“Trying to stick to the colonoscopy prep rules—does anyone know if a little soy sauce is allowed in clear broth? Since it’s very dark, I’m not sure if it’s OK or not.”

A: This is an excellent question because the rules around “clear liquids” can get confusing.

The concern is mainly about dark or red liquids, such as grape juice, cola, or tomato-based products, that can stain the lining of the colon or make it harder for the doctor to see clearly.

Soy sauce itself is not a clear liquid. It’s dark-colored and opaque, so if you drink it straight, it wouldn’t meet the “clear liquid” standard your doctor expects during colonoscopy prep.

However, a small amount of soy sauce added to broth as flavouring is usually okay as long as the broth remains transparent. For example, a light splash in chicken or vegetable broth for flavor is fine. If you add so much soy sauce that you can no longer see through the broth, it is no longer safe for consumption.

In conclusion, do not drink soy sauce alone; a dash in clear broth to improve taste is generally acceptable. Just don’t overdo it so the broth stays light and see-through.

Source:

Glen Garry Gastroenterology https://glengarrygastroenterology.com.au/wp-content/uploads/2023/05/Oliver-Duncan-Bowel-prep-instructions-AM-1.pdf

“My hubby is getting ready for his colonoscopy and loves pickle juice (weird, I know!). Can you tell me if pickle juice is okay on the clear liquid diet before a colonoscopy? It’s technically clear, right? But I’m also worried that it might be too harsh for his gut, I mean, it’s basically vinegar. Please help!”

A: I appreciate how much thought you have put into this, regarding the clarity of pickle juice and the possible effects on the gut. While the rules around the clear liquid diet can sometimes get tricky, we can conclusively rule out pickle juice for two reasons.

The first reason pickle juice is not permissible is directly related to its clarity. Even though pickle juice may look see-through in a glass, it doesn’t qualify as a true “clear liquid” for colonoscopy prep. Pickle juice contains suspended particles from spices and herbs that do not fully dissolve and often leave residue in the colon.

Secondly, pickle juice is highly acidic due to the acetic acid from the vinegar used in the pickling process, and that can be bad news for the gut, as you rightly pointed out in your question. Doctors advise against taking acidic juices on a clear liquid diet because it could cause bloating, cramping, or nausea, especially since the colon and stomach are already sensitive while being cleansed.

In place of pickle juice, permissible clear-liquid options include water, clear broths, electrolyte drinks (like Gatorade), coconut water, apple juice, herbal teas, or plain gelatin—these hydrate without irritating the digestive tract.

In conclusion, avoiding pickle juice on a clear-liquid diet is best. If your husband wants something flavourful, a warm, clear broth is a safer way to keep things interesting.

Source:

Medical News Today https://www.medicalnewstoday.com/articles/318618

“I’m still four days out from my colonoscopy—should I already be changing my diet? What’s safe to eat this early in the prep?”

A: This is quite an interesting question you have posed. Most doctors recommend commencement of the colonoscopy prep diet 3 days before the date of the procedure. However, a fair number of authorities suggest starting 4 days prior. Hence, it wouldn't be too early for you to change your diet four days out from your colonoscopy.

If you decide to start the pre-colonoscopy diet 4 days before your procedure, you want to eat low-fiber foods. This helps reduce residue in the colon and makes your prep easier and more effective.

Permissible Foods

• Grains: White bread, plain bagels, white rice, plain pasta, low-fiber cereals (like cornflakes)
  
• Proteins: Eggs, skinless chicken, turkey, lean beef, fish, tofu, smooth nut butters (no chunks)
  
• Fruits: Apple juice, applesauce, fruits without skin and seeds
  
• Vegetables (well-cooked, without skins/seeds): Carrots, zucchini, peeled potatoes
  
• Other: Plain crackers, broth-based soups (without beans or fibrous veggies), water

Foods to Avoid

• Whole grains (brown rice, whole wheat bread, bran cereal)
• Nuts, seeds, popcorn
• Raw veggies, especially broccoli, cauliflower, cabbage, or salads
• Fruit with skin or seeds (berries, apples, grapes, figs)
• Beans, lentils, legumes
• Fried, spicy, or greasy foods

In conclusion to your question "What to eat 4 days before colonoscopy?", 4 days out, it’s not too early to start adjusting. Eating low-fiber foods now will make your prep smoother and your colonoscopy more accurate. Ultimately, you want to follow your doctor's instructions on when to commence the dietary adjustments.

Sources:

St Johns - Health: https://www.stjohns.health/services/endoscopy/colonoscopy/colonoscopy-instructions/before-your-colonoscopy/

“I’m prepping for a colonoscopy in a few days—does anyone know if plain canned tuna is okay to eat beforehand?”

Answer:

Yes, plain canned tuna is usually allowed in the days leading up to your colonoscopy. To be more specific, canned tuna is fine during the low-fiber diet phase. For obvious reasons, it has to be stopped when switching to clear liquids the day before the procedure.

Here’s why:

Tuna is a lean protein with no skin, seeds, or tough fiber, so that it won’t leave residue in the colon. It’s easy to digest and provides good energy and protein while you’re cutting back on high fiber foods.

However, there are some things to consider when eating tuna before your colonoscopy. Here are helpful tips to keep in mind:

• Stick to plain, canned tuna in water or brine, not oil, sauces, or spicy mixes, which can add extra fat, slow digestion, and increase colon residue.
• Avoid mixing it with raw vegetables, whole-grain bread, or high-fiber add-ins. If you want to make it a meal, combine it with plain white bread and white rice, which are low in fiber.
• The day before your procedure, you’ll need to switch to a clear liquid diet only (broth, tea, apple juice, sports drinks, gelatin, etc.). No tuna is permitted at this point.

In conclusion, canned tuna is a safe, low-fiber protein source in the low-fiber diet stage before colonoscopy prep, but not once you’ve started the clear-liquid phase.

Source:

• Healthline https://www.healthline.com/nutrition/is-canned-tuna-healthy 

"I saw garlic on a ‘don’t eat’ list before a colonoscopy — does anyone know why that is? Seems kind of random. Some sources don’t mention garlic at all, so is it really a problem?"

I understand your scepticism, but I assure you that sources that list garlic as part of foods to avoid are not doing so randomly. Garlic sometimes shows up on colonoscopy “avoid” lists because of two main reasons:

1. Fiber and residue – While garlic cloves are small, they do contain fiber and small particles that can linger in the digestive tract. If eaten in larger amounts (like roasted cloves or garlic-heavy dishes), those bits can make it harder to fully clear the colon, which may reduce visibility during the exam.
   
   
2. Blood-thinning effect – Garlic, especially in supplement form or when eaten in large quantities, can have mild blood-thinning properties. If your doctor plans to remove polyps or take biopsies, they generally prefer you avoid foods or supplements that might slightly increase bleeding risk.
   
   

Occasional small amounts of garlic used in cooking usually aren’t a problem - unless your doctor’s prep instructions specifically say otherwise. The stricter “no garlic” advice is often aimed at patients who take garlic supplements, eat raw garlic in significant quantities, eat very garlicky foods regularly, or are on other blood-thinning medications.

In conclusion, your prep sheet says “no garlic,” so follow it to the letter. Colonoscopy prep works best when instructions are followed precisely. If it’s not mentioned, small amounts in cooked meals are usually acceptable, but skip garlic supplements or heavy raw garlic dishes in the days before your procedure.

Sources:

https://www.endoscopyclinic.co.nz/wp-content/uploads/2022/04/Medication-considerations.pdf

"Weird question maybe, but do they do any kind of drug testing before a colonoscopy? Should patients be worried about that?"

No, a standard colonoscopy does not involve a drug test. Before the procedure, your healthcare team will focus on reviewing your medical history, current medications, and allergies. The main goal of this review is to make decisions to ensure your safety and comfort during the procedure.

The only tests you might have beforehand are those relevant to the procedure. It is customary to check your blood pressure, respiratory rate, and other vital signs before the start of the procedure. You might require additional blood tests, such as a clotting profile or a liver function test, if you have other medical conditions that necessitate such tests.

However, it’s important to be honest about any medications or recreational substances you’ve taken recently, because they can affect how sedation is managed. For example, marijuana users tend to require higher doses of anesthesia medications than non-users (1). Antidepressants, opioids, alcohol, and stimulants are other examples of substances that can impact anesthesia. Therefore, disclosing use of such is not about screening for “illicit drugs” in a legal sense, but more to ensure your safety during the procedure.

The bottom line is this: Colonoscopies are not drug-testing appointments, but full disclosure about substances you’ve used helps the medical team choose the safest anesthesia plan for you.

Sources:

1) https://www.bradfordhospitals.nhs.uk/preparing-for-surgery/recreational-drugs/

“I’m prepping for a colonoscopy and planning my meals for a few days beforehand — is plain white rice allowed any time before the colonoscopy, or should I skip it?”

Planning your colonoscopy prep meals days ahead is the right strategy to maximize the success of your procedure. To answer your question, plain white rice is an excellent option to add to your meal plan in the early stages of preparation but it is not allowed when you are a day away from your colonoscopy.

Let me break it down further.

About 2-3 days before your colonoscopy, you will be asked to start on a low-fiber diet. Compliance to this diet is important because it helps reduce colon residue and optimize visibility during scoping. Plain white rice is low in fiber, making it high in the list of what you should be eating in this timeframe.

Skinless chicken and turkey, fish, eggs, bone broths, seedless fruits, apple juice, and an hydrating coconut water jello are some great options to pair with your plate of white rice.

However, there is a time in the preparation phase when white rice is not allowed. 24 hours before your colonoscopy, you will have to transition to a clear liquid diet to ensure your colon is as empty as possible. As white rice is not a liquid food, it is absolutely impermissible at this point.

Thank you for this question. Drinking water is highly encouraged while preparing for a colonoscopy as it helps mitigate the dehydrating effects of the preparation process. However, even water becomes unsafe if taken too close to the procedure. Currently, the consensus within the medical community is to stop taking all clear liquids, including water, about 3-4 hours before your procedure. So, if your colonoscopy is scheduled for the late morning or afternoon, drinking water through the night should be fine. However, it might be best to use midnight as the cutoff time for early morning appointments.

While I understand that your preference to drink water during the night, doing so too close to your procedure could be harmful. For one, it may reduce the visibility of your colon and force your doctors to cancel the procedure. Another concern is the risk of aspiration, which involves the content of the stomach being regurgitated and inhaled into the lungs. Both these outcomes are thoroughly undesirable, so, stopping water intake at the right time is key.

Ultimately, your doctors have the final say on this since they know your complete medical history and can advise you more holistically. For example, patients with diabetes may be permitted sips of water close to the procedure because of their increased risk of dehydration.

Sorry if this is a silly question, but I’m starting my colonoscopy preparation tomorrow and I’m a little worried… will a clear liquid diet cause diarrhea before I even take the prep drink?

I’ve read that all the broths and juices can keep things moving, and I’m already feeling a bit off from nerves. I guess I’m wondering if I should stay near a bathroom all day or if that’s just once the prep kicks in?

Thanks so much in advance — this website has seriously been such a help.