Fiber: Let’s Dig In.
I have some bad news.
Everyone shouting from the rooftops to eat your leafy greens in order to hit your fiber target is lying to you.
There’s virtually no fiber in lettuce. It’s all a scam to sell more prepackaged salad kits. Big Salad™ is lying to you.
Kidding, kind of.
There is fiber in lettuce, spinach, kale, but it is a pretty trivial amount compared to other sources. And there’s no big scheme to push salads in the name of fiber (that I know of). But, based on the fact that approximately 95% of Americans don’t consume enough fiber in their diets, there does seem to be some confusion around fiber (PMID 30202317), so let’s stick our forks in a piece of broccoli and dive in.
What is fiber?
Fiber is an indigestible complex carb. While it cannot be digested by the human body, our gut microbiome feeds on it.
Why is it so important?
Fiber has quite the resume and for all its benefits, it’s not talked about nearly enough.
Fiber helps you maintain regular bowel movements, some types will help bulk up your stool, some will bind to other compounds, like cholesterol, and overall is linked to many health benefits, including decreased risk of:
Coronary heart disease
Stroke
Hypertension
Diabetes
Obesity
Some GI diseases
(PMID 19335713)
And, like I mentioned earlier, fiber feeds our gut microbiome. More fiber source diversity = greater gut microbiome diversity.
This is important because your gut microbiome is completely unique to you, largely based on your diet. High fiber diets, especially those that have a wide variety of high fiber foods often create the most diverse gut microbiome. A healthy gut microbiome can optimize digestion, immunity, metabolism, brain function, and more. If we can improve our gut microbiome by eating a more diverse array of fiber-rich foods, doesn’t that seem like a no brainer?
How much should I have each day?
A great target is 14g/1,000 calories. More is totally fine.
Some people may experience GI distress as they increase their fiber intake. If you’re looking to increase your fiber by a decent bit, I would do it gradually. Don’t go from 5g to 30g overnight; if you’re currently eating about 5g, shoot for 10g this week and 15g next week. Keep going until you’re shitting nice solid brown logs (genuinely, this should be what your stool looks like - here’s a chart for reference). Shoot for type 3-5.
Image: Lewis, SJ, and Heaton KW: "Stool form scale as a useful guide to intestinal transit time" Scandinavian Journal of Gastroenterology 32: 920–4, 1997
Where can I find it?
Plants!
So I was kind of kidding about the lettuce thing. There is fiber in lettuce, about 2g fiber for every serving (about 85g) of Romaine. Compared to something like raspberries which contain about 8g fiber for every serving (about 1 cup, or 123g).
The “Super Six” is a great classification of high fiber foods - fruits, vegetables, legumes, whole grains, seeds/nuts, and herbs/spices.
How can I (realistically) increase my fiber intake AND diversity?
It can seem really daunting to go from 15g to 25g, especially since fiber is often consumed in pretty small quantities, but it is doable. Without much effort, too!
Here are some of my favorite ways to boost my fiber each day and prioritize different sources:
Add seeds, nuts, herbs, and spices to foods you’re already eating (like eggs, yogurt, toast, smoothies etc.)
Focus on a plant-heavy diet.
Create a tradition where you make a new vegetable side dish one day of the week.
Find a pre-packaged fiber option at the grocery store for busy days.
Make swaps like low carb tortillas and air-popped popcorn.
Pay attention to what fruits and veggies are in season for the time of year when trying new things.
Peruse your grocery store, or a farmers market, and pick out new produce.
Instead of topping yogurt, granola, or oatmeal with one type of berry, do a variety.
Keep prepped fruits and veggies at eye level in your refrigerator for easy snacks.
The moral of the story - when it comes to something we can do right now to improve our health, consuming adequate amounts of fiber (from various sources) is a top contender.
In case you need some inspiration, my favorite fiber sources are stovetop popcorn, a giant bowl of Frosted Mini Wheats, and a bowl of sliced strawberries in strawberry flavored greek yogurt.
