Tag Archives: omega 3 fatty acid

Omega-3S From Fish Oil Supplements No Better Than Placebo For Dry Eye 

Yesterday, a patient I’m seeing for atrial fibrillation told me that he was taking fish oil supplements that his eye doctor had recommended and sold to him for dry eyes. This patient reads my blog and knows that I strongly recommend not taking fish oil supplements (unless your triglycerides are >500). At the time I told him I didn’t know the literature on fish oil and dry eyes but that I was skeptical of any proven benefit.

It turns out that in April of this year an NIH-sponsored study concluded that Omega-3s from fish oil supplements are no better than placebo for dry eye.

The NIH story on this study notes that

Despite insufficient evidence establishing the effectiveness of omega-3s, clinicians and their patients have been inclined to try the supplements for a variety of conditions with inflammatory components, including dry eye. “This well-controlled investigation conducted by the independently-led Dry Eye Assessment and Management (DREAM) Research Group shows that omega-3 supplements are no better than placebo for typical patients who suffer from dry eye.”

I suspect that one by one the various alleged benefits of fish oil supplements will be proven to be nonexistent.  I’m not sure the general public will stop buying snake or fish oil  then but I feel like one by one I’m getting my patients off them. Doing my part to save the ocean bottom-feeders.

Krillingly Yours,

-ACP

N.B. I’m writing this while flying to Miami to begin the great Galapagos adventure and the Voyage of the Samba.

Organic Milk, Grass-fed Cows and Omega-3 Fatty Acids

The skeptical cardiologist has to admit that when he drinks milk or puts it in his coffee or cooks with it he almost exclusively drinks “organic”, non-homogenized milk obtained from dairy cows which are grass-fed and spend most of their lives grazing in a pasture.. In previous blogs I’ve laid out the evidence that supports that dairy products in general do not increase the risk of heart and vascular disease and, in fact, may lower that risk.

Full fat dairy has gotten a bad rap because it contains high levels of saturated fat. However, just as total fats were inappropriately labeled as bad , it is now clear that all saturated fats are not bad for the heart.

Although I recommend full fat dairy products to my patients I haven’t emphasized the organic or grass-fed aspect because I didn’t think there was enough good evidence that this is healthier than other kinds of milk and it is more expensive. There is evidence from small studies that cows consuming a more natural diet of grass and legumes from a pasture have higher levels of omega-3 fatty acids in their milk than those confined indoors and eating corn.

I keep my eyes (and ears) open for papers in this area.. One such paper appeared in the online peer-reviewed publication PLOS recently. I was driving to the hospital, listening to NPR when I first heard about it. Melissa Block was interviewing NPR correspondent Allison Aubrey . Her take, in a more subdued written form here is similar to many news outlets.

Allison summarized the findings as follows

The researchers compared organic and conventional milk head-to-head. They analyzed about 400 samples over an 18-month period, to account for seasonal differences. And the samples were taken from, you know, all different parts of the country. And they found that organic milk had about 62 percent more of the heart healthy omega-3s, compared to conventional milk.

When asked for an explanation she said

It really comes down to watch what the cows were eating. Organic milk is produced from cows that spend a lot more time out on pasture, and they’re munching on grasses and legumes. And these greens are rich in omega-3 fatty acids. So as a result, the milk they produce has more omega-3 fatty acids.

Wait a minute! I said , you’re confusing “organic” and “grass-fed” or “pasture raised ” they are two totally different things although they can overlap. I totally get the concept of a healthier diet for the cows increasing omega-3s in their milk but I haven’t seen anything that would suggest reducing pesticide or antibiotic usage does that. The radio did not respond. Also, I asked, is it possible to use the term omega-3 without prefacing it with “heart healthy”?

Once you start demanding to know more about the conditions of the cows that made the milk you drink things can become complicated. A cow can be grass-fed but not pasture raised, meaning that it stayed indoors and was fed hay. A cow can be outside “grazing ” but be given corn to eat. Prior to looking at the PLOS one article, I did not assume organic implied anything about how the cows were fed or grazed.

It turns out that in 2010 the USDA announced guidelines that mandated, among other things, for a dairy to be called “organic”, its dairy cows had to spend at least 120 days grazing on pasture.Thus, there is some correlation between organic and pasture raised/grass-fed but not a complete one.

The PLOS one study looked at geographical variation in the difference between organic and conventional milk fatty acid content. Northern California was the only region in which there was no significant difference. The authors speculated that this was because conventional farmers in Norther California usually have cows that roam on the pasture and eat grass and legumes. Thus, it appears the differences between organic and conventional milk are primarily due to what the cows were eating rather than the presence or absence of pesticides, antibiotics, GMOs, or hormones.

Allison Aubrey went on to say

But you know, I should say that there’s a trade-off here because in order to get all these extra omega-3s, you’ve got to drink whole milk. And you know, if you opt for the low-fat dairy – say, 1 percent fat -you’ve skimmed off most of these omega-3s. So the question is, you know, can you afford the extra calories in fat. If you choose the whole milk, you might need to trim a few calories from elsewhere in your diet.

To which I responded “Yes, by all means drink whole milk, there is no evidence that it adds to obesity. You will naturally want less calories down the line and you will get the benefit of good saturated fats.”

I'll continue to pay extra to drink milk from Trader's Point Creamery that I pick up at Whole Foods. I like their milk because I've visited their farm in Indiana and talked to their (plastic surgeon) owner and I like what he says on the website about their milk (ignoring the part about a “better immune system”.

We let our cows graze on 140 acres of pesticide free pasture, which results in milk with more healthy fats like Omega 3 and CLA (conjugated linoleic acid). Grassfed milk also contains more nutrients like beta carotene and vitamins A and E than milk produced using standard feeds. To all of us this means more nourishment and a better immune system for our bodies.

I’m going to end with the summary from the PLOS one article (DMI=dry matter intake, LA=linolenic acid, an omega-6 fatty acid) which emphasizes the importance of grazing and forage-based feeds not the organic aspects of milk.

We conclude that increasing reliance on pasture and forage-based feeds on dairy farms has considerable potential to improve the FA profile of milk and dairy products. Although both conventional and organic dairies can benefit from grazing and forage-based feeds, it is far more common—and indeed mandatory on certified organic farms in the U.S.—for pasture and forage-based feeds to account for a significant share of a cow’s daily DMI. Moreover, improvements in the nutritional quality of milk and dairy products should improve long-term health status and outcomes, especially for pregnant women, infants, children, and those with elevated CVD risk. The expected benefits are greatest for those who simultaneously avoid foods with relatively high levels of LA, increase intakes of fat-containing dairy products, and switch to predominantly organic dairy products.

Eggs and Heart Disease

The Wonderful Egg and Your Heart

photoI think eggs are wonderful. They are little balls of nutrition that can be prepared in numerous fascinating ways to make breakfast interesting and delicious. I particularly like omelets.  Alas, when I was training as a medical student the medical establishment had embraced the diet-heart hypothesis. It was felt that dietary cholesterol and fat (subsequently modified to saturated fat) by increasing levels of cholesterol in the blood (subsequently modified to raising levels of bad or LDL cholesterol) were responsible for the increasing rate of coronary heart disease that was being observed.

This certainly made sense at the time: If you eat too much cholesterol, of course it’s going to raise your blood cholesterol levels and contribute to the buildup of those nasty cholesterol plaques that would clog your arteries and give you heart attacks and strokes.

Since egg yolks contain 210 mg of cholesterol on average (more recent data suggest they only contain 184 mg/egg), eggs became a target of the dietary police.

The American Heart Association (AHA, the same organization that until recently endorsed sugar-laden cereals like Cocoa Puffs as  “heart healthy”) had decided decades ago to recommend restricting egg consumption. In 2010, AHA guidelines restricted everybody’s total cholesterol to <300 mg per day on the flimsiest of evidence.  From the AHA guidelines:

“Although there is no precise basis for selecting a target level for dietary cholesterol intake for all individuals, the AHA recommends <300 mg/d on average. By limiting cholesterol intake from foods with a high content of animal fats, individuals can also meet the dietary guidelines for saturated fat intake. This target can be readily achieved, even with periodic consumption of eggs and shellfish. As is the case with saturated fat intake, reduction in cholesterol intake to much lower levels (<200 mg/d, requiring restriction of all dietary sources of cholesterol) is advised for individuals with elevated LDL cholesterol levels, diabetes, and/or cardiovascular disease.”

The official US dietary guidelines on the topic of dietary cholesterol read as follows

“the body uses cholesterol for physiological and structural functions, but it makes more than enough for these purposes. Therefore, people do not need to eat sources of dietary cholesterol. Cholesterol is found only in animal foods. The major sources of cholesterol in the American diet include eggs and egg mixed dishes (25% of total cholesterol intake), chicken and chicken mixed dishes (12%), beef and beef mixed dishes (6%), and all types of beef burgers (5%). Cholesterol intake can be reduced by limiting the consumption of the specific foods that are high in cholesterol. Many of these major sources include foods that can be purchased or prepared in ways that limit the intake of cholesterol (e.g., using egg substitutes). Cholesterol intake by men averages about 350 mg per day, which exceeds the recommended level of less than 300 mg per day. Average cholesterol intake by women is 240 mg per day.

Dietary cholesterol has been shown to raise blood LDL cholesterol levels in some individuals. However, this effect is reduced when saturated fatty acid intake is low, and the potential negative effects of dietary cho- lesterol are relatively small compared to those of saturated and trans fatty acids. Moderate evidence shows a relationship between higher intake of cholesterol and higher risk of cardiovascular disease. Independent of other dietary factors, evidence suggests that one egg (i.e., egg yolk) per day does not result in increased blood cholesterol levels, nor does it increase the risk of cardiovascular disease in healthy people. Consuming less than 300 mg per day of cholesterol can help maintain normal blood cholesterol levels. Consuming less than 200 mg per day can further help individuals at high risk of cardiovascular disease.”

Americans were being told to severely restrict their egg consumption, especially if they had high cholesterol levels, diabetes, or heart disease. Even one egg a day seemed too much. As a cardiologist in training I dutifully took these recommendations to heart. I can’t tell you how many egg beater or egg white omelets I cooked over the next 25 years.

As more evidence accumulated, however, the bulk of the scientific evidence was coming down clearly on the side of eggs and the lack of effect of dietary cholesterol on blood cholesterol levels. As The Skeptical Cardiologist I began embracing the heresy of eating eggs, yolk and all, about two years ago.

Several large epidemiological studies have examined the association of egg consumption and serum cholesterol. The Framingham Heart Study examined the serum cholesterol in high versus low egg consumption and found no significant difference in either men or women. The association between self-reported dietary intake of eggs and serum cholesterol was examined in a population of 12,000 men in the Multiple Risk Factor Intervention Trial. Paradoxically, the men who consumed more eggs had lower serum cholesterol than those who consumed fewer eggs.In the Third National Health and Nutrition Examination Survey (NHANES III), the diets of 20,000 participants were evaluated.

“Compared to egg consumers, nonconsumers  had higher rates of inadequate intake (defined by Estimated Average Requirements (EAR) or < 70% Recommended Dietary Allowance (RDA)) for vitamin B12 (10% vs. 21%), vitamin A (16% vs. 21%), vitamin E (14% vs. 22%) and vitamin C (15% vs. 20%). After adjusting for demographic (age, gender and ethnicity) and lifestyle variables (smoking and physical activity), dietary cholesterol was not related to serum cholesterol concentration. People who reported eating > or = 4 eggs/wk had a significantly lower mean serum cholesterol concentration than those who reported eating < or = 1 egg/wk (193 mg/dL vs. 197 mg/dL, p < 0.01”

Study after study in the next 20 years showed that egg consumption was not associated with coronary heart disease and strokes. A more recent study from Spain shows no association of egg consumption on cardiovascular disease. A meta-analysis of all prospective cohort studies published in 2013 concluded that there was no association between higher egg consumption and coronary heart disease or stroke. Studies (randomized controlled trials) that  actually prove that egg consumption causes cardiovascular disease are totally lacking. Nutritional guidelines should have concluded  that there was no reason to restrict egg consumption in the vast majority of Americans.

Unfortunately, the AHA guidelines (and mainstream nutritional advisors) to this day continue to embrace the 300 mg/ day limit on cholesterol (although most other countries have dropped it). Most of my patients, having heard that eggs are bad for the heart, mistakenly try to restrict the amount they eat or eat egg whites. I see my fellow doctors in the doctors’ lounge taking boiled eggs out of the refrigerator, scooping the yolk out and eating only the egg white.

Why doesn’t more cholesterol in the diet lead to higher blood cholesterol level and subsequently to heart attacks? The answer is complicated, beyond the scope of this blog, but it illustrates how amazingly complex the body’s regulation of lipids and lipoproteins is, as well as how complicated the process of atherosclerosis is.

There are at a very basic level 3 main types of fat that doctors measure in the blood to help us gauge heart disease risk: the low density lipoprotein (LDL)  cholesterol portion or “bad”, the high-density lipoprotein (HDL) cholesterol or “good,” and the triglycerides (esterified fatty acids). On a very simplistic level, we tell patients that higher LDL levels tend to build up fatty plaques, whereas higher HDL levels can be thought of as reducing fatty plaques. When we eat an egg there is a complex reaction to the fats, proteins, sugar, and cholesterol absorbed into the blood stream.cholesterol graphic Although the LDL rises (which might increase coronary artery disease (CAD) risk), the HDL also rises (which might lower CAD risk) and there is a variable response of triglycerides. To further complicate things, each of the cholesterol fractions has  good forms and bad forms. LDL can be in a large, “fluffy” state that is not prone to promoting plaque formation or a small, dense form that does promote plaque formation. Eggs seem to promote the less atherogenic forms of both LDL and HDL. In addition, inflammation plays an important role in the process of atherosclerosis. Certain components of egg yolks may actually reduce inflammation, making plaque formation less likely.

Certain components of eggs may be beneficial and outweigh any theoretical concern about cholesterol consumption.. Eggs are the major sources of lutein and zeaxanthin, two potent anti-oxidants, which in addition to their recognized protective effects against macular degeneration and cataract formation, may also reduce LDL oxidation.

Eggs also contain choline, a nutrient that is needed for membrane formation, methylation and acetylcholine biosynthesis, which plays a major role in normal fetal development. Some studies suggest a role of choline in protecting against Alzheimer’s disease

Eating eggs may contribute to weight loss compared to eating carbohydrates. A recent study compared two different breakfasts, a bagel-based and an egg-based breakfast. During the egg period, men had a significantly lower caloric intake not only in the next meal, but also in the following 24 hours.

To make things more complicated, all eggs are not created equal. Hens that are allowed to range freely on a farm and eat grass, bugs and what might be considered their normal diet, have a different amount of omega-3 fatty acids than those that are fed grain. Given America’s current obsession with fish oil supplements (see my prior post), this makes these eggs perceived as healthier. By manipulating the diet of hens, even those stuck in cages, the omega-3 content of eggs can be increased. Is this healthier?

The limit on dietary cholesterol of 300 mg imposed by the AHA and the USDA in their guidelines, unnecessarily has my patients worrying about cholesterol in all the things that they eat. For example, there is a lot of cholesterol in shellfish. There is no evidence that eating shellfish is bad for the heart or your cholesterol profile. For example, this recent study showed no effect of eating cold water prawns on plasma cholesterol or lipoproteins.

The Bottom Line:

Eggs are an affordable (15 cents/egg) source of high quality protein and fat. Although they contain a lot of cholesterol, there is no evidence (with the possible exception of diabetics) that egg consumption is related to risk of coronary heart disease; they may in fact reduce the risk of stroke.

Since this new evidence has emerged, I regularly enjoy the deliciousness of a three egg omelet with cheese and other ingredients without guilt and I encourage my patients to do the same.photo Personally, especially in my home kitchen, I try to eat eggs that come from hens that are raised under more natural and humane circumstances as I view them as healthier than eggs from factory farms.

Not everyone is an egg lover and I’m fine with that. There is no evidence that you have to eat them. You could feel towards them as did Alfred Hitchcock :

“I’m frightened of eggs, worse than frightened, they revolt me. That white round thing without any holes … have you ever seen anything more revolting than an egg yolk breaking and spilling its yellow liquid? Blood is jolly, red. But egg yolk is yellow, revolting. I’ve never tasted it.”hitch

Omega-3 fatty acids, and heart disease: Do fish oil supplements prevent heart attacks or death from heart disease

In recent years, a steady stream of experts, including the ubiquitous Dr. Oz, Screen shot 2013-01-26 at 9.47.51 AMhave advised every one to take fish oil supplements to protect their heart health

In fact, there is little to no evidence that fish oil supplements or fish oil enhanced foods should be consumed for any health purpose.
Omega-3 fatty acids (also known as  ω−3 or n−3) are polyunsaturated fatty acids (PUFA) that can be derived from marine or plant oils. They are considered essential fatty acids in humans, vital for normal metabolism but not synthesized by the human body.

The long chain omega-3 fatty acids eicosapentanoic acid (EPA) and docosahexanoic acid (DHA)  are felt to be the most beneficial. The best food source of DHA and EPA is cold water fatty fish and shellfish. The fish highest in these fatty acids are salmon, sardines, mackerel, herring and tuna.

Alpha-linolenic acid (ALA) is an omega-3 fatty acid which is predominantly found in plant oils (flaxseed, canola, and soybean oils) and walnuts. It can, to a limited extent, be converted in human bodies  to EPA and DHA, thus can be considered a precursor.

There is some evidence that consuming fish on a regular basis is associated with lower risk of coronary heart disease and stroke. Therefore, I can agree with current AHA and USDA guidelines which recommend consumption of fatty fish at least twice a week and I advise this for my patients.

Predominantly on the basis of one very positive study performed in Italy in 1999 (the GISSI study, which gave EPA/DHA to heart attack survivors), most cardiologists, the AHA, and the supplement industry had concluded by 2005 that fish oil reduced mortality and cardiac morbidity. The best evidence then was that the fish oil supplement was helpful after a heart attack (so-called secondary prevention). However, there was a very powerful urge to extrapolate this recommendation to patients without heart disease (so-called primary prevention).

Such expanded recommendations were reflected in the media. For example, Forbes proclaimed

“One Supplement That Works:

A lot of nutritional supplements are quack medicines. Not fish oil”

By 2009 sales of OTC fish oil supplements had risen 18% in one year to 739 million and Americans were buying 1.8 billion worth of foods (such as margarine and peanut butter) fortified with extra omega-3s. By  2011, Americans were spending 1.1 billion on supplements.

GlaxoSmithKline developed and patented a high-concentration fish oil (Lovaza) that gained an indication for treating high triglycerides which had global sales of 1 billion dollars in 2008. Supported by heavy advertising and promotion to physicians (through dinner lectures, lunches and other promotions), this expensive version of fish oil is widely prescribed by physicians for reasons other than the very high triglyceride elevations it has an indication for.

Forbes wrote

“In the history of nutritional supplements there’s something striking about omega-3: the fact that it works. Much of the $25 billion a year that Americans spend on supplements is money down the drain”

While the second part of that sentence is true (the vast majority of supplements/nutraceuticals/minerals that Americans take in a search for longevity or arthritis relief are worthless) the first part is not true.

The subsequent  hype for the benefits of fish oil supplements, especially in the world of nutritional supplement has been outrageous and inaccurate.

A typical product description reads as follows.

“We believe this is the highest quality Omega-3 available.
This highly concentrated Pharmaceutical Grade Omega-3 Fish Oil delivers 800mg of EPA and 600mg of DHA.
The important benefits of Omega-3 have been proven in thousands of independent studies by universities, governments, and health organizations. Because of such research, people around the world are now taking fish oil for reasons ranging from brain development, mild depression and heart function to arthritis and our immune systems.
It causes NO fishy or un-pleasant after taste.
This Omega 3 has been verified by a 3rd party to be Mercury Free.”

If one reads further down the page, however, the most important sentence is the following (and this is true for all supplements_






These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease

So , the fish oil pushers  make a series of totally unsubstantiated claims about the benefits followed by the statement that it is not intended to benefit any one in any way.

The most recent systematic review and meta-analysis of omega-3 fatty acid supplementation and the risk of major cardiovascular events (published Sept. 2012,) concluded:

“overall, omega-3 PUFA supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction,  or stroke based on relative and abolute measures of association”

Studies performed in the last 5 years of omega-3 PUFA supplementation do not support a role for them in reducing heart disease, either in high risk individuals without documented heart disease or those who have already had heart attacks.

Most of my patients continue to take fish oil supplements because they think that there may be a benefit without any down side. However, there are a number of potential down sides that should be considered.
1. There is no government regulation or measurement of the contaminants in fish oil supplements.
According to Consumer Reports

“Most tested pills are claimed to be “purified” or “free” of PCBs, mercury, or other contaminants, claims that have no specific regulatory definition, the Food and Drug Administration says. The agency has taken no enforcement action against any omega-3 maker over PCBs or other contaminants, an FDA spokeswoman said, because it has seen no public-health risk”

2. A major source of the fish oil in fish oil supplements, menhaden, is being over fished. Menhaden are a sardine-like forage fish that range in huge schools from Canada to Florida and into the Gulf. As filter feeders, they form an important base of the marine food chain. They have historically been harvested for food and later, for use as fertilizer and more recently for use in aquaculture and in omega-3 supplements. This fish, which has been called “the most important fish in the sea,” feeds on phytoplankton and is essential for a healthy marine ecosystem. The Atlantic States Marine Fisheries Commission (ASMFC) recently approved a 20% decrease in fish catch for the Atlantic Coast menhaden bait and reduction fisheries, The numbers of these fish have declined by 90% in the last 4 decades. Without doing extensive research on your particular fish oil supplement you can’t be sure you aren’t contributing to  this problem.

So, the bottom line on fish oil supplements is that  the most recent scientific evidence does not support any role for them  in preventing 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.)

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, I advise following Michael Pollan’s simple advice

“Eat food. Mostly plants. Not too much”