When we tackled the topic of food myths last month, our inbox was flooded with more reader-submitted followup myths than we could debunk at one time. We asked our nutritionists back to debunk some more common misconceptions about food, health, and nutrition that are still widely believed, even though there's overwhelming evidence to the contrary. We also asked them some of your questions. Here's what they said.
"I love being taken to task," Alannah DiBona Boston-based nutritionist and wellness counselor said, and went on to explain that your suspicions were correct. Skipping a meal does not appreciably change your metabolic rate, and it certainly doesn't send your body spinning into a fat-saving "starvation mode." However, that doesn't mean you should skip eating if you're hungry and the clock happens to be have passed an arbitrary time. When you do, your blood sugar plummets, which results in cravings and increased hunger pangs. When you do sit down to your next meal, your body will send you messages that you're hungrier than you actually are, and you're likely to overeat. The best advice? Eat when you're hungry, and eat something appropriate for the time of day. If it's 9pm and you're not headed to bed for another three hours, have a light snack instead of going to bed hungry.
As for the so-called "starvation mode?" DiBona notes that it actually takes two to three weeks of consistently low caloric intake and at least 24-hours of no caloric intake for your body to compensate with significant metabolic shifts. The United Nations University has an excellent (if not old) paper on the effect of low and no-calorie diets on people of otherwise normal weight that illustrates exactly when the basal metabolic rate begins to trend downward after a dietary change.
This myth has been circulating for so long—even among bodybuilding circles—that there's an excellent article at Bodybuilding.com explaining that while protein is a needed component in any healthy diet, there's entirely too much emphasis on it when it comes to adding muscle. In fact, the American Dietetic Association and the FDA have specific guidelines for an appropriate diet conducive to resistance training. They suggest limiting your protein intake to no more than 1.7 grams per kilogram of body weight (or 0.77 grams per pound of body weight).
Worse, too much protein in your diet can actually be a bad thing. Alannah DiBona noted that too much protein can stress the digestive system, and the Physicians Committee for Responsible Medicine (PCRM) points out there's research to support the position that super-high-protein diets actually lead to other health problems. While that research isn't conclusive, everyone agrees: a balanced diet—of which protein is a component—that scales with your resistance training is the key to building muscle mass.
As with many things, the key with sodium is moderation, and the problem with the myth is that it speaks in absolutes. People with hypertension and high blood pressure can and should monitor and limit their salt intake to help control their blood pressure. People with normal blood pressure, on the other hand, have no reason to fear or limit their sodium intake aside from the FDA's daily recommended amount. There's mounting evidence to support the notion that salt isn't all bad.
That said, don't reach for the salt shaker just yet. We said moderation was key, and unfortunately most American diets are bereft of moderation. Salt definitely has an impact on the body's ability to regulate blood pressure. Most food prepared in kitchens and restaurants is incredibly over-salted, and the amount of sodium in preserved and processed foods is remarkably high. One 2006 study (PubMed, login required) points out that while normal salt intake may not cause hypertension, the increasing amount of salt in our diets may be a contributing factor, especially among people already at risk.
The National Heart, Lung, and Blood Institute at the National Institutes of Health stands by a 1998 statement on the matter advising most people reduce their sodium intake, and last year the FDA agreed. If you're worried about your salt intake, DiBona has a suggestion for you: "It's been common scientific knowledge for 20 years that potassium and sodium balance each other; consuming more potassium (in the form of spinach, broccoli, bananas, and beans) can have a regulatory effect on blood pressure."
It's a delicate balance. Too little sodium in your diet is unhealthy. Too much sodium in your diet is also unhealthy. A good, moderate amount (at or around the FDA guidelines) is fine. People who already have high blood pressure or are at high risk for hypertension and heart disease should monitor their sodium intake carefully and talk to their doctor about their particular case. Either way, don't be afraid of the salt, just enjoy it sensibly.
The problem with storing your beans in the freezer is that they can absorb odors from other foods, they can grow ice crystals that will damage the beans and impart unwanted flavors, and the moisture in the air and change in temperature has a negative effect on those delicious oils. The reason most coffee fans will tell you not to freeze coffee is because it's so incredibly difficult to control for these possibilities. They're right, if coffee tasted better and kept longer frozen, you'd buy it in the frozen food section. That said, it may be difficult, but it's not impossible to properly freeze coffee, and it shouldn't keep you from freezing coffee if you have a little more than you'll be able to use in a week or two.
First of all, don't grind it—keep it whole bean. Then, make sure you pack it as tightly as you can in an airtight container or bag, and then get as much of the air out of it as possible before sealing it up and putting it in the back of the freezer in an opaque container. Only remove it when you're ready to use the whole thing. Don't open the container and subject the coffee to all of those bad influences in the freezer just to get a few beans out. If you do it properly, your coffee can stay good in the freezer for a short while until you're ready to bring it back to temp and drink it. Home-Barist.com did a remarkably well-controlled double-blind experiment with experienced coffee tasters, and they all were unable to tell the difference between fresh coffee and properly frozen coffee.
The key here though is properly frozen. If you love your coffee, it's probably not a risk worth taking unless you score a huge haul of your favorite bean. If you scoff at coffee snobs and don't really care about subtleties in flavor, it won't matter to you anyway.
Speaking of mercury in fish, yes—current research does suggest that pregnant women avoid fish that are particularly high in mercury during pregnancy. The FDA, the Canadian Food Inspection Agency, and the US Department of Agriculture all have a number of published studies on the topic. The FDA also hosts a page outlining the amount of Mercury in different fish, updated annually.
If it's parasites or other risks associated with sushi that worry you more than mercury, Andy Bellatti suggests you put your mind at ease. "Fish served in sushi restaurants has been previously flash frozen, which kills parasites as effectively as cooking," he explains. He also points to Steven Shaw's book Asian Dining Rules: Essential Eating Strategies for Eating Out at Japanese, Chinese, Southeast Asian, Korean, and Indian Restaurants, which explains that most fish used for sushi in restaurants around the world are farmed to avoid the problems with parasites in wild fish. "Fish like tuna are not particularly susceptible to parasites because they dwell in very deep and cold waters. Sushi restaurants typically use farmed salmon to avoid the parasite problems wild salmon have," he explains. The fish that are at times likely to have parasites, like cod or other whitefish, aren't used for sushi anyway and are generally served fully cooked.
Alannah DiBona concurs. "Most body builders and athletes would probably keel over if they knew the truth: amino acids (the basic building blocks of muscle tissue) are made by plants, not animals. Humans can get these proteins by eating animals, but a properly balanced diet of greens, nuts, fruits, grains and veggies will pack a sufficient amount of protein for muscular development."
The Harvard School of Public Health also supports the point, and explains that it's really the "protein package" that counts, as in the other nutrients and fats that come with the protein that matter. They point out that while a delicious porterhouse is a great source of protein, it's also very fatty. A cup of cooked lentils will deliver the same protein to your plate, with a fraction of the fat (although whether it's as tasty is up for debate!)
He's right: the manufacturers approach the FDA and note that additional research needs to be done, but the components of their sweeteners are all classified as safe, so the sweetener should be as well. Therefore it gets the "GRAS" label, and goes to market unless there's a reason to stop them.
There is good news, however. No organization that's tested artificial sweeteners to date have found evidence to suggest that artificial sweeteners are linked to illness. The Mayo Clinic does a great job of explaining how artificial sweeteners are made, and suggests some natural sweeteners that impart more flavor, have an equally low glycemic index, and can be just as healthy as artificial ones. The Harvard Medical School takes a slightly more conservative approach, and explains that while the American Dietetic Association and the FDA have approved the artificial sweeteners, moderation is key until the matter is fully settled.
Finally, The National Cancer Institute has an excellent page outlining the current state of research into connections between artificial sweeteners and cancer. While some studies have implied there may be a link, nothing is clear and what evidence there is is tenuous at best. 100% safe? No. 100% dangerous? Nope. What should you do? Practice moderation, or switch to a natural sweetener. I'm a big fan of agave nectar.
"While unsaturated fats like monounsaturated (found in avocados, olive oil, pecans, and almonds) and Omega-3s (found in flax, hemp, chia, seaweed, and fatty fish) are very healthy, a high intake of omega-6 fatty acids (corn, soybean, and cottonseed oils are especially high) is linked with cellular inflammation, which is believed to be a significant factor in the development of many chronic diseases," Andy Bellatti says. Again, it's a lack of moderation that's to blame. "Fast food chains often boast about the use of cooking oils free of trans-fats and low in saturated fat, but the bad news is that the oils they use are generally high in omega-6 oils. Although omega-6 is an essential fatty acid, the typical American consumes an exorbitant amount (the ideal ratio of omega-3 to omega-6 is 1:3, and the average American these days consumes anywhere from 1:20 to 1:25). The saturated fatty acids in coconut and cocoa (either pure unsweetened cocoa powder or chocolates with a cocoa content of 80% or higher) offer many heart-healthy benefits."
The University of Maryland Medical centre has additional guidelines on the benefits of omega-3s and the issues that arise when the ratio of omega-3s to omega-6 fats are out of balance. For even more reading, this study by The centre for Genetics, Nutrition and Health (PubMed, login required) goes into deeper detail about the importance of keeping a proper balance, and how badly most western diets are out of that balance.
In reality, this one is easy to debunk. Lobsters have no vocal cords. It's just not possible for them to "scream" in any way we could hear, in any circumstance. The sound you may hear is expanding air bubbles trapped in their shells expanding and finding an avenue of escape from their bodies while they boil.
Lobsters are invertebrates and have a primitive nervous system. Whether or not they feel pain in the way you or I would if we were injured or burned is debatable, and as none of us will ever be a lobster, it's impossible to know whether the sensory response associated with injury in a lobster is anything like what we would call "pain". A number of recent studies indicate they do feel pain, or at least pain in their own way. After all, every animal has some method of registering dangerous stimuli and responding to it in a way the discourages contact with that stimuli again.
If you love lobster but don't relish the notion of dropping them into a boiling pot of water alive, consider putting them in the freezer first, or splitting their brain in half with a well-placed cut before cooking. Chilling them makes them torpid and sedated and splitting their brain will kill them instantly just before you drop them in the water.
This time we wanted to establish a common theme with our myths. Moderation is the key to a good, healthy diet. There are very few absolutes when it comes to food and health, very few things that are all bad or all good. Keep that in mind when you're grocery shopping or re-examining your diet.
Remember, you can debunk your own food myths with a little research and some healthy scepticism about what you read on the internet.
Myth 1: Skipping a Single Meal Will Slow Your Metabolism and Force Your Body into "Starvation Mode"
"I love being taken to task," Alannah DiBona Boston-based nutritionist and wellness counselor said, and went on to explain that your suspicions were correct. Skipping a meal does not appreciably change your metabolic rate, and it certainly doesn't send your body spinning into a fat-saving "starvation mode." However, that doesn't mean you should skip eating if you're hungry and the clock happens to be have passed an arbitrary time. When you do, your blood sugar plummets, which results in cravings and increased hunger pangs. When you do sit down to your next meal, your body will send you messages that you're hungrier than you actually are, and you're likely to overeat. The best advice? Eat when you're hungry, and eat something appropriate for the time of day. If it's 9pm and you're not headed to bed for another three hours, have a light snack instead of going to bed hungry.
As for the so-called "starvation mode?" DiBona notes that it actually takes two to three weeks of consistently low caloric intake and at least 24-hours of no caloric intake for your body to compensate with significant metabolic shifts. The United Nations University has an excellent (if not old) paper on the effect of low and no-calorie diets on people of otherwise normal weight that illustrates exactly when the basal metabolic rate begins to trend downward after a dietary change.
Myth 2: Eat a High-Protein Diet to Gain Muscle Mass
You've probably heard the myth that gulping down thick protein shakes and letting meat take over your diet will help you bulk up faster. Not so, says Seattle-based Registered Dietitian Andy Bellatti. He explains, "gaining muscle mass requires two things: weight training that stresses the muscles and consuming extra calories. Eating a high-protein diet that doesn't meet increased caloric needs is not conducive to gaining muscle mass. By simply eating more calories from healthful, whole foods (ie: grains, nuts, seeds, fish), you will take care of all the necessary nutrients that support muscle growth."This myth has been circulating for so long—even among bodybuilding circles—that there's an excellent article at Bodybuilding.com explaining that while protein is a needed component in any healthy diet, there's entirely too much emphasis on it when it comes to adding muscle. In fact, the American Dietetic Association and the FDA have specific guidelines for an appropriate diet conducive to resistance training. They suggest limiting your protein intake to no more than 1.7 grams per kilogram of body weight (or 0.77 grams per pound of body weight).
Worse, too much protein in your diet can actually be a bad thing. Alannah DiBona noted that too much protein can stress the digestive system, and the Physicians Committee for Responsible Medicine (PCRM) points out there's research to support the position that super-high-protein diets actually lead to other health problems. While that research isn't conclusive, everyone agrees: a balanced diet—of which protein is a component—that scales with your resistance training is the key to building muscle mass.
Myth 3: Salt is Bad For You
This myth has its roots in scientific fact. Part of the problem is that salt has been painted as all good and all bad over the years, as both the cause of high blood pressure and heart disease in some cases, and a maligned source of added deliciousness in others. Alannah DiBona explains, "In the 1940s, Duke University researcher Walter Kempner, M.D., famously used salt restriction to treat people with high blood pressure. As the average American diet grew increasingly processed and pre-packaged, excessive levels of sodium became difficult to avoid, and salt quickly became demonized."As with many things, the key with sodium is moderation, and the problem with the myth is that it speaks in absolutes. People with hypertension and high blood pressure can and should monitor and limit their salt intake to help control their blood pressure. People with normal blood pressure, on the other hand, have no reason to fear or limit their sodium intake aside from the FDA's daily recommended amount. There's mounting evidence to support the notion that salt isn't all bad.
That said, don't reach for the salt shaker just yet. We said moderation was key, and unfortunately most American diets are bereft of moderation. Salt definitely has an impact on the body's ability to regulate blood pressure. Most food prepared in kitchens and restaurants is incredibly over-salted, and the amount of sodium in preserved and processed foods is remarkably high. One 2006 study (PubMed, login required) points out that while normal salt intake may not cause hypertension, the increasing amount of salt in our diets may be a contributing factor, especially among people already at risk.
The National Heart, Lung, and Blood Institute at the National Institutes of Health stands by a 1998 statement on the matter advising most people reduce their sodium intake, and last year the FDA agreed. If you're worried about your salt intake, DiBona has a suggestion for you: "It's been common scientific knowledge for 20 years that potassium and sodium balance each other; consuming more potassium (in the form of spinach, broccoli, bananas, and beans) can have a regulatory effect on blood pressure."
It's a delicate balance. Too little sodium in your diet is unhealthy. Too much sodium in your diet is also unhealthy. A good, moderate amount (at or around the FDA guidelines) is fine. People who already have high blood pressure or are at high risk for hypertension and heart disease should monitor their sodium intake carefully and talk to their doctor about their particular case. Either way, don't be afraid of the salt, just enjoy it sensibly.
Myth 4: Never Freeze Coffee to Store It
Whether or not it's okay to freeze coffee is so hotly debated that there's very little consensus on it, but not for the reasons you might think. Most purists will tell you to never ever freeze coffee, and their intentions are good. Contrary to popular belief, coffee is not a shelf-stable product. The oils on the surface of the beans that give coffee its delicious flavor go rancid very quickly when exposed to light, heat, moisture, or open air. Coffee beans are also porous, so anything that gets on the surface of the beans may check in and never check out.The problem with storing your beans in the freezer is that they can absorb odors from other foods, they can grow ice crystals that will damage the beans and impart unwanted flavors, and the moisture in the air and change in temperature has a negative effect on those delicious oils. The reason most coffee fans will tell you not to freeze coffee is because it's so incredibly difficult to control for these possibilities. They're right, if coffee tasted better and kept longer frozen, you'd buy it in the frozen food section. That said, it may be difficult, but it's not impossible to properly freeze coffee, and it shouldn't keep you from freezing coffee if you have a little more than you'll be able to use in a week or two.
First of all, don't grind it—keep it whole bean. Then, make sure you pack it as tightly as you can in an airtight container or bag, and then get as much of the air out of it as possible before sealing it up and putting it in the back of the freezer in an opaque container. Only remove it when you're ready to use the whole thing. Don't open the container and subject the coffee to all of those bad influences in the freezer just to get a few beans out. If you do it properly, your coffee can stay good in the freezer for a short while until you're ready to bring it back to temp and drink it. Home-Barist.com did a remarkably well-controlled double-blind experiment with experienced coffee tasters, and they all were unable to tell the difference between fresh coffee and properly frozen coffee.
The key here though is properly frozen. If you love your coffee, it's probably not a risk worth taking unless you score a huge haul of your favorite bean. If you scoff at coffee snobs and don't really care about subtleties in flavor, it won't matter to you anyway.
Myth 5: Pregnant Women Should Avoid Eating Sushi
This myth comes from the misconception that raw fish and mercury go hand-in-hand. Putting the issue of mercury in fish aside (of which there is an issue, but more on that later) there's nothing in any of the warnings about eating fish during pregnancy that indicates that raw fish specifically is somehow more of a risk than cooked fish. If you're pregnant and love sushi, there's no reason to avoid it unless your favorite sushi involves fish that are generally high in mercury anyway.Speaking of mercury in fish, yes—current research does suggest that pregnant women avoid fish that are particularly high in mercury during pregnancy. The FDA, the Canadian Food Inspection Agency, and the US Department of Agriculture all have a number of published studies on the topic. The FDA also hosts a page outlining the amount of Mercury in different fish, updated annually.
If it's parasites or other risks associated with sushi that worry you more than mercury, Andy Bellatti suggests you put your mind at ease. "Fish served in sushi restaurants has been previously flash frozen, which kills parasites as effectively as cooking," he explains. He also points to Steven Shaw's book Asian Dining Rules: Essential Eating Strategies for Eating Out at Japanese, Chinese, Southeast Asian, Korean, and Indian Restaurants, which explains that most fish used for sushi in restaurants around the world are farmed to avoid the problems with parasites in wild fish. "Fish like tuna are not particularly susceptible to parasites because they dwell in very deep and cold waters. Sushi restaurants typically use farmed salmon to avoid the parasite problems wild salmon have," he explains. The fish that are at times likely to have parasites, like cod or other whitefish, aren't used for sushi anyway and are generally served fully cooked.
Myth 6: Animal Protein is Better than Plant Protein, or Vegetarians and Vegans Never Get Enough Protein
Protein is protein, regardless of its source, and there's nothing to the myth that animal protein is somehow better than plant protein. In fact, all animal protein comes by way of plants somewhere along the food chain. You can get protein from a number of sources other than meat, and your body is just as good at absorbing it. Beans, cheese, nuts, and even broccoli are all foods high in protein. "Every single food (except for oils and certain fruits) contains protein. A cup of cooked oatmeal has as much protein as a medium egg," Andy Bellatti explains. "A serving of almonds (23, to be exact) contains the same amount of protein you get in a stick string cheese. Beans are very high in protein. Even spinach, broccoli, and potatoes offer protein."Alannah DiBona concurs. "Most body builders and athletes would probably keel over if they knew the truth: amino acids (the basic building blocks of muscle tissue) are made by plants, not animals. Humans can get these proteins by eating animals, but a properly balanced diet of greens, nuts, fruits, grains and veggies will pack a sufficient amount of protein for muscular development."
The Harvard School of Public Health also supports the point, and explains that it's really the "protein package" that counts, as in the other nutrients and fats that come with the protein that matter. They point out that while a delicious porterhouse is a great source of protein, it's also very fatty. A cup of cooked lentils will deliver the same protein to your plate, with a fraction of the fat (although whether it's as tasty is up for debate!)
Myth 7: Artificial Sweeteners are 100% Safe
This is a tricky myth to tackle, because there's so much active research going on in this department. The important thing to remember is that artificial sweeteners are currently regulated by the US Food and Drug Administration, and the FDA classifies them as "GRAS," or "Generally Regarded As Safe." Not very encouraging, is it? It shouldn't be: the FDA will be the first to tell you that the GRAS classification is an industry-applied term, not one the FDA determines through independent testing. Andy Bellatti explains, "Artificial sweeteners are labeled as 'GRAS' by the FDA, but here's the disturbing twist: it is manufacturers that determine that (there is no formal FDA approval process). Some previously 'GRAS' additives, like orange dye No. 1, ended up being banned due to concerns of their health effects."He's right: the manufacturers approach the FDA and note that additional research needs to be done, but the components of their sweeteners are all classified as safe, so the sweetener should be as well. Therefore it gets the "GRAS" label, and goes to market unless there's a reason to stop them.
There is good news, however. No organization that's tested artificial sweeteners to date have found evidence to suggest that artificial sweeteners are linked to illness. The Mayo Clinic does a great job of explaining how artificial sweeteners are made, and suggests some natural sweeteners that impart more flavor, have an equally low glycemic index, and can be just as healthy as artificial ones. The Harvard Medical School takes a slightly more conservative approach, and explains that while the American Dietetic Association and the FDA have approved the artificial sweeteners, moderation is key until the matter is fully settled.
Finally, The National Cancer Institute has an excellent page outlining the current state of research into connections between artificial sweeteners and cancer. While some studies have implied there may be a link, nothing is clear and what evidence there is is tenuous at best. 100% safe? No. 100% dangerous? Nope. What should you do? Practice moderation, or switch to a natural sweetener. I'm a big fan of agave nectar.
Myth 8: Unsaturated Fats Are Good, Saturated Fats Are Bad
Considering most food labels break the fat content into these two categories, it would be nice if we could say one was good and the other was bad and call it a day. Unfortunately it's just not that easy. The terms "saturated" and "unsaturated" have been co-opted into marketing terms. The truth lies with the type of fat you're eating, where you're getting it, and how much of it you're eating."While unsaturated fats like monounsaturated (found in avocados, olive oil, pecans, and almonds) and Omega-3s (found in flax, hemp, chia, seaweed, and fatty fish) are very healthy, a high intake of omega-6 fatty acids (corn, soybean, and cottonseed oils are especially high) is linked with cellular inflammation, which is believed to be a significant factor in the development of many chronic diseases," Andy Bellatti says. Again, it's a lack of moderation that's to blame. "Fast food chains often boast about the use of cooking oils free of trans-fats and low in saturated fat, but the bad news is that the oils they use are generally high in omega-6 oils. Although omega-6 is an essential fatty acid, the typical American consumes an exorbitant amount (the ideal ratio of omega-3 to omega-6 is 1:3, and the average American these days consumes anywhere from 1:20 to 1:25). The saturated fatty acids in coconut and cocoa (either pure unsweetened cocoa powder or chocolates with a cocoa content of 80% or higher) offer many heart-healthy benefits."
The University of Maryland Medical centre has additional guidelines on the benefits of omega-3s and the issues that arise when the ratio of omega-3s to omega-6 fats are out of balance. For even more reading, this study by The centre for Genetics, Nutrition and Health (PubMed, login required) goes into deeper detail about the importance of keeping a proper balance, and how badly most western diets are out of that balance.
Myth 9: Lobsters Scream In Pain When Boiled
This one is often conflated with the issue of whether or not lobsters feel pain when boiled, which is another matter entirely. Many people report that when they put a live lobster into a pot of boiling water, they hear noises that sound like tiny screams coming from the pot. One person - likely feeling a little guilty about tossing a live lobster into a pot of boiling water - probably told their friends the poor thing was "screaming", and the myth was born.In reality, this one is easy to debunk. Lobsters have no vocal cords. It's just not possible for them to "scream" in any way we could hear, in any circumstance. The sound you may hear is expanding air bubbles trapped in their shells expanding and finding an avenue of escape from their bodies while they boil.
Lobsters are invertebrates and have a primitive nervous system. Whether or not they feel pain in the way you or I would if we were injured or burned is debatable, and as none of us will ever be a lobster, it's impossible to know whether the sensory response associated with injury in a lobster is anything like what we would call "pain". A number of recent studies indicate they do feel pain, or at least pain in their own way. After all, every animal has some method of registering dangerous stimuli and responding to it in a way the discourages contact with that stimuli again.
If you love lobster but don't relish the notion of dropping them into a boiling pot of water alive, consider putting them in the freezer first, or splitting their brain in half with a well-placed cut before cooking. Chilling them makes them torpid and sedated and splitting their brain will kill them instantly just before you drop them in the water.
Myth 10: Turkey Makes You Sleepy Because Of Its Tryptophan Content
It's true that turkey is a great source of tryptophan and that tryptophan makes us sleepy. However, turkey isn't the only food that's high in tryptophan. "Chicken, tuna, mushrooms, scallops, shrimp and soybeans contain just as much tryptophan as - and, in some cases, more tryptophan than - turkey," Andy Bellatti says. To boot, after eating, the body diverts blood from other areas of the body to the stomach in order to aid digestion, making us lethargic and warm in the belly. Andy elaborates:"When the pancreas releases insulin after a meal, blood levels of amino acids decrease - except for tryptophans. So, when amino acids cross the blood-brain barrier, the most abundant one within that pool is tryptophan. Once in the brain, tryptophan stimulates serotonin production, which imparts relaxation and sleepiness.In essence, it's not just the turkey that makes you sleepy. It's the combination of eating a lot of food and eating a lot of food with high tryptophan content. This one's been debunked so many times that it's surprising it's still around, but it is. The alcohol in that bottle of wine on the dinner table doesn't help matters much either.
Here's the catch - the higher our blood sugar levels rise after a meal, the more insulin the pancreas releases (and the more amino acid levels, except for tryptophans, decrease). Simple carbohydrates raise blood sugars more than other foods.
Eating turkey by itself will not impart any sleepiness since turkey is a high-protein, low-carb food (it does not make blood sugar levels rise as much arse simple carbohydrates). You'd literally have to eat an entire turkey in one sitting in order for the tryptophan to have an effect.
This time we wanted to establish a common theme with our myths. Moderation is the key to a good, healthy diet. There are very few absolutes when it comes to food and health, very few things that are all bad or all good. Keep that in mind when you're grocery shopping or re-examining your diet.
Remember, you can debunk your own food myths with a little research and some healthy scepticism about what you read on the internet.