Why is Oil Bad for You?

Mark Hyman | February 11, 2016

We were all trained that vegetable oils were good and butter was bad. We were told, even by government and medical associations, to use more vegetable, seed and bean oils (like soybean, corn, safflower, canola). Chances are, you've been convinced by the government and food industries that vegetable oils are safe to use as a heart-healthy alternative over traditional saturated fats.

We were told that traditional fats like butter, lard and coconut oil caused high cholesterol and clogged arteries, leading to heart disease. Experts advised us to avoid saturated fat and eat more polyunsaturated fatty acids (PUFAs), especially omega 6 fats.

These are the so-called “vegetable” oils many of us grew up on. Found at your typical grocery store, these clear, tasteless, highly refined and processed oils include corn, soybean, canola, safflower and sunflower oils.

These highly unstable, highly inflammatory oils were given a gigantic push by advisory groups we trusted, even our government’s own dietary guidelines. Many well-respected scientists and our doctors told us to stop using saturated fats and use the polyunsaturated fats instead.

Turns out they were completely wrong.

Why Vegetable Oils Should Not Be Part of Your Diet

In a 2010 review at Tufts University, Dr. Dariush Mozaffarian concluded there is a clear benefit from cutting out saturated fats and increasing our intake of PUFAs. However in 2014, the very same scientist reviewed all of the literature again. This meta-analysis, which reviewed 72 studies, found no benefit to reducing saturated fats or increasing PUFAs, except for omega 3 fats.

Is it any wonder we are so confused? If the experts can’t even agree and they change their perspective every few years, what are the rest of us to do?

Let me cut through this confusion. The very idea that vegetable oils are better than saturated fats (like butter and lard) comes from the belief that they lower total and LDL cholesterol, so they presumably reduce our overall risk of heart disease.

Following this type of advice means swapping out butter, meat and lard for vegetable oils including corn, soybean, sunflower, canola and safflower oils, which are all omega 6-rich, inflammatory polyunsaturated fats.

Yet if we look at human history, we consumed much more omega 3 fats and much less omega 6 fats than we currently do, since wild foods are very rich in omega 3 fats. The main source of omega 3’s today is fish, yet wild game and wild plants, which are very high in omega 3s, used to be a much bigger part of our diet.

Grass-fed cattle significantly increases the omega 3 content of the meat, producing a more favorable omega 6 to omega 3 ratio than grain-fed beef. Virtually all of the beef and animal products your great grandparents ate were pasture-raised, organic, grass-fed and contained no hormones or antibiotics. There was simply no other kind of meat to eat.

Introducing refined oils into our diet and moving away from grass-fed and wild animals increased our omega 6 fat intake. Corn, soy, cottonseed and canola oils skyrocketed, while omega 3 fats have dramatically declined. In that surge, many Americans sadly became deficient in these essential omega 3 fats.

Omega 6 fats not only fuel your body’s inflammatory pathways, but also reduce availability of anti-inflammatory omega 3 fats in your tissues, resulting in more inflammation.

In other words, omega 6 fats undo any benefit eating omega 3s would normally give you. They also reduce conversion of plant-based omega 3 fats (called alpha-linolenic acid or ALA) into the active forms of omega 3s called EPA and DHA by about 40 percent.

Consuming too many omega 6 fats also increases the likelihood of inflammatory diseases and links to mental illness, suicide, and homicide. In fact, studies have shown a connection between mood disorders and inflammation in the brain.

Dr. Joseph Hibbeln from the National Institutes of Health has researched the impact of omega 6 and omega 3 fats on our health and recommends focusing on the ratio of essential fatty acids. He explains that over-consuming omega 6 fats and under-consuming omega 3 fats may increase risk of:

  • Heart disease
  • Type 2 diabetes
  • Obesity
  • Metabolic syndrome or pre-diabetes
  • Irritable bowel syndrome
  • Inflammatory bowel syndrome
  • Macular degeneration (eye damage and blindness)
  • Rheumatoid arthritis
  • Asthma
  • Cancer
  • Psychiatric disorders
  • Autoimmune disease

As you can see, a diet high in omega 6 fats is not ideal for optimal health. We can’t blame ourselves for this catastrophe. Most of us were taught to use these refined oils at a young age. Unfortunately, this has resulted in the worst epidemic of chronic disease in history, with global explosions of heart disease, type 2 diabetes and obesity (or what I call diabesity), and cancer.

Bottom line: We’ve got to move away from these inflammatory fats.

What Fats and Oils Should You Eat?

What types of oils and fats should we choose that protect our heart and brain and reduce inflammation? I prefer traditional fats, such as:

  • Extra-virgin, cold-pressed, organic coconut oil – my personal favorite because it is excellent cell fuel, is highly anti-inflammatory and may help with improving your cholesterol panel
  • Extra-virgin, cold-pressed, organic olive oil
  • Avocados
  • Grass-fed meats
  • Grass-fed butter
  • Nuts—walnuts, almonds, pecans, macadamia; not peanuts
  • Fatty fish—sardines, mackerel, herring and wild salmon—that are rich in omega 3 fats

Has your perception of fat changed since learning about which fats are healthy and which fats you should avoid? Let us know by sharing your story in the comments below.


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Mark Hyman

Mark Hyman, MD, believes that we all deserve a life of vitality - and that we have the potential to create it for ourselves. That’s why he is dedicated to tackling the root causes of chronic disease by harnessing the power of Functional Medicine to transform healthcare. Dr. Hyman and his team work every day to empower people, organizations, and communities to heal their bodies and minds, and improve our social and economic resilience.

Dr. Hyman is a practicing family physician, an eight-time #1 New York Times bestselling author, and an internationally recognized leader, speaker, educator, and advocate in his field. He is the Director of the Cleveland Clinic Center for Functional Medicine. He is also the founder and medical director of The UltraWellness Center, chairman of the board of the Institute for Functional Medicine, a medical editor of The Huffington Post, and has been a regular medical contributor on many television shows including CBS This Morning, the Today Show, CNN, The View, the Katie Couric show and The Dr. Oz Show.

Dr. Hyman works with individuals and organizations, as well as policy makers and influencers. He has testified before both the White House Commission on Complementary and Alternative Medicine and the Senate Working Group on Health Care Reform on Functional Medicine. He has consulted with the Surgeon General on diabetes prevention, and participated in the 2009 White House Forum on Prevention and Wellness. Senator Tom Harkin of Iowa nominated Dr. Hyman for the President’s Advisory Group on Prevention, Health Promotion, and Integrative and Public Health. In addition, Dr. Hyman has worked with President Clinton, presenting at the Clinton Foundation’s

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