Protein and Fiber Benefits: Why You Need Both to support Aging Well

By: Ana Reisdorf, MS, RD

Protein and fiber have been getting a lot of well-deserved attention lately. These are two important nutrients that support your health in different ways. Protein plays a role in maintaining and repairing muscle, while fiber supports digestive health and helps keep your gastrointestinal system functioning normally.

Getting enough of both nutrients can become especially important as you get older. Muscle mass naturally tends to decline with age, while changes in appetite, food intake, medications, and activity can make meeting your nutrition needs more challenging.

Fortunately, adding more protein and fiber to your diet doesn’t have to mean completely changing the way you eat. Understanding what these nutrients do and knowing a few simple food sources can make it easier to get more of both.

Why Protein and Fiber Matter for Everyday Wellness

Protein and fiber serve very different functions in the body, but both are important for overall health.

Protein is a macronutrient made up of building blocks called amino acids. Your body uses these amino acids to build and repair tissues and make important compounds such as enzymes and hormones. Protein is particularly important for maintaining muscle tissue throughout adulthood.

Fiber is a type of carbohydrate found primarily in plant foods. Unlike most carbohydrates, fiber isn’t fully broken down and absorbed in the small intestine. Instead, different types of fiber travel relatively intact through the GI tract, where they support digestive regularity and interact with the gut microbiome.

What Does Protein Do?

If you've ever wondered why protein is important, one key reason is muscle health. Your muscles are continuously renewing themselves by breaking down old tissue and building new tissue. Getting enough protein in your diet supplies the amino acids your body needs to support this natural process. 

This becomes particularly relevant with age because older adults may gradually lose muscle, making it even more important to get enough protein.  Protein can’t support muscle health alone; it works alongside physical activity, particularly resistance or strength exercise, to keep muscles strong. 

Protein also helps your body:

1. Repair cells and other body tissues.
2. Produce enzymes involved in chemical reactions throughout the body.
3. Make hormones and other signaling molecules.
4. Support the structure of tissues such as skin, hair, and connective tissue.

In other words, protein supports far more than muscle; it plays a role in nearly every tissue and process in the body.

How Much Protein Do I Need?

For healthy adults, the 2025-2030 Dietary Guidelines for Americans recommend 1.2-1.6 grams per kilogram per day for protein. But needs may be different for older adults, who may benefit from increased protein intake, particularly for maintaining muscle mass and physical function.

Wondering how much protein may fit your needs? Check out our online protein calculator that can provide a more personalized estimate based on your age, weight, and activity level.

What Is Fiber and Why Is It Important?

Dietary fiber is the portion of plant foods that your digestive enzymes cannot completely break down. So, does fiber help with digestion? Yes, although its effects depend partly on the type of fiber you eat. Eating adequate amounts of fiber is one of the best ways to support gut health.

There are different kinds of fiber. Some fibers absorb water and form a gel-like substance in the digestive tract; these are called soluble fibers. Others add bulk to stool and help food move through the digestive system, called insoluble fibers. Fermentable fibers can also serve as food for bacteria in the large intestine.

Many plant foods contain a combination of soluble and insoluble fiber, so you generally don’t need to carefully track each type of fiber. Eating a variety of fruits, vegetables, legumes, whole grains, nuts, and seeds can help provide the different types of fiber your body needs.

How Much Fiber Per Day Do You Need?

While individual fiber needs may vary, a good guideline for most people is 25-35 grams per day.

Many people fall short of the recommended fiber intake, so increasing fiber-containing foods can be a great goal to support digestive health. If your current diet is fairly low in fiber, however, increase it gradually. Adding a large amount all at once can lead to gas, bloating, or abdominal discomfort.

Fiber also needs fluid to pass through the digestive system, so if you are going to increase your fiber, make sure you are drinking adequate fluids.

Easy Ways to Add More Protein and Fiber to Your Diet

A simple strategy is to look at meals and ask two questions: Where is my protein? Where is my fiber?

Good protein sources include:

• Poultry
• Fish
• Meat
• Dairy foods
• Soy foods
• Eggs
• Beans
• Lentils
• Nuts
• Seeds

Fiber-containing foods include:

• Fruits
• Vegetables
• Whole grains
• Beans
• Lentils
• Nuts
• Seeds

For breakfast, that could mean oatmeal topped with fruit and nuts alongside a protein-rich food. Lunch might include chicken or tuna with a whole-grain wrap and vegetables. At dinner, beans can add both protein and fiber alongside other protein foods, vegetables, and whole grains.

Some foods, particularly beans, lentils, nuts, and seeds, provide both protein and fiber, so you can get both in one serving

Nutritional drinks can also be a convenient option when it is difficult to meet nutrition needs through meals alone. For example, BOOST® Advanced Nutritional Shake provides 35 grams of high-quality protein and 4 grams of prebiotic fiber per serving. BOOST Plus® Nutritional Shake provides 14 grams of high-quality protein and 4 grams of fiber per serving.

If increasing protein is the primary goal, BOOST® High Protein Nutritional Shake provides 20 grams of high-quality protein per serving and can be served alongside a high-fiber food source.

The Bottom Line

Protein and fiber aren’t the same, but both can play an important role in everyday nutrition.

Protein supplies the amino acids needed to build, repair, and maintain muscle and other tissues. Fiber supports digestive function, bowel regularity, and interactions between diet and the gut microbiome.

Instead of trying to overhaul your diet overnight, start by identifying a few meals that could use more protein or fiber. Small changes like adding beans to a soup, choosing a whole grain, including a fruit that’s a good source of fiber with a snack, or finding a convenient protein source can add up over time.

The goal isn’t to make every meal perfect. It’s to consistently give your body the nutrients it needs to help you stay nourished, active, and strong.

References:

1. Protein in diet. Accessed August 31, 2026. https://medlineplus.gov/ency/article/002467.htm
2. Barber TM, Kabisch S, Pfeiffer AFH, Weickert MO. The health benefits of dietary fibre. Nutrients. 2020;12(10):E3209.
3. Olaniyan ET, O’Halloran F, McCarthy AL. Dietary protein considerations for muscle protein synthesis and muscle mass preservation in older adults. Nutr Res Rev. 2021;34(1):147-157.
4. Kennedy RF, Rollins BL. Dietary Guidelines for Americans, 2025–2030.; 2025. https://cdn.realfood.gov/DGA.pdf
5. Nishimura Y, Højfeldt G, Breen L, Tetens I, Holm L. Dietary protein requirements and recommendations for healthy older adults: a critical narrative review of the scientific evidence. Nutr Res Rev. 2023;36(1):69-85.
6. von Muhlenbrock C, Aronsohn F, Quera R, Madrid AM. The role of dietary fiber in the gastrointestinal tract: when, how and why? Best Pract Res Clin Gastroenterol. 2025;79(102080):102080.