Beyond lactose intolerance: You may not be digesting these common foods

Lactose intolerance is the inability to break down the sugars that belong specifically to milk. If you get gassy or feel a cramping sensation after you drink milk or eat anything that contains milk, it may be the milk sugars that you can’t digest.

What happens when you can’t digest certain sugars?


Compared to sugar alcohols found in sugar-free treats, Lakanto is much easier to digest. Unlike sugar alcohols, Lakanto will not ferment in the large intestine.

These sugars do not get absorbed where they should, in the small intestine, and instead, they end up being food for bacteria later on down the line. Fermentation of undigested sugars happens in the large intestine, which is where stools are formed.

While you may digest some sugars, you may find that you feel better when you avoid others.

These sugars, which we can’t digest and that end up feeding bacteria and fungal overgrowth in the gut, are known as FODMAPs. FODMAP is an acronym that stands for fermentable oligo- di- mono-saccharides and polyols. Gastroenterologist Dr. Peter Gibson developed the FODMAP list of foods to treat patients with IBS (irritable bowel syndrome).

This is how FODMAPs affect a healthy gut

What all FODMAPs have in common is that they are all rapidly fermented somewhere along the gastrointestinal tract, specifically in the far end of the small intestine or in the large intestine.

What does this rapid fermentation look like? There may be:

  • Abdominal cramping
  • Bloating
  • Brain fog
  • Constipation
  • Depression
  • Diarrhea
  • Fatigue
  • Gas
  • Headache
  • Heartburn

These symptoms can be painful and overwhelming, but there is good news when it comes to how what you eat affects your digestive health.

In a 2014 Australian study conducted on 30 IBS patients and eight healthy individuals, dietary data were collected for one week. Patients were then assigned to random groups to receive 21 days of a FODMAP diet or a typical Australian diet, followed by a 21-day “washout period” before the alternate diet began. IBS participants saw gastrointestinal symptoms improve on the low-FODMAP diet. Most notably, pain, bloating, and flatulence were reduced.1

FODMAPs have become so important in IBS rehabilitation, with an estimated one in seven adults suffering from IBS, that Department of Gastroenterology researchers at Monash University launched a low-FODMAP app to track low-residue foods and manage IBS symptoms. And, a FODMAPs diet may improve quality of life for those with IBD.2

A 2019 Journal of the International Society of Sports Nutrition study found that a low-FODMAP diet may also be extra-helpful for runners, alleviating gastrointestinal distress.3 Another 2019 study noted that low-FODMAP eating may be safe and useful for some adolescents and children.4

Is it time to hit “reset” on your health? Here’s where to get started.

The 5 FODMAP foods to watch out for

A key thing to remember: Everyone is different.

This means that while you may digest some sugars, you may find that you feel better when you avoid others. And because a neighbor or a family member has different bacteria and different enzymes in their gut, they may have a completely different experience with these same foods.

Lactose is the most famous FODMAP. But there are several other common foods that make the FODMAP list.

FODMAPs hide out in the most surprising places:

1. Beans and lentils.

  • Oligosaccharides are short strands of simple sugars. Remember, to be a FODMAP, these sugars have to be difficult to break down.
  • Common foods in this group are several varieties of beans and lentils.
  • One enzyme that the human gut does not have (but bacteria do) is called alpha-galactosidase (a-gal). This enzyme is particularly important for digesting beans, and it is the active ingredient in Beano.

2. Wheat, onions, and cabbage.

  • Also an oligosaccharide, wheat contains a type of sugar called a fructan.
  • Fructans are found in inulin and other common foods, such as Jerusalem artichokes, cruciferous vegetables like cabbage and cauliflower, onions, scallions, and avocados.

3. Milk sugars.

  • Lactose is a milk sugar and a disaccharide.
  • Cow, sheep, and goat’s milk all contain lactose.

4. Fruit, agave, and honey.

  • Fructose, which is fruit sugar, is a monosaccharide. If you eat more fructose than your small intestine can absorb, it becomes food for bacteria and ferments.
  • Keep in mind: We can only digest around 20 to 25 grams of fructose in one sitting.
  • All high-fructose fruits fall into this category — also, sweeteners that contain fructose like agave, high fructose corn syrup (HFCS), and honey.

5. Xylitol, apples, and peaches.

  • Polyols are sugar alcohols. Examples of sugar alcohols are xylitol, maltitol, and sorbitol. These sugar alcohols taste sweet but are not absorbed as sugar. They are commonly used in “diabetic candy,” in sugar-free mints, and in chewing gum.
  • Xylitol is a popular sweetener for those who avoid sugar and is a FODMAP polyol. If you find that you have trouble with sugar alcohols like xylitol, try using Stevia or Lakanto that contains erythritol. Erythritol is a four-carbon polyol and, unlike other polyols, it’s well-absorbed.
  • While sugar alcohols are fermentable in the large intestine, when eaten in excess they can also lead to osmotic diarrhea. Natural sources of polyols are apples, peaches, and pears.

Don’t forget the Principle of Uniqueness. Figuring out which foods are hard to digest could be the key to your digestive success:

1. Remember that you may not need to eliminate all FODMAP foods.

2. Often, the foods we eat every day are the ones that affect us most.

3. It takes time and patience to figure out which foods you can’t fully digest.


  1. 1. Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014 Jan;146(1):67-75.e5. doi: 10.1053/j.gastro.2013.09.046. Epub 2013 Sep 25. PMID: 24076059.
  2. 2. Selina R. Cox, James O. Lindsay, Sébastien Fromentin, Andrew J. Stagg, Neil E. McCarthy, Nathalie Galleron, Samar B. Ibraim, Hugo Roume, Florence Levenez, Nicolas Pons, Nicolas Maziers, Miranda C. Lomer, S. Dusko Ehrlich, Peter M. Irving, Kevin Whelan. Effects of Low-FODMAP Diet on Symptoms, Fecal Microbiome, and Markers of Inflammation in Patients With Quiescent Inflammatory Bowel Disease in a Randomized Trial. Gastroenterology, 2019; DOI: 10.1053/j.gastro.2019.09.024.
  3. 3. Melanie Wiffin, Lee Smith, Jose Antonio, James Johnstone, Liam Beasley, Justin Roberts. Effect of a short-term low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet on exercise-related gastrointestinal symptoms. Journal of the International Society of Sports Nutrition, 2019; 16 (1) DOI: 10.1186/s12970-019-0268-9.
  4. 4. Stephanie C Brown, Kevin Whelan, Richard B Gearry, Andrew S Day. Low FODMAP diet in children and adolescents with functional bowel disorder: A clinical case note review. JGH Open, 2019; DOI: 10.1002/jgh3.12231.
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