Fish in your diet – healthy or not!?

Stay healthy | 2019

 

Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy).

Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.

MediHelp International, together with LAMP Insurance, and in collaboration with NESA has created the NESAcard based on the wish to offer access to high standards medical services to patients all over Europe.

 

This way, MediHelp contributes to the medical science development and is actively involved in the international social responsibility advocacy.


Fish can be an important part of a healthy diet. It depends on the environmental pollutants (contaminants), but this fact is true for every food.

Fish is sources of healthful omega-3 fats and low in saturated fats, is rich in other nutrients and a good source of well-digestible proteins.

According to the study data available until 2017, the consumption of fish seems to promote health and reduce certain disease risks. However, it also depends on the fish species and its processing form.

For the consumption of fatty fish (salmon, herring, sardines or smaller mackerel species) or taking fish oil, there is scientific evidence for benefits in the context of the heart and blood vessels, as well for the brain, eyes and nervous system.

  

Larger predatory fish, such as Tuna, potentially containing more pollutants - especially for mercury, marine animals are a potential source. Don’t eat big Tuna, swordfish, big mackerel species (e.g. king mackerel), shark or other large predators, because they often contain high levels of mercury.

  

 

Albacore (“white”) tuna has more mercury than light tuna.

Even smaller fish, such as those mentioned above, may contain mercury and other pollutants, but the studies indicate that the benefits are is greater than the potential risks.

Omega-3-FA (DHA and EPA) is important for the brain development

 

For the early brain development of a fetus and baby, the omega-3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish or such oils) were found to be important for optimal development of a baby’s brain and the nervous system; but even low doses of mercury could have the opposite effect during certain developmental phases of the brain.

So, women of childbearing age and even more pregnant and nursing mothers should consume 2 seafood servings per week, but of selected species and reduce or avoid the larger predatory fish as well as crustaceans and on sea bottom living animals.

Also other potentially higher pollutant contaminated foods they should avoid, even more than other people (this topic will be treated separately in another newsletter).

The adverse long-term effects of low-level mercury in adults are not clearly researched; In addition to the disadvantages of mercury for the nervous system it may modestly decrease the cardiovascular benefits of fish intake. Without a doubt it is advantageous to reduce the fish species that have very high mercury contamination.

The Omega-3- fatty acids are generally important for the functions of the nervous system – and so the eyes - also for older people. The research date shows that consumption of 1 to 2 servings of fish per week may reduce the risk of stroke, depression, and Alzheimer’s disease.

Cyrus A Raji CA, et al. Regular fish consumption and age-related brain gray matter loss. Am J. of Prev Med. 2014; 47(4):444-51

The statements about such study results always use the term "can reduce risks" because there can always be many factors that need to work together to produce significantly high results. Insofar as too many interfering factors act simultaneously, the positive effects may be obscured, but this does not mean that then it makes no sense, e.g. to have these nutrients in your diet.

For the omega-3 fatty acids (DHA and EPA) there are many very convincing indications for their health-promoting effects. One should not only pay attention to the statistical calculation possibilities of risk reduction or benefit, we must know their biological functions and effects. These are well researched, so it is very peaceable to ensure consumption in the diet.

The omega-3 fatty acids from fish (EPA and DHA) are good for the

  • Support of the brain, the eyes and nerve development,
  • Maintenance of normal brain function
  • Maintenance of normal heart function
  • Maintenance of normal blood LDL cholesterol levels
  • Maintenance of Maternal health during pregnancy and lactation
  • Support of the skin and mucous membranes of the digestive tract
  • Support of anti-inflammatory effects on the membranes cell structure

For example, by consuming about 2 servings of fish per week at long term, the risk of heart disease could be reduced by an average of 36% (e.g. by reduction of cardiac rhythm disturbances, decreasing blood pressure and heart rate, reduction of inflammation and of unfavorable blood lipid levels, and improvement of blood vessel function)

Look at the origin and potential pollution contamination

Beside mercury other pollutants in fish are polychlorinated biphenyls (PCBs), dioxins, plasticizer through microplastic and even pesticide. But the majority of such pollutants in the food supply come from non-seafood sources, including meats, dairy, eggs, and vegetables.

Plasticizer and other unfavorable substances through microplastics will be more important in the fish in the future, but there will probably be no reason to avoid the fish. After all, you will not be able to avoid many foods that are automatically contaminated by the environmental impact (we need better protection of the environment and the ecosystem!). In the context of our food we will only be able to pay attention to the quality and the place of origin as well as to optimize the body's detoxification systems. This is ensured by the balanced composition of the diet with an emphasis on vegetable diet with the thousands of phytochemicals. This is followed by newsletters.

Fish of coastal areas of populated countries could be more polluted. If you eat local freshwater fish of known clean lakes or breeding ponds or ocean fish e.g. from very north or south Atlantic or Pacific, there is less pollutant contamination. Look at the origin and catch areas of the fish.

Does it have to be fish, or are omega-3 fatty acids from plant sources equally good?

  

   

First, it should be emphasized that the omega-3 fatty acids of plants (the ALA form; Alpha-Linolenic Acid), e.g. from vegetable oils (flaxseed or rapeseed oil) also have positive cardio-protective effects and should be consumed more, especially if you do not consume fish.

But, even though they have this, their biological effects are not equivalent to DHA and EPA, and the protective effects are significantly lower. If there are special risks, the EPA and DHA forms can better compensate for them.

You should also look at the exact composition of fatty acids in vegetable oils. Some have too high a proportion of omega-6 FA, which can have disadvantages (promotion of inflammation etc.); it depends on the ratio between omega-3 and omega-6 fatty acids.

More recent methods of fatty acid extraction nowadays also produce supplements with the DHA and EPA forms from certain microalgae (e.g. EPA through Nannochloropsis oculate or Cryptophytes mesostigmatica oil, DHA through Schizochytrium oil). This is a very good alternative to the fish oils for the supplementation of these valuable fatty acids. The microalgae also have the advantage that they have no mercury contamination and could be cultivated under controlled conditions.

The microalgae supplements should contain several microalgae so that both EPA and DHA are sufficiently abundant. Preparations with only the DHA form are not that potent. Studies on animals that received only one of the forms showed less protective effects - e.g. for protection of brain and nerve cells, compared to fish oil, which always contains both forms.

 

Microalgae – Nannochloropsis sp.
image by CSIRO science research organization Australia

Microalgae are important for life on earth; they produce approximately half of the oxygen and together with bacteria, they form the base of the food-chain oft living organism.  Most of these microalgae species produce valuable substances like phytochemicals, antioxidants, fatty acids, enzymes etc.

Microalgae can be cultivated under controlled conditions without pollutants and have ecological advantages.


A controlled study with the microalgae Nannochloropsis oculata, which showed a better bioavailability for EPA compared to krill oil, but does not contain DHA, also showed an increase in the DHA form in the serum of the study participants (DHA can be formed from the EPA). In the study, the microalgae oil of Nannochloropsis (with 1.5 g EPA and no DHA) was compared to krill oil (with 1.02 g EPA and 0.54 g DHA) supplemented per day. [Kagan, M. et al. Lipids in Health and Disease 2013, 12, 102–112]

Nevertheless, as a precaution, supplements should be chosen from different microalgae with EPA and DHA.

Fish from ecologically intact areas without significant pollutant levels is certainly a healthy food even beyond the topic of omega-3 fatty acids. The World Cancer Research Fund found int meta-analysis of many studies, that fish could reduce colon cancer risks (one of the most common forms of cancer in industrialized countries), while meat (especially red meats) increases colorectal cancer.

As in the newsletter on meat and its forms of preparation, it depends on additional factors. Thus, colon cancer is increased by the combination of several risk factors; and vice versa certainly only lowered by the combination of several protective factors. This topic will follow by an extra newsletter.

Prof. Werner Seebauer

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