Posted By Dr. Mercola | November 23 2011 | 52,203views |
Disponible en Español
Story at-a-glance
- Fish is a rich source of heart-healthy omega-3 fats, and eating baked or broiled fish was found to reduce risk of heart failure in postmenopausal women. However, deep-fried fish—likely due to being cooked in vegetable oils—was linked to an increased risk of heart failure
- While the medical establishment has advised you to consume vegetable oils (i.e. trans fats) instead of saturated fat in order to prevent heart disease, human trials have conclusively demonstrated that vegetable oils increase your risk of heart disease and should be avoided
- Fish is no longer an ideal source of omega-3 fats, due to widespread contamination with toxins like mercury and PCB’s. A healthier alternative is to take a high-quality animal-based omega-3 supplement, such as krill oil.
By Dr. Mercola
A recent study published in the journal Circulation, Heart Failure, sought to ascertain whether fish or the fatty acids they contain are independently associated with risk for incident of heart failure among postmenopausal women.
The study looked at the diet of close to 85,000 women.
Their consumption of baked and broiled fish, fried fish, omega-3 fats and trans fats were determined from a questionnaire.
The study found that the manner in which the fish was cooked was crucially important.
The authors concluded that:
"Increased baked/broiled fish intake may lower [heart failure] risk, whereas increased fried fish intake may increase [heart failure] risk in postmenopausal women."What's interesting about this is that while fish is generally considered a healthful food due to its heart-healthy omega-3 fat content, the addition of harmful trans-fat (which you get when you deep-fry the fish in vegetable oil) effectively cancels out any health benefits of the fish you might otherwise have received.
So carefully choosing your cooking methods, and your cooking oils, can make or break your meal from a nutritional standpoint. Aside from that, I'll also address other safety concerns that apply to virtually all fish today, and how to help circumvent these dangers.
The Importance of Animal-Based Omega-3 Fat for Heart Health
The relationship between animal-based omega-3 fat and heart-health has been well established, with deficiency equating to an increased risk of heart disease. These effects have been shown in hundreds of experiments in animals, humans, tissue culture studies, and clinical trials. But that's not all. The overall health benefits of omega-3 fats go far beyond heart health.
In fact, if you go to the omega-3 fat page on GreenMedInfo.com, you will see a list of scientific studies demonstrating the benefits of omega-3s for more than 250 different diseases, which is powerful confirmation of their broad-reaching scope. One reason omega-3s are so good for you is their anti-inflammatory properties, especially the omega-3s from animal sources—EPA and DHA—found primarily in fish, shellfish and krill. These animal-based omega-3 fats act to prevent heart disease in a number of different ways.
For example, they:
Help prevent arrhythmias (ventricular tachycardia and fibrillation) Inhibit synthesis of cytokines (which regulate inflammatory responses) and mitogens (which stimulate of T-cell activation) Are antithrombotic (prevent clotting) Help inhibit atherosclerosis Have anti-inflammatory properties Stimulate endothelial-derived nitric oxide. This helps protect your heart by relaxing blood vessels and lowering blood pressure Help reduce triglyceride (fat) levels in your blood Help lower high blood pressure (alleviate hypertension)
The Link Between Trans Fat and Heart Disease
For decades, you've been advised to consume vegetable oils instead of saturated fat in order to prevent heart disease. Unfortunately, the medical establishment chose to banish the wrong fat to improve health...
Human trials have conclusively demonstrated that vegetable oils DO NOT decrease atherosclerosis or decrease your risk of dying from cardiovascular disease. On the contrary, studies have revealed that vegetable oils may increase your risk of heart disease, and might also increase your risk of cancer after a period of about five years!
In light of previous research into the harmful effects of trans fats on heart health, the results from the featured study do not come as a great surprise. It only strengthens the link between trans fats and heart disease, and indicates that this harmful effect is potent enough to cancel out the otherwise beneficial omega-3 content of the fish consumed. Previous research has also found that trans fats can interfere with your body's use of omega-3 fats, which may also help explain why deep-fried fish resulted in greater harm.
So what's the bottom line?
Simple.
Avoid commercially deep-fried fish (and avoid deep frying in vegetable oil if you're cooking it from scratch), because you're likely not going to derive any benefit from the omega-3 in the fish. Meanwhile, baked or broiled fish, using good-old-fashioned butter—which is a healthful saturated fat—is a wiser choice, if you're going to eat fish (and I'll discuss the reasons why you may want to limit your fish consumption, despite it being such a rich source of omega-3).
How Trans Fats Harm Your Heart
Last year, scientists claimed to have finally discovered one of the mechanisms by which dietary trans-fats cause hardening of the arteries, also known as atherosclerosis. It appears these damaged fats suppress the responsiveness of TGF-beta, a key protein that controls growth and differentiation in your cells. In a nutshell, trans fats cause dysfunction and chaos in your body on a cellular level, and the ramifications are significant. One 2009 study revealed that among women with underlying coronary heart disease, eating trans-fats increased the risk of sudden cardiac arrest three-fold!
Besides heart disease, other studies have linked trans-fats to:
- Cancer: They interfere with enzymes your body uses to fight cancer.
- Diabetes: They interfere with the insulin receptors in your cell membranes.
- Decreased immune function: They reduce your immune response.
- Problems with reproduction: They interfere with enzymes needed to produce sex hormones.
- Obesity
Why Most Fish is No Longer a Healthful Food Choice
So, it's pretty safe to say that fish steeped in trans-fat is not going to do your health any favors. But what about eating fish in general? Is it really an ideal source of essential omega-3 fats, as long as you cook it appropriately? In a perfect world, fish would be a near-perfect food -- high in protein and full of essential nutrients and fats. But our world is not perfect, and, sadly, neither is our fish supply. Just take a look at these somber reports on the contamination levels of our fish stocks:
Pregnant women in particular are dissuaded from consuming fish, as methylmercury can have lasting negative effects on your developing child's health, affecting their attention span, language, visual-spatial skills, memory and coordination. It is estimated that nearly 60,000 children each year are born at risk for neurological problems due to methylmercury exposure in the womb.
- A 2004 study on fish living in lakes and reservoirs found that more than half contained excessive levels of mercury -- so much so they were deemed unsafe for children and pregnant women to eat.
- Laboratory tests in New York released in 2007 found so much mercury in tuna sushi that two or three pieces a week at some restaurants could be a health hazard. Ten percent of the tuna samples were unsafe for all consumers, because they contained mercury levels above 1.0 ppm, which is the legal action limit for fish sold in the U.S.
- According to a 2009 U.S. Geological Survey study, scientists detected mercury contamination in every fish sampled in nearly 300 streams across the United States. More than a quarter of these fish were found to contain mercury at levels exceeding the criterion for the protection of people who consume average amounts of fish, established by the U.S. Environmental Protection Agency.
- According to a 2009 report, the rate of mercury contamination in tuna and other Pacific fish has increased 30 percent since 1990.
- An estimated 40 percent of all U.S. exposure to mercury comes from eating contaminated tuna from the Pacific. And roughly 75 percent of all human exposure to mercury in general comes from eating fish!
It is for these reasons that I do not recommend eating fish -- whether farm-raised or from an ocean, lake, river or stream -- unless you have lab results in your hand that can attest to its purity.
An important point to remember though is that if you're not eating fish, you need to make sure you're getting your omega-3 from some other source. Fortunately, you can easily meet your omega-3 needs by taking a high-quality krill oil supplement, instead of risking your health by eating contaminated fish.
The Best and Worst Fish You Can Put on Your Plate
If you're not willing to give it up completely, at least educate yourself on the "best" and "worst" fish options. The larger the fish, the likelier they are to have high levels of environmental toxins like mercury. Predatory fish such as large tuna, swordfish, shark and mackerel can have mercury concentrations in their bodies that are 10,000 times higher than those of their surrounding environment, according to The National Resources Defense Council.
There are still some safe areas out there, such as certain waters in Alaska, but it will require some patience to find fish from these sources. I finally found Vital Choice wild red salmon, the purity of which I've confirmed through third-party lab testing, and it's currently the main source of fish I eat. Smaller fish, like anchovies and sardines, are also an option, as their small size makes them far less likely to be contaminated.
If you insist on eating typical, store-bought fish, however, and want to know more about the extent of your mercury exposure, I urge you to check out the online mercury calculator at GotMercury.org to get an idea of the risks. You can also ameliorate some of the dangers by taking a mercury chelator with your meal. Examples include green clays like Zeolite, or chlorella.
Please do not make the mistake of thinking that farm-raised fish is safer than wild-caught. In fact, farm-raised fish can be a far more hazardous choice. Studies have consistently found levels of PCBs, dioxins, toxaphene and dieldrin, as well as mercury, to be higher in farm-raised fish than wild fish. Further, farm-raised fish, like factory-farmed meat, is pumped full of antibiotics, hormones and even chemicals to change their color (such as to make salmon appear pink).
How You Cook Your Food Matters!
Last but not least, I want to stress the point that how you cook your food really does matter, and that cooking can destroy many of the inherent health benefits of most foods.
Francis Pottenger, a contemporary and friend of Weston A. Price, discovered that every food has a "heat labile point." This is the temperature point at which food changes its chemical configuration. Pasteurization, deep-frying, and barbecuing are all forms of cooking where food is heated past the heat labile point.
Your body is designed to eat foods of certain chemical configurations—which is related to your ancestral history.
If these configurations change, whether due to 'unnatural' cooking methods, or chemical additives, your body may not be able to properly digest and assimilate that food as it doesn't have the appropriate enzymes for the job. When the food does not digest and assimilate properly, it can sit in your gut, where it can become toxic. For example, carbohydrates can start to ferment; proteins putrefy, and fats become rancid. These toxins irritate the lining of your gastrointestinal tract and can upset your gut flora, causing overgrowth of candida and other pathogens. Many of today's ills can be traced back to improper and unnatural cooking and processing.
Ideally you'll want to eat as many foods as possible in their raw, unprocessed state; typically organic, biodynamic foods that have been grown locally, and are therefore in season. I recommend consuming about 80 percent of your food raw, and only lightly cooking the remaining 20 percent.
Granted, unless you like sushi, few people would opt for raw fish, but as illustrated by the featured study, wisely choosing how you cook your fish can make a big difference. Carefully poaching or baking until tender and flaky, while avoiding over-cooking the fish are your best bets.
When cooking any kind of food, also keep the following tips in mind:
- Use a stable oil like coconut oil for all your cooking and baking
- Avoid using non-stick or aluminum cookware
- Avoid overcooking your food
