decrease in size at older ages, and certain brain regions seem to degrade more than others, omega-3 fatty acids may be able to prevent or slow any effects due to such loss of neurons.
Similar results were obtained when learning and memory-impaired mice were given either a high- or low-DHA diet for 8 weeks. (Petursdottir AL et al, 2008) At the end of the study, the mice that were fed high-DHA diets showed better memory function in a T-maze foot shock avoidance test. Further, these mice had higher level of DHA in their brain than those consuming a low-DHA diet, indicating that the diet corresponds with the levels of the fatty acid in the brain. This study agrees that memory can be improved with omega-3 fatty acids, and also shows that diet has a large effect on the brain. What food is consumed can cause an increase or decrease in different kinds of molecules in the brain. Thus to increase levels of omega-3 in our brain, we must consume meals rich in these fatty acids.
In another study, 31 patients with Parkinson's disease and Major Depression were analyzed; one group was treated with fish oil and the other with mineral oil for 3 months (da Dilva TM et al, 2008). The two groups were then separated again, half taking antidepressant medication and the other not. The results of the study showed that patients who consumed fish oil supplements showed improvements in depression, whether or not they took the antidepressants. Not only can fatty acids improve brain performance, but they can also improve mental wellness. This is significant because not only is it important for the elderly to be able to remember things well and execute tasks adequately, but they must also live without depression so they can enjoy themselves.
From these results, it seems that claims about omega-3 fatty acids from fish oils improving brain function and preventing, or at least slowing, the onset of debilitating neurological disorders as we age are factual. There is no research that supports the opposite results. Though there may be some research that did not see significant improvement in the brain with high level of fatty acid consumption, there are no studies with results stating they negatively affect the brain.
The consumption of fatty fish to increase our omega-3 levels must be conditional, however. These coldwater fish tend to be high on the oceanic food chain. Because of this, fish in polluted areas of the sea could possibly have high levels of metals such as mercury that are actually bad for our health. The levels of pollution must be monitored, and restrictions should be implemented on the sale of fish with possible high metal concentrations. Also, farm raised fish do not contain the amounts of omega-3 that wild fish have. Just as a diet of fatty fish can provide us with omega-3 fatty acids, the diet of the fish determines the levels of the fatty acids in their bodies. When purchasing fish for meals, people should choose wild versus farm raised to obtain the beneficial nutrients that fish oil contains. Preparation of the fish for the meal should also be taken into consideration; deep-frying fatty fish not only gives a meal unhealthy saturated fats, it also depletes the meat of the beneficial unsaturated fats. (http://www.webmd.com/cholesterol-management/features/low-cholesterol-diet-fatty-fish) As such, people must take into consideration the source and type of the fish consumed and its preparation as to its ultimate health benefits.
Another potential hazard to high omega-3 fatty acid consumption is that these fats are known blood thinners. For most people, this should not have any negative effects on health. However, many elderly patients may be taking blood-thinning medications. The combination of such medications with high-DHA diets has the potential to thin the blood to devastatingly low levels. As with most medications and nutrition recommendations, and because of these possible negative affects of diets high in fatty fish, omega-3 consumption should be in moderation. Most diets today are deficient in these essential fats and thus increasing fish consumption to moderate levels (two to three servings per week) could pose great benefits to health; however, beware of diets of extreme fish consumption as they could bring about negative consequences.
In accordance with these restrictions, the inclusion of fatty fish in one’s diet is highly encouraged, especially for the elderly. This will supply the brain with the essential omega-3 fatty acids it needs to continue to perform at its best in old age. Neurodegenerative disorders, like Parkinson’s and Alzheimer’s disease, are detrimental to those unfortunate to develop them. As we continue to develop drugs and procedures that extend human life, prevention of elderly brain function deterioration must be kept as a focus of our attention. Diets high in fatty fish is one such way to decrease the chances of losing mental capabilities; however, the effects of such diets will vary from person to person and there are many other factors that contribute to the health of the aging brain. Omega-3 is a start towards improved wellbeing, and definitely a healthy choice.
Aging and the Brain. Retrieved September 27, 2009 from http://www.aarp.org/health/brain/aging/
Bouchez, Colette. (2008). Good Fat, Bad Fat: The Facts About Omega-3. Retrieved October 1, 2009 from http://www.webmd.com/diet/guide/good-fat-bad-fat-facts-about-omega-3
da Silva TM, Munhoz RP, Alvarez C, Naliwaiko K, Kiss A, Andreatini R, et al. (2008). Depression in Parkinson's disease: a double-blind, randomized, placebo-controlled pilot study of omega-3 fatty-acid supplementation. Journal of Affective Disorders, 111(2-3):351-9. Retrieved September 27, 2009 from PubMed. [PMID: 18485485]
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What You Should KnowAbout Omega-3 Fish Oil. Retrieved October 1, 2009 from http://www.omega-3.us/
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