Our eyesight is so precious and something we tend to take for granted.
As we get older, subtle changes start to occur with our eyesight, we discover the need for longer arms to be able to read clearly and magnification for road maps in order to be able to decipher road names.
Cataracts are a well known phenomenon, but what about one of the leading causes of blindness in the elderly, called age-related macular degeneration or AMD?

In AMD central vision is lost in an area called the macula. This occurs as a result to damage to the retina. The effect is such that it makes reading and face recognition difficult. Imagine looking through the lens of a camera and having the centre of the image you are looking at being so blurry so that you can only see the periphery clearly.

It is also common, affecting around 10% of the population aged between 66 to 74 years. The degree of macular degeneration that develops varying from person to person.

So where does eating fish fit in?

Omega-3’s provide us with essential fatty acids, which we need for normal brain cell function and to protect our blood vessels against atheroscleosis. Consuming a diet high in omega-3’s is thought to protect the eye from retinal damage. Studies using mice have shown that consuming more dietary omega-3 resulted in slower progression of the disease and a lowering of associated inflammatory molecules.

In 2007 the University of Melbourne undertook a meta-analysis, evaluating the results from nine studies with over 88,000 participants including 3000+ who had AMD.
The results showed eating a diet with a high intake of omega-3 fatty acids was associated with a 38% reduction of the risk of developing advanced AMD, while eating fish twice a week was associated with a reduced risk for developing either early and late AMD.

Brain cells (and hence neural retinal cells) require long chain fatty acids from omega-3s for their formation. The outer cells of the retina are continually being shed and regenerated so a continuing supply of omega-3 is essential.

A new study from the John Hopkins School of Medicine looked at whether eating fish made a difference in the incidence of AMD in a group of 2391 people aged 65 to 84 years. The participants undertook a questionnaire looking at their fish and shellfish consumption and they were examined for signs of AMD. Of the group 227 people had early AMD, 153 had intermediate stage disease and 68 had advanced AMD. This study reported that eating omega-3 rich fish and shellfish protects against advanced AMD. They found noted that most of the participants including the control group were already eating fish at least once a week, but interestingly those with advanced AMD were significantly less likely to consume high omega 3 fish and seafood.

There are other risk factors for AMD such as smoking and obesity, however the research strongly suggests that consuming omega-3 from fish is eye protective.

Refs:
1. Tuo et al. A High Omega-3 Fatty Acid Diet Reduces Retinal Lesions in a Murine Model of Macular Degeneration. American Journal Of Pathology, 2009; DOI: 10.2353/ajpath.2009.090089
2 Elaine W-T. Chong; Andreas J. Kreis; Tien Y. Wong; Julie A. Simpson; Robyn H. Guymer. Dietary {omega}-3 Fatty Acid and Fish Intake in the Primary Prevention of Age-Related Macular Degeneration: A Systematic Review and Meta-analysis. Arch Ophthalmol., 2008;126(6):826-833 [link]
3 Bonnielin K. Swenor, Susan Bressler, Laura Caulfield, Sheila K. West. The Impact of Fish and Shellfish Consumption on Age-Related Macular Degeneration. Ophthalmology, 2010; DOI: 10.1016/j.ophtha.2010.03.058

A study has just been published in JAMA which found that giving supplements of Omega-3 (DHA) to people with mild to moderate Alzheimer’s disease did not produce any reduction in the rate of cognitive decline, indicating that supplementation in this group would not be warranted.
In this study a group of 402 people with either mild to moderate Alzheimer’s disease, 60% of the group received supplementation of 2 gm of DHA, the other 40% received placebo over an 18-month period. They underwent cognitive testing using the Alzheimer’s Disease Assessment Scale and Clinical Dementia Rating. A sub sample of 102 subjects also underwent functional MRI scanning to look for the rate of cortical atrophy.
The study found no benefit of the supplementation on the ADAS-Cog score or rate of brain atrophy during the time of the trial.
Many people currently take Omega-three’s as a supplement, commonly as fish oil capsules and include fish in their diet on the basis of other studies, which have suggested that this is a way to reduce one’s personal risk of developing dementia or Alzheimer’s disease .
So should we stop doing this?

Absolutely not. The difference here in this study is that they were looking at people who had been already diagnosed with Alzheimer’s.

An earlier study in 2006 at the respected Karolinska Institute had previously looked to see if DHA and EPA (Omega-3) supplements given to a group of people with either diagnosed Alzheimer’s disease or a small sub-group with very early cognitive impairment would be useful as a means of slowing the progression of the disease. This study also found no benefit of supplementation in those already diagnosed with Alzheimer’s.
However those who only had mild cognitive impairment did show some benefit. They had less cognitive decline on mental testing than a control group over a 6-month period, and when the control group received the supplements over a second 6-month period their rate of decline decreased as well. Here the authors proposed that is may be because the omega-3 fatty acids exert an anti–inflammatory effect. Inflammation is believed to be part of the neuropathological development of Alzheimer’s. The comment then was perhaps the anti-inflammatory effect of the Omega-3’s could only be of use prior to too much neuropathological change being evident.
The 2006 study only included a very small number of subjects (32 people) Larger studies with bigger cohorts of those with mild cognitive impairment as well as those at risk of Alzheimer’s are needed to see if Omega 3-s may be of benefit in halting the earlier progression of the disease.
The conclusion from the latest study supports the literature that supplementation with DHA is not beneficial in established mild to moderate Alzheimer’s.

Meanwhile there is plenty of evidence to support continuing to enjoy eating fish and taking Omega-3 supplements as a means of reducing our relative risk of developing cognitive decline and dementia.

Bon appetit!

Journal References:
1. K. Yaffe. Treatment of Alzheimer Disease and Prognosis of Dementia: Time to Translate Research to Results. JAMA: The Journal of the American Medical Association, 2010; 304 (17): 1952 DOI: 10.1001/jama.2010.1625
2. J. F. Quinn, R. Raman, R. G. Thomas, K. Yurko-Mauro, E. B. Nelson, C. Van Dyck, J. E. Galvin, J. Emond, C. R. Jack, M. Weiner, L. Shinto, P. S. Aisen. Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease: A Randomized Trial. JAMA: The Journal of the American Medical Association, 2010; 304 (17): 1903 DOI: 10.1001/jama.2010.1510
3. JAMA and Archives Journals (2006, October 11). Omega-3 Fatty Acids May Slow Cognitive Decline In Some Patients With Very Mild Alzheimer’s Disease. ScienceDaily. Retrieved November 4, 2010, from http://www.sciencedaily.com¬ /releases/2006/10/061010022736.htm

Eat fish.

Simple isn’t it. Yet how may of us are

a) aware of the benefits to our brains of including fish regularly in our diet and

b) how many of us actually put it into practice even though we know it’s good for us?

So what is it about fish that is so good for the brain?

Fish Oil, lovely fish oil, full of Omega-3.

And it’s not just a case of any old fish. The recommended fish to have are the fish that are carnivorous ie they eat other fish, that don’t live too long (because they can accumulate too much mercury which is toxic!) and they tend to be cold water fish.

So, having ascertained that, it’s simple. Just pop down to your nearest fish market or supermarket and ask for the best carnivorous, short lived, cold water fish bursting with Omega-3 they have fresh today.

The fish that are particularly recommended include:

Salmon, Sardines, Herring, Tuna. Mackerel and Anchovies.

So what are these Omega-3s? Well, they are polyunsaturated fatty acids and they are essential as an essential component for all cell membranes for the whole body. The key fatty acid for our brain is DHA (or Docosahexaenoic acid for short).

The body can produce its own DHA but not in adequate quantities, hence we need to include it in our diet.

The structure of the cell membrane around each cell determines what can pass in or out of the cell. If we lack sufficient Omega-3 building blocks to maintain the normal structure and integrity of the cell membrane then the cell concerned may not function as well. If this is a brain cell then obviously our brain will not be functioning to its best level.

As we get older our ability to produce our own DHA also declines, again making supplementation through our diet increasingly important.

Can’t stand fish? Well, we can also derive ALA (alphalinoleic acid) another source of Omega-3s from plant sources including kiwifruit, walnuts, avocado, tofu and flaxseed.

Having sufficient Omega-3 will keep our brain and eyes  healthy, help in stabilising mood, and lower our risk of developing depression and dementia.

Omega-3 assists our ability

to learn

to focus

to problem solve

to remember

to improve communication between brain cells and

to protect us from oxidative damage.

Pass the tin of tuna now please.

And yes, there is more in terms of benefits for our general health. Not only are the Omega-3s good for our brains, they help our blood fats by reducing our triglyceride levels, improve the elasticity of our blood vessels and help to lower blood pressure. They help to keep the blood thin and prevent clots and have been demonstrated to be important in maintaining a normal heart rhythm.

Convinced yet?

So how much do we need?

Two to three meals of fish per week is the current recommendation.

This can be fish that is tinned or fresh, baked or grilled or prepared in any way you like.

I was brought up on “fish fingers” as a child, which can be a great way to introduce kids to fish if they are not keen on fish on it’s own.

And we always had fish on Fridays.

Fish and chips as a take away meal will add another serve each week. Many of the better “chippies” now offer grilled fish as an alternative to the deep fried, battered and crumbed varieties plus side salads as an alternative to the greasy hot chips. Though being rather partial to the occasional “hot chip” I can rationalise having them knowing the rest of the meal is good for me.

Tinned tuna, salmon and sardines are an easy way to include a serving in a roll or sandwich for lunch.

How much Omega-3 is in a regular serving of fish?

Canned sardines 2000mg per 100g
Atlantic salmon 1000-2000mg per 100g
Swordfish >1000mg per 100g
Whitebait 700mg per 100g
Canned tuna >600mg per 100g
Mackerel 400mg per 100g
Mullet 400mg per 100g
Sardine 300mg per 100g
Tuna 300mg per 100g
Snapper 220mg per 100g
Whiting 100mg per 100g
Barramundi 100mg per 100g

Mussels 400mg per 100g
Oyster 350mg per 100g
Squid/octopus 300mg per 100g
Prawns 150mg per 100g
Lobster/Crayfish 100mg per 100g

(Source: Associate Professor Peter McLennan, Smart Food Centre and Graduate School of Medicine, University of Wollongong)

And the fish skin apparently contains three times the amount of Omega -3 of the flesh.

Eating the fish skin may be good for you, but I have to admit I’m not so keen! It has to be really crispy to entice me to eat it.

The other thing that can be done of course is to take fish oil capsules taking two 1000mg capsules per day.

And for those of you put off by “fish burp” from some capsules, keeping them cold in the fridge seems to help and there are some “burp free” varieties on the market.

Some clever marketers have also manufactured fish oil capsules for kids (enticing them with the thought that these will make them smarter and perform better at school) by making the capsules in the shape of little fish. Great idea if it will persuade the kids to take them, especially if they are fish haters and refuse to eat fish in their diet.

So what is the one thing we can do to keep our memory razor sharp?

Eat fish, preferably three times a week.

Enjoy.