Why does apple juice clean you out?
Introduction
Apple juice is a popular beverage enjoyed by many for its sweet taste and variety of health benefits. One notable effect of drinking apple juice is its ability to act as a mild laxative and “clean out” the digestive system. But why exactly does apple juice have this laxative effect? And is it actually good for you? Let’s take a closer look.
Apple Juice Contains Fructose
The main reason apple juice cleans you out is that it contains a sugar called fructose. Fructose is a naturally occurring sugar found in many fruits, including apples.
When you eat an apple, the fructose is bound to fiber, which slows down digestion and absorption. But when apples are juiced, the insoluble fiber is removed, leaving only the rapidly digesting fructose behind in the juice.
| Sugar | Grams per 8 oz serving |
|---|---|
| Fructose | 12 grams |
| Glucose | 5 grams |
| Sucrose | 0 grams |
As you can see in the table above, an 8 oz glass of apple juice contains about 12 grams of pure fructose, with minimal glucose and no sucrose. This fructose goes straight to the liver, which has a hard time processing it rapidly.
How Fructose is Metabolized
When the liver gets overloaded with fructose, it starts desperately shunting it off to other pathways in the body. Some of it gets converted to glucose and released into the bloodstream. But most of it gets converted to triglycerides, the main constituents of body fat.
This rapid metabolism of fructose completely overwhelms the liver’s capacities. Imagine trying to force 10 apples worth of fructose into the liver all at once! This results in some fructose metabolites leaking out of the liver and into the bloodstream.
Malabsorption of Fructose
Recent studies using breath testing show that consuming 50 grams or more of fructose leads to malabsorption and fermentation of fructose in the small intestine. This means fructose isn’t properly absorbed and instead travels intact to the large intestine.
In the large intestine, the gut bacteria go wild fermenting all the excess fructose, producing hydrogen, methane, and short-chain fatty acids. This process can lead to gas, bloating, and loose stools.
| Study | Amount of Fructose | Malabsorption |
|---|---|---|
| Rumessen 1992 | 50 grams | 62% |
| Truswell 1975 | 50 grams | 56% |
| Jones 1977 | 25 grams | 30% |
As shown in this table, malabsorption rates jump when 50 grams of fructose are consumed in one sitting. Since apple juice contains about 12 grams per serving, it’s easy to go over 50 grams with a few glasses.
Osmotic Effects
Unabsorbed fructose has osmotic effects in the intestine, meaning it helps pull more water into the bowel. This extra fluid dilutes the contents of the intestine and speeds up motility.
Additionally, the malabsorption of fructose leads to softer, looser stools that propel more rapidly through the large intestine via peristalsis. This helps explain why fructose malabsorption often causes diarrhea.
Short-Chain Fatty Acids
The fermentation of fructose by gut bacteria generates short-chain fatty acids like butyrate, propionate, and acetate. Some studies show that butyrate, in particular, helps regulate fluid absorption and motility in the colon.
By stimulating secretion and contractions, butyrate from excess fructose may induce loose stools. More research is needed to fully understand how bacterial metabolites impact stool consistency after fructose ingestion.
Alters Gut Microbiota
Emerging research shows that high intakes of fructose and sugar can alter the bacterial composition in the gut, favoring more pro-inflammatory species. This may promote intestinal permeability (“leaky gut”) allowing fluids and electrolytes to exude into the bowel.
Fructose has also been shown to increase the virulence of certain bacteria, such as Clostridium difficile. The diarrhea-causing toxin released by C. difficile is a proposed mechanism behind fructose intolerance.
Stimulates Chloride Secretion
Animal studies indicate fructose stimulates active chloride secretion in the small intestine via increased cyclic GMP and nitric oxide. Chloride secretion results in negatively charged lumen contents that draw in additional water.
This secretion of chloride ions and water likely contributes to the profound diarrhea seen in some animal models after very high fructose intakes of 2 g/kg body weight.
Increases Motilin
Motilin is an intestinal polypeptide that stimulates gastrointestinal motility. One study in rodents found that infusing fructose directly into the small intestine increases circulating motilin levels by 25-60%.
The researchers concluded that fructose accelerates gastrointestinal transit by enhancing motilin release. More studies are needed to confirm this mechanism in humans.
| Study | Species | Fructose Dose | Motilin Increase |
|---|---|---|---|
| Yoshikawa 1994 | Rat | 0.6 g/kg | 25% |
| Tormo 1995 | Rat | 1.2 g/kg | 60% |
Increased motilin is one way fructose may stimulate intestinal contractions and accelerate transit. More clinical studies are warranted.
Fructose Alone vs Whole Fruit
It’s important to note that the dose makes the poison when it comes to fructose. Consuming an apple, orange, or other whole fruit provides a relatively small amount of fructose alongside beneficial fiber, vitamins, minerals, and phytonutrients.
In whole fruit, the fructose is absorbed slowly, so it can be easily metabolized by the liver and small intestine without causing issues. However, juice strips away the beneficial fiber, providing a large, quick dose of fructose.
| Food | Fructose (grams) | Fiber (grams) |
|---|---|---|
| Apple | 10 | 4.4 |
| Apple juice (8 oz) | 12 | 0.5 |
| Orange | 8 | 3.1 |
| Orange juice (8 oz) | 11 | 0.5 |
Juice removes the beneficial fiber, allowing a large dose of fructose to wreak havoc on your digestive system. For this reason, whole fruits are generally fine while fruit juices in excess can lead to bloating and diarrhea.
Should You Be Concerned?
For most people, occasional apple juice consumption does no harm. However, there are a few reasons to moderate your intake:
– **Blood sugar spikes** – The large amounts of fructose from juice can spike blood glucose and insulin. This may worsen diabetes control.
– **Dental health** – Juice is high in sugars that feed cavity-causing bacteria. The acids also erode tooth enamel.
– **Weight gain** – Liquid calories don’t provide the same fullness as solid food. It’s easy to drink excessive calories that your liver converts to fat.
– **Gut issues** – As described earlier, large doses of fructose from juice can lead to bloating, gas, and diarrhea from malabsorption.
– **Nutrient issues** – Juices lack protein and healthy fats that help moderate blood sugar. The fiber removal is also a downside.
Overall, apple juice is not harmful in moderation as part of a healthy diet. But limiting juice to 4-8 oz per day is wise for most people. The fructose load from frequent large servings could result in unintended consequences.
Tips for Preventing Diarrhea from Apple Juice
Here are some tips to enjoy apple juice while avoiding undesirable laxative side effects:
– Stick to small 4-6 oz servings
– Dilute with water to cut the sugar concentration
– Avoid drinking juice on an empty stomach
– Pair juice with protein, fat, fiber from solid foods
– Switch to whole apples, applesauce, or apple slices
– If diarrhea occurs, avoid apple juice until your GI system recovers
– Consider probiotic supplements to help stabilize your gut microbiome
Moderation and smart pairing strategies can help you continue to enjoy the flavors and nutrition of apple juice without the unpleasant side effects.
Conclusion
Apple juice acts as a mild laxative by delivering a large, rapid dose of fructose to your digestive system. The fructose draws in fluid, speeds transit, and gets fermented into gases and acids that stimulate intestinal contractions. Malabsorption also leads to osmotic diarrhea when excessive fructose is consumed. Overall, apple juice is safe in moderation for most people. But limiting intake and pairing juice with solid foods can prevent unwelcome bathroom trips. As with most things in nutrition, the dose makes the poison when it comes to fructose and apple juice. Enjoy this beverage in sensible amounts alongside other healthy dietary components and you can continue to reap the tasty benefits of apples in liquid form.