Leafy greens on purple background

Gut Bacteria and Leafy Greens

Doug Cook, RDN

Written by: Doug Cook, RDN

Updated: November 30th, 2022

Leafy greens have long been promoted as a healthy food. Even Canada’s Food Guide used to have a directional statement about 50 years ago to include a dark green vegetable every day. I remember this advice as one of the nutritional nuggets my grandmother used to share with me; that and to have a dark orange vegetable daily too.

The message to have one serving of dark green vegetables was later removed from the previous Food Guides but in 2007, it made a comeback but then again, was removed in the 2019 version which is a missed opportunity in my opinion. It was then re-added in 2020, which you can view in Canada’s Food Guide here.

Dark green vegetables are a great source of folate, lutein and zeaxanthin and beta carotene that supports your heart, brain, and eyes. They’re also an important source of the much-needed magnesium too. But that’s not all, dark green leafy vegetables, in particular, have unique health-promoting properties.

Leafy greens and gut health

Important research has found how your gut bacteria, a.k.a. microbiota, love to feed on a unique sugar molecule [don’t panic ‘sugar’ is just another word for carbohydrate] found specifically in leafy green vegetables.

This discovery may help to explain how certain good bacteria protect your gut and promote health.

The results of the study show that leafy greens are essential for feeding your microbiota in a way that is different than how dietary fiber and prebiotic fiber does. When your intestinal residents have access to their preferred food, they reproduce! They have children, and their children have children, who have even more children and so on 🙂 .

As the number of good bacteria in your gut increases, they limit the ability of less desirable bacteria from reproducing and colonizing your digestive tract. It’s all an issue of real estate. The preferred bacteria crowd out the trouble makers. Let’s face it, there’s only so much space and it’s better for your gut and your health to have more of the good guys.

Time to get more sulfoquinovose

The unique sugar in question is, say it with me, sulfoquinovose (SQ for shore).

As mentioned, SQ is nothing more than a type of carbohydrate found in leafy greens.

Each year, green leafy vegetables around the world produce this sugar in enormous amounts; more than enough to feed all the gut bacteria of the entire human race that are craving it.

FUN FACT: 

SQ  is produced at the colossal rate of 10,000,000,000 tons (that is 10 gigatons) per annum and is degraded by bacteria as a source of carbon and sulfur.

Like prebiotic fibers in other foods such artichokes, SQ increases the number of good bacteria in your gut. What’s a little different about SQ is that it contains sulfur – the ‘S’ in the diagram below.

SQ is the only sugar molecule that has sulfur. Why does this matter? Because, the bacteria in your gut LOVE sulfur and why not? Sulfur is a critical mineral that is needed for building protein. You’re not the only one who makes protein; the trillions of bacteria that you have living in, on and around you do as well.

Dr Goddard-Borger puts it plainly this way: the discovery could be exploited to cultivate the growth of ‘good’ gut bacteria. “Every time we eat leafy green vegetables we consume significant amounts of SQ sugars, which are used as an energy source by good gut bacteria.”

E coli to the rescue

What?

Escherichia coli – E coli for short – are a common type of bacteria that normally live in the digestive tracts of animals and humans.

Most strains of E coli are harmless. If you have a negative reaction when you hear E coli, it’s because of the harmful strain “E coli o157 H7” that sometimes makes its way into the food supply. Outbreaks of harmful E coli-based food poisoning are referring to this particular strain, not the others.

But there are other strains of E coli that are protective. In the case of leafy green vegetables, SQ feeds the beneficial type of E coli which provides a protective barrier between you and other potentially pathogenic bacteria that reside in your gut.

FUN FACT: 

When we ‘eat’ leafy greens full of sulfur, our bacteria digest and absorb it. They use it to make proteins for themselves and then, when the bacteria die and are released via pooping, the sulfur makes its way back into the environment where it is used by other organisms to use, grow, live and reproduce. The circle of life 🙂

Getting more SQ is easy peasy! 

Eat more leafy greens, every day.

Salads: use mixed dark green leafy vegetables as a base for your salads. Use a single vegetable or mix it up by using several different ones as a base for a variety of flavours and textures.

Sauteed: not the best for leaf lettuce but all the other greens do well being sauteed with onions, bell peppers, garlic, and oil. You can steam them slightly too in the pan by adding a little chicken or vegetable stock.

Stuffed: add any raw leafy green to your next submarine, sandwich or wrap. While not technically a sandwich or wrap, try adding some while leafy greens underneath your poached eggs or avocado toast.

Soup it: add leafy greens to stews and soups to ‘up’ the SQ content of your next winter lunch or dinner.

Blend and drink it: probably one of the easiest ways to sneak in some leafy greens. I add raw spinach to smoothies ALL-THE-TIME. Dark green or Romaine lettuce works well here too. Kale not so much unless you have a super fancy blender like a VitaMix which blends the coarse stocks really well.


Study Reference:

Gaetano Speciale, Yi Jin, Gideon J Davies, Spencer J Williams, Ethan D Goddard-Borger. YihQ is a sulfoquinovosidase that cleaves sulfoquinovosyl diacylglyceride sulfolipidsNature Chemical Biology, 2016; DOI: 10.1038/nchembio.2023


Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, mental health.  Follow him on FacebookInstagram and Twitter

Related Articles:

View all News & Articles

cdhf talks supporting the immune system for back to school

CDHF Talks: Supporting your Child’s Immune System for Back to School

Acne and Digestive Health

turmeric

Benefits of Turmeric

man eating processed foods

What are Processed and Ultra-Processed Foods?

hockey face-off

Nutrition Guide for Athletes

rise cycling event banner

RISEUp for Digestive Diseases Event

WDHD Banner

World Digestive Health Day: A Healthy Gut

low fodmap vegetarian meal

Plant-Based Eating & the FODMAP Diet

woman eating functional foods

Functional Foods: The Power of Probiotics

parent and child discussing kids nutrition

Nutrition Tips for Children

digestive health microbes

Why Should We Care About Our Digestive Health?

Young female doctor consulting an elderly patient in her office on a low-residue diet

Low Residue Diet: What is it and Who is it for?

coffee beans in mug

Is Coffee Bad for Digestion?

fast food stacked on table

Low FODMAP Fast-Food Meals

bowel model and fresh fruit

How to Aid Healthy Digestion

Gifts for Guts

man on grey background with puzzle pieces surrounding head

The Link Between the Gut and Mental Health 

low fodmap diet on a phone

Understanding the low FODMAP Diet

Women speaking online on computer with a registered dietitian

Online Nutrition Courses from Registered Dietitians

Family eating healthy meal

Family Friendly Snack Ideas

Yoga for Digestion

5 Strategies for Living Gluten-Free

salad with apple beets and chickpeas

Increase Your Fibre Intake

Types of Berries

The Power of Berries- Colourful and Kick-Ass Nutrition

Porrdge

Creamy, High Protein Breakfast Porridge

Bowl of Slaw

Crack Slaw Stir-fry

Grocery shopping with list

Make your Weekly Grocery Shop a Breeze: Amanda’s Top 5 Tips

Peppermint

Peppermint Fixes More Than Just Bad Breath

Spoons full of different prebiotics

Gut Health and Prebiotics

Family smiling into camera

5 Nutrition Tips for You and Your Family this Summer

Does Hot Weather Affect Digestion?

Women looking at labels in the grocer store

Understanding Fibre Nutrition Claims

Beginning frame of Understanding Fibre Animation

Understanding Fibre Animation

Fibre Benefits

Fibre & Its Benefits

Hand squeezing a grapefruit

Diets Used for IBS

friends smiling in kitchen

7 Day Gluten-Free Diet Plan

Women and male bathroom stall

Managing your Digestive Health in the Workplace Webinar

Taking a photo of food

Diet & Lifestyle Changes for Inflammatory Bowel Disease (IBD)

Cutting up meat and vegetables in the kitchen

Eating for 1 Trillion

Women laughing in yoga pose

Wait… My Gut Affects My Mental Health?

heart shaped bowls filled with fruits

10 Ways to Strengthen Your Microbiome

Kefir

What is Kefir and is it Good for You?

Women holding a salad

Busting Gut Health Buzz Words

Exercising and drinking water

Trying to Eat Healthier? Make it a Habit!

Bowl of healthy salad and tofu

Mental Health and Nutrition

Turkey pesto meatballs

Turkey Pesto Meatballs

Person on computer at home working

Staying Healthy at Home!

Man drinking water

Pre and Post Surgery Nutrition and Lifestyle Strategies to Optimize your Recovery

Brown bag of groceries spilling out of bag

How to Manage Stress Eating and Snack Smart at Home

Drinking water side eye pink background

The Importance of Staying Hydrated: General Hydration and Virus Recovery

Egg and leeks

How to Stay Fuller Longer

Pregnant women in pink shirt smiling down at stonach

Prenatal Health and Your Baby

woman comforting elderly man

Preventing GI Disorders in Adults and the Elderly

Candy

Trick or Treating Safely with Digestive Conditions

CDHF Talks: The Role of Nutrition/Diet in a Healthy Gut Microbiota

Bone broth

Is Bone Broth Healthy?

Leafy greens on purple background

Gut Bacteria and Leafy Greens

CDHF Partners with Metro and their Wellness Program Catered to Digestive Health Issues

World Digestive Health Day: Obesity

Person grocery cart shopping

Help with Choosing Healthy Grocery Products

Senior and adult cooking in the kitchen

Diet & Nutrition Tips for Seniors and their Caregivers

Dietary Fibre vs Prebiotics: Animation

CDHF Talks: Protein and Fibre

peaches

Tips for Eating Well with Rising Food Costs

man holding takeout box and clutching stomach

What is a Food Intolerance?

meal planning sheet

Two Day Meal Plan with Lactose Intolerance

nutrition plan for immune system and gut health

How Nutrition Can Support Gut Health and the Immune System

Common food allergies o blue background

What is a Food Allergy?

The Power of Oats: Can They Play a Role in the Gluten Free Diet?

Feeding your Microbiota Fibre, Prebiotics, and Probiotics

Women drinking wine with pink microbe background

Alcohol and IBS

Digestive Health 101 Webinar

healthy foods

Diet & Lifestyle Changes for Inflammatory Bowel Disease (IBD)

Clipboard that says diet plan surrounded by healthy smoothies and vegetables

Diet Plan for Gastroparesis

healthy food at dinner table

Nutrition Tips for Aging Well

Astro yogurt on a kitchen counter

Lactalis Canada Introduces Astro® PROTEIN & FIBRE Yogourt

The Cultured Coconut bottle on a kitchen counter

The Cultured Coconut – CDHF Certified Product

apples and a bottle of apple cider vinegar

Apple Cider Vinegar for Digestion. What’s the Deal?