Fish, Heart Health, COVID-19 and Your Pregnancy Diet

Fish, cardiovascular health, and COVID-19 —how do these things relate, or how are we going to tie them together in today’s article? The answer has to do with omega-3 fatty acids, which are turning out to be increasingly important to health, especially the heart and blood vessels, the more that we learn about them. You may know of people taking omega-3 supplement pills, which usually contain fish oil, because fish —certain fish more than others— is where we find them in the greatest abundance. This topic will get us into a discussion of heart health, pregnancy health, mercury contamination, and even COVID-19, but let’s start by saying that there are three main omega-3 fatty acids available in dietary sources. These are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Of these three, the easiest one to find in food is ALA; this one you can find in certain plant products, notably flax seeds, so vegans are able to get good amounts of it. However, really what your body needs are the other two: DHA and EPA. Your body can make these from ALA, but only makes them in small quantities using ALA as a starting point, and that’s where fish and fish oils enter the picture, because they really are the most accessible way to supply your body with DHA and EPA. If you are vegan, don’t despair, as there are products derived from algae that can supply you with EPA and DHA, but they tend to cost more money.

The story of omega-3 fatty acids goes back to the 1970’s, when researchers discovered that diets rich in these chemicals substantially lowered concentrations of serum triglycerides, meaning the quantity of subunits of fat molecules in a given volume of blood. Over the years, researchers found powerful connections between high omega-3 levels in the diet and in body tissues and reduced risk of cardiovascular disease and possibly other major diseases. In recent years, some evidence has also begun to mount that intake of high levels of DHA and EPA may also improve one’s serum cholesterol numbers. What the data are starting to suggest is that deficiency of omega-3 fatty acids could be almost as influential a risk factor for coronary artery disease (disease of the arteries that supply the heart itself) as tobacco smoking. Also, over the past half century, scientists have learned that omega 3 fatty acids, EPA and DHA in particular, are extremely important in pregnancy.

Consequently, omega-3 fatty acids, usually in the form of fish oil, are a big seller among nutritional supplements, and even are added to some formulations of multivitamin and mineral supplements, including those you might take while pregnant. What many people don’t like about omega-3 fatty acids concentrated into supplement capsules, is that the ones that come from fish, such as salmon, pack in a lot of odor that can make your mouth smell like that of your cat —very fishy— whereas products using omega-3 fatty acids from other sources, such as krill, sometimes processed extensively to end up with just the fatty acids and no odors, can be quite expensive.

But certain fish, such as salmon and sardines, generally contain such high quantities of EPA and DHA that eating a few portions per week can load you up with good amounts of these fatty acids. But, as you may know from other posts here on The Pulse, discussions about eating fish entail discussions about the risk of mercury contamination. Mercury is a heavy metal that is particularly dangerous when part of organic compounds (organic mercury), resulting from industrial processes that contaminate Earth’s oceans and other bodies of water. Mercury accumulates in biological tissue and can have profoundly detrimental effects in numerous organs, including the brain. In fact, the expression “mad hatter” come from an era when hat makers were known to develop psychiatric problems that later were found to result from exposure to mercury in the hat making process of that time period. Thinking about increasing your fish consumption to epitomize the development of your fetus’ brain, it certainly makes sense to make sure that you avoid dangerous levels of mercury that could harm your brain, and your child’s brain, more than a lack of omega-3 fatty acids.

This sounds like a Catch-22, but it’s not. It just means that you need to be choosy about your fish. Fish that are notorious for high levels of mercury contamination include swordfish, shark, tilefish, bigeye tuna, orange roughy, Chilean sea bass, and some others that you can look up. Don’t eat those while you are pregnant, and eat them only rarely when you are not pregnant.

Salmon, which is among the best sources of EPA and DHA, even among fish, is actually not so bad when it comes to mercury. Wild salmon, which tends have the highest omega-3 levels, has a little bit of a mercury problem, but not so much that you can never have it while pregnant. On the other hand, farmed salmon may have not quite the amount of omega-3 fatty acids as its wild counterparts, but the mercury levels tend to be quite low, so you can have a lot of it. The really good news is that, thanks to genetic modification technology, the salmon situation is getting better. The first “GMO” salmon —GMO is really a ridiculous term— is on the market from AquaBounty Technologies, and may be the beginning of a trend. The basic idea of AquaBounty is farmed salmon that grows to more than double the size of its non-GMO counterparts, and does so in less than half the time. This creates more protein and more omega-3 fatty acids —more meat— with much less going into the process, including time that the fish would spend accumulating mercury, which already is reduced compared with wild salmon. This reiterates a point that I have made to you previously, that “GMOs” are a good thing, that “non-GMO” should not be a desirable thing, if you are worried about health, as well as sustainability and other environmental issues.

Genetically engineered salmon is a good segue into the final topic of this post, which ties omega-3 fatty acids into COVID-19, because of growing connections between the mentalities and personnel of the anti-GMO and anti-vax movements. This is because of a discovery, published recently in the prestigious scientific journal Nature, relating EPA and linolenic acid to the ability of SARS-CoV2 (the virus that causes COVID-19) to infect cells. Previously, we have discussed how the virus uses its spike protein to attach to a protein called the ACE-2 receptor located on many types of body cells, including certain cells in the lung. This leads to COVID-19 disease, but to attach to ACE-2 the spike protein needs to be in a particular conformation, meaning a particular three-dimensional shape. One of the numerous criticisms that anti-vaxxers have been throwing at scientists is that vaccinating people with mRNA that causes our cells to produce spike protein (for the sake of generating an immune response against the spike protein) will cause the vaccinated cells somehow to penetrate and disrupt other body cells, just like a viral infection. But scientists working on various vaccines for COVID-19 and previous SARS diseases (SARS, MERS) thought of this unlikely scenario a long time ago, and consequently designed the vaccines to create spike proteins in the conformations that do not attach to ACE-2. They simply have to encode a couple of proline amino acids into a certain spot in the spike protein sequence.

Now, the study, which was a laboratory study, looking at the effects of omega-3 fatty acids and other fatty acids on SARS-CoV2, found that what linolenic acid and EPA do is to lock the spike protein into the nonbinding conformation, thus preventing it from being able to bind to ACE-2 and infect cells. Does this mean that, among the other benefits, consuming omega-3 fatty acids will offer protection against COVID-19? Possibly, judging by the mechanism demonstrated in the laboratory study, but it is still early in the game and we will see where the research goes.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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