Eat Fat to Burn Fat? The Skinny on the Ketogenic Diet

This is the second in a series of collaboration between Don’t Eat the Pseudoscience and In Defense of Processed Food. Head over to the site and explore, and stay tuned for more! Check out our first collaboration HERE!

Last week I went to a birthday party. Andrew, the birthday boy, shared that he’d been on the ketogenic diet for 3 months. He’d lost 10 pounds and felt great. The party food was fatty and delicious–we dined on jalapeno poppers with cheddar cheese and bacon, made our own beef and pork tacos with shredded cheese, bell peppers, and onion in lettuce wraps, and at the end celebrated with a low-sugar peanut butter cake covered in whipped cream and dark chocolate. Chips and tortillas were available for the non-keto eaters, and a wonderful time was had by all.

The ketogenic or “keto” diet has skyrocketed in popularity over the past few years, reaching the highest interest in the summer of 2018. It is heavy in proteins and fats, encouraging users to consume meats, eggs, cheeses, fish, nuts, butter, oils, seeds, and fibrous vegetables. The goal of the keto diet is to bring carbohydrates down to less than 5% of a person’s daily calories by eliminating most grains, fruit, starchy vegetables, legumes, and sweets and replacing those calories with fat.

This isn’t the first time we’ve heard the hype about low-carb diets. The Atkins diet, which became popular back in the 70’s, recommended consuming fewer carbohydrates and replacing those calories with high protein and fat. The ketogenic diet takes it one step further by advocating for even further carbohydrate reduction and increased fat, which shifts the body’s metabolism into burning fat.

Carbohydrates are the easiest to metabolize and thus the body’s first choice for energy. During metabolism, carbs are broken down into glucose molecules which are either immediately used to fuel our tissues or converted into glycogen, a storage form of glucose in the liver and muscles. Excess glucose is stored in the body as fat. In contrast, fats are broken down into smaller molecules known as ketones and fatty acids, which are then transformed into components which can be used as energy.

While the Dietary Guidelines for Americans recommends that carbohydrates make up 45 to 65 percent of total daily calories, the ketogenic diet recommends consuming 5-10% carbohydrates, 20-25% protein, and 70-80% fat. “Going keto” or beginning a ketogenic diet means the body must switch to metabolism of fats as a supply of energy to accommodate the lack of carbs. This typically happens when one consumes only 20-50g of carbohydrates per day for two to four days. The body is flooded with ketones as it moves to a lipid metabolism, inducing a metabolic condition called ketosis or ketogenesis, which gives the diet its name.

The body experiences several changes as it shifts to accommodate the new form of calories. First, the glycogen stores in the body disappear. Glycogen is bound up in water, so dieters will find themselves needing to urinate frequently as their bodies deplete these stores. The loss of glycogen and glycogen-bound water results in immediate weight loss, which may be encouraging to dieters. In addition, the process of transitioning from a glucose metabolism to a lipid metabolism may cause symptoms that some have termed the “keto flu.”  The most common symptoms include headache, fatigue, nausea, dizziness, irritability, leg cramps, constipation, bad breath, and heart palpitations. Ketogenic diet patients reported fatigue, headache and diarrhea during their first week, peaking on day 4 and leveling off after day 7. These symptoms may be due to sugar withdrawals and electrolyte deficiency from water loss.

The ketogenic diet was originally developed in 1921 as a therapeutic diet for epileptic patients. Fasting was known to be effective in reducing seizures and doctors discovered that a very high fat, low carb diet could simulate the metabolic effects of fasting or starvation by forcing the body to use primarily fat as a fuel source. During fasting, the fatty acid breakdown from the body metabolizing fat stores produces certain ketone bodies which are able to cross the blood-brain barrier and provide anticonvulsant properties in the brain. While the exact mechanism by which this happens is unclear, some theories indicate that this change in fuel production could make brain cells more resilient in the face of metabolic demands during seizures or the presence of ketone bodies may favor the synthesis of a “calming” inhibitory neurotransmitter called GABA. Treating epilepsy with the ketogenic diet instead of anticonvulsants can relieve patients from medication with known negative cognitive and behavior effects.

Blocking glucose metabolism has been highly effective in reducing seizures in epileptic patients, and has also shown promise for promoting healthy blood sugar in type 2 diabetics in the short-term , although a review found no difference found after the first year of treatment. It can be challenging to discern dietary impact—one meta-analysis found there to be no difference in glycemic control between those on a low carb diet and those on a high carb diet. They suggested that the lack of effect may be because patients were unable to achieve the strict prescribed carbohydrate intake of as little as 20g.  The benefits from the ketogenic diet only come about when people go into ketosis and eating more than 20g a day prevents ketosis. The keto diet is also currently being investigated as a medical intervention for polycystic ovary syndrome, neurodegenerative diseases, and cancer as blocked glucose metabolism has been correlated with reduced brain and body inflammation in mice.

The current keto-hype, however, is about weight loss. The ketogenic diet claims to aid in weight loss in two ways. First, by forcing the body to burn fat, which takes more energy to digest and break down than carbohydrates. This is referred to as “increased energy expenditure”. Second, by reducing the consumption of calories through a feeling of fullness or reduced appetite due to the floating ketone bodies in the blood.

There are many promising studies that show weight loss from a ketogenic diet for up to one year.  One put participants on a strict ketogenic diet, even measuring ketones in blood/urine to validate ketogenesis. Over a 6 week period they observed mild weight loss.  Another with 132 severely obese patients found that participants on a carbohydrate-restricted diet lost more weight than those than on a calorie- and fat-restricted diet.

A third study had participants alternate between a ketogenic diet, a low-carb non-ketogenic diet, and a normal Mediterranean diet. Significant weight loss and reduction of body fat percentages were observed only during ketogenic periods compared to the two other diets. In addition, if the patients complied with the prescribed Mediterranean diet (which was relatively strict: 1800 kcal/day) during the maintenance period, no weight regain was observed at 12 months.

A big challenge in studying the ketogenic diet is poor adherence. To ensure compliance, one study confirmed 17 overweight volunteers to metabolic wards for 8 weeks. The first four weeks they ate a high-carbohydrate, high sugar diet and the second four they were switched to a carefully designed low-carbohydrate low-sugar diet. After switching to the keto diet participants immediately lost an average 3.5 pounds, which was attributed to body water loss. Over the 28 day ketogenic diet period the participants lost 4.8 pounds with 1 pound from body fat while consuming about 300 fewer calories per day. Overall, the ketogenic diet increased energy expenditure by ~100 calories/day after adjusting for body weight and composition, which was complicated by the loss of weight from water. Researchers concluded that the ketogenic diet contributed to weight loss and increases in energy expenditure that were near the limits of detection.

The initial data we have about the ketogenic diet shows positive results in weight loss, but we have less data on long-term effects of this diet with regard to losing weight and keeping it off, as well as the enduring effects on health.  In mice we have seen that a high-fat diet may cause initial weight loss and then over time rebound in weight but this has not been shown in humans. A review article published in the journal Diabetes suggests that we need additional data to draw definite conclusions about this diet, which would come from robustly controlled long-term studies (minimum of 2 years) in which carbohydrate, fat, energy and dietary fiber intake are carefully monitored along with changes in body weight.

While the ketogenic diet has been shown to help with weight loss, the drastic metabolic shift comes with potential negative physiological effects. One of the biggest concerns doctors cite about the ketogenic diet is the impact on liver and kidneys, as well as the small possibility of ketoacidosis which is when the blood becomes acidic due to a ketone build-up. Keto dieters are at an increased risk for developing kidney problems, potentially including kidney failure. Patients on the keto diet are typically urged to supplement with oral potassium citrate to reduce or delay the production of painful kidney stones,which occurred in 6.7% of one study’s participants. In addition, rodents put on the ketogenic diet have shown development of non-alcoholic fatty liver disease and insulin resistance, although we have not yet seen the same results in humans.

Another side-effect of the ketogenic diet is that physical activities may be more exhausting. Patients following the ketogenic diet experienced a negative impact on physical performance, including reduced endurance capacity, maximum work load and faster exhaustion. The reduction in peak power is likely due to lowered muscle glycogen stores from decreased carbohydrates. The study found that physical fitness was not impacted in a way that would impair daily life, but may be a matter of concern for competitive athletes.

One review of studies found that participants on low carb diets lost more weight compared to participants on low fat diets, but also increased their LDL cholesterol.  Increased LDL-cholesterol, or “bad cholesterol” is associated with a higher risk of cardiovascular disease. A separate meta-review concluded that low-carbohydrate, non-energy-restricted diets appear to be at least as effective as low-fat, energy-restricted diets in inducing weight loss for up to 1 year.  However, just like the previous review they noted unfavorable changes in LDL-cholesterol.

Some of the physiological repercussions of this diet may depend on what types of foods are being consumed instead of carbohydrates. A study tracking the long-term effects of dietary carbohydrates on mortality found that both high and low percentages of carbohydrate diets were associated with increased mortality, with the lowest risk observed at 50–55% carbohydrate intake. They observed that low-carb diets that replace carbohydrates with proteins and fat from animal sources were associated with higher risk of mortalitycompared to those that replace carbohydrates with proteins and fats from plant sources.

In a review of all current diets including Paleo, Vegan, Gluten-free, Whole30, and more, US News Health ranked the Keto diet 39th—dead last. Concerns include repercussions for cycling in and out of the diet, and that it can be especially risky for those with liver or kidney concerns, who should avoid it altogether. One major downside of the Keto diet is that it doesn’t specify the type of fats to replace carbs, despite decades of prior research indicating that animal-based proteins and saturated fats are linked to increased risk of cardiovascular disease. Another concern is that a diet containing 70% fat may be naturally lower in fruits and vegetables, which could lead to deficiency in vitamins and minerals and a decline in overall health.

In addition to the physiological concerns, there are also more practical ones. The Keto diet may be a challenge to maintain over time and may not work with everyone’s lifestyle.  To be a true Keto diet adherent, a diet must be <10% carbohydrates and >60% fat to induce and maintain the increased levels of circulating ketone bodies. To stay in a state of ketosis one must constantly maintain a certain percentage of carbohydrates, meaning that a slice of cake at a company party is enough to throw the metabolism back to burning carbs and storing fat.

A recent review paper summarizes the current state of affairs: “results regarding the impact of such diets on cardiovascular risk factors are controversial, both in animals and humans, but some improvements notably in obesity and type 2 diabetes have been described. Unfortunately, these effects seem to be limited in time, and more studies are therefore warranted to better assess the effects of a long-term ketogenic diet.”

So what should we say to the Andrews of the world, or to those who are considering making the leap? Ultimately there isn’t enough data for us to fully understand the long-term effects and it’s not clear at what point the benefits outweigh the risk, particularly to vulnerable populations or those with other health issues. While many dieters have seen drastic weight loss after the ketogenic diet, and there are many enthusiasts withand without medical credentials, the choice to make a big metabolic change should only be done after consulting with a doctor.

If you have chosen to make the leap, let us know about your experiences in the comments! Please invite me to all your fun keto parties and in the mean time I’ll be sure to eat enough donuts for both of us.

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Erica

Erica Kenney is a food scientist with a BS from UC Davis and a MS from University of Georgia. Her master’s thesis was on the emotions of coffee drinking and she’s particularly interested in how people feel about their food. Doesn’t everybody have a lot of feelings about their food? She worked in product development with fruits and vegetables, as a technician in a flavor lab, and currently works as a sensory analyst at E&J Gallo Winery.

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Bite Coin? How blockchain can help us keep track of food from the farm to your plate.

By Matt Teegarden and Lily Yang

This is the first in a series of collaboration between Don’t Eat the Pseudoscience and In Defense of Processed Food. Head over to the site and explore, and stay tuned for more!

Around 2017, Bitcoin and the cryptocurrency craze exploded across the internet and popular media. At its core, cryptocurrency promised a new and decentralized financial system that could exist without banks, governance, or other entities keeping track of transactions. While cryptocurrency in itself is rather interesting, what has really begun to tickle our fancy is the technology that actually enables cryptocurrency: blockchain.

Block-whatnow?

A blockchain is…just as it sounds…a chain…of blocks.  But each of these blocks is essentially a small packet of data that details a transaction (like one company selling an ingredient to another).  The way this chain is set up makes the data within each block impossible to alter. What’s more, the chain is not stored in one single place; instead, information is stored and continuously updated across various sections of the chain as it gets longer (as one ingredient moves to join other ingredients in a food product). In this, blockchain actually has many applications far beyond virtual coins. But why are people geeking out about the application of this technology in the food industry?

One word: traceability.

OK, cool, but why is traceability so important?

Traceability is the ability to follow a food, or an ingredient in a food, back to its original source. Given how incredibly gigantic and global our food system is though, traceability is no easy task. Think about a food you really like- let’s take a peppermint hot chocolate mix, since we’re in the holiday spirit. The peppermint pieces inside this hot chocolate mix probably did not come from the same food company that sells it (or if you were to make a mix for a friend, you may have sourced many ingredients from different companies). The peppermint flavor in these pieces is likely sourced from yet another company who likely did not grow the herb the flavor was derived from. The flow of ingredients from the farm, into a food item, onto the store shelf, and into your home is known as the food supply chain.

Tracing things all the way through the food supply chain can be incredibly time consuming and complicated. Currently, most traceability information is not collected and stored in an easily accessible and centralized place. Because it is not all located in one place, right now, it can be very difficult to quickly trace a food or ingredient back to its original source.

Imagine a situation like the recent E. coli outbreak in romaine lettuce. While the CDC was able to identify that romaine lettuce was the carrier of the harmful bacteria, for a while, no one knew from where this romaine lettuce came. Without a solid answer and just in time for Thanksgiving, the CDC’s initial advisory that ALL romaine lettuce be thrown away was very general. Let’s be real, though, who actually wastes valuable stomach space on salad at Thanksgiving dinner?  The process of tracing the tainted lettuce back to its original source (aka: where it was grown) is difficult because not only are there more than 1500 lettuce farms in the US, but, even a simple product like lettuce can pass through many hands (distributors, farms, etc.)  before it makes it to the store.

Eventually, the CDC was able to trace the outbreak source to a small region and is currently evaluating several farms there. In light of the scale and severity of this (and other) outbreaks, there has been a push for enhanced traceability in the food supply chain using…you guessed it: blockchain! Blockchain’s benefits to traceback and securing the food system has become so popular that both Forbes and Wired have addressed the issues as it pertains to food outbreaks and making our food system safe!

How could blockchain enhance traceability and what does that mean to me?

First off, blockchain has the potential to simplify food traceability by virtue of collecting data in one system that is mutually owned by all participants in the chain.  This allows all parts of the food supply or food system to “talk” to one another, creating a more harmonious, transparent, and accountable system: from the grower, to the packing house, to the distributor, to the markets, all the way up to YOU as the consumer.  And because all the information on how items travel through the supply chain is centralized and linked together, tracing something back to any point in the supply chain can take just minutes instead of days or weeks.

Is blockchain being used in the food industry now?

Because it is an emerging technology, blockchain is still making its way into actual practice for many companies.   One company that has widely publicised their commitment to blockchain is, Walmart. Through its new Food Safety Initiative, Walmart is working very closely with IBM Food Trust, to develop traceability capabilities (fun rhyme!) utilizing blockchain technology. This is actually a huge deal because Walmart is starting to demand that their food suppliers, like the companies that provide their stores with leafy greens, use blockchain-enabled technology themselves.   Other food-related start-ups, organizations, and initiatives like Goodr, Uber Eats, new food technologies, and the IFT Global Food Traceability Center are promoting and using blockchain technologies. .

Despite all its benefits, the integration of blockchain into the food industry still has a ways to go. As with most technologies, there is always an adaptability curve.  Most importantly, this technology needs to remain economically viable and also attainably accessible by all players throughout the supply chain. Nonetheless, blockchain shows incredible promise to enhance the way the food industry does business and improve the end product for the consumer.

For more dives and thoughts on all this, please refer to some other links at Food Safety News  and NeurochainTech.

You can also watch the now FDA Commissioner (but previously head of safety at Walmart), Frank Yiannias, discuss the Walmart Food Safety Initiative.


Matt

Matt is a PhD student at Ohio State, where he also finished his B.S. and M.S. degrees in food science.  His current research aims to understand how berries might impact oral health.  Outside of the lab, Matt enjoys cooking (that’s a given!), outdoorsy activities, and getting his hands on as many sweets as possible! (Follow him on Twitter! @teeinthegarden)

 

Lily

Lily L Yang (mind the “L”), consistently refers to herself in the 3rd person. Her magnificent Taiwanese hair – which has a life and body of its own hails from the great state of California. She once received a B.S. in Food Science from UC Davis before working for a few years at the USDA. Currently a PhD candidate – after obtaining a MS in Food Science – at Virginia Tech studying Food Science (specializing in food safety / food microbiology, risk communication / assessment, consumer behavior, and E. coli  in beef), Lily consumes inordinate amounts of food (usually noodles or dumplings), while randomly lifting heavy things and putting them down on an X, Y, and Z axis, while also simultaneously perusing the world wide interwebs for fabulously adorable pictures of puppies, hedgehogs, bunnies, bumblebees, Catbugs, Perry, and other such delightful fluffy things! Hellbent on world domination, Lily will endlessly rage to music +180bpm. (Follow her on Twitter! @glozu4ia)

When Real Pseudoscience Affects Real People

I often find it difficult to pull my head out of my research.  In focusing so much of my energy on finishing my dissertation, it’s easy to forget why I ever decided to pursue a career in food science and why I became interested in communicating its value.

A few weeks ago, I was lucky to meet someone who reminded me why.

I am part of a student group called Citation Needed at Ohio State that focuses on empowering students and the community to make informed decisions on issues in food and agriculture. We occasionally host coffee hours where we discuss particularly hot topics, and our most recent was about GMOs.

As everyone settled into their seats, a woman I had never seen before entered the room. She grabbed a few pieces of cheese and fruit and sat in the seat next to mine.  We briefly bonded over our mutual dislike of brie before the group conversation began. After only a few minutes, my new friend launched into a lengthy description of every health malady she had experienced in recent years. The cause? GMOs.

MattPseudo

In these types of situations it is so tempting to wield scientific authority and slash through every bit of misinformation someone believes. But if I have learned one thing through my involvement in science communication, it is just as powerful to listen.

By listening, I learned a lot about where her concerns about GMOs stem from. In her furious search for answers about her health problems, she quickly fell prey to internet pseudoscience. She believed that GMOs gave her cancer and caused the rashes that cover her body. What’s more, she’s recently started to land on her feet after a period of homelessness and is struggling to follow a GMO-free diet.

As she was sharing her story with me, she asked in exasperation, “what is a GMO? Has anybody ever seen one?” Unfortunately this question is all too common in this context. There are countless others who don’t understand what GMOs are, yet they use them as a scapegoat for various health problems.  

By the end of our conversation, it was hard to keep my emotions in check. My new friend was so incredibly afraid of food, and it broke my heart. I wanted to triumphantly rescue her from the grips of the pseudoscience that was viciously consuming her life, but in the end, it is entirely her choice what foods she decides to purchase. The best thing I could do for her was listen and help her digest the scientific basis as to why she has other options.

Now as I piece together my dissertation, I am doing so with new resolve. I am even more motivated to do science, read science, share science with everyone, and, most importantly, be compassionate.

Remember, don’t eat (or share) the pseudoscience.


File_000
Matt

Matt is a PhD student at Ohio State, where he also finished his B.S. and M.S. degrees in food science.  His current research aims to understand how berries might impact oral health.  Outside of the lab, Matt enjoys cooking (that’s a given!), outdoorsy activities, and getting his hands on as many sweets as possible! (Follow him on Twitter! @teeinthegarden)

The Magic Behind the Unicorn Frappuccino

If you haven’t heard of the latest come-and-gone Starbuck’s craze, you must be living under a rock! The Unicorn Frappuccino, AKA the most Instagrammable drink on the market, has swept across the nation. This bane of baristas has already been criticized for being a veritable sugar bomb. Now, when people are buying frappuccinos they aren’t doing it for their health. In general, frappuccinos in are a treat to be enjoyed every now and then. Let’s be honest here, the Unicorn frapp isn’t even the most sugary thing on the Starbuck’s menu board. That  aside, let’s talk about what makes the unicorn frapp so cool: dat color doe.

A quick glance at the ingredient list in this magical elixir provides us a glimpse into the beautiful cacophony. The magical ingredients we’re most interested in here are the Sour Blue Powder and the Pink Powder. The blue hue is provided by spirulina, a blue-green algae, and the pink comes from a mix of fruits and vegetables, including apple, cherry, radish, and sweet potato. The real magic happens happens when you mix your frappuccino and watch it turn from purple to pink!

But is it magic? Or, more likely…chemisty? The other secret here is the citric acid in the sour blue powder. As you mix the drink, the citric acid is mixed in causing the whole drink to become more acidic, which is also why the flavor changes from sweet to sour.

But why does this cause the color to change?

The pigments responsible for the color in the pink powder are anthocyanins. Anthocyanins are present in many fruits and vegetables including blueberries, cranberries, red cabbage, and eggplant. These molecules have a special property that causes them to change color based on the pH. When the citric acid dissolves, the pH shift causes the drink to become more acidic (lower pH); this causes the anthocyanins, which start out purple, to change their structure slightly, and thus appear beautifully pink!

So, if you’re sipping this exciting new concoction while you scroll through the comments from all your jealous Instagram followers, remember… you have chemistry to thank! It’s not magic, it’s science (so don’t eat the pseudoscience)!

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John in unicorn mode

Hailing from central California, John is a PhD candidate (Update: he did it! Dr. Frelka to you!) at Ohio State University studying how processing affects the physical properties of different food products. John has a B.S. and M.S. in Food Science from UC Davis where he studied both consumer food science and food microbiology. As a self-proclaimed nerd, John spends his free time reading comic books and playing board games. According to John, the major food groups are coffee, beer, and buffalo chicken dip. (Follow him on Twitter! @madfoodscience)

 

Daaaaaamn Panera, Back at it Again with the Pseudoscience.

Between tromping through Baguette Falls while whacking out azodicarbonamide, glycerides, artificial colors, and artificial flavors (i.e. amyl alcohol and benzaldehyde), and gallivanting around Crisp Valley Farms spotting the unwanted “No-Nos” trespassing on the property (i.e. hydrolyzed protein, polydextrose, MSG, and sodium erythorbate), Panera Bread continues its pursuit in educating consumers on the perils of “artificial” food additives and preservatives while feeding the pseudoscience madness in a cute new game. Of course, don’t forget the unusual/artificial “alien” sounds accompanying the destruction of each chemical. Luckily for the consumer, upon winning and defeating the awful droves of supposedly detrimental and awful food additions, one wins a coupon!

Panera Bread Land of Clean
Panera Bread “Land of Clean”

Panera Bread LLC introduced its “No-No List” in 2015 in an effort to be more transparent and to provide clean menu options. Complete with a video campaign, and now the “Land of Clean” game, the list focuses on chemicals and hard-to-pronounce additives that consumers find unfriendly at a glance. For example, the No-No list currently contains compounds like MSG, autolyzed yeast extract, and glycerides. Additionally, the list has previously contained common chemicals like tocopherol (it’s actually Vitamin E) and ascorbic acid (Vitamin C). As a response to this misleading philosophy, we at Don’t Eat the Pseudoscience also came out with our own video to explain why these chemicals aren’t bad and how they already naturally occur in your food products.

Panera’s vision for transparency and healthfulness, while laudable, creates its own set of flaws by promoting pseudoscience through instilling fear of complex words in consumers. These changes and deletions of ingredients do not necessarily reflect positive, healthier options. A quick glance at Panera’s menu reveals some items that are not only rather high in calories – per serving – but may also approach one’s daily limits of sodium, saturated fat, and total fat. A few examples: a panini that is 1,040 kcal per serving with 46 grams of fat (out of 65g / day); another sandwich has 18g of saturated fat (out of 20g/day). Daaaaaamn Panera…way to continue spreading the pseudoscience!

damn-panera

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MSG: Friend or Foe?

“The most prominent symptoms are numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitation.”

This terrifying set of symptoms sounds like a heart attack, but is actually the description of the ailments of “Chinese Restaurant Syndrome” as described by Dr. Robert Ho Man Kwok in a letter to the editor for the New England Journal of Medicine. Dr. Kwok claimed that he would consistently experience this syndrome after consuming Northern Chinese fare with his colleagues. In the letter, he attributed these symptoms to one of three possible culprits: cooking wine, excess levels of salt, or monosodium glutamate (MSG) used in the food. A number of individuals soon followed with similar letters affirming that they too had experienced this set of symptoms. As MSG is the only ingredient that differentiates Chinese food from other restaurant cuisines, MSG became the sole antagonist for this so-called Chinese Restaurant Syndrome. And thus MSG became enemy #1 overnight after a single a non-expert letter to the editor.

MSG is used as an ingredient to elicit the savory flavor, or umami taste, in foods. As the newest addition to the basic tastes, umami is less recognizable than sweet or salty. Our perception of umami is generally attributed to our evolutionary roots. Amino acids, the building blocks of proteins, elicit the flavor of umami which could have signaled to our early ancestors that a specific food was a good source of protein. Glutamic acid is a specific amino acid that triggers umami taste. Adding a sodium molecule to glutamic acid yields the compound we know as monosodium glutamate, or MSG.

Much of the research around umami and MSG is from Japan. Soups are often prepared with seaweed in Japanese cuisine to deliver a unique savory flavor. In the early 20th century, salts of glutamic acid like MSG were isolated in natural soup preparations that use seaweed as an ingredient, revealing that MSG was a primary source of that desirable flavor. While the idea to add pure MSG as an ingredient to foods in order to increase the perception of savory came much later, the practice of adding MSG-containing ingredients has been around for a long time. For example, breaking down or hydrolyzing proteins using heat or aging processes like fermentation creates these free amino acids which elicit umami taste. That’s why hydrolyzed vegetable protein or hydrolyzed yeast extract (hello, Marmite and Vegemite!) are such popular ingredients around the world. Ask any chef, and they’ll tell you that the ideal dish is one that balances the five basic tastes creating a deeper and more lasting flavor profile.

chinese-restaurant-syndrome
From Ink Chromatography Blog

MSG has been a gras (generally recognized as safe) food ingredient since 1958 by the FDA, and the Codex Alimentarius categorizes glutamate and all of its various salts as flavor enhancers. However, after the Chinese Restaurant Syndrome came on the scene, MSG became hotly contested as an additive that causes adverse effects like migraines and asthma. In response to this public outcry, a comprehensive safety review was conducted on MSG and other umami-inducing salts in 1987 by the Joint FAO/WHO Expert Committee on Food Additives. They concluded that MSG does not pose a health risk. In fact, they did not deem it necessary to specify a daily intake level as the quantity of glutamate to cause acute toxicity was so high. This was later confirmed in another evaluation in 1991 by the Scientific Committee for Food of the Commission of the European Communities.

On average, Americans consume approximately 0.55 g/day of added glutamate in foods which is similar to the daily consumption in the UK. Compare that to the average Asian consumer who ingests 1.2-1.7 g/day of added glutamate. Additionally, it has been shown time and time again that the human body metabolizes all forms of glutamate the same way—added or naturally-occurring. In fact, contrary to popular thought, glutamate levels in the blood do not increase after foods with high levels of added glutamate are ingested.

In general, there is weak evidence, at best, that links MSG to Chinese Restaurant Syndrome symptoms. In the most comprehensive study to date, a collaborative research project between Boston University, Harvard University, Northwestern University, and the University of California at Los Angeles investigated the effects of glutamate on self-reported MSG-sensitive subjects. Out of the 130 subjects included in the testing, only two had consistent responses to glutamate samples in a double-blind, placebo-controlled, randomized trial. Furthermore, the symptoms themselves were not reproducible among the glutamate-containing samples. This was not a statistically significant response, and keep in mind that these are self-reported sufferers of Chinese Restaurant Syndrome effects. The researchers concluded that glutamate does not cause reproducible sensitivities reported by some consumers.

the-truth-behind-notorious-flavor-enhancer-msg
From Business Insider

In addition to general sensitivity, there have been several specific symptoms “linked” with MSG including hives/swelling, asthma, stuffy nose, and headaches/migranes. The research addressing each of these is outlined below:

Hives/ Swelling (urticaria/ angio-oedema) – Many studies that investigate the link between MSG and these allergic skin reactions are difficult to interpret because subjects are used that are prone to allergic reactions, and they are often asked to refrain from taking any antihistamines during the testing period. This confounds the results because it makes it almost impossible to ascertain what is causing rash-like symptoms. In a study that asked subjects to reduce the antihistamine use to the lowest levels possible, there was no reproducible link between skin swelling and MSG consumption during double-blinded trial. There have been single cases (two) where urticaria and angio-oedema can be caused by MSG ingestion, though this is extremely rare.

Asthma – Similar to the hives studies, asthma studies are convoluted because subjects are used that report asthmatic symptoms to Chinese foods, and those subjects are asked to refrain from asthma medication. It is difficult to separate effects from the consumption of glutamate or withdrawal from preventative attack medication. Furthermore, the results within studies and between studies have not been reproduced in subjects, and it has been reported that no long-term health effects exist in epidemiological studies. There is no consistent evidence that glutamate ingredients trigger asthma symptoms.

Stuffy nose (rhinitis) – There are very few studies in this area, but a weak link has been established between MSG ingestion and rhinitis in three patients. These results have not been repeated; therefore, not enough research has been conducted to make scientifically-informed conclusions.

Headaches/ Migraines – It is hypothesized that glutamate may interfere with acetylcholine synthesis which may be the cause of reported migraines upon consumption of foods with added glutamate. However, there have been zero clinical trials to date testing glutamate and migraine/headache symptoms specifically, so there is no in vivo evidence linking the two.

The crisis of Chinese Restaurant Syndrome wreaked havoc on the food and restaurant industries simply by the submission of one infamous letter to the editor in 1968. Immediately MSG began to be phased out, where possible, from food products which spurred research and systematic reviews of glutamate food additives. As a result of that heightened research, there is no significant evidence for harm from glutamate except in an extremely small subset of the population. In fact, research in the area has highlighted positive effects from MSG including its role in several facets of digestion and reduction of sodium in foods at levels up to 30-40%.

In a time of hypersensitivity toward food additives, the story surrounding MSG’s stigma should be a cautionary tale to not rush to judgment before banning certain ingredients from your diet. Always read articles (including this one) from a critical point of view. And look to the scientific literature rather than an opinion on the safety of a particular food ingredient.


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Kelsey is originally from Minnesota and received her B.S. in Food Science from Purdue University. Most recently, she attained an M.S. in Food Science from Penn State where her research focused on mitigating the taste of bitter for pediatric medications. She lives in New York as a confectionery technologist (candy product development = dream job!). Kelsey loves eating cookie dough by the spoonful, collecting cookbooks, and watching old episodes of Top Chef. You can follow along with her adventures in the kitchen on her blog Appeasing a Food Geek! (Follow her on Twitter! @Kelsey_Tenney)

Kombucha: The Fungus in Your Tea

For the uninitiated, kombucha, a slightly sweet, slightly acidic, carbonated beverage made from fermented tea, may not sound like an appetizing beverage. But some enthusiastic supporters claim that it is a miracle elixir, reporting that kombucha aids digestion, gives relief from arthritis, acts as a laxative, prevents microbial infections, helps in combating stress and cancer, and vitalizes the physical body.

A simple Google search for “kombucha health benefits” reveals more extreme conceptions about kombucha: that it is spiritually cleansing, comes from outer space, is a natural psychic defense against negative energies and protects from evil thoughts. In this article we will go into a little detail on the background of kombucha, how kombucha is made, and whether its suggested health benefits stand up to science.

Kombucha is made by fermenting sugared tea with a symbiotic culture of bacteria and yeast (scoby). This scoby is also referred to as a kombucha mushroom or tea fungus and is similar to the “mother” used to make vinegar.IMG_3630

Pictured: Kombucha beverage with scoby

Kombucha is sold worldwide in retail stores and online, usually in refrigerated, single-serve bottles. It can also made at home using a starter culture, sugar, and tea. Black tea and white sugar are the preferred substrates for preparation, but green tea can also be used. Fermentation gives the kombucha tea a lightly sparkling fruity sour flavor after a few days and a stronger vinegar flavor after prolonged incubation. While some enjoy the pleasant carbonated acidic beverage, others find it to be too strong; a large variety of flavored kombuchas including ginger, cherry, and guava have been formulated to appeal to varying taste preferences.

Food historians believe kombucha originated in in northeast China, in Manchuria, in 220 B.C. This “Divine Che” was prized during the Tsin Dynasty for its detoxifying and energizing properties. Kombucha is thought to have been given its name when a physician named Kombu brought the tea fungus from China to Japan. It was later traded to Russia and Eastern Europe and became popular in Germany and France in the 1950s. In the 1960s Swiss scientists reported that drinking kombucha was as beneficial as eating yogurt, which helps explain the health hype of kombucha today.  

Home-brewed kombucha is traditionally fermented for a week in gallon-sized glass containers.  During fermentation, the scoby floats as a cellulosic pellicle layer on top of the tea. The scoby consists of acidophilic yeast and acetic acid bacteria embedded in a microbial cellulose layer. The exact microbial composition of kombucha varies depending on the source of the inoculum but is guaranteed to contain various species of Acetobacter including Acetobacter xylinium. During fermentation, A. xylinum produces a thin cellulose film where the cell mass of bacteria and yeasts is attached, enhancing the association between the bacteria and fungi. 

During the brewing process, a new “daughter” tea fungus is formed at the tea surface while the “mother” is submerged below. The Internet abounds with a variety recommended uses for excess mother scobys including facials, smoothies, candy, pet food, compost, and crafts.  The cellulose matrix produced by A. xylinium is also the basis for the chewy Filipino delicacy “nata de coco.” A. xylinum cellulose mats have also shown potential as a novel wound healing system.

As the tea ferments, scoby microbes break down the black tea ingredients and sucrose to produce acetic, lactic, gluconic, and glucuronic acids, ethanol, and glycerol. Kombucha fermentation also produces B-vitamins—scientists found that kombucha contains 161% more vitamin B1 and 231% more vitamin B12 than unfermented sweetened black tea. The final composition and concentration of metabolites depends on the fermentation length, sugar concentration, and the tea fungus itself. Essentially, the yeast cells break down sucrose into fructose and glucose and then metabolize these sugars, mainly fructose, to make ethanol and carbon dioxide. The acetic acid convert the metabolized glucose into gluconic acid and the ethanol into acetic acid. The caffeine and xanthines in tea help A. xylinium stimulate cellulose synthesis. Ethanol and acetic acid are both antimicrobial agents, protecting the tea fungus from contamination.

Yeasts and bacteria in kombucha are involved in metabolic activities that utilize substrates by different and complementary ways. Yeasts hydrolyze sucrose into glucose and fructose by invertase and produce ethanol via glycolysis, with a preference for fructose as a substrate. Acetic acid bacteria make use of glucose to produce gluconic acid and ethanol to produce acetic acid. During fermentation the pH value of kombucha beverage decreases due to the production of organic acids.

Scientific studies suggest kombucha has probiotic, antioxidant, antimicrobial, and detoxifying properties. However, all available research on kombucha was performed in cell or animal models. The lack of human clinical trials means it is impossible to truly substantiate whether these properties translate to real health benefits from regular kombucha consumption. (Read more about how important human studies are versus animal studies here)

Like sauerkraut, kefir, kimchi, yogurt, and a number of other fermented foods, unpasteurized kombucha may contain good-for-you bacteria that can aid digestion and help maintain intestinal health. Kombucha tea fractions have been shown to reduce lung and prostate cancer cell invasion, motility, and survival. Microbes in scoby produce antioxidants from tea polyphenols that protect liver cells against oxidative damage. Due to its acetic acid and catechin content, kombucha has been shown to be effective in inhibiting both Gram positive and Gram negative pathogenic microorganisms. Kombucha also contains glucuronic acid, a compound known to react with toxins or carcinogens forming a glucuronide complex which can then be excreted, hence speeding the elimination of harmful compounds from the body. Glucuronic acid can also be turned into glucosamine, a beneficial substance associated with cartilage, collagen, and fluids related to the treatment of osteoarthirits.

     However, it bears repeating: these studies were all performed in vitro or in animal models—not in human clinical trials! There are therefore no proven benefits to consuming kombucha. Additionally, there are risks associated with kombucha. Consuming kombucha can result in an upset stomach, acidosis, and possible allergic reactions. The unpasteurized tea, while rich in probiotics, may also pose a food safety threat, particularly for those who are pregnant or have compromised immune systems. Even though the scoby protects itself against foreign microorganisms, contamination is always possible. Home fermentation carries an inherent risk and failure to take proper precautions with regards to sterility and acidification can lead to unwanted, harmful bacteria such as Clostridium botulinum. Adherence to strict preparation protocol, particularly maintaining a low pH, is necessary to avoid the risk of serious illness. Therefore any home-production of kombucha should be done with great caution.

        So, in the end, is kombucha truly a health drink? We may never know beyond anecdotal claims. Because kombucha is a living food and it changes from batch to batch, the scientific community is less likely to spend money researching its clinical effects. If you enjoy the taste, and have a healthy immune system, then drink commercial kombucha with pleasure, and homemade brews with caution. The probiotics and antioxidants may provide some small benefit as part of a healthy diet, but don’t expect that kombucha, by itself, will prevent or cure any illness.


 

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Erica graduated from University of Georgia with a master’s in Sensory Science. Her thesis project was on the emotions of coffee drinking with a focus on coffee connoisseurs. (Follow her on Twitter! @Ericalovesfood)