What happens to your gut health when you drink fruit juice regularly

Medically reviewed by Robert Burakoff, MD

Key Takeaways

• All-juice diets (such as juice cleanses) can trigger an unhealthy shift in the gut microbiome, which can negatively affect the digestive system lining and increase inflammation.
• The sugar and simple carbohydrates in fruit juice can quickly raise blood sugar levels and erode tooth enamel (increasing the risk of dental cavities).
• Eating whole fruits is recommended rather than replacing them with fruit juice.

Drinking fruit juice regularly, especially those types with added sugar, can have negative health effects such as unbalancing the gut microbiome and increasing the risk of type 2 diabetes or tooth decay. Moderate consumption of certain fruit juices (tart cherry, cranberry, and blueberry) may offer benefits, but fruit juice should not replace whole fruits in your diet.

1. Your Gut Microbiome May Become Imbalanced

The food we eat affects the makeup of the microorganisms that naturally live in our digestive system (the gut microbiome). The balance of "helpful" and "unhelpful" bacteria and other microbes can shift based on our diet.

In general, fruit juices naturally contain high levels of sugar, mainly fructose. Some juices and juice blends also contain added sugars. Diets high in sugar can push the makeup of the gut microbiome in an unfavorable direction. This is a condition called dysbiosis:

• In one study, participants drank a juice-based diet or ate a plant-based diet. Compared with the plant-based diet, the juice-based diet increased the number of bacteria in the mouth and gut associated with inflammation.
• In addition, the gut microbiome shifted in ways that may increase the risk of gut permeability ("leaky gut") and cognitive decline (reduced attention, memory, and reasoning skills). The researchers warn that even a short-term all-juice diet may have negative effects on the microbiome.
• Mouse studies show similar effects on the microbiome. High amounts of dietary sugar increase the amount of bacteria in the microbiome that degrade the intestinal mucus layer. The weakened inner intestinal layer becomes more permeable, thereby promoting inflammation, as shown in the human study. 

2. Your Risk of Cavities Increases

The risk of dental caries (cavities) increases with the amount of simple carbohydrates in the diet, such as sugars. The sugar and acid in some juices (such as orange juice) may wear down tooth enamel over time. The weakened tooth enamel increases the risk of cavities.

Some tips to reduce the effects of fruit juice on teeth include:

• Don't brush teeth right away after drinking juice.
• Drink juice quickly to limit the time it is in contact with teeth.
• Rinse the mouth with plain water after drinking juice.
• Use a straw to drink juice.

3. Your Risk of Type 2 Diabetes Increases

One meta-analysis examined several studies to determine how the amount of sugar in the diet affects the risk of type 2 diabetes. The researchers found that for every serving of fruit juice people drank, the risk of developing type 2 diabetes increased by 5%.

The authors point out that fruit juice is not a good replacement for whole fruits. Fruit juice contains nutrients, but it has more sugar than whole fruits and doesn't contain any fiber. Fiber is important for slowing the absorption of sugar and regulating blood sugar levels to prevent spikes.

4. Your Calorie Intake Increases

Adding fruit juice to a regular diet may increase total daily calories. The research is conflicting on whether this leads to weight gain. Some big meta-analyses show that drinking 100% fruit juice doesn't lead to weight gain, while others show that it does.

People who drink 100% fruit juice (as opposed to "fruit drinks") don't usually eat less fruit. One benefit of eating whole fruits is that they contain fiber, among other nutrients. Fiber has many positive effects on gut health. Recommendations are for people to eat whole fruit rather than drink juice.

5. Juices With Potential Benefits Include Tart Cherry, Cranberry, and Blueberry Juice

Some types of fruit juice have shown benefits in studies—specifically, moderate amounts of tart cherry, cranberry, and blueberry juice:

• Tart cherry juice: In one small study, patients received either 30 milliliters (about 1 ounce) of tart cherry juice daily or a placebo. Those who received cherry juice were more alert and experienced less fatigue than those who received the placebo.
• Cranberry juice: In two different studies, people drank 8 ounces (240 mL) of unsweetened or dextrose-sweetened cranberry juice for 12 weeks. One study showed no effect on fasting glucose, while the other showed lower fasting glucose levels. In a third study, people had lower C-reactive protein levels (a marker for inflammation) after 16 ounces (480 mL) of cranberry juice for 8 weeks.
• Blueberry juice: Anthocyanins, substances found in blueberries, may reduce inflammation and protect against some age-related diseases. In one study, older adults showed improved memory and found it easier to switch between tasks after 90 days of drinking 15 to 20 ounces of blueberry juice.

Read the original article on Verywell Health