Tag Archives: omega-3 fatty acids

Still More Evidence That Fish Oil Supplements Do Not Prevent Cardiovascular Disease

Avid readers of the skeptical cardiologist know that he is not an advocate of fish oil supplements.

One of my first posts (1/2013) was devoted to taking down the mammoth OTC fish oil industry because recent scientific evidence was clearly showing no benefit for fish oil pills.

I concluded:

", the bottom line on fish oil supplements is that  the most 
recent scientific evidence does not support any role for them  inpreventing heart attack, stroke, or death. There are potential 
down sides to taking them, including contaminants and the impact on the marine ecosystem. I don’t take them and I advise my
patients to avoid them (unless they have triglyceride levels 
over 500.)"

Despite a lack of evidence supporting taking them, the fish oil business continues to grow,  buttressed by multiple internet sites promoting various types of fish oil (and more recently krill oil)  for any and all ailments and a belief in the power of “omega-3 fatty acids”.

Another Meta-Analysis Concludes No Benefit To Fish Oil Supplements

A publication this month evaluated the 10 randomized controlled trials involving 77 917 thousand individuals that have studied fish oil supplements in preventing heart disease. The writers concluded that fish oil supplements do not significantly prevent any cardiovascular outcomes under any scenario.

It was written by a group with the ominous title of “The Omega-3 Treatment Trialists’ Collaboration.”

The Omega-3 Treatment Trialists’ Collaboration was established to conduct a collaborative meta-analysis based on aggregated study-level data obtained from the principal investigators of all large randomized clinical trials of omega-3 FA supplements for the prevention of cardiovascular disease, using a prespecified protocol and analysis plan. The aims of this meta-analysis were to assess the associations of supplementation with omega-3 FAs on (1) fatal CHD, nonfatal MI, stroke, major vascular events, and all-cause mortality and (2) major vascular events in prespecified subgroups.

The authors conclusions:

. Randomization to omega-3 fatty acid supplementation (eicosapentaenoic acid dose range, 226-1800 mg/d) had no significant associations with coronary heart disease death (rate ratio [RR], 0.93; 99% CI, 0.83-1.03; P = .05), nonfatal myocardial infarction (RR, 0.97; 99% CI, 0.87-1.08; P = .43) or any coronary heart disease events (RR, 0.96; 95% CI, 0.90-1.01; P = .12). Neither did randomization to omega-3 fatty acid supplementation have any significant associations with major vascular events (RR, 0.97; 95% CI, 0.93-1.01; P = .10), overall or in any subgroups, including subgroups composed of persons with prior coronary heart disease, diabetes, lipid levels greater than a given cutoff level, or statin use.

Nothing. Nada. No benefit.

There is clearly no reason to take fish oil supplements to prevent cardiovascular disease!

American Heart Association Sheepishly Recommends Fish Oil Supplements

If the science was conclusive on this in 2013 why did the American Heart Association (AHA) issue an “advisory” in 2017  suggesting that the use of omega-3 FAs for prevention of coronary heart disease (CHD) is probably justified in individuals with prior CHD and those with heart failure and reduced ejection fractions?

The AHA advisory is clearly misguided and relies heavily in its discussion on a 2012 meta-analysis from Rizos, et al. published in 2012.

Oddly, this is the study that prompted me to write my first fish oil post in 2013

The AHA advisory totally distorts the completely negative conclusions of the Rizos meta-analysis, writing:

A meta-analysis published in 2012 examined the effects of omega-3 PUFA supplementation and dietary intake in 20 RCTs that enrolled patients at high CVD risk or prevalent CHD and patients with an implantable cardioverter-defibrillator (total n=68 680). That meta-analysis demonstrated a reduction in CHD death (RR, 0.91; 95% CI, 0.85–0.98), possibly as the result of a lower risk of SCD (RR, 0.87; 95% CI, 0.75–1.01).11

Strangely enough, if you look at the conclusions of Rizos, et al. they are

No statistically significant association was observed with all-cause mortality (RR, 0.96; 95% CI, 0.91 to 1.02; risk reduction [RD] -0.004, 95% CI, -0.01 to 0.02), cardiac death (RR, 0.91; 95% CI, 0.85 to 0.98; RD, -0.01; 95% CI, -0.02 to 0.00), sudden death (RR, 0.87; 95% CI, 0.75 to 1.01; RD, -0.003; 95% CI, -0.012 to 0.006), myocardial infarction (RR, 0.89; 95% CI, 0.76 to 1.04; RD, -0.002; 95% CI, -0.007 to 0.002), and stroke (RR, 1.05; 95% CI, 0.93 to 1.18; RD, 0.001; 95% CI, -0.002 to 0.004) when all supplement studies were considered.

Nothing. Nada. No significant benefit!

The AHA was so confused by their own advisory that in the AHA news release on the article they quote Dr. Robert Eckel, a past AHA president as saying he remains “underwhelmed” by the current clinical trials.

“In the present environment of evidence-based risk reduction, I don’t think the data really indicate that fish oil supplementation is needed under most  circumstances.”

The end of the AHA news article goes on to quote Eckel as indicating he doesn’t prescribe fish oil supplements and the science advisory won’t change his practice:

Eckel said he doesn’t prescribe fish oil supplements to people who have had coronary events, and the new science advisory won’t change that. “It’s reasonable, but reasonable isn’t a solid take-home message that you should do it,” he said.

AHA: Wrong On Coconut Oil and Fish Oil

It’s hard for me to understand why the AHA gets so many things wrong in their scientific advisories. In the case of the recent misguided attack on coconut oil , their ongoing vilification of all saturated fats, and their support for fish oil supplements I don’t see evidence for industry influence. The authors of the fish oil supplement advisory do not report any financial conflicts of interest.

There is, however, one bias that is very hard to measure which could be playing a role: that is the bias to agree with what one has previously recommended.  The AHA issued an advisory in 2002 recommending that people take fish oil. Changing that recommendation would mean admitting that they were wrong and that they had contributed to the growth of a 12 billion dollar industry serving no purpose.

Personally, I am aware of this kind of bias in my own writing and strive to be open to new data and publications that challenge what I personally believe or have publicly recommended.

In the case of fish oil supplements for preventing cardiovascular disease, however, the most recent data supports strongly what I wrote in 2013:

Don’t take fish oil supplements to prevent heart disease.

Americans want a “magic-bullet” type pill to take to ward off aging and the diseases associated with it. There isn’t one. Instead of buying pills and foods manipulated and processed by the food industry which promise better health, eat real food (including fish) eat a lot of plants and don’t eat too much.

Piscinely Yours,

-ACP

N.B. I have no patients on the two prescription fish oil supplements available, Lovaza and Vascepa. I wrote about Vascepa here

Below is an excerpt:

Like the first prescription fish oil available in the US, Lovaza, VASCEPA is only approved by the FDA for treatment of very high triglycerides (>500 mg/dl).

This is a very small market compared to the millions of individuals taking fish oil thinking that  it is preventing heart disease.

The company that makes Vascepa (Amrin;$AMRN)would also like to have physicians prescribe it to their patients who have mildly or moderatelyelevated triglycerides between 200 and 500 which some estimate as up to 1/3 of the population.

The company has a study that shows that Vascepa lowers triglycerides in patients with such mildly to moderately elevated triglycerides but the FDA did not approve it for that indication.

Given the huge numbers of patients with trigs slightly above normal, before approving an expensive new drug, the FDA thought, it would be nice to know that the drug is actually helping prevent heart attacks and strokes or prolonging life.

After all, we don’t really care about high triglycerides unless they are causing problems and we don’t care about lowering them unless we can show we are reducing the frequency of those problems.

Data do not exist to say that lowering triglycerides in the mild to moderate range  by any drug lowers heart attack risk.

In the past if a company promoted their drug for off-label usage they could be fined by the FDA but Amarin went to court and obtained the right to promote Vascepa to physicians for triglycerides between 200 and 500.

Consequently, you may find your doctor prescribing this drug to you. If you do, I suggest you ask him if he recently had a free lunch or dinner provided by Amarin, has stock in the company (Vascepa is the sole drug made by Amrin and its stock price fluctuates wildly depending on sales and news about Vascepa) or gives talks for Amarin.

If he answers no to all of the above then, hopefully, your triglycerides are over 500.

.

 

 

 

 

The Impact of Organic Foods On Human Health: European Perspective

The skeptical cardiologist obtains most of his groceries from Whole Foods, something the eternal fiancée insists on.  At least part of my preference is related to Whole Foods’ focus on organic produce and part to their focus on sustainable and healthier meat and fish.

A recent report from the European Parliament reviews the existing scientific evidence regarding the impact of organic food on human health. I think this document, (eu-organic-food) is a reasonable summary of the science in this area. The summary can be broken down into 4 key points:

  1. Very few studies have directly addressed the effect of organic food on human health. They indicate that organic food may reduce the risk of allergic disease and obesity, but this evidence is not conclusive. Consumers of organic food tend to have healthier dietary patterns overall. Animal experiments suggest that identically composed feed from organic or conventional production has different impacts on early development and physiology, but the significance of these findings for human health is unclear.

Meaning: We just don’t have good evidence to support routine use of organic foods.

2. In organic agriculture, the use of pesticides is restricted. Epidemiological studies point to the negative effects of certain insecticides on children’s cognitive development at current levels of exposure. Such risks can be minimised with organic food, especially during pregnancy and in infancy, and by introducing non-pesticidal plant protection in conventional agriculture. There are few known compositional differences between organic and conventional crops. Perhaps most importantly, there are indications that organic crops have a lower cadmium content than conventional crops due to differences in fertiliser usage and soil organic matter, an issue that is highly relevant to human health

My take. A 2014 review concluded that “the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cadmium

The review also concluded that ” the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops/crop-based foods…… phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanin.

3. Organic milk, and probably also meat, have a higher content of omega-3 fatty acids compared to conventional products, but this is not likely to be nutritionally significant in light of other dietary sources.

My take. I disagree. I wrote about why I only consume full-fat dairy products that are “organic” and come from grass-fed cows here. There are a lot of benefits, beyond increased omega-3 fatty acids, in consuming dairy that comes from cows that eat grass versus corn and are treated properly.

4. The prevalent use of antibiotics in conventional animal production is a key driver of antibiotic resistance. The prevention of animal disease and more restrictive use of antibiotics, as practiced in organic production, could minimise this risk, with potentially considerable benefits for public health.

My take. I agree. Cut out the antibiotics. Other countries seem to be able to do this.

I would also agree with the conclusion of  The Lancet’s editorial comment (Organic Food: Panacea for Health?)  on the EU paper:

Large, prospective, long-term studies are needed as well as deeper examination of agricultural policy and health. Much still rests on the provision of robust multidisciplinary research to guide future food choices for health.

Until we get such studies, I will be erring on the side of caution and consuming food with the least amount of pesticides, cadmium and antibiotics possible.

EUingly Yours,

-ACP

Cioppino and Cholesterol in the City by the Bay

IMG_2812
Crab cioppino from Sotto Mare. The crab is quartered and you must use utensils to get at it.

The other night  I had the best cioppino I have ever had. I’ve had variations of this wonderful tomato-based seafood stew  all over the world (including the legendary bouillabaisse in Marseilles) but I left my heart with the Dungeness crab cioppino served at Sotto Mare Oysteria and Seafood restaurant in North Beach, San Francisco. It makes sense, since cioppino was invented by Genoan fishermen from the SF Bay Area in the 19th century who threw together the freshest catch from their day at sea.

The recipe for Sotto Mare’s cioppino is actually available online as follows:
¼ cup olive oil
1 tsp. crushed red chile flakes
8 cloves garlic, finely chopped
3 cups fish stock
1 ½ cups whole peeled tomatoes in juice, crushed
10 leaves basil
1 lb. cod, cut into 2″ chunks
1 lb. cleaned calamari, bodies cut into ½″-wide rings
12 oz. medium shrimp, deveined
12 oz. bay scallops
16 clams, cleaned
16 mussels, cleaned
2 2-lb. Dungeness crabs or snow crab legs, halved
Kosher salt and freshly ground black pepper, to taste

It involves a lot of shellfish: calamari, shrimp, scallop, clams, mussels, crabs and I think a large part of what made it so good was the freshness of the shellfish obtained from the nearby Pacific Ocean.

Shellfish, Dietary Cholesterol and Cardiovascular Risk

Shellfish contain a lot of cholesterol and many of my patients have been told to minimize or avoid shellfish, especially shrimp, due to concerns they will exceed the (completely arbitrary) 300 mg daily limit suggested by the American Heart Association and the USDA nutritional guidelines.

There is no scientific basis for being concerned about the amount of cholesterol one consumes when eating shellfish (or for any food for that matter, as I previously wrote about with regard to eggs here)

But there are definitely warnings out there on the internet and traditional new media from seemingly responsible authorities.

This blurb from  the Physician Committee for Responsible Medicine is typical of the misinformation:

“Since our bodies make plenty of cholesterol for our needs,we do not need to add any in our diet. Cholesterol is found in all foods that come from animals: red meat, poultry, fish, eggs, milk, cheese, yogurt, and every other meat and dairy product. Choosing lean cuts of meat is not enough; the cholesterol is mainly in the lean portion. Many people are surprised to learn that chicken contains as much cholesterol as beef. Every four-ounce serving of beef or chicken contains 100 milligrams of cholesterol. Also, most shellfish are very high in cholesterol. All animal products should be avoided for this reason. “

The Physician Committee for Responsible Medicine appears to be a front for vegan-promotion. They go on to state that every 100 mg of cholesterol you consume raises your cholesterol by 5 mg/dl and that

“Every time you reduce your cholesterol level by 1 percent, you reduce your risk of heart disease by 2 percent.  For example, a reduction from 300 mg/dl to 200 mg/dl (i.e., a one-third reduction) will yield a two-thirds reduction in the risk of a heart attack”

A Fox News publication simultaneously extolls the virtues of shrimp consumption (noting that “three ounces of shrimp (or about seven medium-sized shrimp) has a mere 84 calories, 1g of fat, and an impressive 18g of lean protein” and that they are a great source of selenium, “an antioxidant that fights cancer-causing free radicals in your body”) and warns you against eating it (“If you are watching your cholesterol, it’s best to go easy on shrimp because four large shrimp have 42.5mg of cholesterol”)

Other publications advise those with high cholesterol or higher risk of heart disease to choose low-cholesterol varieties of shellfish over shrimp.

The Science Supporting Shrimp

Let’s look at what is actually known about consuming shrimp and shellfish.
A study of over 13,000 subjects (the ARIC study) found no increased risk of cardiovascular disease in the high shellfish consumers versus the low shellfish consumers.

A study in 1996 compared consuming a diet with 300 grams (about 10 oz.)  of steamed shrimp/day (providing 590 mg of cholesterol daily) versus a baseline diet of 107 mg/ cholesterol in 18 individuals without cholesterol problems.  The shrimp consumers compared to baseline had a 7% higher LDL or bad cholesterol but a 12% higher HDL or good cholesterol. Thus, the ratio of total to good cholesterol went down. We now know that this ratio is a much more important risk marker for cardiovascular disease than the total cholesterol. Triglycerides dropped significantly when subjects were consuming shrimp versus the baseline, low cholesterol diet.

A 1990 study looked at multiple different types of shellfish substituted for meat, cheese and eggs, and found that oyster, clam, crab and mussel diets (with lower cholesterol and higher omega-3 fatty acid profiles) lowered VLDL triglycerides and VLDL cholesterol.  These shellfish diets, except for the mussel diet, also lowered LDL and total cholesterol. Shrimp and squid had no effect on the lipid profiles.

 Benefits of Shrimp and Shellfish Consumption

I’ve focused on shrimp in this post because it has the highest cholesterol content of all shellfish and therefore is the most likely to be considered bad for heart patients or patients with high cholesterol. I’m presuming if I can convince you that shrimp are heart healthy, then you will believe that all shellfish are.

shrimp contentsTake a look at this chart of the nutrient composition of shrimp and you can understand that, once you eliminate  unsubstantiated fears of the cholesterol content, this a great food.

I am not a big advocate of examining the macronutrient composition of foods in order to predict their health benefits. This approach to nutritional science resulted in the development of highly processed low-fat monstrosities that currently sit in boxes and bags and line the most prominent parts of supermarket shelves. The overall effect of foods on the cardiovascular system depends on an incredibly complicated interaction of food components, bacteria in the gut and genetic predispositions: areas we are only beginning to understand. However, for those readers who are concerned about such things there is reassurance.

Start with the fact that there are no carbohydrates in shellfish: since carbs and added sugar are likely the biggest culprits in our obesity epidemic, shrimp and shellfish are great tools in helping to manage weight.  Shrimp have a very high percentage and quality of protein content for muscle building.

Some avid shrimp promoters insist that shrimp should be consumed regularly to reduce the risk of both cancer and heart disease.  The fat in shrimp is mostly polyunsaturated fat with a high ratio of omega-3 to omega-6 which is considered optimal . Eating 100 ounces of shrimp daily gives you 180 mg of EPA and DHA (considered the most important of the omega-3 fish oils for heart health) daily, close to the 250 mg daily the USDA recommends for most adults.

Astaxanthin has been found to be a potent natural antioxidant, exceeding ten times the antioxidant activity of β-carotene and 500 times that of α-tocopherol. The astaxanthin level of wild shrimps has been reported to vary between 740 and 1400 μg/100 g in edible meat portions.

If I were a vegan or vegetarian I would consider slipping shrimp into my dishes instead of tofu.

Adulterated Shrimp

The cioppino recipe above doesn’t add a lot to the shellfish and fish: a little olive oil and tomatoes, basil and garlic-these things are not going to jack up the calories, sugar or fat content.

Depending on how you cook shrimp, the resulting dish will have markedly different nutrient composition compared to the raw nutrients listed above.

Breading and deep frying the shrimp takes 3 oz from 60 calories to 206 and the fat grams from 1 to 10.  I suspect that you or your body will figure this out and eat less later. Given the fairly low fat and carbohydrate content of the Sotto Mare cioppino, I am ashamed to admit, I ate that whole bowl pictured above (which the menu said could be shared between two).

The SOSC doesn’t share my love of cioppino; she ordered the linguine with clam sauce. Three ounces of clams have only 26 mg of cholesterol but it seems to me the majority of calories in this dish are coming from the carbs in the pasta and whatever the composition of the sauce is. In any event, the SOSC pronounced it the best she has ever had.

Mercury in Shellfish

The level of mercury is a concern in all the fish that we consume.  Fortunately a recent study from Maine University found that shrimp is very low in mercury.mercury by type of shrimp This included varieties from Thai shrimp farms, Maine shrimp farms and the Gulf of Mexico. In comparison to other types of fish, shellfish are universally on the low end of the mercury level graph as shown below.mercury in fish

 

 

 

Fear neither the  cholesterol nor the mercury in shrimp and consume your cioppino with gusto and without guilt!