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You’ve likely heard that getting enough fiber is an important part of an overall healthy diet, and you’re wondering how you can bump up your intake by adding fiber to your protein shakes.
You can add fiber in protein shakes by using whole foods like berries, seeds, veggies or grains, or by adding a fiber supplement (psyllium husk) or using a high-fiber protein powder.
With that said, it’s important to spread your fiber intake evenly over the day, with no more than 8g in a protein shake, as over doing your fiber intake can block protein absorption.
- For some people, consuming a large amount of fiber can reduce protein absorption by a small amount.
- The benefits of fiber to lower the risk of disease, improve digestive health, and maintain a healthy weight outweigh the risk that protein absorption might be slightly decreased.
- There are many whole food options available to increase fiber intake without the need to turn to specific fiber supplements.
Does Fiber Slow Down The Absorption Of Protein?
Yes, fiber slows down the absorption of protein. In fact, a large amount of fiber can actually block a small amount of protein from being absorbed at all, by reducing its digestibility. The decrease in protein digestibility is less than 10%, which is not considered significant, and it doesn’t happen for everyone.
Keep in mind that these impacts happen with large amounts of fiber, for example adding 25g of supplemental fiber per day on top of normal dietary intake.
Plus, there is already a certain amount of individual variation between different people in terms of their ability to digest protein.
So, some people following a high-fiber diet see no impact on protein digestion; others can experience a reduction of 2-10% in protein digestibility.
For example, someone eating 150g of protein per day who adds a LOT of fiber (>25g addition) could miss out on 2-15g of protein. This is less likely to happen if fiber intake is increased slowly over time, and if fiber intake is spread evenly throughout the day.
Why Should You Add Fiber To Your Protein Shake?
You should add fiber to your protein shake as an easy, convenient, and delicious way to increase your daily fiber intake. Getting enough fiber has a host of benefits, including lowering the risk of certain diseases, improving digestion and gut health, lowering cholesterol and helping to maintain a healthy body weight.
Most Americans do not consume anywhere near enough fiber, with an average intake of only 16g, which is well below recommended levels.
The recommended levels vary slightly depending on the source, with the USDA recommending 25g for women and 38g for men, and the American Heart Association suggesting 25-30g per day.
Lower Disease Risk
Eating enough fiber (at least 25-29g) reduces the risk of dying from cardiac disease, stroke, type 2 diabetes and colon cancer.
Fiber helps with digestion in both of its forms: soluble fiber (which absorbs water and creates a gel-like substance) adds bulk to poop and helps it move smoothly in the intestines; insoluble fiber remains unchanged during digestion and promotes normal movement of the intestines.
Improve Gut Health
Adding fiber, especially if you consume a high protein diet, can help to improve gut health. It turns out that fiber is a good source of energy for the helpful bacteria that live in our colons, and striking the right balance between helpful and harmful bacteria is a key element for a happy gut.
If you’re concerned about your cholesterol levels, getting enough fiber helps to reduce cholesterol levels, and is part of a heart-healthy diet.
Eating enough fiber can help you to maintain a healthy body weight by helping you to feel full. Fiber takes up space in your stomach without providing calories, so it provides a sense of fullness and reduces the risk of overeating.
- Related Article: 34 Tips For Getting Used To Eating Less (Science-Backed)
10 Ways To Add More Fiber To Your Protein Shake
1. High-Fiber Protein Powder
The easiest way to add fiber to a protein shake is to choose a protein shake that already has added fiber.
For example, F-Factor 20/20 Fiber/Protein has 20g of fiber and 20g of protein per scoop. I actually consider this too much fiber to consume all at once, just in case it does reduce the digestibility of the protein for you.
I recommend using no more than half a scoop of this powder (10g fiber and 10g protein) along with half a scoop of regular protein powder.
OWYN Only What You Need Plant-Based Protein Powder and Vega Essentials Plant Based Protein Powder each have 2g of fiber per serving (and 20g of protein).
Protein powders that are marketed as meal replacements also tend to be higher in carbohydrates and fiber than regular protein powder. Vega All-in-One Shake has 6g of fiber (and 20g of protein).
Legumes are a great whole food source of fiber, and they are also naturally high in protein.
When I make a chocolate protein shake, I like to blend in half a cup of black beans along with 1 tbsp of unsweetened cocoa powder. They make my shake thick and filling, and the cocoa powder perfectly hides any bean flavor at all.
For vanilla protein shakes, I use half a cup of navy beans or white kidney beans (cannellini beans) instead, since they are pale in color and have a very mild flavor that I can’t taste at all. You can see for yourself with my Vanilla White Bean Protein Smoothie recipe, below.
Here is a handy chart to show you how much fiber and protein you will get from half a cup of common legumes:
|Legume||Fiber per half cup||Protein per half cup||Calories per half cup|
|Red Kidney Beans||7.20g||7.83g||122|
|Cannellini (White Kidney) Beans||6.48g||9.72g||151|
Berries are another great whole food source of fiber, and they are very low in calories. They are perfect for putting in protein shakes, and they add great color and flavor.
Plus, they provide beneficial antioxidants like vitamin C, which can help keep you from getting sick.
|Berry||Fiber per half cup||Protein per half cup||Calories per half cup|
You can definitely add oats in a protein shake to increase the fiber – each half cup (40g) of dried rolled oats has 4g of fiber.
Although you can use dried oats, the best way to include oats in a protein shake is to use fully cooked, cooled oats that are added to your other protein shake ingredients in a blender.
5. Bran (Corn, Oat, Rice, or Wheat)
Bran is the hard outer layer of cereal grains such as corn, oat, rice, or wheat. Bran is an excellent source of dietary fiber, as well as essential fatty acids. But, it is removed when whole grains are processed into refined grains (which is why whole grains and whole grain products are such an important part of high-fiber diets).
You can buy just the bran and add a spoonful or two to your protein smoothie (or yogurt, cereal, soups, or salads) to boost the fiber content.
|Bran (¼ cup)||Fiber per half cup||Protein per half cup||Calories per half cup|
6. High-Fiber Vegetables
In the same way that you can put fruit (like berries) in a protein shake, you can also add high-fiber vegetables.
I like to use frozen cauliflower florets – they have practically no taste, but they add fiber and micronutrients and when they are blended, they make my smoothie thick and creamy.
|High-Fiber Vegetables||Fiber per half cup||Protein per half cup||Calories per half cup|
|Avocado||⅓ cup (50g)||3.35g||80|
|Broccoli||1 cup, chopped (91g)||2.37g||31|
|Cauliflower||1 cup chopped (107g)||2.14||27|
|Spinach||2 cups (60g)||1.32g||14|
- Related Article: 14 Best Vegetables For Building Muscle (Rated By Dietician)
7. High-Fiber Seeds (Chia or Flax)
While seeds are primarily a source of fat, they also provide protein and fiber as part of their small but mighty packages.
This makes them the perfect choice to sprinkle into protein shakes.
Beyond whole food choices like the legumes, berries, vegetables and seeds listed above, there are also certain additives and supplements that are high in fiber.
8. Thickening Gums (Carrageenan, Guar Gum, or Xanthan Gum)
Many common thickening agents are actually sources of soluble fiber – they work by drawing in water, which provides volume and stability to the mixture.
A little goes a long way when it comes to thickening gums – I use ¼ to ½ tsp of xanthan gum when I want my protein shake to have a thick texture like a milkshake.
Resist the urge to use 1 full tsp just to boost the fiber content – you’ll end up with a shake that is impossibly thick and you’ll have to eat it with a spoon.
- ½ tsp of guar gum has 1.5g of fiber
- ½ tsp of xanthan gum has 1g of fiber
- ½ tsp of carrageenan has 1g of fiber
9. Psyllium Husk
Psyllium husk is a form of soluble fiber that is used in brand-name fiber supplements like Metamucil. But you can save yourself the price tag of a brand name product, and just buy plain psyllium husk powder on its own.
1 scoop (5g) of psyllium husk has 4g of soluble fiber.
10. Fiber Supplements
Finally, if you can’t meet your recommended daily fiber intake with the various whole food options, above, there are a variety of brand-name concentrated sources of fiber on the market. These can come in handy if you can’t eat whole foods for a period of time, perhaps due to illness or injury.
Most name brand fiber supplements provide a similar amount of fiber per serving (2-3g). So, it really comes down to your preference in terms of flavor (some are unflavored whereas others are flavored, with orange being the most common), and price point.
|Meals||Regular Menu||Kids Menu|
|Metamucil||1 rounded teaspoon (5.8g)||3g|
|Benefiber||1 stick (4g)||3g|
|Citrucel||1 heaping tablespoon||2g|
3 High-Fiber Protein Shake Recipes
Straight from my kitchen to yours, I’m excited to share some of my favorite high-fiber protein shake recipes with you.
Vanilla White Bean Smoothie
- Calories: 270
- Fiber: 7.5g
- Protein: 38g
- Fat: 0.5g
- Carbs: 30g
No one will ever know that it’s more than just vanilla beans that make this great-tasting protein smoothie that is high in fiber. Cannellini (white kidney) or navy beans add fiber and protein, but their mild flavor is completely masked by the vanilla so all you taste is creamy goodness.
- 1 cup water
- 1 scoop vanilla protein powder (I use Transparent Labs 100% Grass-Fed Whey Protein Isolate in French Vanilla)
- ½ cup cannellini beans, drained and rinsed
- 5 drops liquid stevia in French Vanilla
- Handful of ice cubes
- Optional: sprinkle of pink Himalayan salt
Very Berry Chia Smoothie
- Calories: 215
- Fiber: 8g
- Protein: 28g
- Fat: 5g
- Carbs: 14g
If purple is the color of royalty, this brightly-colored smoothie will have you feeling like a king or queen. This low-carb smoothie makes a great choice for a high-protein 200-calorie snack, and it can be a good choice if you are using protein shakes to lose weight.
- 1 cup water
- 1 scoop chocolate or vanilla protein powder (I use Diesel New Zealand Whey Isolate in Milk Chocolate)
- ½ cup (70g) frozen berry blend (I use 365 by Whole Foods Market Berry Blend Organic)
- 1 tbsp chia seeds (I use Spectrum Essentials Organic Chia Seed)
- Handful of ice cubes
- Optional: sprinkle of pink Himalayan salt
Sticky Toffee Protein Smoothie
- Calories: 350
- Fiber: 6g
- Protein: 33g
- Fat: 3g
- Carbs: 49g
This delicious protein smoothie is a perfect choice for pre- or post-workout to give you long-lasting energy in the form of complex carbohydrates from the oatmeal, and quick-digesting carbs and natural sweetness from the dates.
It’s also a delicious and healthy alternative choice for dessert!
- 1 cup water
- 1 scoop (30g) vanilla protein powder of choice (I use Diesel New Zealand Whey Isolate in French Vanilla)
- ½ cup (40g) rolled oats + 1 cup water
- 2 large dates, pitted (30g)
- Handful of ice cubes
- Optional: sprinkle of pink Himalayan salt
- Cook or soak the oats in the water for up to 30 minutes before making the shake to allow them to blend more easily.
- Then, combine the ingredients in the order listed in a high-speed blender and process until smooth.
Related Article: Salt Before Workout: Is There Science To Support This Practice?
Other Factors To Consider When Adding Fiber To Protein Shakes
When you’re thinking about adding fiber to your protein shakes, you’ll also want to make sure that you’re not increasing your intake too quickly, that you’re drinking enough water, and that you know when you’re getting enough fiber.
Increasing Fiber Intake Slowly
If your current fiber intake is low (<16g), then trying to double it all at once isn’t a good idea. This could lead to digestive discomfort in the form of gassiness, bloating, and abdominal pain.
Instead, aim to add just a few grams of fiber to one of your meals every few days. Within a few weeks, you’ll be much closer to the targets.
For example, if you currently eat only 10g of fiber per day, try adding 3-4g to your protein shake for a few days (3-5). Then, add another 3-4g at breakfast and wait a few days. Continue this process until you can comfortably hit your recommended total daily fiber intake.
Drinking Enough Water
Since fiber (specifically soluble fiber) absorbs water, it is important for you to drink enough water when you increase your fiber intake.
Our general recommendation is to take your body weight in pounds, divide by two, and aim to drink that number of ounces of water each day.
For example, a person who weighs 150lbs would aim to drink 75oz of water each day.
- Related Article: Do Protein Shakes Dehydrate You? 7 Reasons You’re Thirsty
Other Sources Of Fiber
Just like we remind people that they have to be aware of their total daily caffeine intake from all sources when they look at the amount of caffeine in their pre-workout, it’s also important for you to consider all sources of fiber in your day.
The only way to know for sure whether you are getting enough fiber (but not too much) is to track your intake using an app that will record fiber as a subtotal within your carbohydrate intake.
This will let you know if you are getting the recommended 25-30g of fiber per day. Plus, if the app has a “per meal” feature, you can see if your intake is spread evenly over the day, or if certain meals are very high in fiber and others are very low.
Optimally, aim to have 5-10g of fiber at each meal, and 2-5g of fiber at each snack.
Frequently Asked Questions
Can I Add Psyllium Husk To My Protein Shake?
Yes, you can add psyllium husk to your protein shake. Each tsp adds 4g of fiber. I recommend adding no more than 2 tsp to a protein shake, which adds 8g of fiber (about ⅓ the recommended daily intake for women and ¼ for men). Shakes that are high in fiber should be consumed away from the training window.
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About The Author
Lauren Graham is a Precision Nutrition Level 1 certified nutrition coach. She focuses on helping busy professionals balance healthy eating and purposeful movement. Lauren has a background in competitive swimming and is currently competing as a CrossFit athlete. She has a passion for training, teaching, and writing.
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