Is Xylitol Safe?

xylitolWe continue on our journey of looking at different sweeteners today. Xylitol is on the menu today and so lets take a look at this substance and see what we discover. Xylitol is becoming popular in many foods and snacks. It’s a sweetener that is about as sweet as sucrose. It is found in nature but produced commercially chemically. On a personal note I think xylitol has what I can only describe as a “cooling” taste in my mouth, but that’s just me. So what else can we learn about xylitol. Study time!

Insulin and GI

In dogs after administration of xylitol and insulin response was seen. 1,2,3 Insulin did raise more with xylitol than with glucose. It is important to remember two big things from these studies; first is that these are dogs, second is these were infusions of xylitol rather than being ingested. Would ingested xylitol cause a greater response than glucose? I don’t know but it does appear to raise insulin.

After administration of xylitol, researchers measured a significant increase of insulin in the portal veins in man. 4

In another study 5 subjects were given 30gm glucose and 30mg xylitol (months apart) and their insulin responses as well as GIP and motilin. GIP (glucose-dependent insulinotropic peptide) is a hormone that increases insulin secretion. This action is greater when glucose is ingested rather than infused. Motilin does a number of things including stimulation of the motility of the gut. So in this study a solution of xylitol or glucose was given and they measured these factors. Insulin rose in both solutions but more so in glucose. In fact it was a very small increase with xylitol. GIP was not affected by xylitol but was by glucose. Glucose increased motilin and caused faster stomach emptying than xylitol. So what did the xylitol do you ask? Cause diarrhea. Yup it gave 3 of the 5 subjects the runs. The researchers attributed this to an osmotic difference. This is consistent with many reports that xylitol causes Montezuma’s revenge. The good part though is that it only happened that one time and after bowel evacuation the 3 volunteers had no more problems. 5 Very similar effects were seen in both men and rat subjects. 6

Another effect of xylitol, as mentioned above is that it can slow gastric emptying. This may be helpful to help a person feel full longer. A study looking at this gave subjects 25gm xylitol in solution at 10 AM. Others were given other sweet solutions such as fructose and sucrose. At 11 they were given a meal of eggs. The xylitol group maintained the food in their stomach for roughly 30min longer than the others groups. In another part of the study the same preloads were given and 1 hour later the subjects were allowed to eat at an “attractive buffet” (according to the researchers). Calorie intake was measured and the group that had 25gm preload of xylitol ate significantly less calories (690 +/- 45 with 25g xylitol vs 920 +/- 60 with water). 7

It think it’s important to keep this in context. These people were consuming 60 kcal before a meal to consume on average 230 kcal less. Now this would be a net reduction for the people in this study of 170kcal/meal. Not bad but the potential for diarrhea I’m sure would increase with that kind of dose if taken regularly.

So it appears that xylitol does have a very small impact on insulin and definitely the potential for an impact on your porcelain throne. It may also help you eat less when consumed about an hour before meals. What else can xylitol do?


Xylitol is touted as having beneficial properties on dental health, most especially with caries (cavities). One reviewer of articles believes this is due to increased saliva production from xylitol gum and candies rather than preventing bacteria from being able to metabolize the xylitol. 8 Saliva has chemicals that are responsible for tooth remineralization and health. Elderly folks who have chronic dry mouth are at increased risk of having caries. Some believe that streptococcus mutans (the bug responsible for laying down plaques and excreting acid) are responsible for caries and xylitol has been shown to stop this bug from doing it’s nasty deeds. 9,10 It’s possible that xylitol doesn’t interfere with the internal nutrient system in the individual teeth like sucrose does, but that is the topic of an entire article.

Don't let this be the result of poor dental health

Don’t let this be the result of poor dental health

An entire article looking at data has concluded that xylitol chewing gum is beneficial in preventing dental caries. 11 It should be noted it has to be done 3-5 times per day after meals and for at least 5 minutes. Chewing on one piece for 2 hours once a day might not do a thing. Another study done over 40 months in Belize showed that children who chewed xylitol gum had a significant reduction in caries over those who had xylitol-sorbitol combo and most definitely over sugar base gums. 12


Xylitol isn’t calorie free like some people may think. While sugar has close to 4kcal/gram, xylitol has 2.4kcal/gram. So if you’re using xylitol in cooking be aware that while you aren’t putting as many calories in that dish as sugar, you’re still putting calories into the food. So really you can only say that it is a lower calorie alternative to sugar, not a no calorie option.


There are actually nose sprays that one can use to help treat sinus problem and maybe even help resolve sinus and ear infections. Xlear is one company that makes such products. Because the xylitol helps disrupt bacterial plaques it is thought that they can help balance in the nose and ear. I’ve never tried them but if you have and had success I’d love to hear about it.


Some people have had problems with the gut after ingesting xylitol. As mentioned above xylitol can cause diarrhea and maybe fermentation can arise because it arrives to the colon pretty much untouched. There are no large trials that I know of showing adverse effects. Lack of evidence isn’t an indictment but for me xylitol goes into my book as once in a while probably ok but not regularly. This is a natural substance but you don’t get a lot of it naturally and there’s probably a reason for that. Sugar is also natural but really you don’t get a ton of it in nature all in one spot, at least in most areas. We humans condense it down and create abundance. If you are having ill effects but think you’re doing good for say your teeth, then you should reconsider using it. It’s never good to sacrifice one organ system for the other. Try to treat the whole system. Also, xylitol is toxic to your dog. Do not give xylitol to your dog!

If anyone has had any experience with xylitol please share down below. I love hearing anecdotal stories about how they affect different people.


1.Kuzuya, Takeshi, Yasunori Kanazawa, and Kinori Kosaka. “Stimulation of insulin secretion by xylitol in dogs.” Endocrinology 84.2 (1969): 200-207.

2.Kuzuya, Takeshi, Yasunori Kanazawa, and Kinori Kosaka. “Plasma insulin response to intravenously administered xylitol in dogs.” Metabolism 15.12 (1966): 1149-1152.

3.Hirata, Yukimasa, et al. “Blood glucose and plasma insulin responses to xylitol administrated intravenously in dogs.” Biochemical and Biophysical Research Communications 24.3 (1966): 471-475.

4.Berger, W., et al. “Insulin concentrations in portal venous and peripheral venous blood in man following administration of glucose, galactose, xylitol and tolbutamide.” Hormone and Metabolic Research 5.01 (1973): 4-8.

5.Salminen, Eeva K., et al. “Xylitol vs glucose: effect on the rate of gastric emptying and motilin, insulin, and gastric inhibitory polypeptide release.” The American journal of clinical nutrition 49.6 (1989): 1228-1232.

6.Salminen, Eeva K., et al. “Xylitol vs glucose: effect on the rate of gastric emptying and motilin, insulin, and gastric inhibitory polypeptide release.” The American journal of clinical nutrition 49.6 (1989): 1228-1232.

7.Shafer, Rex B., et al. “Effects of xylitol on gastric emptying and food intake.” The American journal of clinical nutrition 45.4 (1987): 744-747.

8.Alanen, Pentti. “Does chewing explain the caries-preventive results with xylitol?.” Journal of dental research 80.7 (2001): 1600-1601.

9.Beckers HJ. Influence of xylitol on growth, establishment, and cariogenicity of Streptococcus mutans in dental plaque of rats. CariesRes 1988;22(3):166-73.

10. Grenby TH, Phillips A, Mistry M. Studies of the dental properties of lactitol compared with five other bulk sweeteners in vitro. Caries Res 1989;23:315-9.

11.Burt, Brian A. “The use of sorbitol-and xylitol-sweetened chewing gum in caries control.” J Am Dent Assoc 137.2 (2006): 190-6.

12.Makinen, K. K., et al. “Xylitol chewing gums and caries rates: a 40-month cohort study.” Journal of Dental Research 74.12 (1995): 1904-1913.


Is Stevia Safe?

steviaWell we’ve hit the major artificial sweeteners in previous posts in this series. Today we look at a natural sweetener, stevia.

Stevia (stevia rebaudiana) is a sweetener that many people have been using for hundreds of years. It is native to Central America and South America. The leaves are around 40 times sweeter than sugar and the extract is about 300 times sweeter. It dissolves very quickly in and can have somewhat of a bitter aftertaste.

So we can’t call stevia an artificially sweet seduction since it is natural. But is it another sweet seduction or is it a winner to make things oh so wonderfully sweet?

Study Time!

In a study of rats, 0.5mg/kg of stevia lowered blood glucose levels in diabetic rats and glucose tolerance testing in normal rats. It also reduced insulin sensitivity in the diabetic rats and enhanced insulin secretion and insulin utilization.1

So even though insulin increased, sensitivity and utilization of the insulin was better. That is important to remember. If insulin merely goes up and isn’t used because of sensitivity, that is bad. If insulin goes up and is used, like in healthy individuals that’s ok. That’s the way it’s supposed to be.

In another study of diabetic induced rats, stevia was used to compare blood glucose levels with normal and diabetic controls. Subjects were fed 150mg/kg, 200mg/kg and 250mg/kg of stevia per day. Significant decreases in blood glucose were measured as well as non-significant decreases in body weight. Glimepiride (a diabetic drug which increases insulin secretion) was also used as a comparator. Glimepiride lowered blood glucose significantly more than stevia at all doses.2

In yet another rat trial, rats were made diabetic and given stevia, methi seeds, stevia with methi seeds, or glimepiride. They were followed for 60 days. Blood glucose decreased the greatest with glimepiride, next with methi and stevia combo, then methi alone, then with stevia alone. Stevia did create a significant effect on blood glucose by itself. 3

Another study shows that rats fed lots of fructose were able to decrease insulin resistance with a good ol dose of … guessed it, stevia.4

In an actual human study, subjects were given preloads of stevia, aspartame or sucrose before being fed a meal. 20 min after the meal blood was drawn and glucose and insulin measured. Compared to sucrose, aspartame and stevia produced less postprandial glucose levels. Stevia produced significantly lower insulin levels compared to aspartame and sucrose.

In another human study in subjects undergoing glucose tolerance tests, 5 grams of steavia leaves were given at 6 hour intervals for 3 days. The groups were separated into stevia and an aqueous arabinose solution. Stevia increased glucose tolerance and decreased glucose levels during the study.6

Other effects

Stevia appears to have some fertility effects, at least in rats. In one study a water decoction (a way of extraction by boiling chemicals from herbs or plants) was given to rats that were fertile. The infertility continued for 50-60 days after intake stopped. To the researchers no other effects were noticed. This was in females.7

In male rats in chronic (60 days according to the paper) administration produced,

“produced a decrease in final weight of testis, seminal vesicle and cauda epididymidis. In addition, the fructose content of the accessory sex glands and the epididymal sperm concentration are decreased. Stevia treatment tended to decrease the plasma testosterone level” 8

So these poor buggers not only had smaller testes but also less sperm and decreased testosterone. Not exactly a thrilling side effect.

Gut Flora

Stevia doesn’t appear to alter gut flora which is a good thing. The bacteria are able to alter it to steviol however that was the end of it. The tests were done with samples from human donors in vitro.9, 10  How’s about that for donating to science!? We can suppose that this would translate over to a real life human intestine but you never know in these types of studies. This information is promising though.

Blood Pressure

In a study in China, participants were given 500mg of stevia 3 times per day for two years vs placebo and blood pressure was measured. A significant decrease was noted after 1 week. The change was from 150 [7.3] to 140 [6.8] mm Hg; DBP, from 95 [4.2] to 89 [3.2] mm Hg. That’s not too bad. A side note from this study is that more people on placebo had a thickening of the left ventricle than people on stevia (34% vs 11.5% respectively) Quality of life scores were better with stevia. There was no difference in adverse effects between groups.11

Another study found no difference in blood pressure using 3 different doses of stevia, up to 15mg/kg/day.12 This for me would be the 500mg three times daily. The difference in this study is that it was dosed twice daily rather than three times daily. Is this enough to make a difference? I don’t know. I could develop all kinds of protocols for a study to look at these questions but the real question is does this harm you? In both of these studies no adverse effects were seen compared to placebo.

Some have claimed that stevia will raise epinephrine and cortisol. I can’t find any evidence to support this. If anyone has anything I’d love to see it. If that is true it would be a big ding against stevia but again I can’t find evidence to support it.

Stevia may also have oxalates in them which can be problematic for people with kidney stones made from the same substance. I can totally buy that the leaves have them, but I haven’t been able to confirm the extract.

Final thoughts….for now

It looks as though stevia is probably OK for use. If a person is having problems with infertility it may be best avoided. Some forms are sold with other fillers like maltodextrin so they may not truly be zero calories, although if you’re using 1 packet of the stuff it will be less than 4 calories. But if you’re using bulk you’ll have to take care like you would with sucralose, which you’ll never find in my house. Nasty stuff that is!

If you’re diabetic or worried about blood sugar then it appears stevia is beneficial, at least to some degree. Like I always say, try it out and see what happens to you because you and I are not the same people, and neither of us are rats.

You probably won’t find me using 500mg caps of stevia for blood pressure reduction either since I feel that a good diet and some movement will likely take care of that, but it won’t raise it either (unless you’re eating it with junk). From time to time you might see me sweeten something with it, but not regularly and certainly not in bulk. I like my testes the way they are thanks.


1.Chen, Tso-Hsiao, et al. “Mechanism of the hypoglycemic effect of stevioside, a glycoside of Stevia rebaudiana.” Planta medica 71.02 (2005): 108-113.

2.Sumon, M. H., et al. “Comparative efficacy of powdered form of stevia (Stevia rebaudiana Bertoni) leaves and glimepiride in induced diabetic rats.” Bangladesh Journal of Veterinary Medicine 6.2 (2008): 211-215

3.Rafiq, Kazi, et al. “Comparative efficacy of stevia leaf (stevia rebaudiana bertoni), methi seeds (trigonella foenum-graecum) and glimepiride in streptozotocin induced rats.” International Journal 2229 (2011): 7472.

4.Chang, J-C., et al. “Increase of insulin sensitivity by stevioside in fructose-rich chow-fed rats.” Hormone and metabolic research 37.10 (2005): 610-616.

5.Anton, Stephen D., et al. “Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels.” Appetite 55.1 (2010): 37-43.

6.Curi, R., et al. “Effect of Stevia rebaudiana on glucose tolerance in normal adult humans.” Brazilian journal of medical and biological research= Revista brasileira de pesquisas médicas e biológicas/Sociedade Brasileira de Biofísica…[et al.] 19.6 (1986): 771.

7.Planas, G. M., and J. Kucacute. “Contraceptive Properties of Stevia rebaudiana.” Science (New York, NY) 162.3857 (1968): 1007.

8.Melis, M. S. “Effects of chronic administration of< i> Stevia rebaudiana</i> on fertility in rats.” Journal of ethnopharmacology 67.2 (1999): 157-161.

9.Gardana, Claudio, et al. “Metabolism of stevioside and rebaudioside A from Stevia rebaudiana extracts by human microflora.” Journal of agricultural and food chemistry 51.22 (2003): 6618-6622.

10.Koyama, E., et al. “In vitro metabolism of the glycosidic sweeteners, stevia mixture and enzymatically modified stevia in human intestinal microflora.” Food and Chemical Toxicology 41.3 (2003): 359-374.

11.Hsieh, Ming-Hsiung, et al. “Efficacy and tolerability of oral stevioside in patients with mild essential hypertension: a two-year, randomized, placebo-controlled study.” Clinical therapeutics 25.11 (2003): 2797-2808

12.Ferri, Letícia AF, et al. “Investigation of the antihypertensive effect of oral crude stevioside in patients with mild essential hypertension.” Phytotherapy Research 20.9 (2006): 732-736.

Artificial Sweeteners-Artificially Sweet Seductions

sugar lipsArtificial sweeteners are an interesting topic. They took years to first get approved by the FDA and have been making lots of money as they are added into pretty much anything that is normally sweet. They have also been quite a recommended lot to people who have diabetes as an alternative to sugar. I mean it does make sense that if you have a sweet substitute with no calories that is a good thing, especially in diabetes right?

Lets take a look at some of the claims. I think this is really important to look at because if you’re not paying attention you too could be ingesting these artificial, lab cooked up molecules. Is this a bad thing?


We’ll start this journey with sucralose (Splenda). It’s a molecule that is anywhere from 320-1000 times as sweet as sugar. 1 That’s demonstrably sweet. Sucralose, if bought in small tablets can sweeten just about anything because it is so freaking strong. One of the problems though is that unless you buy the small tablet forms or pure sucralose you’re going to get a product that is typically mixed with glucose or maltodextrin as a bulking agent. Now sucralose may have no calories, but maltodextrin and glucose most definitely have calories as they are polysaccharides and a monosaccharide respectively (multiple linked sugar chain and single molecule). So every time you put a cup of Splenda or another generic brand you are actually putting a number of calories into your recipe. So again, unless you’re using the small tabs which are typically pure sucralose, and very potent, you’re eating more calories then what they lead you to think.

Insulin Response

Another fault many people claim with sucralose is that it raises insulin levels. Many have stated this with other artificial sweeteners as well. So is it true? Lets find out.

In one study subjects took either sucralose in water or plain water before a glucose test. Blood sugar and insulin response was measured. Increased insulin secretion, area under the curve (total insulin exposure), and a decrease in insulin clearance resulted. 2 This study says YES, that there IS an effect.

In another study, intragastric infusions of sucralose were given to subjects. No increase in GLP-1 or insulin or gastric emptying was seen. 3 This study says there is NO difference.

Another study using sucralose, maltodextrin+sucralose, or a modified feeding protocol. There was no increase in insulin or other factors after the sucralose but not after the maltodextrin. This means maltodextrin raised insulin levels as expected but sucralose did nothing. 4 This study also says NO.

In the UK subjects were given 1gm/day of sucralose for 12 weeks. Again no differences in blood glucose or insulin levels were seen. 5 This study says NO.

So it appears that with the exception of 1 study, sucralose doesn’t really cause insulin increases on ingestion, at least in the short term. I haven’t seen any long term studies and really those are the studies that are super important and hard to perform. But in the short term sucralose doesn’t raise insulin except maybe when paired with other carbohydrate. This may or may not pan out but it also may be important to keep this study in mind because there may be some sort of synergy between surcralose and another carbohydrate source where none is seen with sucralose alone. Longer term studies are needed to really know if this causes problems in the long term. I would suspect it would. Anytime you raise insulin levels for the same load of glucose, that’s not a good thing.

On its own though there doesn’t seem to be an issue with raising insulin. So apparently you can enjoy sucralose without other carbs, but can it do anything else?


Gut bacteria is becoming a hot topic in the realm of health sciences. We are learning more and more about the relationship of our gut bacteria and our health and are beginning to find associations between different bugs and different conditions. On study looks at what happened in rats after 12 weeks of taking sucralose.

Rats were fed, 100, 300, 500 or 1000mg/kg for 12 weeks. I have to say that this a a huge dose. For a person weight 75kg or 165 lbs, that’s 7.5gm and at the high dose that’s 75gm. It wasn’t clear if that was the total dose of sucralose or the branded version this is cut with maltodextrin or glucose. If it was the latter then it makes much more sense, but again they weren’t clear. According to the study,

“the numbers of total anaerobes, bifidobacteria, lactobacilli, Bacteroides, clostridia, and total aerobic bacteria were significantly decreased” 6

After 12 weeks of recovery these changes did not revert back to what they were at baseline. This could have consequences on people in the long term as we learn more and more about our gut flora. The other thing this experiment showed that the sucralose affected p-glycoproteins and cytochrome p-450 in the gut. These are responsible for the metabolism and excretion of various other chemicals, including drugs. That could mean a change in the long term for people that may need to be on a specific medication. (Not that we’re hoping that someone has to be on medications long term). It may also affect nutrient absorption.

Anecdotally I’ve read and heard about rashes, migraines, increased blood sugar, dizziness, gut problems and some have claimed weight gain. I have no doubt that these effects could be contributed to sucralose, especially the gut problems and increased blood sugar. Although I just showed that on its own it doesn’t seem to affect blood sugar, in combo with other carbohydrate loads insulin increased over baseline. Ultimately you have to find out for yourself, but my advice is to stay clear.

Personally I don’t like sucralose. I don’t care for the taste (when I used to drink fruit juices regularly I thought it made my grapefruit juice taste like crap) and I’m just not a fan of artifical sweeteners. I try to stay away from sugar as much as possible. I’d be interested in hearing what you think or any personal experiences you have.


1. Michael A. Friedman, Lead Deputy Commissioner for the FDA, Food Additives Permitted for Direct Addition to Food for Human Consumption; Sucralose Federal Register: 21 CFR Part 172, Docket No. 87F-0086, April 3, 1998

2.Pepino, M. Yanina, et al. “Sucralose Affects Glycemic and Hormonal Responses to an Oral Glucose Load.” Diabetes care (2013).

3.Ma, Jing, et al. “Effect of the artificial sweetener, sucralose, on gastric emptying and incretin hormone release in healthy subjects.” American Journal of Physiology-Gastrointestinal and Liver Physiology 296.4 (2009): G735-G739.

4.Ford, H. E., et al. “Effects of oral ingestion of sucralose on gut hormone response and appetite in healthy normal-weight subjects.” European journal of clinical nutrition 65.4 (2011): 508-513.

5.McNeil (1996) A 12 week study of the effect of sucralose on glucose homeostasis and HbA1c in normal healthy volunteers. Submission
to FDA: McNeil Specialty Products Company Internal Report no. E169. Mcneil Specialty Products Company Food Additive Petition
7A3987 (Sucralose).

6.Abou-Donia, Mohamed B., et al. “Splenda alters gut microflora and increases intestinal p-glycoprotein and cytochrome p-450 in male rats.” Journal of Toxicology and Environmental Health, Part A 71.21 (2008): 1415-1429.