How the Food Matrix Impacts Nutrient Absorption with Sports Dietitian Marie Spano

In Episode 123 of The Eat for Endurance Podcast, I’m joined by Marie Spano, MS, RD, CSCS, CSSD, a highly respected sports dietitian and nutrition communications specialist.

Marie currently is the sports RD for the Washington Nationals and Atlanta Hawks, and has previously worked with powerhouse teams including the Atlanta Braves (World Series champions in 2021), Chicago Cubs, and more. I’ve been trying to get her on my show for years, so I’m extra excited to share this conversation with you.

In this episode, Marie and I dive into the food matrix and how it impacts nutrient absorption for everyone, but especially for athletes. This is an important topic, because many people only think about individual nutrients (e.g. fat, carbs, protein, etc) when they look at a food label, when they also need to be considering how these nutrients interact with each other within a food, plus how they change when a food is cooked or processed. 

If you’ve never heard of the food matrix and you’re wondering why dietitians like Marie and I nerd out about it so much, this episode is for you.

Listen on Apple Podcasts

Listen on Spotify

Watch on YouTube

What is the Food Matrix, and Why Should You Care?

One of the biggest takeaways from my conversation about the food matrix with Marie is that food is so much more than the sum of its nutrient parts. 

“You can’t just look at protein, fat, or carbs in isolation. You have to consider how those nutrients interact within the food itself, and how the structure of the food changes the way your body uses them.” – Marie Spano, MS, RD, CSCS, CSSD

The food matrix refers to the physical and chemical structure of a food, and how the nutrients and non-nutritive compounds (like fiber or polyphenols) inside that food interact with one another. It’s not just about what nutrients are present, but how they’re absorbed, digested, and ultimately utilized by the body. Cooking, blending, or processing a food can impact the food matrix, sometimes enhancing nutrient absorption and sometimes reducing it.

So why should you care about the food matrix as an athlete? Let’s break it down with some real-world examples:

• Nutrient absorption & bioavailability: Two foods with the same nutrient label may not deliver the same benefits.

  • For example, calcium from dairy tends to be more bioavailable than calcium from some plant foods (e.g. spinach), thanks to the surrounding matrix of proteins and other compounds that support absorption

• Satiety & hunger cues: Think about how different it feels to eat a whole orange versus drinking orange juice. The juice may give you a quick hit of energy, but the intact fibers in the whole fruit slow digestion and may keep you fuller longer

  • Both juice and a whole orange are beneficial in different situations

• Gut health: Fibers, antioxidants, and other plant compounds interact with the gut microbiome in unique ways depending on whether they come from whole, minimally processed foods or more refined sources.

  • Both whole and more processed foods can have a place in an athlete’s fueling plan, but it’s all about timing and context

• Performance outcomes: For athletes, the food matrix can directly influence energy availability, recovery, and even how you tolerate certain foods before or during exercise.

  • Sometimes breaking down the food matrix (like opting for white rice or a sports drink) is exactly what your body needs to perform at its best

    
    

When you think about nutrition, don’t just look at the numbers on the label. The form a food takes and the matrix it comes packaged in are just as important for how it fuels you.

Listen on Apple Podcasts

Listen on Spotify

Understanding Macros in the Food Matrix

When most people think about fueling, macronutrients (protein, carbs, and fat) are often at the forefront of their mind. But as Marie points out, the food matrix changes how each of these macronutrients is digested, absorbed, and used by the body. 

Protein 

Protein isn’t just about hitting a daily gram target (despite what all the influencers on Instagram are sharing these days). It's also about quality, digestibility, and context.

• Animal vs. plant sources: Animal proteins are generally more bioavailable, meaning your body can absorb and use them more efficiently. Plant proteins may come packaged with fiber or compounds that slow digestion, which is why plant-based athletes often need higher overall protein intake to get the same benefit

• Processing matters: Whey protein powder will digest very differently than a steak or a serving of lentils. In some cases (like post-workout recovery), a “broken down” form of protein can be beneficial for quick absorption. In other contexts, a slower-digesting protein can help with satiety and sustained energy

Carbs

Carbs often get labeled as “good” or “bad,” but the food matrix shows us it’s not that black and white. Processing can sometimes enhance nutrient absorption, so it’s not always the enemy.

This is where many athletes get tripped up and it’s something I always stress with my clients, especially those who are afraid of those so-called “bad” carbs. In reality, those carbs can be the perfect tool in the right context. 

• Whole vs. refined: A bowl of brown rice and a slice of white bread both contain carbs, but the surrounding fibers, starch structure, and processing level make them behave differently in your body.

  • Whole grains provide more fiber and micronutrients, but refined carbs can be an athlete’s best friend when quick energy is needed (like before a long run or during an endurance race)

• Fueling for performance: Before or during a hard workout, breaking down the food matrix (think sports gels, white rice, or juice) can give you quick energy without GI distress. At other times, intact carbs (like oats, beans, or whole fruit) are better choices for satiety, blood sugar balance, and overall health

Fat 

Fat is another nutrient where form matters just as much as the amount.

• Whole vs. processed sources: Eating a handful of almonds is different from drizzling almond oil on your salad. The intact nut slows digestion and provides fiber, while the oil delivers fat in a more concentrated, easily absorbed form

• Absorption of other nutrients: Many vitamins (A, D, E, and K) require fat for absorption. Pairing fat with plant foods (e.g. olive oil on roasted veggies or avocado with salsa) can actually enhance the bioavailability of certain nutrients

• Satiety and performance: Athletes don’t typically rely on fat for immediate performance fuel, but the structure of fat-rich foods can play a big role in satiety, meal balance, and energy availability

The food matrix changes how we experience, digest, and use protein, carbs, and fat. By paying attention to the form of these foods and when we consume them, we can optimize overall health and performance. 

Micronutrients & Non-Nutritive Compounds in the Food Matrix

While macros usually steal the spotlight, the micronutrients and non-nutritive compounds in food are just as critical for overall health and athletic performance. Once again, the food matrix plays a huge role in how your body absorbs, processes, and benefits from these nutrients.

Fiber 

Fiber is one of the most influential components of the food matrix, especially for gut health.

• Whole vs. processed foods: You get more fiber in if you eat an apple or a bowl of lentils compared to drinking apple juice or having a refined grain. Whole food fibers slow digestion, stabilize blood sugar, and keep you fuller longer

• Gut microbiome benefits: Different fibers feed different types of gut bacteria, influencing everything from immunity to inflammation

• Performance considerations: While fiber is great for long-term health, it’s not always ideal before a long or hard workout. Too much roughage can lead to GI distress, which is why athletes often turn to lower-fiber options like white rice or bananas when fueling around training

Antioxidants

Antioxidants (compounds like vitamin C, vitamin E, and polyphenols) help protect the body against oxidative stress, which can increase during intense exercise. But how they’re absorbed depends heavily on the food matrix.

• Food form matters: A smoothie may release certain antioxidants more quickly than whole fruit, but chewing an orange provides a different release pattern that can be beneficial for satiety and digestion

• Cooking and absorption: Some antioxidants become more bioavailable when cooked (like lycopene in tomatoes), while others degrade with heat. Getting a mix of raw and cooked fruits and veggies ensures you get a good balance in your nutrition plan

• Timing for athletes: Antioxidants are essential for recovery and long-term health, but mega-dosing them (especially in supplement form) may actually blunt training adaptations. The natural food matrix provides antioxidants in more balanced, effective doses.

  • Instead of stressing about a supplement, think about building a colorful plate. Plus, it’s a lot more enjoyable to eat your antioxidants than to swallow them in pill form

Polyphenols and Other Plant Compounds

Beyond vitamins, minerals, and fiber, foods contain countless bioactive compounds (polyphenols, flavonoids, and phytochemicals) that work together in ways we’re still learning about.

• Synergy in foods: The health benefits of berries, dark chocolate, coffee, and tea aren’t just about one “super compound.” They come from the interaction of multiple compounds in their unique food matrices

• Impact on performance: Polyphenols have been studied for their potential to improve blood flow, reduce inflammation, and enhance recovery. Athletes who eat a variety of colorful plant foods benefit from these effects without needing isolated supplements

  
  

When it comes to micronutrients, variety and form matter. Include whole, colorful, minimally processed foods (in addition to whatever else you eat) to get a wide array of nutrients and compounds that work together to support health and performance.

How to Apply the Food Matrix to Your Fueling Strategy

So what does all this science actually mean when you’re planning meals, snacks, and your fueling strategy? The food matrix may sound complicated, but the main takeaway is simple: think about food in context, not just in numbers.

Here are a few ways to put this into practice:

• Mix it up: Rotate foods and preparation methods to unlock different benefits

• Use processing to your advantage: Refined carbs and proteins can be helpful around workouts, while whole, fiber-rich foods are best for meals away from training

• Pay attention to timing: Choose foods based on whether you need quick fuel, sustained energy, or recovery

• Think beyond labels: Nutrient numbers matter, but the form and matrix matter too

• Listen to your body: Notice how different foods make you feel and use that feedback to guide your choices

  
  

The food matrix reminds us that nutrition is more than math. By considering food structure, context, and timing, athletes can fuel smarter, recover faster, and perform at their best.

Ready to Optimize Your Fueling Strategy?

If this episode left you curious about how to apply the food matrix to your everyday eating and performance nutrition, I’d love to help.

I’ve worked with runners, cyclists, triathletes, and other endurance athletes for over 10 years to fine-tune both daily fueling and race-day strategies. Whether you’re struggling with GI issues, underfueling, or just want confidence in your nutrition plan, I offer support at every level.

Here’s what one of my clients had to say about our time working together:

“I worked with Claire to optimize energy and endurance during long days playing beach volleyball. We also worked on gut issues I was experiencing since having 2 kids. Claire is understanding, thorough, professional, and so amazing at what she does. I now know what and when to eat to feel good pre and post workout. No more crashing in the middle of the day and no more migraines. Bloating during workouts is now completely gone. I can't recommend Eat for Endurance enough for all your fueling needs. “

-Molly B. 

If you’re ready to put the food matrix (and other fueling strategies) into practice, here are a few ways I can support you:

• Join my membership service, Fuel for Life Crew, for $30/month (cancel anytime)

• Check out my free nutrition downloads

• Browse my library of nutrition masterclasses (all are included inside the Fuel for Life Crew membership)

• Fill out a new client inquiry form if you’re interested in 1:1 nutrition coaching (spots limited)

Your nutrition doesn’t have to feel overwhelming or complicated. Together, we can make fueling simple, personalized, and most importantly, effective for your training and everyday life.

Support the Podcast

I'd be so appreciative if you would help support this free content! 

Here are a few easy ways:

• Leave a 5-star rating and write a review wherever you get your shows

• Subscribe/Follow The Eat for Endurance Podcast so you don't miss an episode

• Shop all your favorite sports nutrition products (Skratch, Tailwind, Momentous, etc) using my affiliate codes

• Join my Patreon community

Disclaimer: All information provided is for educational and entertainment purposes only and is in no way meant to replace individual medical and nutrition recommendations.