Authors: Chris Kresser
Tags: #Health & Fitness / Diet & Nutrition / Diets, #Health & Fitness / Diet & Nutrition / Weight Loss
The final category of response to gluten is tolerance. Dr. Weston Price, the American dentist who studied the health of traditional peoples (see
here
), documented cultures that maintained excellent health while also consuming gluten-containing grains, such as the people of the Loetschental Valley in Switzerland. If gluten can make so many ill, why did these people remain so healthy? We don’t currently understand all of the factors that contribute to gluten sensitivity, but genetics certainly plays a strong role in CD, and it probably does in NCGS as well. Researchers believe that
patients who test negative for the two main genes associated with celiac disease—HLA-DQ2 and HLA-DQ8—are significantly less likely to have NCGS. Diet, the gut flora, immune status, and other factors we don’t yet understand all influence susceptibility to NCGS and CD.
The problem is it’s difficult to know what category of gluten response you’re in. Fewer than one in six people who have CD are aware they have it, and the percentage is almost certainly lower in the case of NCGS. The testing is flawed, and the symptoms are so broad and nonspecific that many doctors and patients with symptoms not typically associated with gluten sensitivity will overlook the possibility of NCGS or CD. Another issue is that we don’t currently understand what moves someone from tolerance to intolerance or sensitivity.
Considering the seriousness of the conditions that gluten sensitivity can cause, the fact that there is no need for gluten in the human diet, and the low nutrient density and bioavailability of gluten-containing grains, I recommend that everyone perform a gluten challenge to determine whether he or she is intolerant. If you have a reaction to gluten when you add it back into your diet after the three-month period without it, it’s crucial that you strictly avoid gluten indefinitely. If you do not react to gluten, I still recommend avoiding it for the most part because of its potential to cause harm and our uncertain understanding of what shifts people from tolerance to intolerance. That said, if you don’t have an obvious reaction to gluten, an occasional piece of bread or gluten-containing food when you’re out with friends or traveling is unlikely to cause problems.
At this point you may be asking yourself,
If the nutrient-density scores for grains are so low, even without taking bioavailability into account, and gluten is so potentially toxic, why are these grains constantly referred to as healthy?
That’s a great question, and it’s not easy to answer quickly. There are many reasons for the emphasis on grains in the American diet, including their low price and ease of storage, a
widespread lack of understanding of the nutrient inhibitors they contain, and the misguided fear of animal foods that has swept our nation over the past sixty or so years.
But the low nutrient scores of grains and their potential toxicity should make you question the American Heart Association’s recommendation that you consume six to eight servings of grains a day. Following this advice will almost certainly result in your eating a less nutrient-dense diet, especially if the grains are in refined form (which is by far the most common way they are consumed in the industrialized world).
In addition to their generally low nutrient density, grains have significant nutritional shortcomings. For example, they contain no retinol (active vitamin A) at all and, with the exception of yellow corn, no beta-carotene (retinol’s precursor) either. Nor do grains contain vitamin C or vitamin B
12
. In the context of a mixed diet containing fish, meat, and fruits and vegetables, these shortcomings aren’t particularly problematic. But in people following grain-heavy vegetarian and vegan diets, they can be serious problems.
Poor nutrient content is not the only thing to be concerned about when it comes to grains. As I’ve explained in this chapter, many grains contain proteins capable of provoking an immune response or allergic reaction. Gluten, which is found in wheat, barley, rye, and (sometimes) oats, is the best example of this.
Overall, the evidence indicates that grains are a suboptimal food source when compared to meat, fish, vegetables, fruits, and nuts. Does that mean you should strictly avoid them 100 percent of the time? Not necessarily. In my clinical practice, I’ve found that most people feel better without any grains or legumes in their diets. However, if you’re fundamentally healthy, and you’re following a nutrient-dense diet, you may be able to tolerate them in moderation. If you do choose to include grains and legumes in your diet, they should be prepared properly (soaked, sprouted, or fermented) to improve nutrient bioavailability and inactivate food toxins, and they should never replace more nutrient-dense foods like animal products, vegetables, and fruits. See my website for links to resources on how to properly prepare grains and legumes.
Industrial seed oils are oils made from the seeds of plants such as corn, soybean, cotton, sunflower, and safflower. Historically they’ve been used in a variety of applications, ranging from manufactured products (e.g., soaps, candles, perfumes, cosmetic products, and insulators) to lubricants to pet-food additives to fuel (e.g., biodiesel). (Their use in the preparation and manufacturing of so many products is why they’re referred to as “industrial” seed oils.) But today they’re marketed primarily as heart-healthy oils and used in just about all processed, packaged, and refined foods, as well as in most restaurant kitchens. This has led to a dramatic increase in the consumption of these oils. For example, intake of soybean oil has increased by more than a thousandfold since the early 1900s, and consumption of linoleic acid, the primary fatty acid in seed oils, has risen by more than threefold.
We’re only beginning to understand the consequences of such a dramatic increase in seed-oil consumption, but based on current evidence, I believe they should be minimized in the diet for three reasons:
•
They contain high amounts of linoleic acid (LA), which some research suggests is harmful when consumed in excess.
•
They are easily oxidized (damaged), and oxidative damage is associated with numerous modern inflammatory diseases.
•
There’s no strong evidence that they protect against heart disease in humans, and there is some evidence that they may increase the risk.
Let’s look at each of these reasons in more detail.
Linoleic acid (LA) is an essential fatty acid, which means the body requires it for proper function but can’t synthesize it and must obtain it from the diet. However, the actual requirement for LA is very small: as little as 0.1 percent of total calories consumed per day. Studies show that intake of LA in the modern diet averages between 4 and 10 percent of
total calories per day (mostly from highly processed seed oils), which means we’re getting up to one hundred times the amount required.
In contrast, most traditional cultures had very low intakes of LA, and what they got came exclusively from whole foods like vegetables, nuts and seeds, and meat. As you’ll see below, LA from industrial seed oils has a different effect on the body than LA from whole foods, because it is more likely to oxidize.
Linoleic acid is highly vulnerable to oxidation when exposed to heat (during food processing or cooking). It promotes the formation of compounds called OXLAMs, which are by-products of LA associated with a variety of diseases ranging from Alzheimer’s to fibromyalgia to nonalcoholic fatty liver disease (NAFLD). OXLAMs are a major component of oxidized LDL and atherosclerotic plaques, and play a central role in development of heart disease. Oxidized linoleic acid causes atherosclerosis in animal studies, and at least one human study has shown that higher intake of LA in the presence of risk factors for oxidative damage (like smoking) increases the risk of heart disease. Reducing linoleic acid intake has been shown to decrease circulating OXLAM levels.
High intakes of linoleic acid are particularly problematic when the long-chain omega-3 fat DHA, found exclusively in seafood, is absent from the diet. This creates a pro-inflammatory environment in the body and may also interfere with neurological function because of the important role DHA plays in the brain and nervous system. Unfortunately, the combination of high LA intake and low DHA consumption is a common scenario in the typical modern diet, which is high in processed and refined foods and low in cold-water, fatty fish.
For years we’ve been taught that saturated fats found in such foods as red meat and butter will clog arteries and cause heart attacks and that vegetable oils are a heart-healthy alternative. As of 2013 the American Heart Association still recommended using liquid vegetable oils (like corn,
safflower, sunflower, soybean, and canola oils) or nonfat sprays for cooking and drastically limiting use of coconut oil, butter, palm oil, and other saturated fats.
Yet these recommendations are based on outdated evidence that is decades old. While it’s true that some early studies suggested that vegetable oils were heart-healthy, those studies did not distinguish between the effects of omega-3 and omega-6 polyunsaturated fats (which I’ll cover in the next chapter) found in these oils. More recent research that studied the effects of omega-3s and omega-6s separately found that vegetable oils high in omega-6 linoleic acid did not prevent heart disease and in fact may actually increase the risk. One study demonstrated that, compared to control subjects, patients who increased their intake of linoleic acid and reduced their saturated-fat intake had a higher risk of death from cardiovascular disease and all other causes. This occurred despite a reduction in LDL and total cholesterol in these patients. An analysis of other randomized controlled trials—considered the gold standard of medical evidence—also found that higher intakes of linoleic acid increased the risk of heart disease and death.
Finally, it’s important to note that industrial seed oil has almost no nutritional value: it is a calorie-dense but nutrient-poor substance. Given the serious health problems it can contribute to and the fact that it was entirely absent from the diets of healthy, traditional cultures, I think it’s wise to avoid industrial seed oils as much as possible.
Studies going back more than forty years have shown that naturally occurring sugars in fruits and vegetables are beneficial to health and do not promote weight gain. Traditional cultures like the Hadza of north-central Tanzania and the Kuna of Panama obtain a large percentage of their total calories from foods that are high in natural sugars, such as fruit, starchy tubers, and honey. Yet they are remarkably lean, fit, and free of modern disease.
However, excess refined sugar—in the form of table sugar and high-fructose corn syrup—is a different story. Added sugars are harmful
primarily because they promote overeating and weight gain. When people add fat to their diets, they tend to eat less of something else (usually carbohydrates), and if they eat more carbs, they’ll usually eat less fat. However, the same kind of swap is not true for increased sugar intake—especially when the sugar is in liquid form (e.g., soft drinks and other sugar-sweetened beverages). Most people fail to reduce their caloric intake to compensate for the extra calories they’re consuming in sweetened drinks. For example, a study of 323 adults found that subjects who increased the number of calories they obtained from sugar-sweetened beverages didn’t then decrease the amount of calories they got from other foods and thus had greater calorie intake overall. Another study showed that total calorie intake among sixteen patients was greater on the days that sugar-sweetened beverages were given at lunch than on the days they weren’t. Added sugar causes weight gain whether it’s eaten in the form of glucose or fructose; contrary to popular belief, excess fructose is no more fattening than excess glucose.
Excess weight isn’t just a cosmetic problem—it contributes directly to metabolic and cardiovascular disease. Studies consistently show that overeating and fat gain cause insulin resistance. Insulin resistance, in turn, is associated with diseases ranging from diabetes to heart disease to Alzheimer’s.
Added sugar can also cause problems in the digestive tract, where it promotes bacterial overgrowth in the small intestine and may cause gas, bloating, and constipation or diarrhea. Excess fructose may be particularly harmful for the gut; it’s poorly absorbed and leads to bacterial fermentation and excess gas production, particularly in people with digestive problems. In fact, there’s almost no end to the list of problems too much refined sugar in the diet can cause. About twenty years ago, Nancy Appleton, PhD, began researching all the ways in which sugar destroys health. Over the years, the list has continuously expanded, and it now includes 141 points. Here’s just a small sampling (the entire list can be found on her blog). Excess sugar:
•
Suppresses the immune system
•
Causes imbalances of essential minerals like copper and zinc
•
Decreases tissue elasticity and function
•
Interferes with nutrient absorption
•
Causes tooth decay
•
Decreases growth hormone levels
•
Contributes to depression and other mood disorders
•
Increases the risk of breast cancer
There’s a lot more to the Paleo diet than removing food toxins from your diet. That said, if everyone on a standard American diet stopped eating cereal grains, industrial seed oils, and excess sugar tomorrow, I’m willing to bet that the rates of obesity, diabetes, heart disease, and just about every chronic inflammatory disease would plummet over the next decade. As I said at the start of this chapter, if going on a full-scale Paleo diet seems overwhelming or if you’re not prepared to do it for whatever reason, begin with eliminating (or at least greatly reducing) these toxins in your diet. If you’re like most of the people I’ve worked with, you’ll feel like a different person. And that will give you the motivation and energy you need to take the next steps toward feeling even better.