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Duke University Study – Beware of Splenda

by Dr. Stephen Gangemi on March 19, 2009

Four years ago I wrote about Splenda and the health problems it causes. You can read the April 2005 article by checking the archives. Now, a major study has come out from Duke University proving just how dangerous Splenda (sucralose) really can be.

Splenda is only becoming more and more popular as its users think they are making a safe switch from Nutrasweet (aspartame). It is now in many sports drinks, water products (Propel) and many protein/carbohydrate products athletes use. And don’t forget all those diet drinks and foods out there. Recently even Lance Armstrong has put Splenda in his FRS sports drink. He markets the drink as “healthy energy” and “powered by quercetin”. Quercetin is a powerful antioxidant, and a natural antihistamine and anti-inflammatory; I use it often especially for patients with seasonal allergies, inflammatory conditions, and immune system problems.  For a cancer survivor and major cancer spokesperson, Lance’s addition of quercetin in a drink does little when he taints the “health drink” with a substance proven to suppress the immune system by 50+%. Last I checked the immune system is pretty important when it comes to fighting and preventing cancer. Yeah, that’s sarcasm, but I cringe every time I hear about this amazing drink and see the number of people who drink it because they want to follow Lance. Over half of your immune system is located in your digestive tract via the microflora and Duke now says that Splenda will lighten your load there by half. And other studies, as I note in my April 2005 article, show thymus gland suppression by 40%. Enough said.

A new study from the Duke University Medical Center has found that ingestion of the artificial sweetener sucralose will kill off 50% of beneficial microflora in the gut, as well as altering the pH and affecting P-glycoprotein (P-gp) levels in the digestive tract. The rat study concluded that the P-gp effect could result in medications used in chemotherapy, AIDS treatment and treatments for heart conditions being shunted back into the intestines, rather than being absorbed by the body.

Sucralose, which is commonly known under the commercial name Splenda, has previously come under fire for causing gastrointestinal problems, migraines, seizures, dizziness, blurred vision, allergic reactions, blood sugar increases and weight gain. Says James Turner, the chairman of the national consumer education group Citizens for Health, “”The report makes it clear that the artificial sweetener Splenda and its key component sucralose pose a threat to the people who consume the product.” Other artificial sweeteners, particularly Nutrasweet, have received similar criticism for adverse effects.


Splenda alters gut microflora and increases intestinal p-glycoprotein and cytochrome p-450 in male rats.

Abou-Donia MB, El-Masry EM, Abdel-Rahman AA, McLendon RE, Schiffman SS.

Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27708, USA.

Splenda is comprised of the high-potency artificial sweetener sucralose (1.1%) and the fillers maltodextrin and glucose. Splenda was administered by oral gavage at 100, 300, 500, or 1000 mg/kg to male Sprague-Dawley rats for 12-wk, during which fecal samples were collected weekly for bacterial analysis and measurement of fecal pH. After 12-wk, half of the animals from each treatment group were sacrificed to determine the intestinal expression of the membrane efflux transporter P-glycoprotein (P-gp) and the cytochrome P-450 (CYP) metabolism system by Western blot. The remaining animals were allowed to recover for an additional 12-wk, and further assessments of fecal microflora, fecal pH, and expression of P-gp and CYP were determined. At the end of the 12-wk treatment period, the numbers of total anaerobes, bifidobacteria, lactobacilli, Bacteroides, clostridia, and total aerobic bacteria were significantly decreased; however, there was no significant treatment effect on enterobacteria. Splenda also increased fecal pH and enhanced the expression of P-gp by 2.43-fold, CYP3A4 by 2.51-fold, and CYP2D1 by 3.49-fold. Following the 12-wk recovery period, only the total anaerobes and bifidobacteria remained significantly depressed, whereas pH values, P-gp, and CYP3A4 and CYP2D1 remained elevated. These changes occurred at Splenda dosages that contained sucralose at 1.1-11 mg/kg (the US FDA Acceptable Daily Intake for sucralose is 5 mg/kg). Evidence indicates that a 12-wk administration of Splenda exerted numerous adverse effects, including (1) reduction in beneficial fecal microflora, (2) increased fecal pH, and (3) enhanced expression levels of P-gp, CYP3A4, and CYP2D1, which are known to limit the bioavailability of orally administered drugs.

I'm a board certified chiropractic physician and clinical nutritionist with a passion for true natural health care. I implement dietary & nutritional therapies, exercise & movement practices, and lifestyle changes along with manual therapy techniques to help the body heal and prevent illness and injuries.


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  1. carole florian permalink

    I am a diabetic, what am I suppose to use for sugar?

  2. Sprocket permalink

    It s better eating fruits , as they have natural sugars in them , honey s fine also , I m also diabetic Carole .

    Quantities are very important also .

    Exercices like walking or exterior housekeeping s pretty good also .

    Thanx for this post Dr !

  3. In truth, we probably don’t need research to conclude that there’s something wonky about hacking nature to appease our desires. We are drawn to sweets things, as I understand it, because of fruit. So eat more fruit is the common advice, but I can tell you that isn’t working for most people we see. There are too many other factors at play, starting with their habits, and let’s not talk about people’s sense of entitlement. If I just go about telling people to not eat sugar, or reduce their intake, I may as well give up now. In comes the alternatives.

    As a fitness professional I have found we are fighting endless battles in the war to help individuals fight to better health. The staggering data I have is on people in western culture, and now other places too, growing more and more obese. It has been my field experience that every effort we can make to find a diet that is reduced in calories, and meets a person’s likes, has merit. The more they can reasonably adhere to lower calorie intake, the better chance I stand of improving their quality of life via lower bodyfat. Sugar is by no means the evil nutrient some would argue, but I don’t think anyone would say it should take priority on one’s nutrient intake. It’s 4 crummy (and yummy) calories per gram. But some people find the more they eat, the more they crave, the more they want to eat, and the harder the war becomes. Replacing sugar helps dramatically to get results.

    What’s the concern here? To me the bigger issue at hand is diabetes, cancer, coronary heart disease, high blood pressure, type 2 diabetes, stroke, ad nauseum… I hear you saying just don’t fool yourself Splenda is somehow healthy. Neither is methadone. At some point people are going to have to learn healthier eating habits, but in the meanwhile Splenda is helping them win some battles.

    Am I totally lost here Doc?

    • I don’t think Splenda is helping them win any battles. Especially with even more recent studies like the one several months ago in Nature discussing how sucralose and aspartame effect the gut biome to the point of increasing blood sugar levels 2-4 fold.

      • Thanks Doc. I appreciate your reply and perspective. While these studies are certainly interesting, they don’t match my experience in the field… for what it’s worth. Perhaps this is my confirmation bias showing, but telling clients who enjoy their sweets that they shouldn’t eat sugar is about as helpful to them as telling an alcoholic he should really cut back. I can, however, get them to drop their calories with sugar substitutes, and live to fight another day.

  4. Raymond cunningham permalink

    Is raw stevia good to use

  5. ChandlerBob permalink

    So, Doc, if a person is to indulge a bit, which is the healthier choice, Sugar, Honey, or Sucralose (or some other form of artificial sweetner)?

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