Tag: DHA

Fish oil reduces age-related blindness

Claus Hancke

October 14, 2009

New U.S. study shows that intake of fish oil may reduce the incidence of age-related blindness by 30%

There seems to be no end to blessings from fish oil.

Fish oil is the end stages in the development of omega-3 fatty acids which is transformed from alpha-linolenic acid in a number of processes to E.g. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which then are converted to prostaglandin E 3 with a wide range of health-promoting properties.

The fish oils EPA and DHA are some of the strongest anti-inflammatory nutrients, we can consume. This is probably one of the reasons why they reduce the risk of blood clots, but they also reduces blood triglycerides, reduces inflammation in rheumatic diseases, enhances children’s learning capacity, reduces the risk of pre-eclampsia (pregnancy–induced high blood pressure) and premature birth, and gives brighter children from pregnant women who took fish oil and much more.

It is indeed difficult to see the end of the health-promoting properties, we can get from fish oil, and new scientific findings seems to emerge all the time which support its use.

Thus, even last week when researchers from the National Eye Institute in Bethesda, MD, USA, 7 October published a study in the American Journal of Clinical Nutrition.
Scientists have over 12 years studied 1,837 people with moderate to severe risk of age-related central blindness in the form of central atrophy or macular degeneration.

For both types of blindness, it appeared that the incidence was 30% lower in the group that took the most fish oil (0.11% of total caloric intake) compared with the group that took the least.

Although previous studies have been uncertain in its conclusions, the authors believe that the figures can be generalized, this is both a cheap and readily available intervention opportunity against risk families with high incidence of these diseases.

In times when the collective consensus have shouted in our ears that we should eat less fat, it is important to use common sense, read the research properly and stand firm.

Fat is healthy, and fat is vital!

One should obviously not wallow in margarine, french fries and chips, but make sure to eat well from the healthy fats as olive oil and especially fish oil.

It can be ingested as a liquid, as capsules, or as very attractive food.

Fish is not only healthy but also tastes very good indeed. Many people are nevertheless troubled by the increasing presence of heavy metals in fish, but if you avoid the large predatory fish as swordfish and tuna, there is significantly less in for example salmon and trout, especially if they are caught in clean rivers and lakes.

There are however problems with farmed fish, which often contains pretty much omega-6 fat, due to the fish feed composition. And this we should avoid. We already get far too much omega-6, especially linoleic acid, found in the cheap cooking oils with corn and sunflower oil, so as to avoid further bias, we must select the oily fish that are caught in the wild and not farmed.

We must remind you that in a previous newsletter we described two studies that showed that even eggs contain substances that prevent the age-related central blindness, so it may be, we soon will see a Danish ban against bread with eggs and herring. In Denmark food is not allowed to prevent a disease!

Enjoy your meal.

By: Claus Hancke, MD 

References:

  • Sangiovanni JP, Agron E, et al. Omega-3 Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: a prospective cohort study from the Age-Related Eye Disease Study, Am J Clin Nutr, 2009 Oct 7 (E-pub. Ahead of print)
  • Mares JA, Larowe TL, et al. Predictors of optical density of lutein and zeaxanthin in retinas of older women in the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women’s Health Initiative. Am J Clin Nutr., 2006, 84(5): 1107-1122.
  • Wenzel AJ, Gerweck C, et al. A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women. J Nutr., 2006; 136(10):2568-73.

Fish oil is good for the heart and the brain

Claus Hancke

August 21, 2006

There is no doubt that fish oil is good for the heart. This has been shown by a new extensive survey on the subject. But no one knows how much is ideal.

The scientific interest for fish oil is enormous. Since September of last year, almost 800 articles about fish oil have been publicised in established journals.

This is with very good reason. Notably, fish oil contains two types of fatty acid, both of which are attributed with having a positive effect against many serious chronic diseases. If this is even in part true, it should be considered very imprudent not to receive fish oil every day. The primary disease that it is believed to prevent is cardiovascular disease, but there is also good reason to believe that fish oil works against, for example, depression, dementia, arthritis, and diabetes, even though there is no concrete evidence as of yet in these areas.

The two fatty acids are called EPA (eicosapentic acid) and DHA (docosahexaenoic acid). Together they compose one third of the contents of fish oil and two thirds of the concentrated fish oil products, which can be found in capsule form.

Much attention has been given to DHA which, contrary to EPA, is found in large amounts in the brain (14% of the cerebral cortex’s fat content) and in even greater amounts in the retina (22%). Breast fed children have much higher concentrations of DHA in their brains than bottle fed children (babies cannot produce DHA themselves). It is hard to believe that there are no consequences of receive too little.

There are an incredible number of adults who take supplements of fish oil daily to maintain their cardiac health.

But does it work?

Six months ago a group of English researchers maintained that it does not. They had looked at all of the relevant studies and then calculated the averages of their results. In their opinion, the results showed that fish oil neither protects the heart nor lengthens life span. This is just the opposite of what was previously believed.

This meta-analysis was strongly criticized and, as discussed in another of The Danish Vitality Council’s newsletters (“Fish Oil – Still indispensible”) there were so many question raised by the analysis that it lacked credibility.

Doubts regarding the dosage
This is now supported by a summary article from the distinguished American Journal of Clinical Nutrition. According to the head authors, a group of researchers undertook an extensive survey, taking “a large step forward” in spreading light into the darkness. There is no longer much doubt that fish oil reduces the overall risk of premature death and the risk of death due to a blood clot in the heart, and that it possibly reduces the risk of stroke.

Completing this survey was an extensive project. The researchers first read summaries of 8,039 scientific articles. They then picked 842 relevant articles from these to be read in their entirety. 46 articles of these 842 met the strict quality requirements and were studied further. The researches requirements regarded the length of the studies (at least one year), the dose of the fish oil given, and proper documentation.

How big are the advantages and how much fish oil should one take? This actually cannot be answered with certainty! The studies surveyed were too different regarding the dose given, the type of participants, the time taken, and so on to answer such questions. It is simply bad form to establish any averages, as the English researchers did. But if one wants to draw conclusions anyway, it is safe to guess that the overall risk of premature death and the risk of death due to cardiac disease can be reduced by 15-20% or more.

It is however nearly certain that fish oil helps those who have had a blood clot in the heart and wish to avoid another. But what about the dose, how much should one take?

Until more information surfaces, we should rely on the American Heart Association’s recommendations, which are based on estimates. Heart patients should receive 1 gr. EPA + DHA daily. This is the equivalent of about two large capsules of 1 gr. concentrated fish oil. Everyone else should receive at least half this amount. This can be achieved by eating fatty fish for dinner 1-2 times weekly.

There is a lot of knowledge lying in wait, not just about fish oil and the heart. More results will surface in the next year. While we wait we wait in the knowledge that it is important to get enough.

By: Vitality Council

References:
1. Wang C et al. n-3 fatty acids from fish or fish-oil supplements, but not á-linolenic acid, benefit cardiovascular disease outcome in primary- and secondary-prevention studies: A systematic review. Am J Clin Nutr 2006;84:5-17.
2. Deckelbaum R et al. n-3 fatty acids and cardiovascular disease: navigating toward recommendations. Am J Clin Nutr 2006;84:1-2.
3. Distribution, interconversion, and dose response of n-3 fatty acids in humans. Am J Clin Nutr 2006;83(suppl):1467S-76S.

www.ajcn.org

Children Get Smarter From Taking Fish Oil

Claus Hancke

October 24, 2005

The omega-3 fatty acid DHA in fish oil is an important building block for the brain. DHA deficiency in the first years of life may impact the normal development of the child’s brain.

Are children getting smarter from eating fish? Recent studies suggest that fatty acids in fish oil can help certain children with ADHD or dyslexia. But what about infants?

From the last third of fetal life to the end of the second year of life, children’s brains grow so strongly that one speaks of a brain growth spurt. During this period, a lack of a number of vital nutrients, such as fish oil, will affect brain function. The American Journal of Clinical Nutrition recently published a comprehensive review of what is known about fish and young children’s brains.

As a starting point, it is known that the polyunsaturated n-3 fatty acid DHA (docosahexaenoic acid) is highly concentrated in the cell walls of nerve cells. DHA is one of the two important n-3 fatty acids in fish oil. The other is EPA (eicosa-pentaenoic acid). EPA can be converted to DHA, and to a certain extent they can both be formed from the n-3 fatty acid alpha-linolenic acid in e.g. linseed oil.

But does it form enough in a child who is not breastfed or gets oily fish? The question is relevant. It is known that breast-fed babies have up to 40% more DHA in the brain’s gray matter than bottle-fed babies. In addition, it is known that young animals and probably also infants, even if they are neither near-sighted nor far-sighted, will see a little less sharply if they lack n-3 fatty acids. The significance of this is debated.

The importance of DHA has been investigated e.g. by comparing bottle-fed babies with breast-fed babies who got DHA from breast milk. Bottle babies have also been compared with other bottle babies who have received n-3-enriched formula. The children have been tested for intellectual and motor development, attention, etc.

Greater attention
In these kinds of experiments, it has been shown that breast-fed babies fare slightly better on average than bottle-fed babies. But is the difference due to DHA? Nursing mothers may function slightly better than non-nursing mothers, and may have better social relationships, etc. When you correct for this, the differences diminish. Furthermore, there are many other differences between milk substitute and mother’s milk other than the DHA content.

It becomes somewhat clearer when you compare bottle babies, where only half receive extra n-3 supplements. Here the results have been mixed, but on one point a difference has been seen quite consistently: Infants who receive n-3 supplements have a greater capacity for visual attention, i.e. to follow the things they see. This important result has also been obtained in experiments with monkeys.

In animal experiments with rodents, the clearest differences have been found. This is due, among other things, to the fact that these experiments can be set up, so that the difference in brain DHA becomes particularly large. Animals that are starved of n-3 fat become less agile, find it harder to find their way around a maze, etc. Even if there are only minor differences in brain DHA, the animals that do not get fish oils are weakened. Roughly speaking, this is what is known.

So what can be concluded? The authors do not claim that children should demonstrably have n-3 supplementation during the brain spurt. But they claim, after sifting through 258 scientific papers, that the need cannot be ruled out.

– Small differences in brain DHA, which most likely occur between bottle-fed babies with and without n-3 supplementation, may have effects that are currently difficult to detect but could be important, it says. Or to put it more simply: Remember to give babies and toddlers fatty fish or fish oil! They seem to be getting wiser from it.

By: Vitality Council

Reference:
Mc Cann J C, Ames, Bruce N. Is docosahexaenoic acid, an n-3 long chain polyunsaturated fatty acid, required for development of normal brain function? An overview of evidence from cognitive and behavioural tests in humans and animals. Am J Clin Nutr 2005;82:281-95

www.ajcn.org
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