First Edition of Gut Advisor Newsletter!

May 2025 | Smoothie cleanses, seed oils, and SIBO

Author

Lisa Goehler
May 15, 2025

Gut Advisor

Hi friends,

Welcome to our inaugural edition of the Gut Advisor Newsletter! This is a monthly newsletter where we address new (or older, but relevant) research findings as well as summarize recent findings or gut-related news. Here, “gut-related” is broadly interpreted, so we will be covering anything that might affect the gut, both “top down” and “bottom up”. This means brain/mind things (“top down”) such as psychology of stress, resilience, and emotion regulation, as well as body-based things (“bottom up”) including inflammation and typical comorbidities of gut disorders, such as pain conditions and autoimmunity.

Dr. Lisa Goehler

Table of Contents

News & Views

Here, we will highlight recent findings from the scientific literature and other news sources, as well findings that are new to us(!) and what we think about them.

Can dietary fiber replace fecal transplants?

Nature magazine (a high profile prestigious scientific journal) recently published a paper showing that dietary fiber was more effective than fecal transplant at improving gut microbe populations messed up by antibiotics1 .

The study was done with mice, so it may not translate to humans, but it supports what we have been saying about the dynamic nature of gut microbe populations. Microbes do not “colonize” the gut like previously assumed, but rather, they survive and grow based on what nutrients there are for them in our guts. That is – what we eat.

Smoothie cleanses: the good and the (potentially) bad

I have been hearing about various “cleanses” for more than thirty years now. Most recently, people have been asking me about benefits and possible risks of “smoothie cleanses”. These smoothies contain lots of green vegetables that purportedly “cleanse” toxins from the body. There is no evidence that they can actually do that, but including more green vegetables in the diet should be helpful overall, because green vegetables contain many anti-oxidant and essential fatty acids (omega 3 and omega 6) that contribute to good nutrition and may be able to counter inflammation2 .

Important note:

Green vegetables contain oxalates, which can exacerbate kidney diseases when ingested in high doses (such as in cleanses). People who need to be wary of smoothie cleanses include people with kidney diseases, bariatric surgery, and antibiotic use3 .

Misconception of the Mononth
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Seed oils drive inflammation and chronic disease

Every month we will address a popular misconception about food or other topic that can affect the gut. Most misconceptions involve a kernel of truth, that is then extrapolated on beyond reality, usually to convince you that something, such as a food item, is a threat. So we will identify the kernel of truth, and assess the rest.

Where did this claim come from?

The idea that “seed oils” are intrinsically pro-inflammatory and contribute to conditions such as pain and heart disease has been circulating for a while. The mechanism proposed revolves around either that the processing needed to extract the oils for the seed, or that because seeds, like most plant-based foods, contain the essential fatty acid omega 6, or both.

The kernel of truth: processing does matter

In this case, there is real cause to be concerned about the processing needed to extract oils from seeds. This involves heat and chemicals, which can damage (oxidize) the oils. Oxidized oils can potentially be pro-inflammatory4.

A safer option is “cold-pressed” seed and other vegetable oils, which have not been subject to such processing. Probably the “safest” option is extra virgin olive oil, which just need to be pressed. Olive oil has been collected this way for many centuries. However, olive oil is “heavier” than other vegetable oils which may not be preferred for all cooking uses.

In my opinion, occasional use of seed oils is unlikely to be a health risk, especially if what is being cooked contains fresh colorful vegetables, which can contain anti-oxidants to mitigate any potential risks.

On Omega 6 fats

The real misconception here is that the omega 6 fats in the oil are pro-inflammatory. That’s not true. Both omega 6 and 3 are anti-oxidant, which can mitigate effects of inflammation2.

Omega 6 is required for the synthesis of the endocannabinoids and prostaglandins. Whereas some prostaglandins do contribute to the inflammatory response, others are anti-inflammatory and promote healing.

In any case, omega 6 fatty acids are incorporated into cell membranes after you eat them, where they stay until given a signal to leave the membrane to be turned into e.g. endocannabinoids or prostaglandins. So, omega 6 only contributes to inflammation when it is called to do so by conditions in the body, such as infection5.

Follow the money

Sources highlighting the risk of lipid oxidation with plant-based oils, such as seed oils, typically tout saturated fats (such as ghee/butter or lard) as “healthy” alternatives. Often the sources turn out to be meat industry or meat industry-friendly entities, and the objective seems to be to sell more meat-based products. But although saturated fats are more resistant to oxidation than the plant based unsaturated fats, they do get oxidized during heating/cooking as well – it just takes a little longer.

For home cooking oxidized fats may not be as much of a concern as they are for commercial cooking, including fast food. Many fast food restaurants do not change the oil frequently (if at all) so a great deal of the oil they are cooking with will be oxidized after being heated for many hours or even days.

Journal Club

Every month, we pick a published (and peer reviewed) article to highlight and discuss.

This month’s selected article

Title

Efficacy of an Irritable Bowel Syndrome Diet in the Treatment of Small Intestinal Bacterial Overgrowth: A Narrative Review.

Authors

Wielgosz-Grochowska, J.P., Domanski, N., Drywień M.E.

Publication

Nutrients, 2022

Is there evidence to support treatment of SIBO (small intestinal bacterial overgrowth) with a diet used to treat IBS (irritable bowl syndrome)?

Title Translation

We think this paper is worth a read! Check it out →

Background

  • SIBO (Small Intestinal Bacterial Overgrowth) is a gut condition whereby there is in imbalance in gut microbes (dysbiosis) in the small intestine, leading to symptoms of bloating, cramping, and changes in bowel habits (constipation, diarrhea).

  • So far, the main treatment for SIBO is a round or more of antibiotics, but the condition frequently recurs.

  • In many ways, SIBO is similar to irritable bowel syndrome (IBS) but there is hardly any research on SIBO compared to what there is for IBS.

Main Takeaways

  • The vast majority of the papers the authors found studied people with IBS. The findings provide good support for dietary intervention/lifestyle change for IBS. Specifically, mindful eating (especially good chewing) was associated with fewer IBS symptoms, as was probiotic supplementation with antibiotics.

  • A key finding supported diets with fiber, or even fiber supplementation, for IBS symptoms. But again, there is little research on SIBO.

  • Overall, the results provide a rationale for dietary interventions for SIBO, but possible benefits are not yet known.

In my opinion, it is a good idea to approach SIBO in a way similar to IBS. IBS is considered to be a Disorder of Gut-Brain Interaction, and treatments for it are more holistic/integrative that what is typically done for people diagnosed with SIBO.

Dr. Lisa Goehler

What we're Eating

Every month we will highlight an easy to make, gut healthy dish that we are eating now!

Youvetsi

I saw this recipe in a social media post from Business Insider. The author, Anneta Konstantinides, reports on her father’s attempts to recreate a favorite dish from his home country of Greece. The article is worth a read and can be found here.

The original recipe calls for beef stew meat chunks, but because I am allergic to beef and pork (and all other mammal meat except primate), I substitute portabella mushroom chunks. I’m also thinking that next time I make it I will add some Greek olives, as well.

Ingredients

  • 4 portobello mushroom caps

  • 16 oz Orzo

  • 1 cup tomato-based pasta sauce

  • 1 lemon, juice

  • 1 cup chopped fresh Italian (flat leaf) parsley

  • 1/3 cup red onion, chopped

  • 4 garlic cloves, chopped

  • 1 cup (or so) feta cheese (1/4 block)

  • Shredded parmesan

  • ~ 2 Tablespoons oregano (separated, 1 for the mushroom roasting, 1 for sprinkling over mushrooms & feta)

  • ~ 1 Tablespoon garlic powder

  • Red wine (about 2/3 cup)

  • Olive oil

Steps

  1. Cut mushroom caps into chunks and roast, tossed in the olive oil and red wine, with garlic powder & oregano, at 350 for 20 minutes. This can be done ahead. Mushrooms can be stored in the refrigerator for a few days, but don’t forget to save the liquids.

  2. Juice the lemon and set aside Chop the parsley, onion, and garlic Chop feta cheese into small chunks

  3. Preheat oven to 350 degrees F

  4. With a slotted spoon, remove the mushrooms from the pan with their juices, and spread evenly in the bottom of a large (e.g. 9 X 13) baking dish. Evenly sprinkle the feta cheese among them. Sprinkle oregano over that.

  5. In a 4 cup measuring cup, put the pasta sauce, the juices from the mushrooms, and the lemon juice. Add water to bring volume up to 4 cups.

  6. In a large pot, heat enough olive oil to cover the bottom, and sauté the onions, garlic, and parsley until the onion begins to become translucent and the parsley becomes bright green.

  7. Add the 4 cups of liquid and when it boils, add the orzo and stir. Cook for 1-2 minutes then remove from heat and ladle the contents of the pot over the mushrooms & feta, evenly distributing the orzo. Sprinkle parmesan over the top and bake for about 30 minutes. Remove from oven and let rest for 10 minutes or so to let the juices absorb.

Enjoy!

Our youvetsi

Community Affairs

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Gut Advisor website

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References

1 Diet outperforms microbial transplant to drive microbiome recovery in mice, Kennedy et al. Nature, 2025

2 Beneficial Outcomes of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Human Health: An Update for 2021., Djuricic I, Calder PC., Nutrients. 2021 Jul 15

3 Green smoothie cleanse causing acute axalate nephropathy, Makkapati et al. Case Reports, American Journal of Kidney Disease, 2018

4 Oxidized dietary lipids induce vascular inflammation and atherogenesis in post-menopausal rats: estradiol and selected antihyperlipidemic drugs restore vascular health in vivo., Folahan JT, Olorundare OE, Ajayi AM, Oyewopo AO, Soyemi SS, Adeneye AA, Okoye II, Afolabi SO, Njan AA., Lipids Health Dis. 2023 Jul 26

5 Omega-6 fatty acids and inflammation. Innes JK, Calder PC., Prostaglandins Leukot Essent Fatty Acids. 2018 May;132:41-48. doi: 10.1016/j.plefa.2018.03.004. Epub 2018 Mar 22.