Is Xylitol Dangerous?

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Over the past few years, research papers have suggested that sugar alcohols, specifically erythritol, may increase blood clotting and potentially lead to a major adverse coronary event or MACE for short. It gave me pause — to the extent that I stopped using sugar-free gum when I work out. The same research group recently presented a paper at a major heart disease conference suggesting that xylitol may do the same. I’m going to present some facts about what I’ve found, and you can make your own decision.

The Facts on Xylitol

Xylitol is a sugar alcohol. It is not an artificial sweetener. Some discussions have labeled it as such, but that’s wrong.

Our body makes xylitol along with other sugar alcohols. The amounts vary, but on average, the amount is 5 to 10 grams per day.

Pure xylitol powder contains 4 grams of xylitol. The highest processed food source is sugar-free dark chocolate at 1.2 grams of xylitol per ounce of chocolate. None of the studies collected data on sugar alcohol intake.

The research on xylitol and other sugar alcohols is limited to large observational studies. No randomized controlled trial exists. Therefore, while the relationship proposed between MACE and sugar alcohol intake is curious, it’s going to take specific randomized controlled trials to determine any cause and effect.

The problem with the current state of research is that it doesn’t preclude that some people may naturally produce more endogenous xylitol than others. That has to be separated out at some point in time.

One thing is true: xylitol can be lethal for dogs, even in small amounts like chewing gum! Make sure you keep any sugar alcohol products including gum away from all animals.

The Current Bottom Line on Sweeteners

I think that the research on sugar alcohols should continue but without the hyperbole. What’s often not stated is the impact sugar alcohols can have on gut bacteria. Even if sugar alcohol can have some role in MACE, the gas production can keep consumers from using it in excessive amounts. As for me, I still chew gum while I work out, but my gut works overtime producing gas if I eat foods with sugar alcohols in them. I’d rather pass on the sugar alcohols than pass gas, so it’s regular old gum for me.

A Note on the Memo

While I love writing the Memos and helping you live a healthier life, drchet.com is still a business, so I’m hoping to increase product sales. If I have a product in the store that relates to the Memo’s subject, I’ll be highlighting it in a P.S., starting today with an option if you decide xylitol isn’t for you.

What are you prepared to do today?

        Dr. Chet

Bottom Line on Sucralose

P.S. If you’re going to stop using xylitol, you’re going to need another sweetener. Sucralose has been widely criticized, but is it warranted? Check out The Bottom Line on Sucralose at drchet.com; get the MP3 or PDF to learn more for only $1.99 (free for Insiders).

References:
1. CVD Res 2025. (121)1319–1329 https://doi.org/10.1093/cvr/cvaf091
2. Eur Soc Cardiology 365. 2026. Poster: The association of Xylitol and incident cardiovascular events: the CLSA and EPIC-Norfolk cohort studies

The Memo: AI-Free Zone

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I’m still bugged about the topic I wrote about last week, polyphenols in fruit. It’s not that I don’t think it was an interesting topic. It was. Why did it show up in press release now when it was published in 2023? My sense is that AI was involved, based on what I’ve read and what I’ve researched in the past. I’m going to change the way I select topics to write about.

But that’s not the real reason I’m writing this. It is to let you know that everything that’s posted on my website was written by me. I do use a specific AI to search for background research on topics (one expert said to think of AI as an eager research assistant, and that’s how I use it). I read research papers that AI finds, and I know the field well enough to know a good source from one that’s bad. Once I read enough research, I write about the topic. Then my editor of 36 years verifies what I’ve written makes sense or recommends changes that makes it clear what I intended to write. Then it goes to you.

It’s not that AI doesn’t offer to write something, but it doesn’t have a database of life experiences in addition to my knowledge base. It cannot think, has never run a marathon, got a knee replaced, or dealt with any of the human conditions we face. If you read what it writes, it sounds hollow because when AI writes, it’s not choosing the best word—it’s giving you the most common word to occur in that particular phrase.

One area is not free from AI: the illustrations. Paula says it’s almost impossible to find art that hasn’t been touched by AI. It’s not just the image of a hippo in a track suit eating ice cream; it’s almost every image, no matter how ordinary, but we work hard to make sure the images aren’t misleading and try to exclude anything made with generative AI.

Just know that the Memo and everything I write or say originated with me. This is an AI-free zone and is going to stay that way.

What are you prepared to do today?

        Dr. Chet

Fruit: Variety is the Key

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I didn’t want to hold you in suspense, so I already revealed that you can put the banana in your smoothie if you like. I’ll tell you why, but first a little more about the study.

The biggest issue, which the researchers acknowledge, is the limited number of subjects. Eight subjects just aren’t enough, nor is 11 in the second study, to be able to make generalizations applicable to others. While it’s interesting, not every subject was impacted in the same way. The researchers didn’t use scatter plots so we could see exactly how the subjects were impacted individually.

The take-home message is don’t blend the fruit with the banana until you’re ready to drink it if you want to maximize polyphenol content, but there’s more to it than that.

Three Observations

Part of the reasoning the researchers had was that people may be selecting their foods based on the polyphenol or phytonutrient content. Have you ever selected the fruits you put in your smoothie, or even those you want to eat, based on the polyphenol levels? I haven’t. I eat fruit because it’s available, better tasting in season than not, and I want to reach that eight to ten servings per day. Polyphenols have never crossed my mind once in that decision.

While I’ve talked about the limited benefits of the study, there are three things we can take away from it.

  1. If you like a banana in your fruit-based smoothie, there’s no reason to change that approach. Even if this were a large study with enough subjects to increase the power and actually be meaningful, you’re not eating the same smoothie three or four times a day; either you’ll get tired of it or your body will adapt. To take a line from a movie, “Nature finds a way.”
  2. You should eat a variety of fruits and vegetables throughout the day. If you eat enough fruit from a variety of sources, you’ll get the polyphenols at some point. You don’t have to eat in some strange schedule to maximize phytonutrient content.
  3. If this study shows anything, it’s that taking phytonutrients in supplement form is an excellent way to complement a good diet. If you already use products with plant concentrates and phytonutrients in them, you may be ahead in the phytonutrient game. 

These studies were well thought out and well executed as pilot studies; let’s hope this is a prelude to a larger study from the same research group in the near future. One question I have is whether the consistent consumption of the same banana-blueberry smoothie consumed regularly over six months shows the same results or would there be some form of adaptation resulting in more polyphenol absorption? If I find out, you’ll hear it here first. What are you prepared to do today?

        Dr. Chet

Reference: Food Funct., 2023, 14, 8217–8228

Should You Skip the Banana?

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Over the years, I think I’ve made it clear that I don’t drink smoothies of any type. I’m also aware that it’s a preferred method for many people to get their fruit, protein, fiber, and other nutrients in a convenient manner. That’s why a recent press release for a study published in 2023 caught my attention; it claimed that bananas may impair the phytonutrient benefit of blueberries when blended in smoothies, specifically the polyphenols. Let’s look at the study.

The reason for the study was to test a specific enzyme known to reduce polyphenol content in fruit: polyphenol oxidase (PPO). Bananas contain a high amount of it; would it reduce the potential phytonutrient content of the berries? Researchers recruited subjects for two studies; eight volunteers for the first, 11 for the second. They tested whether a banana added to blueberries in almond milk impacted the phytonutrient content as well as the amount actually absorbed into the body. There were two controls: first, another smoothie made without banana, and a capsule with a specific flavanol content taken with almond milk. The second test did the same thing but did not blend the banana with the blueberry and milk.

The polyphenol capsule and the fruit without the banana came out about the same in polyphenol absorption.

The question is simple: does this really impact your morning smoothie with a banana? I’ll let you know on Saturday. Okay, I won’t make you wait—put the banana in the smoothie if you like it.

Tomorrow night is the Insider Conference call. You can still become an Insider or purchase a Guest Pass for $9.95 by 8 p.m. ET Wednesday, and a replay will be available within the following week if you can’t make it live. The topic is Sugar and Carbs—Fact or Fiction as well as answering your questions.

What are you prepared to do today?

        Dr. Chet

Reference: Food Funct., 2023, 14, 8217–8228

Carbs and Insulin: Diet Matters

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On Wednesday, I told you about a study of people who experienced an energy crash after eating carbs. The next study was more pragmatic: we have non-diabetic people who seem to have reactive hypoglycemia (RH), but can we treat it with diet alone? This is a concern because many believe that RH in these people may be a precursor of pre-diabetes and type 2 diabetes. This time, the researchers recruited 40 normal-weight subjects with RH symptoms to see if a dietary intervention could improve symptoms over a year. After testing all subjects, only 12 subjects actually had blood sugars below 55 mg/dl, the more-or-less agreed upon lower boundary for blood sugar.

After assessing their initial diet, subjects met with a dietician four times over the next six months. They were taught the nuances of a Low Glycemic Index Diet in private sessions with a dietician. The subjects were asked to follow that diet for the next three months, with a follow-up session with the dietician midway to fine-tune the diet. The same pattern was followed for the Mediterranean diet. The subjects were tested for RH symptoms after each diet; then for the next six months, they were told to follow any diet they chose based on what they’d learned. All subjects were tested again after 12 months.

A couple of results stood out to me. After six months, the subjects ate an average of four times per day instead of the three times before the study began. Second, they allowed more time between each meal than they had before. While they were instructed on portion sizes during the training periods on each diet, there were no limitations on how much they ate or and no counting calories.

When it comes to the symptoms associated with RH, five of the seven tested were significantly reduced. The researchers attributed it to a healthier eating pattern. After the 12-month study, 80% of the subjects leaned toward the less-complicated Mediterranean diet, which increases the number of whole grains, vegetables, beans, and nuts.

What do we know now that we didn’t know then? Two things: diet matters when it comes to hypoglycemia in non-obese, non-diabetic subjects. Further, individual attention, even just four sessions within six months, is enough to help people make better choices. Whether that lasts more than a year is unknown, but we also know this: the most powerful hormone in the body—insulin—doesn’t cause the insulin overshoot phenomenon in otherwise healthy people. The search for the cause continues.

The Insider Conference call will be next Wednesday September 16 at 9 p.m. ET, and the topic will be Sugar and Carbs—Fact or Fiction. Some of the facts and fictions covered will be:

  • Does eating sugar cause diabetes or pre-diabetes?
  • Can type 2 diabetics eat sugar?
  • Which organ wants and uses more sugar than any other?
  • What are hidden sources of sugar on nutrition labels?
  • Can overeating carbohydrates cause non-alcoholic liver disease?
  • And even more, plus answers to your questions.

The Guest Pass for this Insider Conference call will be available just like last month for $9.95. Sign up before 8 p.m. Wednesday to be included, and a replay will be available within the following week.

GuestPass

Click on the ticket
to sign up!

What are you prepared to do today?

        Dr. Chet

Reference: Nutrients 2022. (14) 497. https://doi.org/10.3390/nu14030497

Carbohydrates and Insulin

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On a typical busy morning, a person has a fairly good dose of carbohydrates in the form of a sugary cereal, a bagel, a pastry, or a breakfast sandwich from a drive-thru. Then a couple of hours later, they seem to crash—not their car, but their energy seems to drain away. Maybe they start to sweat and even get some brain fog. If it happens with regularity, people get concerned and may even see their doctor. Is this a food problem? A metabolic problem? We’ll spend some time talking about it; let’s begin with a couple of studies.

The first study recruited a group of healthy subjects who had symptoms like I mentioned. They were tested, together with a healthy control group that had never responded that way, for a condition known as “reactive hyperinsulinemia,” also called the insulin overshoot phenomenon. In short, that means too much insulin is released and can drop the blood sugar below 55 mg/dl.

The researchers tested all subjects for problems in processing carbohydrates: oral glucose tolerance test, mixed meal tolerance test and a bunch more.

They found no specific pattern in either group of subjects:

  • Some in both groups had symptoms, but their blood sugar never went too low.
  • Some had their blood sugar go below 55 mg/dl with no apparent symptoms.
  • In subjects with glucose lower than 55 mg/dl, none had a high insulin level to cause that effect.
  • Not one subject responded with problems to the mixed meal tolerance test.

The conclusion was that a lot more research has to be done to find out why what everyone thinks is happening really isn’t happening in everyone. Fortunately, this same research group did an interesting follow-up. We’ll talk about that on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: J. Pers.Med. 2021,11,276. https:// doi.org/10.3390/jpm11040276

Three Challenges

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This weekend is the last holiday of the summer or the first of the fall, depending on how you look at it. I’d like to challenge you to try three different tasks if they are not part of your regular routine. I’ve talked about high-intensity interval workouts a lot the past couple of months. I’m also going to be talking about weight training soon, and the change in weather is coming. Here are three challenges with limited explanations.

HIIT

No matter where your fitness level is now, you can increase your fitness level faster with HIIT than continuous training—that’s why I want you to try some form of interval workout at least once. It can be on any piece of aerobic workout equipment or none at all. The basic concept is to warm up, increase the pace or the resistance for 30 to 90 seconds and then back into easy pace for about 3 minutes. Then repeat the cycle 4 or 5 times. Try that twice this week. Stay within any limitations your physician has given you.

Deadlift

The deadlift is one of the most basic lifts in weight training. You begin with the barbell on the floor, and keeping your back straight, you lift the barbell until your knees lock. Then repeat. The heavier the weight you can lift, the more overall body strength you can gain. It involves the hands, buttock, thigh, calf, core, trapezius, lats, deltoids, and dozens of small core muscles.

Proceed with caution—you must protect your lower back! For some of you, it may be simply standing up from a chair with your hands hanging at your sides. It may also be standing on an exercise tube, feet a shoulders width apart, and standing up, upper body erect, while holding on to the tube. Light dumbbells. Heavy dumbbells. Barbell. Machine at your gym. The number of repetitions and sets are up to you. But as you do it, lift with your legs, not your back. Try it twice over the next week. Remember, respect your orthopedic limitations. This is an exercise for overall strength. It may take time to build up strength in your lower back, but we all have to start somewhere.

Flu Shot

Schedule and get your flu shot. Check to make sure you’re up to date on your tetanus shot as well. Get it done now.

I know some of you are not fans of vaccinations. I know that many people say, “The only time I got a flu shot, I got the flu.” Actually, that demonstrates how weak your immune system really was. We don’t get the flu shot not to get the flu; we get the flu shot to stimulate the immune system to get ready for other similar viruses. You still may get the flu or some other virus, but your immune system will be better able to handle it. It may end up being a milder case. I’ll be covering research on this in the near future. The challenge stands. Paula and I will be getting ours along with Riley and his mom.

I hope you enjoy the last holiday before Thanksgiving; I’ll be back in your inbox next week. Let’s see how you do on the three challenges I threw down before then.

What are you prepared to do today?

        Dr. Chet

Functional Essential Fatty Acids

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Understanding that linoleic acid is the essential omega-6 fatty acid and alpha-linolenic acid (ALA) is the essential omega-3 fatty acid, the logical question would be what about fish oil and other sources of omega-3 fatty acids? It’s just a little complicated, but let me explain.

It’s true that in humans, we can use ALA to make EPA and DHA. The problem is that it isn’t a dominant biochemical pathway. That’s why the phrase “functional essential fatty acids” are used to describe EPA and DHA. Another way of saying it is that to function at optimal levels, we should get DHA and EPA from either food sources or from dietary supplements every day.

DHA is critical to brain and eye health while EPA has anti-inflammatory properties. The best sources of EPA and DHA would be seafood. For vegetarians, there are some products available that contain these functional fatty acids derived from algae; it’s only a matter of time before the more easily reproducible sources like algae and seaweed replace fish as the primary source found in supplements.

Seed Oils

I’ve written about seed oils several times. I do not disagree that we overconsume seed oils, but most are found in ultra-processed foods; that’s why we end up with the disproportion of omega-6 to omega-3 fatty acids eaten in our society as a whole. There’s no problem lowering the amount of intake of omega-6s. If you want to use oils in cooking, safflower, sunflower, corn, and soybean oil have the best omega-6 profile; you can certainly find non-bioengineered and organically grown sources of those oils if you want. If you’re going to get oils from food, you might as use the sources with the highest amount of linoleic acid per serving.

What are you prepared to do today?

        Dr. Chet

References:
1. Linus Pauling Institute. Essential Fatty Acids
2. J Lipid Res 2014 DOI 10.1194/jlr.R055095

Essential Fatty Acids

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There are always controversies in nutrition. With all that’s been written about seed oils and sources of omega-3 fatty acids, I thought we’d go back to the basics this week—back to what are the essential fatty acids, seen above floating in the bloodstream. Similar to essential amino acids, essential fatty acids are the fats that we cannot make ourselves; therefore, they must be obtained from the foods that we eat. We can make plenty of saturated fats from carbohydrates and even proteins, but we can’t make the two essential fatty acids (FA).

The two essential fatty acids are the omega-6 fatty acid called linoleic acid (LA) and the omega-3 fatty acid called alpha-linolenic acid (ALA). With those as a base, other fatty acids can be made that have a variety of important functions in the body; the most important function is making cell membranes. If you have adequate amounts of these essential fatty acids, it simply means your cells will work better. The sources for these oils are all plant based: seeds, nuts, and oils from those foods.

Men need about 17 grams of ALA per day while women need about 11. Women need about 1.1 grams of LA per day while men need 1.6 grams per day. That seems like such small amounts when you consider that works out to fewer than 150 calories for women and 200 calories for men, using oils as the primary source.

What about the omega-3s we hear about all the time like EPA and DHA? I’ll get into those on Saturday.

What are you prepared to do today?

        Dr. Chet

References:
1. Linus Pauling Institute. Essential Fatty Acids
2. J Lipid Res 2014 DOI 10.1194/jlr.R055095

Exercise Rules!

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The top sumo wrestlers weigh an average of 355 pounds. I watched a little wrestling when Konishiki, a Hawaiian sumo, was popular; he had been the heaviest sumo up to that time weighing over 600 pounds. The question is with weighing so much, are sumo wrestlers at risk for weight-related disease? It comes down to the visceral fat issue.

The sumos train for five or six hours first thing in the morning. Think about moving your body weight or more for that long every day. This isn’t just lifting weights—you’re trying to grab, hold on, and move 300 to 400 pounds for hours every day. The sumos have massive core, hip, thigh, and calf muscles. No doubt they have massive amounts of body fat, but most is subcutaneous fat. The visceral fat is much lower than the 300- to 400-pound North American obese individual and lower than those with comparable body fat.

What protects the sumo is the excessive exercise they get every day. True, they often eat 5,000–10,000 calories per day to gain weight, but they don’t suffer the same issues as sedentary people of the same weight.

The problem begins when they retire and no longer train. Due to their massive size, the risks of increasing visceral fat and disease accelerate. Unfortunately, many succumb to those diseases. The great Konishiki developed kidney failure within the past two years and required a kidney transplant. As of this writing, he’s still alive at 62.

The lesson for all of us is this: until we can lose the excess body fat, we have to stay as active as we can with regular exercise, especially weight training. Preventing the age-related loss of muscle due to sarcopenia and building as much muscle as we can through weight training and aerobic exercise can help reduce visceral fat. It’s not a permanent solution, but doing as much as we can to reduce the risk is significant. Until we can master the first two steps of eating less and eating better, moving more is critical. Exercise rules!

What are you prepared to do today?

        Dr. Chet