Spice Mixes
While there have been a considerable number of studies done with individual spices, few have looked at increasing spice consumption in general. One group at Pennsylvania State University did compare the effects of a high-fat chicken meal with and without a mixture of nine herbs and spices. Herbs and spices were chosen because, ounce for ounce, they have more antioxidants than any other food group (and because the study was funded by the McCormick spice company).92
Unsurprisingly, the people in the spice group experienced a doubling of the antioxidant power in their bloodstreams compared to participants in the spice-free group. Remarkably, though, the spice group ended up with 30 percent less fat (triglycerides) in their blood after the meal and improved insulin sensitivity. The researchers concluded that “the incorporation of spices into the daily diet may help normalize postprandial [after-meal] disturbances in glucose [sugar] and lipid [fat] homeostasis [control] while enhancing antioxidant defense.”
But why experience such disturbances in the first place? The study reminds me of those that show eating greens is particularly protective against cancer among smokers.93 That is, the take-home message shouldn’t be telling smokers to eat greens—it should be telling smokers to quit smoking. Of course, they could do both, which in the context of the spice study would mean adopting an antioxidant-rich, green-light diet, offering the best of both worlds.
Some of my favorite spice mixes are pumpkin pie spice, curry powder, chili powder, Chinese five-spice powder, a savory Indian spice blend called garam masala, an Ethiopian blend called berbere, Italian seasoning, poultry seasoning, and a Middle Eastern blend called za’atar. Spice mixes are a convenient way to provide a balance of flavors while boosting the variety of your spice intake, but make sure to check that the mixes are salt-free.
Is Liquid Smoke Safe?
I don’t know how I lived so long without smoked paprika. I swear it tastes like barbecue crisps. After I first discovered it, I became a smoked-paprika zealot and put it on almost everything, but now I reserve it mostly for greens and when toasting fresh squash and pumpkin seeds. (I’ll bet you aren’t surprised to learn that’s my favorite part of Halloween!) I was concerned there might be carcinogenic combustion products in smoked seasonings (similar to the benzo[a]pyrene found in cigarette smoke and diesel exhaust), but these compounds tend to be fat soluble. So when you smoke a spice or make a water-based solution like liquid smoke, the smoke flavor compounds are captured without capturing most of the smoke cancer compounds. The same can’t be said for smoked fatty foods. While you’d have to chug three bottles of hickory smoke flavoring to exceed the safety limit, a smoked ham or smoked turkey sandwich could take you halfway there, and a single barbecued chicken leg would take you over the top. Smoked fish, such as herring or salmon, appears to be the worst. One bagel with lox could take you ten times over the safety limit.94
Some Risks to Spicing Up Your Life
There are a few spices, however, of which you can have too much of a good thing. Take poppy seeds, for example.
The opium poppy used to make heroin is the same opium poppy that produces the poppy seeds in muffins and bagels. The idea that poppy seeds could serve as the source of appreciable amounts of narcotics was not given much credence despite the existence of an old European custom recommending a poppy seed-filled dummy to quiet a noisy baby.95 It wasn’t given much credence, that is, until a mother tried giving her six-month-old some strained milk in which she had boiled some poppy seeds with the very best intentions of helping the child sleep better. The baby stopped breathing—but luckily survived.96
The cases of poppy seed overdose aren’t limited to children. There’s another case in the literature of an adult who felt “dim feelings in the head” after eating spaghetti with 60 g of poppy seeds on top.97 So what’s the upper limit of poppy seed consumption that’s probably safe? Based on median morphine levels,98 about one teaspoon for every ten pounds of body weight. This means that someone weighing about 150 pounds should probably eat no more than five tablespoons of raw poppy seeds at a time.99
Cooking may wipe out half of the morphine and codeine contained naturally in poppy seeds, which gives you some more leeway when baking.100 Soaking the poppy seeds for five minutes and then discarding the water before adding the seeds to your recipe can eliminate half of that remaining, if you’re making some poppy seed-filled pastry or other baked goods for children. Otherwise, there shouldn’t be any risk at usual levels of intake—unless you’re going in for a drug test, in which case you may want to avoid poppy seeds altogether.101
Too much nutmeg can also be a problem. A paper entitled “Christmas Gingerbread . . . and Christmas Cheer: Review of the Potential Role of Mood Elevating Amphetamine-like Compounds . . .” suggested that certain natural constituents of spices like nutmeg may form amphetamine compounds within the body sufficient “to elevate the mood and to help provide some added Christmas cheer” during the holiday season.102
This hypothetical risk was raised as far back as the 1960s in the New England Journal of Medicine in an article called “Nutmeg Intoxication.”103 The paper pondered whether the age-old custom of adding nutmeg to eggnog arose from the “psychopharmacological effect” described in cases of nutmeg intoxication. Such cases evidently go back to the 1500s, when nutmeg was used as an abortifacient to induce a miscarriage.104 In the 1960s, the spice was used as a psychotropic drug.105 During that decade, mental health professionals concluded that while nutmeg “is much cheaper for use and probably less dangerous than the habit-forming heroin, it must be stated that it is not free from danger and may cause death.”106
The toxic dose of nutmeg is two to three teaspoons. I had assumed no one would ever come close to that amount unintentionally until I saw a report in which a married couple ate some pasta, collapsed, and were subsequently hospitalized. What had happened was a big mystery until the husband revealed that he had accidentally added one-third of a jar of nutmeg to the meal while cooking.107 That’s about four teaspoons of the spice. I don’t know how they could have eaten it! I imagine the poor wife was just trying to be polite.
Another popular and powerful spice is cinnamon, which has been prized for its ability to lower blood sugar levels.108 It works so well that you can even “cheat” on a diabetes test by consuming two teaspoons of cinnamon the night before. Twelve hours later, your blood sugar spike in response to meals will still be significantly dampened.109 Even just a teaspoon a day appears to make a significant difference.110 Unfortunately, cinnamon can no longer be considered a safe and effective treatment for diabetes.
There are two main types of cinnamon: Ceylon cinnamon and cassia cinnamon (also known as Chinese cinnamon). In the United States, anything simply labeled “cinnamon” is probably cassia, since it’s cheaper. This is unfortunate, because cassia contains a compound called coumarin, which may be toxic to the liver at high doses. Unless it’s specifically labeled Ceylon cinnamon, quarter of a teaspoon of cinnamon even a few times a week may be too much for small children, and a daily teaspoon would exceed the tolerable upper safety limit for adults.111 Can’t you just switch to Ceylon cinnamon and get the benefits without the risks? Without the risks, yes, but we’re no longer so sure about the benefits.
Nearly all the studies showing blood sugar benefits of cinnamon have been performed with cassia. We’ve just assumed that the same would apply for the safer Ceylon cinnamon, but it was only recently put to the test. The nice blunting of blood sugars you see in response to cassia cinnamon disappeared when the researchers tried using Ceylon cinnamon instead.112 In fact, all along it may actually have been the toxic coumarin itself that was the active blood-sugar-lowering ingredient in the cassia cinnamon. Thus, sidestepping the toxin by switching to Ceylon cinnamon may sidestep the benefit. So, in a nutshell, when it comes to lowering blood sugars, cinnamon may not be safe (cassia), or it may be safe, but apparently not effective in reducing blood sugar (Ceylon).
I still encourage Ceylon cinna
mon consumption, given that it is one of the cheapest common food sources of antioxidants, second only to purple cabbage. But what’s a type 2 diabetic to do? Even the cassia cinnamon only brought down blood sugars modestly—in other words, it was only as good as the leading diabetes drug in the world, metformin, sold as Glucophage.113 Yes, cassia cinnamon may work as effectively as the leading drug, but that’s not saying much. The best way to treat diabetes is to attempt to cure it entirely with a healthy diet. (See chapter 6.)
Who knew that the herbs and spices you’ve been tossing into sauces and sprinkling onto dishes could have such impacts on your health? Work your creativity in the kitchen and spice up your meals and drinks to make them more flavorful and more healthful—but don’t forget the quarter of a teaspoon of daily turmeric. I am sufficiently convinced by the available body of evidence to single turmeric out as something everyone should add to his or her daily diet.
Whole Grains
Dr. Greger’s Favorite Whole Grains
Barley, brown rice, buckwheat, millet, oats, popcorn, quinoa, rye, teff, whole-wheat pasta, and wild rice
Serving Sizes:
100 g hot cereal or cooked grains, pasta, or sweetcorn kernels
50 g cold cereal
1 tortilla or slice of bread
½ a bagel or english muffin
30 g popped popcorn
Daily Recommendation:
3 servings per day
Consistent with recommendations from leading cancer1 and heart disease2 authorities, I recommend at least three servings of whole grains a day. Harvard University’s preeminent twin nutrition studies—the Nurses’ Health Study and the Health Professionals Follow-Up Study—have so far accumulated nearly three million person-years of data. A 2015 analysis found that people who eat more whole grains tend to live significantly longer lives independent of other dietary and lifestyle factors.3 No surprise, given that whole grains appear to reduce the risk of heart disease,4 type 2 diabetes,5 obesity, and stroke.6 Eating more whole grains could save the lives of more than a million people around the world every year.7
There are so many nutrition claims floating around the Internet that lack scientific backing, but a few especially persistent memes directly contradict the available evidence. When I see books, websites, articles, and blogs parroting claims like “grains are inflammatory—even whole grains,” I can’t help but wonder what alternate dimension the authors call home.
Pick your indicator of inflammation. Take C-reactive protein (CRP), for instance. CRP levels rise within the body in response to inflammatory insults and are therefore used as a screening test for systemic inflammation. Each daily serving of whole grains is estimated to reduce CRP concentrations by approximately 7 percent.8 Furthermore, there’s a whole alphabet soup of inflammation markers that appear to be improved by whole grains: ALT, GGT,9 IL-6,10 IL-8,11 IL-10,12 IL-18,13 PAI-1,14 TNF-α,15 TNF-R2,16 whole blood viscosity, and erythrocyte filtration.17 Or, as presented in less technical terms in the American Journal of Clinical Nutrition, “Whole-grain intake cools down inflammation.”18 Even excluding heart disease and cancer, habitual whole-grain intake is linked to a significantly lower risk of dying from inflammatory diseases.19
What About Gluten?
You’ve probably heard about an autoimmune disorder called celiac disease, in which the consumption of gluten causes adverse reactions, including gastrointestinal problems. Gluten is a group of proteins found in certain grains, including wheat, barley, and rye. Celiac disease is relatively rare, though, affecting less than 1 percent of the population.20 For the more than 99 percent of the rest of us who don’t have the disorder, is gluten okay or, indeed, health-promoting like other plant proteins?
In 1980, researchers in England reported a series of women suffering from chronic diarrhea who were cured by a gluten-free diet, yet none of the women had evidence of celiac disease.21 They appeared to have some sort of non-celiac gluten sensitivity. At the time, the medical profession expressed skepticism that there was such a thing,22 and even now there are experts who question its existence.23 In fact, doctors commonly referred their patients claiming non-celiac gluten sensitivity to psychiatrists because they were believed to have an underlying mental illness.24
The medical profession has a history of dismissing diseases as existing “just in your head.” Examples of these include post-traumatic stress disorder (PTSD), ulcerative colitis, migraines, ulcers, asthma, Parkinson’s, Lyme disease, and multiple sclerosis. Despite resistance from the prevailing medical community, each one of these conditions has subsequently been confirmed as a legitimate disorder.25 On the flip side, the Internet is rife with unsubstantiated claims about gluten-free diets that have spilled over into the popular press, making gluten the diet villain du jour.26 And, of course, the gluten-free processed food industry, today worth billions, has a financial interest in the public’s confusion.27 Whenever that much money is at stake, it’s hard to trust anyone, so as always, stick to the science. And what sort of evidence is there for the existence of a condition presumed to be so widespread?
The first double-blind, randomized, placebo-controlled gluten challenge was published in 2011. Patients complaining of irritable bowel-type symptoms who claimed they felt better on a gluten-free diet—despite not having celiac disease—were tested to see if they could tell if bread and muffins they were given contained gluten or were gluten-free. All the subjects started out gluten-free and symptom-free for two weeks, and then were challenged with one of the two types of bread and muffins. Even those who ate the gluten-free placebo products felt worse, meaning they started out on a gluten-free diet and continued on a gluten-free diet, yet they reported feeling crampy and bloated. This is what’s called the nocebo effect. The placebo effect takes place when you give patients something useless and they feel better; the nocebo effect occurs when you give someone something harmless and they feel worse. Nevertheless, the subjects who received actual gluten felt even worse. So the researchers concluded that non-celiac gluten intolerance may indeed exist.28
However, this was a small study, and even though the researchers claimed the gluten-free products were indistinguishable from those containing gluten, it’s possible that the patients were able to tell which foods were which. So, in 2012, Italian researchers created a double-blinded test with 920 patients diagnosed with non-celiac gluten sensitivity. Each was given capsules filled with either wheat flour or a placebo powder. More than two-thirds failed the test: Those on the placebo got worse, or those on the wheat felt better. But for those who passed, there was a clear benefit to staying on the wheat-free diet, confirming the “existence of non-celiac WS [wheat sensitivity].”29 Note that they said wheat sensitivity, though, not gluten sensitivity. In other words, gluten itself may not be causing gut symptoms at all.
Most people who are sensitive to wheat are sensitive to a variety of other foods too. For example, two-thirds of people with wheat sensitivity have also been found to be sensitive to cow’s milk protein. Eggs appear to be the next leading culprit.30 If you put people on a diet low in common triggers of irritable bowel symptoms and then challenge them with gluten, there’s no effect, calling into question the existence of non-celiac gluten sensitivity.31
Interestingly, despite being informed that avoiding gluten was apparently not helping their gut symptoms, many participants opted to continue following a gluten-free diet as they subjectively described “feeling better.” This led the researchers to wonder if avoiding gluten might improve the mood of those with wheat sensitivity and, indeed, short-term exposure to gluten appeared to induce feelings of depression in these patients.32 Regardless of whether non-celiac gluten sensitivity is a disease of the mind or the gut, it is no longer considered a condition that can be dismissed.33
The next question, then, is what percentage of the population should avoid wheat and other gluten-containing grains? About one in one thousand may have an allergy to wheat,34 and nearly one in one hundred have celiac disease,35 which appears
to be on the rise. Still, there’s less than a one-in-ten-thousand chance that an American will be diagnosed with celiac disease in a given year.36 Our best estimate for the prevalence of wheat sensitivity is in the same general range of celiac disease: slightly higher than 1 percent.37 So only about 2 percent of the population appears to have a problem with wheat, but that’s potentially millions of people who may have been suffering for years and could have been cured by simple dietary means, yet were unrecognized and not helped by the medical profession until recently.38
For the 98 percent of people who don’t have wheat issues, there is no evidence to suggest that following a gluten-free diet has any benefits.39 In fact, there is some evidence suggesting that a gluten-free diet may adversely affect gut health in people without celiac disease, wheat sensitivity, or wheat allergy. A month on a gluten-free diet was found to adversely affect gut flora and immune function, potentially setting up those on gluten-free diets for an overgrowth of harmful bacteria in their intestines.40 This is due, ironically, to the beneficial effects of the very components wheat-sensitive individuals have problems with—such as the “FODMAP” fructans that act as prebiotics and feed your good bacteria, or the gluten itself, which may boost immune function.41 Less than a week of added gluten protein may significantly increase natural killer cell activity,42 which could be expected to improve the body’s ability to fight cancer and viral infections.
The greatest threat gluten-free diets may pose, though, is that they may undermine our ability to diagnose celiac disease, the much more serious form of wheat intolerance. Doctors diagnose celiac by looking for the inflammation caused by gluten in celiac sufferers. But if patients complaining of digestive problems come to the doctor having already eliminated much of the gluten in their diets, physicians might miss the disease.43 Why would getting a formal diagnosis matter if you’re already on a gluten-free diet? First of all, it’s a genetic disease, so you’ll know to test your family. More significantly, though, many people on so-called gluten-free diets are not actually on truly gluten-free diets. Even twenty parts per million can be toxic to someone with celiac. Sometimes, even foods labeled “gluten-free” may not be safe for celiac sufferers.44
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