What is mannitol?

Mannitol is a low-calorie sweetener. It is a carbohydrate, a sugar alcohol, made from fructose and hydrogen [2,3-p.249]. It is poorly absorbed in the small intestine, so it travels to the large intestine where beneficial intestinal bacteria break it (ferment) into gases and short-chain fatty acids (SCFAs), which can be absorbed and provide some energy.

Nutrition Facts:

  • Calories per gram = 1.6
  • Glycemic index (GI) = 0
  • Sweetness, relative to sucrose = 60%
  • Net carbs = zero

Mannitol Origin

Mannitol occurs naturally in mushrooms, marine algae, strawberries, celery, onions, pumpkins [1,2]. In China, mannitol can be produced from seaweeds [3-p.251]. Mannitol as a food additive is semi-artificially produced by adding hydrogen to fructose, which is derived from starch (corn, wheat or tapioca) [2,3-p.249]. Prior to conversion to mannitol fructose is converted to mannose, from which mannitol has got its name [2].

Foods Containing Mannitol

Mannitol is used as a sweetener, anti-caking agent, emulsifier or thickener in chocolate-flavored coatings for ice cream and confections, chewing gum, butter, frozen fish, pre-cooked pasta, infant formula [1,4]. In the European Union, mannitol is labeled as E number E421 [5].

Mannitol can be also used as a carrier in certain vitamin supplements, medicinal syrups and medications.

Mannitol Absorption and Metabolism

Mannitol is slowly absorbed in the small intestine and poorly metabolized. It provides only 1.6 kilocalories per gram [3-p.59].

Possible Mannitol Benefits

Tooth decay. Mannitol does not promote dental caries [1].

Diabetes mellitus. Mannitol has a very low glycemic index (GI = 0) [3-p.9] and does not raise blood glucose and insulin levels [1].

Mannitol Safety

Mannitol is Generally Recognized As Safe (GRAS) by the US Food and Drug Administration (FDA) [6]. Mannitol is approved to use by The Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) [1]. JECFA has determined 50 mg mannitol/kg body weight per day as safe for healthy adults [1].

During Pregnancy

There appears to be no data  about the eventual harmful effects of the sweetener mannitol on the growing fetus.

Side Effects, Dangers

Mannitol attracts water from the intestinal wall (osmotic effect) so it can cause diarrhea if consumed in excess. Mannitol,when ingested in amounts greater than 50 mg/kg body weight (35 g by a 70 kg or 155 lbs person) may cause abdominal pain, excessive gas (flatulence), loose stools or diarrhea. According to one source, the laxation threshold for mannitol in healthy people is about 20 grams per day [3-p.257].

There appears to be no evidence about association between mannitol and cancer.

Mannitol and Cooking

Physical properties:

  • A white crystalline powder [7]
  • 60% as sweet as sucrose with a strong cooling effect [1]
  • Non-hygroscopic – does not attract moisture from the air until it exceeds 90% relative humidity [1,3-p.254]
  • Solubility in water at 77° F (25° C) = 20 g/100 g solution [3-p.158]; poorly soluble in ethanol [7]
  • Melting point = 329-336° F (164-169° C)  [1,7]
  • Does not decompose at 320° F (160° C)  [3-p.158]

Mannitol as a Drug

Mannitol acts as an osmotic diuretic, which means it drags water from the blood into the urine and can thus quickly reduces blood pressure. As an intravenous drug is used to lower the increased pressure within the skull (intracranial pressure or ICP) and in treatment of increased pressure within the eye (glaucoma).

Frequently Asked Questions

1. Is mannitol vegan?

Yes; it is derived from starch or seaweeds.

2. Is mannitol gluten-free?

Mannitol can be derived from wheat, but it should be gluten-free.

Related Nutrients

12 Responses to "Mannitol"

  1. Dorothy McIlroy says:

    Is there a concern with Mannitol added to prescription drugs? I take Levothyroxine and recently the brand Activas was bought by TEVA and mannitol has been added to the drug, I had adverse reactions including fast heart rate when taking the new drug and was admitted to hospital. Stopping the drug stopped the fast heart rate but now I am told the original drug cannot be supplied, thyroxine is a life changing drug and needed for life so where does one go from here? These additives in drugs are dangerous to patients with an intolerance, I avoid all food additives and synthetic sugars so why should I be forced to take a tablet which could kill.

    • Jan Modric says:

      It is not necessary mannitol that caused an adverse reaction, but I can’t say. A doctor can tell which other drugs could be appropriate for you.

    • Estelle Onema says:

      Mrs McIlroy,
      Could you tell me in which country you live in ? Here in France the Levothyrox by Merck has started to add Mannitol in March. We are facing a real health criis. At least 1500 peoples with severe side effects and at least 200 000 with less serious side effects. For the moment le medication has full monopoly.
      Contact me

    • Amy says:

      Hi there I just read your post online about side effects on manatol, I have been taking levothyroxine for a week with this new ingredient in it and have had too stop as I am getting g severe palpitations. Going to the chemist tomorrow to see if I can get my old form of levothyroxine with has almost no extra ingredients in it .

      • Jan Modric says:

        Palpitations are probably from levothyroxine, not from mannitol or other ingredients. So, you may want to discuss with your doctor about adjusting the dose.

    • Mandy McDonald says:

      Hi Dorothy,
      I was diagnosed in 2015 with an under active thyroid, my thyroxin levels quickly stabilised after a couple of tweek’s with Levothyroxine. Recently I have been losing my hair beyond belief, this is obviously causing me a lot of anxiety which doesn’t help.
      I noticed that the packaging for my medication has now got a banner across the top of it stating “New Formulation”, so I took the old leaflet and compared to the new one and noticed Mannitol has been added and lactose has been removed, what I would like to know is if anyone is aware of the side effects that Mannitol can possibly have.
      I know hair thinning can be due to the ageing process and a side effect of Levothyroxine/thyroid problems but this has only just started to happen to me and I’m determined to do something about it.
      I was recently diagnosed with very low Vitamin D and the GP prescribed me a high dosage that I take once a week for seven weeks, I did ask him about my hair but he just said that it wasn’t my thyroid causing it and then listed the other possibilities, I felt guilty for taking his time up on this as there are far worse things in life but right now this is mine.
      I’m going to go onto the UK governments Yellow Card Scheme later today to report what I class as a ‘side effect’ not sure what happens after that but worth a go. Would be good to know if anyone else has noticed their hair falling out since the new formulation of Levothyroxine or is it just a coincidence 🙁

  2. Alex Johnson says:

    Another possible Mannitol benefit, is that in some people it appears to improve Parkinson’s symptoms. This follows Israeli research on fruit flies and mice. It can aid sleep.

  3. Ann coode says:

    I have Parkinson’s and have taken mannitol for six weeks. It has vastly improved my balance along it’s the soowmreeduction of ropinirole

  4. Pearl Girl says:

    I bought a vitamin water recently at the local grocery store . I have been trying to give up regular soda so they had this flavored water on sale—it is carbonated as well as containing vitamins. Zero calories. I read the ingredients last night and saw it contained Mannitol. No wonder I have been so gassy and going a lot! I think I am just goint to get regular selzer or Perrier water. This drink shoud have a warning on it that it causes cramping. I don’t know what the percentage is but I plan on contacting the product maker tomorrow.

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