Catherine Shanahan, MD, Author of Deep Nutrition: Why Your Genes Need Traditional FoodNovember 2017
By Garry Messick
Dr. Catherine Shanahan says her book, Deep Nutrition, written in collaboration with her husband, Luke, grew out of being “overwhelmed by the amount of medical research that did nothing to explain chronic illnesses, or what to do to actually cure them.” Thus began her journey delving into various diets from all over the world, looking for the ones most closely associated with fostering good health and longer lifespans.
Dr. Shanahan eventually arrived at what she calls “the human diet,” which is based on the four nutritional strategies of consuming fresh foods, fermented and sprouted foods, meat cooked on the bone, and organ meats. She also discovered the ways in which what we eat interacts with our DNA and affects not just our health but the health of our offspring.
In the following interview, Dr. Shanahan focuses on some of the most important foods to avoid—namely certain types of vegetable oils and sugar, and the serious damage they can do to your health.
LE: In your book, you mention olive oil, peanut oil, macadamia nut oil and coconut oil as healthy fats that are good for cooking, but you’re extremely critical of other types of commonly used vegetable oils such as corn or canola oil. Can you explain why?
CS: Vegetable oil is the lipid extracted from corn, canola, soy, sunflower, cottonseed, safflower, rice bran, and grapeseed. Vegetable oil doesn’t come from broccoli, and it doesn’t equate to a serving of greens. It is found in almost all ready-made foods, from granola and squishy-soft baked goods, to rice milk and soy milk, to vegetarian cheese and meat substitutes, to frozen meals and side dishes… Dietary vegetable oil can transform ordinary fatty acids into a kind of atomic tornado. Tearing through cellular structures and leaving molecular wreckage in its wake.
Eating vegetable oil doesn’t just mess up your arteries. Those disruptive free radicals can interfere with nearly everything a cell might need to do, leading to almost any disease you can name. At no point in our life cycle is this disruption more devastating than while we’re developing in the womb.
In 2006, when researchers tested the blood of mothers whose babies were born with congenital spinal and heart defects, they found evidence of oxidative stress, exactly what you would expect to find in someone eating lots of vegetable oil. In 2007, an article in Genes to Cells showed how oxidative stress can disrupt hormone production and interfere with hormonal responses, suggesting that women who consume vegetable oil while pregnant are increasing their child’s risk of all kinds of growth deformities and disease. So if you are pregnant or plan on getting pregnant, banish vegetable oil and foods containing vegetable oil from your kitchen, and get the stuff out of your life.
LE: Expand, if you would, on the dangers of commercially processed vegetable oils as they relate to oxidative stress.
CS: Lipid scientists have been publishing papers on this topic for decades, trying to warn us that vegetable oil-rich diets can cause dangerous oxidative stress and are an under-recognized cause of heart disease and accelerated aging. But the most terrifying aspect about vegetable oil is that it’s also destroying the organ most susceptible to oxidative stress, our brains. It’s no exaggeration to say that vegetable oil attacks your family legacy at both ends of the generational spectrum, robbing your children of their physiologic birthright and erasing memories from our parents’ and grandparents’ minds.
Thanks to vegetable oil’s inherent ability to inhibit life, vegetable oils are the chemicals that preserve a Twinkie for years on end. More than any other ingredient, vegetable oil is what puts the “junk” in junk food. A patient of mine on Kauai told me that the paniolos (Hawaiian cowboys) used to cure hide leather to make their saddles using cottonseed oil, but did they eat the stuff? Ho, brah, dat’s lolo (“crazy”). They didn’t eat it, and neither should you.
LE: In what part of the body do the adverse effects of vegetable oil first manifest?
CS: Vegetable oil often initiates its attack on the brain by first attacking the gut. More and more researchers are appreciating the connection between gut and brain function. Inflammation in the gut causes heartburn, which is just the tip of the inflammation iceberg and should serve as a kind of red flag telling us that whatever we’re eating is harmful.
LE: Let’s move on to another major enemy of good health: sugar. People often have a really difficult time cutting it from their diet.
CS: I promise, even if you really love sweet stuff, cutting your sugar intake way down will not be a big deal. Getting rid of sugar allows you to taste the natural sweetness in foods that your palate couldn’t previously detect.
Of course, we need sugar in our bloodstream just to stay alive. But things go awry when you eat more than your body can deal with. Because sugar—in high concentration—is a rarity in nature, the human metabolism is simply not prepared for exposure to the 100-plus pounds the average American now consumes yearly. In a different century, only the wealthy could indulge in sweets made with refined sugar. Now, sugar is a mainstay of the modern diet.
LE: What were your findings after your research into sugar?
CS: I found that the consequences of excess sugar consumption are disastrous, especially in childhood. As sugar seeps into your tissues, it coats the surface of cell membranes, with life-changing consequences.
As a young girl, I would often sneak away to the corner candy store or munch on handfuls of the chocolate chips I would sometimes find hidden in the kitchen pantry, stressing my body’s connective tissues already weakened by my low-fat, low-cholesterol, no-meat-on-the-bone diet. And the sugar encrusting my cells interfered with hormone receptor function, disrupting the complex series of physiologic developments scheduled to take place during puberty. As a result, I had no idea what all the fuss over boys was about until shortly after I went to college.
You may have heard that, on average, we gain ten pounds a decade after the age of 35. Women, in particular, start reporting that they can’t eat like they used to. This phenomenon may be directly related to the biochemical effects of sugar binding to hormone receptors, jamming them, and rendering us insensitive to the hormone insulin. Once you are insulin resistant, blood-sugar levels rise higher still, leading to diabetes and all its related disorders, including weight gain and circulatory and sexual dysfunction.
For the same reasons sugar jams hormone signals, it also clogs nutrient channels, weakening bone and muscle and slowing neural communication, which can impair mood and memory and lead to dementia. While all this is going on, sugar stiffens the collagen in your tendons, joints, and skin, causing arthritis and premature wrinkling, while interfering with the production of new collagen throughout your entire body. And because sugar changes the surface markers your white blood cells need to distinguish indigenous cells from invaders, it opens the door to cancer and infection.
LE: How does sugar do all this damage?
CS: Ever notice how licked lollipops and half-chewed taffy have a tacky feeling? Sugar feels sticky because, once dissolved in water, it reacts with proteins on the surface of your skin to form easily breakable chemical bonds. When you pull your fingers apart and feel that sticky resistance, you’re feeling the tug of those bonds being broken. The process by which sugar sticks to stuff is called glycation. Glycation reactions become permanent due to oxidation reactions. The products of these later oxidation reactions are called advanced glycation end products, or AGEs. And that’s a useful acronym, because AGEs make you age unnaturally fast.
When you toast bread, oxidation reactions generate AGEs in the proteins and sugars present in the wheat. These AGEs change the bread from soft, pliable, and pale, to hard, stiff, and brown because the proteins and sugars form cross-links that stiffen the bread. The same thing happens inside your body as AGEs cross-link normally mobile proteins. This hardens your cells and tissues, making them brittle and stiff. Fortunately, at normal blood-sugar levels, the reactions occur so slowly that cleanup crews of white blood cells keep them under control by breaking them down. The kidney cleans these AGEs from the blood and excretes them from the body. It is principally these waste chemicals that give urine its characteristic yellow color.
LE: What kind of damage does all of this do to your health?
CS: The clinical implications of having your tissues hardened by sugar-protein cross-links are vast and far-reaching. Cross-links turn the semi-permeable surfaces of arteries into impervious walls, preventing nutrients from exiting the bloodstream. When trapped nutrients can’t escape your bloodstream, where do you think they end up? Lining your arteries. When lipoproteins deposit on the arterial lining, they attract white blood cells, and can cause blood clots and/or atherosclerotic plaques. A few cross-links on your white blood cells slow them down, making infections more likely and more serious. Debilitated white blood cells permit nascent cancer cells to grow under their noses, unchallenged. Are your joints creaky and stiff? AGEs can form in them, too. AGEs (primarily from high blood sugar) are one of two major biochemical phenomena that make us look and feel old, the other being free radicals, primarily from vegetable oils.
LE: Collagen is also vulnerable to the effects of vegetable oil and sugar, isn’t it?
CS: You hear all the time about supernutritious foods touted as anti-aging miracles. The combination of sugar and vegetable oil, and its effects on the tissue whose integrity is most related to your physiologic age—collagen—might rightly be called the miracle foods of age acceleration. Because when it comes to staying young and feeling young, collagen is a big deal.
Like other tissue types, collagen is made from raw materials you must eat. Unlike other tissues, however, collagen is uniquely sensitive to metabolic imbalances. When your body is making collagen, it’s performing a physiologic high-wire act, a feat of extraordinary timing and mechanical precision. This level of complexity makes collagen more dependent on good nutrition and more vulnerable to the effects of proinflammatory foods than other tissue types.
Collagens are a family of extra-cellular proteins that give skin its ability to move, stretch, and rebound into shape… Collagens aren’t just in skin; they’re everywhere, imparting strength to all your tissues. Just as strands of collagen running between skin cells hold our outermost layer of skin together, collagens unite adjacent cells in all your glands and organs, from collagen-rich robust tissues like bone and heart valves to squishy soft lower collagen-content organs like brain, liver, and lungs. Bundles of collagen form extended strips and sheets in the sturdier tissues like ligaments and tendons that surround your joints and hold your skeleton together.
If any one of the thousands of steps involved in making collagen goes haywire—which is likely to happen if your diet was poor during critical growth periods, meaning your diet was low in nutrient-rich foods and high in sugar and vegetable oils—the integrity of the finished product is compromised and may break down prematurely. You might imagine that with lesser-quality collagen holding us together, our tissues would start pulling apart and separating after a certain number of years. That’s exactly what causes wrinkling, arthritis, and even circulatory problems.
No matter the strength of your collagen today, how good you feel tomorrow depends a lot on your diet. People who eat proinflammatory foods experience more joint damage on a daily basis because sugar acts like an abrasive in the joints. At night, the small frays and tiny breaks in the collagen that formed during the day must be repaired. But inflammation interferes with healing. Instead of waking up feeling recovered, people on bad diets wake up with stiff joints. Their scars and stretch marks will be more obvious too, because inflammation disorganizes the collagen fibers so that, as tissue heals, it forms irregular lumpy mounds or deep pits, with more disfiguring results.
LE: In closing, how do you advise people to start on a path to better nutrition, as outlined in your book?
CS: I’m not going to try to convince you that adapting a Deep Nutrition lifestyle is something you can do overnight. Unless you’re a chef, or majored in home economics, there are likely quite a few skills you may need to acquire. But there’s no reason you must do it all at once.
Food is like a language, an unbroken information stream that connects every cell in your body to an aspect of the natural world. The better the source and the more undamaged the message when it arrives in your cells, the better your health will be.
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