Bioavailability and Nutrient Density: Optimizing Your Diet for More Nutrition
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Bioavailability and Nutrient Density: Optimizing Your Diet for More Nutrition

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Bioavailability and Nutrient Density: Optimizing Your Diet for More Nutrition

Posted a year ago

Brian Stanton

Brian Stanton


Dr. Kevin R. Gendreau

Dr. Kevin R. Gendreau

Author and Scientific Reviewer

Expert Approved

Eating a nutrient-dense diet is a wise move. Preventing nutrient deficiencies helps you avoid chronic health problems down the road. 

Most people understand the importance of nutrient density, but how’s your knowledge of bioavailability? Spinach may be packed with calcium, but that calcium isn’t especially bioavailable. (Only 5% gets absorbed.[*]) 

Today’s article will boost your understanding of bioavailability. We’ll also cover nutrient density, how cooking affects nutrients, top nutrient-dense food groups, and how to maximize nutrition in your diet. Let’s get started. 

What is Nutrient Density?

The conventional definition of nutrient density looks something like: the amount of beneficial nutrients in a given amount of calories.

In other words, foods with fewer calories and more beneficial nutrients score higher on nutrient density.[*

The beneficial nutrients in question can include:

  • Vitamins like A, C, K, D, B12, and E 
  • Minerals like potassium, magnesium, zinc, iron, and calcium. 
  • Protein
  • Fiber
  • Fatty acids like the omega-3s EPA and DHA
  • Plant-based polyphenols and antioxidants

Fruits and vegetables score highly on nutrient density, while grains and refined foods score poorly. 

The problem with the conventional definition? It penalizes calorie-dense whole foods like meat, fish, and avocados. 

These foods are rich in protein, micronutrients, and fatty acids that are hard to obtain elsewhere. Discouraging their consumption is asking for nutrient deficiencies. 

And so, consider viewing nutrient density separately from calorie density. The goal should be to rack up beneficial nutrients, not necessarily to avoid calorie-dense foods. 

What is Bioavailability?

According to a review in Frontiers in Nutrition, bioavailability “is the fraction of an ingested nutrient that becomes available for use and storage in the body.”[*] It’s the percent of a compound absorbed through the gut and retained in bodily tissue. 

You don’t absorb most of the nutrients you eat. (Bummer!) Did you know that calcium from dairy is only 40% bioavailable? Or that the vitamin K in kale is only 5% bioavailable?[*]

These are just estimates, though. Everyone’s absorption of a given nutrient from a particular food will be slightly different. 

Determining Bioavailability

Here are some factors that influence bioavailability:

  • The presence of other nutrients. Example: calcium is better absorbed when consumed with vitamin D.[*
  • The presence of anti-nutrients. Example: grains, legumes, nuts, and seeds contain a compound called phytic acid which may inhibit mineral absorption.[*
  • The form of the nutrient. Example: heme iron from animal products is better absorbed than non-heme iron from plants.[*
  • Individual factors. Example: folks with digestive issues or a history of gastric bypass surgery may struggle to absorb vitamin B12 from food.[*][*]
  • Cooking. Example: The beneficial compounds naringenin and chlorogenic acid are more bioavailable from cooked (vs. raw) tomatoes.[*

Different protein sources also have different bioavailabilities. This is often assessed by the protein digestibility corrected amino acid score (PDCAAS.)[*] (An acronym designed to be forgotten.) Understanding that 1 is the best score, here’s how some foods score:

  • Egg: 1.0
  • Whey: 1.0
  • Beef: 0.92
  • Black beans: 0.75
  • Peanuts: 0.52

Practically speaking, you’ll never perfectly assess bioavailability. But a working knowledge will help you make wiser dietary decisions. 

How Cooking Affects Bioavailability

Cooking can either increase or decrease nutrient density and bioavailability. Some explanation will help. 

For starters, some foods are better absorbed when cooked. For instance, many types of starch (cassava, sweet potato, etc.) become more bioavailable after cooking.[*

Cooking can also make raw vegetables more digestible. For example, cooked spinach tends to be easier on the gut than raw spinach. 

But cooking may also destroy nutrients. High-heat methods (like boiling) can remove over half the folate in spinach and broccoli, though steaming does not.[*]

The takeaway? To preserve nutrient density, go with gentler cooking methods.

Determining Nutrient Density

How nutrient-dense is a given food? Here are some general principles: 

  • Fruits, vegetables, meat, offal, fish, eggs, nuts, and dairy (if tolerated) are nutrient-dense
  • Grains, snacks, and refined and sugary foods aren’t
  • Legumes are borderline (plenty of fiber and minerals, but poor bioavailability due to anti-nutrients)[*]

Because there’s considerable variation within these categories, it pays to be precise and tabulate your nutrient intake. 

Automate this process by logging your meals with Carb Manager. When you log foods, the app automatically analyzes your micronutrient, protein, fiber, fatty acid, and other nutrient intakes—and displays them like expensive consultants prepared the report. 

Once you know the nutrient density of different foods, you can tailor your diet accordingly. 

Top 8 Nutrient-Dense Food Groups

The following food categories are stuffed with vitamins, minerals, protein, fiber, and other beneficial nutrients. You’ll want to build your diet around them. 

#1: Organ meats

Of the 619 foods analyzed by researchers in The Journal of Nutrition, organ meats won for nutrient density.[*] Beef liver is like nature’s multivitamin—rich in protein, folate, iron, zinc, copper, choline, and other goodies. 

#2: Eggs

Eat eggs for choline (liver health), iron (blood health), and protein (muscle maintenance.) As a bonus, eggs are great for staying in ketosis

#3: Dark leafy greens

Greens like kale, spinach, and chard are high in magnesium, potassium, vitamin K, fiber, and antioxidants. They’re also low in calories, so go ahead and fill your plate with them.  

#4: Fatty fish

Salmon, sardines, and other fatty fish aren’t only high in protein but provide a rare dietary source of the omega-3s EPA and DHA for heart and brain health.[*][*

#5: Meat

If you don’t eat meat or fish, it’s hard (though not impossible) to get enough bioavailable protein. Red meat is also stocked with iron, zinc, and magnesium to keep your blood, bones, and immune system tuned up.  

#6: Nuts

Nuts may contain anti-nutrients like phytic acid, but they’re so densely packed with minerals (copper, zinc, magnesium), fiber, and fatty acids that you win anyway. The healthy fats and protein contained in nuts will also help you feel fuller for longer by suppressing ghrelin (the hunger hormone). This may be very helpful for individuals trying to lose weight.[*]

#7: Fruit

You’ll likely find potassium, vitamin C, and plenty of polyphenols in many of your favorite fruits. Pro tip: enjoy a few blueberries daily for a solid hit of antioxidants. (A compound in blueberries called pterostilbene is now a darling of anti-aging research.[*]) 

#8: Starchy vegetables

Potatoes, sweet potatoes, carrots, and other tubers offer fiber, potassium, vitamin A, vitamin C, and many other nutrients. The people of Okinawa eat (or at least used to eat) plenty of purple sweet potatoes and live past 100 more than almost any other population.[*

Eating To Maximize Nutrient Density and Bioavailability

A whole foods diet is a nutrient-dense diet. Stick to fruits, veggies, tubers, meat, fish, and nuts, and you’ll do fine. 

Also, remember what not to eat. When you avoid grains, soda, sugary foods, and other empty calories, your diet becomes more nutritious by default. 

If you haven’t yet, try tallying your nutrient intake with Carb Manager. Just a few moments of minor effort can provide crucial data for improving your health.