by Mark Hyman
High-Speed CT or EBT Scan
This high-speed X-ray of the heart can help determine if you have cardiovascular disease. It may be helpful in assessing overall plaque burden and calcium score and can inform how aggressive you need to be in terms of prevention. A score higher than 100 is a concern, and a score higher than 400 indicates severe risk of cardiovascular disease.
Carotid Intimal Thickness
This test is done through ultrasound and looks for plaque in the arteries in your neck, which correlates with heart disease and stroke risk.
SHOW YOUR HEART SOME LOVE
Okay, so here’s what we know: Heart disease risk is linked to a variety of factors, including inflammation, insulin resistance, metabolic syndrome, low levels of HDL, high triglycerides, increased LDL particle number and decreased particle size, belly fat, thickness of your blood, blood pressure, smoking, stress, environmental toxins, and age.
Phew… that’s a long list! But here’s the bright spot: Other than age, environmental toxins, stress, and smoking, all of these can be corrected by eating a lower-carb, higher-fat diet. If eating a certain way moves things in the right direction, then that gets my attention.
While it is true that we have cut the death rates from heart disease in middle-aged people because of better drugs and treatments, we have not been winning the war on the increase in the number of new people getting heart disease. In fact, heart disease is spreading like wildfire across the globe and is now the world’s number one killer.
That is why, more than ever, we need to give up on the dietary myths about saturated fat and cholesterol and focus our attention and efforts on addressing the real causes of heart disease, as outlined in this chapter.
6
Vegetable Oils—A Slippery Subject
As you know by now, right on the heels of the “eat less saturated fat” message has been the message to eat more PUFAs, or polyunsaturated fats, especially omega-6 fats. We know these oils well. They are the common “vegetable” oils we all grew up on, including corn oil, soybean oil, canola oil, safflower oil, and sunflower oil—clear, tasteless oils that are highly refined and processed. Advisory groups such as the American Heart Association, the National Cholesterol Education Program, the National Institutes of Health, the government’s dietary guidelines, and many well-respected scientists have been recommending that we substitute polyunsaturated fats for saturated fats.1
Thanks to farm subsidies and the power of Monsanto’s global soybean monopoly, Americans now consume about 18 billion pounds of soybean oil a year. About 20 percent of our calories come from soybean oil, which is 50 percent linoleic acid, an inflammatory omega-6 fat.2 Check your grocery store labels; soybean oil is in almost everything.
At the turn of the century, vegetable oils were almost unknown in the food supply. After the Industrial Revolution, we learned how to process seeds, grains, and beans into refined oils. What’s surprising to most people is that meat and chicken are big sources of omega-6 fats. How can that be? Because industrial farming practices have led farmers to switch their feed from grass to corn and cereal grains, and now those omega-6 vegetable fats comprise a significant portion of “animal” fat. You are what you eat. Or more accurately: You are what your food eats.
With the introduction of refined oils and our shift away from grass-fed and wild animals to industrial animal production, our dietary omega-6 fats have skyrocketed, while omega-3 fats have declined. Now we eat about ten times as much omega-6 as omega-3 oils, and some people eat up to twenty-five times as much. While it is not clear what the exact ratio should be, we do know it’s now way out of whack.
Balance is critical. The omega-6 fats fuel inflammatory pathways in the body, while omega-3 fats are anti-inflammatory. Most important, omega-6 fats reduce the availability of anti-inflammatory omega-3 fats in our tissues (leading to more inflammation) and prevent the conversion of plant-based omega-3s (ALA) into the active forms of omega-3s (EPA/DHA) in the body by 40 percent. That means that even if you eat omega-3 fats, in the presence of excess omega-6 fats, the omega-3 fats don’t work as well.
IS IT OMEGA-3S (FISH OIL) OR OMEGA-6S (VEGETABLE OILS) THAT PREVENT HEART DISEASE?
The first, largest, and most important study I want to review, the Lyon Heart Study, found that increasing omega-3 fats in the diet resulted in a 70 percent reduction in heart attacks and death. This study is often quoted to support the idea that polyunsaturated fats are good. The thing is, PUFAs, or polyunsaturated fats, are not created equally. Omega-3 is protective and omega-6s are harmful in excess.3 And the Lyon Heart Study actually reduced the amount of omega-6 fats, while increasing the omega-3s. It is hard to explain why this fact is ignored when this study is used to promote the benefits of omega-6 oils.
We know it is hard to attack entrenched ideas. But we have to have a deeper look to understand the advice to stop saturated fats and eat more polyunsaturated fats. The standard policy line is that saturated fats are bad and polyunsaturated fats are good. The only way to figure this out is to dig into all the research on this topic. A number of brave scientists have ventured into this hallowed territory and changed the status quo. They are from the National Institutes of Health (NIH) and have no conflicts of interest. Many other scientists in this fight get funding from the food industry.
Two of the leading voices are Dr. Chris Ramsden and Dr. Joseph Hibbeln from the NIH, who have taken a deep view into this controversy. In a series of papers4 they reviewed all the research on this topic, digging deep into history, going all the way back to data hidden away from the 1960s. There are two major kinds of studies, as we have discussed. The first is population or observational studies, which can show correlation but do not prove cause and effect. These can be helpful to highlight correlations among things (like fat and heart disease) but can also lead people down the wrong path because, even though they might show a correlation, they don’t prove cause and effect. That is why we need the second type of study, or experimental studies, often called randomized controlled trials. When these are well done, they can prove cause and effect. Most of our advice about fat in the diet comes from the population-type studies because dietary interventions on a large scale are often very hard to do. But there are some important experimental studies, and Drs. Ramsden and Hibbeln have reviewed them all and taken a look at the long history of fat and saturated fat. They paint a picture of omega-6 fats that contradicts the conventional wisdom.
Here’s what they found:
1. In a review of studies where people consumed a mixture of omega-3 and omega-6 fats, there was in fact a 27 percent reduction in heart attacks and death.
2. If studies increased only omega-6 fats, there was a 13 percent increase in heart attacks.
3. Randomized trials that used omega-6 fats alone (without any omega-3 fats) while reducing saturated and trans fats also showed an increased risk of death.
4. Many of the current recommendations and the analysis on which they were based omitted a number of important studies and didn’t distinguish between studies in which people only consumed omega-6 fats from those in which people consumed a combination of omega-3 and omega-6 fats.
For example, one highly cited study that many scientists consider critical in supporting the recommendations for more PUFAs (which is translated into more omega-6 vegetable oils in food policy) is the Oslo Diet-Heart Study. The participants were told to substitute meat and eggs for fish, shellfish, and “whale beef,” all rich sources of omega-3 fats. They were even given considerable quantities of Norwegian sardines canned in cod liver oil as a “bread spread.” This is about the equivalent of sixteen fish oil pills, about five times the amount given in an Italian study that showed a reduction in sudden cardiac deaths by 40 percent and total deaths by 20 percent.5 The study participants were also told to cut out trans fats and limit refined grains and sugar. All these things reduce the risk of heart disease. This study never proved that high levels of omega-6s were beneficial. They showed only that eating more ome
ga-3 fats and eating less trans fats and sugar and refined grains are protective.
The only trial mentioned in the big recent analysis that is used as the basis to recommend a higher amount of PUFAs from omega-6 in the diet that looked only at an increase in omega-6 fats was the Minnesota Coronary Survey of 4,393 men and 4,664 women. The women in this study more than doubled their risk of heart attack in the first year. This showed an increased risk of heart attacks! In other studies that used corn and safflower oil (mostly omega-6 linoleic acid), participants had a 4.64-fold increased risk for heart attacks and death from all causes. That is a 464 percent increase in bad outcomes from eating too much omega-6 oil.
The Lyon Heart Study, the randomized controlled trial mentioned previously that showed a 70 percent reduction in heart attacks, was the only study that reduced the amount of omega-6 fats below 5 percent of calories while increasing the omega-3 fats.
The final death knell for omega-6 PUFA being touted as a health food was the Sydney Diet Heart Study.6 Drs. Ramsden and Hibbeln went back and dug into all the original data on this big randomized controlled trial done from 1966 to 1973. This study was designed to find out if using more omega-6 oils from safflower oil and cutting out saturated fat would impact heart disease risk. Participants were told to increase safflower oil to 15 percent of calories, while decreasing saturated fat to less than 10 percent of calories and cholesterol to less than 300 milligrams a day. Safflower oil is a concentrated source of linoleic acid, the fat that leads to inflammation in the body. The study did instruct participants to include some margarines, which may have increased trans fats, but both groups had trans fats in equal amounts, so this probably didn’t affect the results. Also the safflower oil margarine was soft and didn’t contain as many trans fats as hard margarine or shortening.
So what did the study show? Compared to the group that ate more saturated fats and cholesterol, the linoleic omega-6 fat group had an increased risk across the board of death from all causes, heart attacks and cardiac deaths. In fact, the omega-6 group had a 37 percent increased risk from heart attacks, despite significant lowering of their cholesterol.
How could this be? Well it turns out the omega-6 fat, linoleic acid, can create a lot of havoc in the body, the kind of havoc that leads to heart disease.
First, omega-6s easily oxidize or go rancid, which makes any cholesterol you do have much more likely to cause heart disease. Even if your cholesterol is low, if it is oxidized or rancid, it is much more likely to cause heart attacks. These fats are called OXLAMs, or oxidized linoleic acid metabolites; think of them as rancid fats. They are what make up the cholesterol plaques in your arteries. Things that increase oxidative stress—such as smoking, excessive drinking, and low intake of dietary antioxidants such as fruits and vegetables—all increase heart disease (and all chronic illnesses).
And these NIH scientists are not alone. A recent review of all the literature published in the Mayo Clinic Proceedings in 2014 pointed out the flawed basis of our current recommendations to lower saturated fat and increase omega-6 fats.7 Unfortunately this advice still has not penetrated the recommendations coming from any advisory group or the government.
What’s clear is that we have been given completely wrong advice over the last 50 years. We were told to cut saturated fat and cholesterol, increase omega-6 PUFAs, and increase our carb intake. This has been a massive failure of public policy and has provided us a window into the challenges of nutrition research. The time has come for a change.
THE FLAWED AMERICAN HEART ASSOCIATION ADVISORY ON OMEGA-6 FATTY ACIDS
The American Heart Association (AHA) recommends that adults get no more than 5 percent of their calories from saturated fat, and urges people to use linoleic-rich (omega-6 polyunsaturated fats, or PUFAs) vegetable oils instead. The AHA advises people to eat at least 5 to 10 percent of their calories in the form of omega-6 PUFAs. The rationale for this is that linoleic acid, unlike saturated fat, lowers LDL (bad cholesterol) levels.
As a result, the average intake of linoleic acid (an omega-6 fatty acid) has risen sharply since the 1960s, and even more dramatically since the early 1900s. Americans consume at least twice the amount of linoleic acid today that they did in the 1960s (at least 7 percent of daily calories, up from 3 percent in 1960).
In 2010, Philip C. Calder, a scientist at the University of Southampton’s Institute of Human Nutrition, published an analysis of the recommendations on linoleic acid.8 Based on the evidence, he warned that while linoleic acid lowers LDL, it also makes cholesterol more vulnerable to oxidation (going rancid) and inflammation, which can increase atherosclerosis, or cholesterol deposits in the arteries. There is also some evidence that it promotes cancer. As one expert UK committee warned, “There is reason to be cautious about high intakes of omega-6 PUFAs, and we recommend that the proportion of the population consuming in excess of about 10 percent of energy [as n-6 PUFAs] should not increase.”
There are many reasons why linoleic acid should be consumed only in moderation, Dr. Calder argues. But the most important are that it increases arachidonic acid, which is pro-inflammatory, and perhaps more importantly acts as an antagonist of omega-3 fatty acids.
Recently, the American Heart Association published an advisory that declared the benefits of increasing omega-6 fatty acids but didn’t address the potential harm. The advisory argued that concerns about inflammation, thrombosis, and LDL oxidation were unsubstantiated.
But Dr. Calder argues that the AHA advisory was flawed. Most of the evidence for the advisory came from observational studies. It also included randomized controlled trials, but the majority of those trials had design flaws. “Although these limitations appear not to have been considered in developing the advisory, they may have influenced its major scientific conclusion (replacing saturated fatty acids with PUFAs lowered cardiovascular events), which is clearly not an omega 6 fatty acid (or linoleic acid) specific summary statement, and so somewhat blurs the boundaries between PUFA [which includes protective omega-3 fats], omega-6 PUFA and linoleic acid,” Dr. Calder wrote.
The AHA advisory and recommendations are based on randomized controlled trials that often did not address the question of omega-6 PUFA or linoleic acid in isolation, “but rather included mixtures of omega-6 and omega-3 PUFA.” And for that reason—and others—Calder wrote, Americans should be cautious about following any recommendations to increase omega-6 PUFA intake. In fact most other studies that separated out the omega-3 and omega-6 fats found that without the omega-3 fats there was no benefit and that the omega-6 fats caused increased risk of heart attacks and death. Let’s look at some of the other risks of the increase in omega-6 fats in our diet.
HOW EXCESS OMEGA-6 FATS AFFECT OUR HEALTH
Dr. Joseph Hibbeln from the National Institutes of Health has researched the impact of omega-6 oils on our health.9 He explains that the overconsumption of omega-6 fats and the underconsumption of omega-3 fats have led to increases in the following:10
Cardiovascular disease
Type 2 diabetes11
Obesity
Metabolic syndrome (pre-diabetes)
Irritable bowel syndrome and inflammatory bowel disease
Macular degeneration (age-related blindness)
Rheumatoid arthritis
Asthma
Cancer
Psychiatric disorders
Autoimmune diseases
Dr. Hibbeln found that the increase of linoleic acid, mostly from soybean oil, in the diet from 1960 to 1999 in five countries studied predicted a 100-fold increase in the risk of homicide deaths.12 Not only do these vegetable oils result in more heart attacks, obesity, and cancer, but they may make people murderers! Considering omega-3 fats make up much of your brain tissue, this makes sense because high intake of omega-6 fats interferes with the benefits of omega-3 fats. Another study on ulcerative colitis showed a 250 percent increased risk of inflammatory bowel disease in the group that consumed the highest amount of linoleic acid.13
D
r. Hibbeln says in his review that the “increases in world LA (linoleic acid) consumption over the past century may be considered a very large uncontrolled experiment that may have contributed to increased societal burdens of aggression, depression, and cardiovascular mortality. It’s quite likely that most of the diseases of modern civilization, major depression, heart disease, and obesity are linked to the radical and dramatic shift in the composition of the fats in the food supply.”
He goes on to say that “increasing tissue concentrations of omega-3 fats on a population level may result in a substantial decrease in health care costs by reducing the illnesses that account for the largest burden of disease worldwide.”
In Part III, you’ll learn what I recommend when it comes to which fats to eat and which to stay away from. Here’s a quick sneak peak:
Cut out refined oils except extra virgin olive oil.
Use extra virgin coconut oil and a little grass-fed butter or ghee.
Stop fearing animal fat, but stick with grass-fed, pasture-raised, and organic.
Get fats from whole foods like avocados, nuts, and seeds.
Are Genetically Modified Crops a Health Danger?
Most vegetable oils are made from genetically modified crops (genetically modified organisms, or GMOs).14
While GMOs are highly controversial and may not be all bad, there are some concerns in the science. The American Academy of Environmental Medicine (AAEM) reported that “several animal studies indicate serious health risks associated with GM food,” including infertility, immune problems, accelerated aging, faulty insulin regulation, and changes in major organs and the gastrointestinal system. The AAEM asked physicians to advise patients to avoid GM foods.15