We’ve all heard that eating healthy, nutrient-dense foods is easy to do, just eat from the “rainbow,” right. Unfortunately, eating a bunch of fruits and vegetables isn’t the whole story when it comes to your health.
Nourishing food needs to provide a wide array of vitamins, minerals, fatty acids, and amino acids needed for essential biological functions. These allow you to build muscle, repair tissue, run metabolic reactions, and anything else you need for basic health.
What a nourishing meal really does is cover your essential macro and micronutrient needs while providing enough calories. Foods that do this well are shrimp, steak, and eggs for example. So what is it about those foods that earns them the health label of nutrient-dense? And more exactly, what are nutrients?
You can think of nutrients as units of nourishment. They provide cellular energy (ATP) or become cellular building blocks. They come in the form of macronutrients and micronutrients.
What are Macronutrients?
The macronutrients are protein, carbs, and fat.
Dietary carbs and fats are the fuels your metabolism uses to make ATP, your body’s energy source.
Protein has a secondary role when it comes to ATP. However, protein is crucial for building new tissue and enzymes.
Dietary protein and fat are the essential macronutrients (not carbs). This is why some people do just fine on low-carb and ketogenic diets.
Macronutrients and micronutrients are really terms to talk about nutrients on two different scales — the big and the small.
Protein, for example, is the macronutrient that gets broken down into the micronutrients, namely amino acids. Beef and shrimp are excellent sources of amino acids, not just because they have a lot of them but because they have a “complete” array of amino acids as well.
What are Micronutrients?
Micronutrients are amino acids, fatty acids, vitamins, and minerals. These are the things you really want to know about when asking yourself whether or not a food is nutrient-dense.
How important are these micros? They aren’t just important — they’re essential. And they’re referred to as such!
Take vitamin B12 for example. Without it you won’t be able to keep up with red blood cell production. This will make you tired, weak, and could eventually prove lethal. Children growing up without enough vitamin B12 can suffer long-term cognitive deficits[*][*].
Minerals like sodium and chloride (together, these form table salt) are essential minerals. They’re also called electrolytes. Manganese is another essential mineral you can find in foods like seaweed, almonds, and spinach.
The omega-3 fat DHA and the omega-6 fats arachidonic acid (AA) are essential fatty acids. They’re important precursors to inflammatory and anti-inflammatory pathways and regulators of cell membrane fluidity.
Nutrient density is a way to quantify how much of the right mix of essential nutrients is truly available to you in a food or meal. It’s an assessment based on quantity and quality.
In a basic sense, nutrient density is how much of a nutrient there is per 100 grams or 100 kcal of food. That’s where most food scoring systems stop despite there being much more to it than that. This makes them unreliable.
Many factors have to be considered in order to understand how nourishing food can be. You have to know things like:
- Does it have the active or inactive form of the nutrient?
- Are anti-nutrients interfering with absorption?
- Do your meals contain enough fat to absorb fat-soluble vitamins?
Let’s unpack a few factors affecting a food’s final nutrient density score, starting with the biggest one — bioavailability.
The more bioavailable a nutrient is, the more of it you body is able to absorb and use. Bioavailability is an umbrella term, meaning it accounts for many factors like:
- Ease of digestion
- Loss of chemical integrity
- Factors interfering with proper metabolism
Let’s clarify the differences using protein and eggs as examples.
You can digest 97% of the protein in eggs without damaging the constituent amino acids or interfering with their use (i.e. metabolism)[*]. This, in addition to the complete range of essential amino acids, is why egg protein is a great protein-rich food.
But did you know that, when matched for protein content, whole eggs are even better than egg whites for building muscle post-exercise[*]?
This fact drives home the point that nutrient density scores need to do more than just count up the nutrients in 100 grams or 100 kcal of food. They have to somehow address the question “How much nutrition am I actually absorbing and using?”
Meat and fish score high on the scale of bioavailable protein sources with a score of roughly 94%. In comparison, cereals are very poor sources of protein with only about 70% of its protein being digestible[*].
That’s a tricky question. There’s a simpler version to get us thinking… Ask yourself, Can I only live on [insert food]? If you can it’s probably a complete, nutrient=dense source of food.
Can you survive only on avocados, for instance? Beef steaks? Chicken eggs? What about beans? If you could run that series of experiments, you’d find out that neither beans or avocadoes would cut it, but beef and eggs could. What explains it?
For starters, in 100 grams of mixed kidney beans, there’s 27% protein by calories, which amounts to about 9 grams.
Twenty-two percent of that isn’t truly digestible, leaving us with 7 grams instead of 9. It’s also low in the sulfur-containing amino acids methionine and cysteine.
If beans are a major staple in your diet, relying on their poor bioavailability can lead to poor protein metabolism. This would limit any potential benefit to eating a supposedly “high-protein” food[*].
Beans also lack vitamin B12, retinol (the active form of vitamin A), and the essential long-chain omega-3 fatty acid called DHA. So all considered, beans aren’t a food you can really live off of. That being said, beans can still be incorporated into various healthy eating patterns. It’s just smarter to rely on a bunch of eggs, salmon, or beef for your protein and other basic nutritional needs.
A two-year metabolic ward study from the 1930s in New York City was the first clinical demonstration of an all-meat (ketogenic) diet being nutritious long-term.
It even showed minor but obvious health improvements in both volunteers[*]. A much more recent study put obese adults on a meat and veggies keto diet for three months and found at the end they basically all had healthy blood work in terms of their micronutrient status.
A diet with lots of animal-sourced foods — with or without plants — appears to be a highly nutritious way of eating. That could be as simple as a surf n’ turf meal with some salmon, a steak and a side salad next to butter-fried potatoes.
For most people, diet personalization is something to look forward to. Some of us are super picky eaters and others are more easy-going, but we should all be interested in knowing which foods are most and least nutrient-dense.
Eggs, seafood, meat, and offal are really where you’ll find the highest quality, complete nutrition.
#1: Chicken Eggs
Chicken eggs (36% protein, 62% fat, 2% carbs). Arguably the highest quality source of animal protein, they contain lots of choline (1.2 g/100g), riboflavin/vitamin B2 (0.5 mg/100 g), vitamin B12 (0.9 μg/100 g) and even some vitamin D (82 IU/100 g). Don’t throw away the yolks! Nutrient density score 9/10.
#2: Fish Eggs
Fish eggs (36% protein, 58% fat, 6% carbs). Fish eggs like salmon roe — or caviar if you’re feeling fancy – are very high in vitamin B12 (20 μg/100 g), vitamin B5/pantothenic acid B5 (3.5 mg), and both of the omega-3s DHA (1 g/100 g) and EPA (1.2 g/100 g). Nutrient density score > 6/10.
#3: Blue Crab
Blue Crab (91% protein, 9% fat, 0% carbs). Yeah, it’s a bit messy to eat. But its whopping 814 μg/100 g of copper and 3.8 mg/100 g of zinc makes it worth it. It’s also got a great complete amino acid profile. Nutrient density score 10/10.
#4: King Mackerel
King Mackerel (58% protein, 42% fat, 0% carbs ). It’s super tasty but a food that’s best eaten fresh. It has a generous amount of selenium (36.5 μg/100 g) and vitamin B3/niacin (8.6 mg/100 g). It’s also cheap, low in heavy metals and not overfished, so go for it! Nutrient density score > 7/10.
#5: Lamb Shoulder
Lamb shoulder (43% protein, 57% fat, 0% carbs ). Cook the shoulder as a classic roast and enjoy its fantastic nutritional profile. It has hefty amounts of zinc (3.8 mg/100 g), the active form of iron called heme-iron (1.2 mg/100 g) and phosphorous (175 mg/100g). Nutrient density score 8/10.
Bacon (77% protein, 18% fat, 5% carbs). Bacon, the keto classic. It’s got quite a bit of vitamin B1/thiamin (0.5 mg/100 g), vitamin B3/niacin (9.6 mg/100 g), potassium (945 mg/100g) and selenium (50.5 μg/100g). We now know no one should fear saturated fat, but surprising to most people is the fact that it actually has more monounsaturated (1.9 mg/100 g) than saturated fat (1.7 mg/100 g)! Nutrient density score 8/10.
#7: Beef Liver
Beef liver (62% protein, 27% fat, 11% carbs). If ever there were a superfood, beef liver would be it. It’s bursting with the active form of vitamin A called retinol (29.3 mg/100 g). That’s about fifty-two times more than carrots (0.56 mg/100 g)! It’s also particularly rich in vitamin B2/riboflavin (2.3 mg/100 g) and vitamin B5/pantothenic acid (10.3 mg/100 g). Last but not least it has a respectable amount of manganese topping out at 0.5 mg/100 g. Nutrient density score 9/10.
#8: Lamb Kidneys
Lamb kidneys (73% protein, 27% fat, 0% carbs). This food isn’t for the faint of heart. It’s a classic dish in many traditions of which the French one is perhaps the most well known. If you give it a try, it’ll reward you with a massive amount of vitamin B12 (50.4 μg/100 g), vitamin B2/riboflavin (1.3 mg/100 g) as well as selenium (93.6 μg/100 g) and iron (6.6 mg/100 g). Nutrient density score 10/10.
Spirulina (64% protein, 10% fat, 26% carbs) is a type of seaweed with a Nutrient density score of > 7/10. It contains substantial amounts of copper (597 μg/100 g) and vitamin B2/riboflavin (0.3 mg/100 g).
Zucchini (25% protein, 17% fat, 58% carbs) is a favorite summer vegetable in the Mediterranean region and has a Nutrient density score of 6/10. It has a decent amount of vitamin C (12.9 mg/100 g) as well as a small amount of manganese (0.2 mg/100 g).
Junk-food is very nutrient-poor. It’s mostly some combination of flour, seed oils, and sugars. Once you know how bread, pasta, bagels, candy and so on are just some combination of flour, seed oils and sugars, it’s easy to understand why avoiding them is important.
#1: Wheat Flour
Enriched wheat flour (14% protein, 4% fat, 92% carbs) is so nutritionally poor that there are legal requirements for nutrients like selenium and non-heme iron to be added back in. Without enrichment, people who rely heavily on wheat flour products could suffer even more marked deficiencies. Nutrient density score of 2/10.
#2: Seed Oils
Seed oils like soybean oil (0% protein, 100% fat, 0% carbs) are concentrated sources of inflammatory and oxidized omega-6 fats that may induce nutrient depleting actions. Except for a little vitamin E (8.2 mg/100 g) it has basically no micronutrient profile to speak of. Nutrient density score of 0/10.
The amounts of sugar in our diet are a major public health threat. Consider fruit juices like orange juice (6% protein, 4% fat, 90% carbs).
Except for some vitamin C (50 mg/100 g) and a modest amount of potassium (100 mg/100 g) it also has no nutritional profile to speak of. It’s also very nutrient depleting given this sugary drink causes spikes in blood sugar and insulin[*].
This can worsen one’s oxidative stress burden, the normal cellular damage we accumulate simply by being alive. This can deplete nutrients by increasing one’s need for them, like vitamin C or vitamin D[*]. Nutrient density score of 2/10.
Following a well-formulated ketogenic diet – or any diet for that matter – involves choosing nutrient-dense foods.
That’s a given. However, there’s more to it than just inclusion. We also need to think about what’s worth excluding. Some foods provoke unhealthy metabolic and inflammatory responses. This can increase the rate at which you cycle through nutrients, thus depleting your hard-won nutrient reserves. So building a truly nutrient-dense diet is a two-step process of inclusion and exclusion.
On the inclusion side, you’ll want to focus on those foods that are the most complete, dense sources of macro and micronutrients. This tends to come from animal-sourced foods. When incorporating plant foods prioritize things like avocados and berries rather than bread, pasta and fruit juice. You get the idea.
On the exclusion side, you’ll want to dodge those inflammatory foods or those causing poor metabolic responses. They can cause antioxidant depletion for instance, which then increases your need for micronutrients involved in the antioxidant activity.
The foods to avoid typically come down to being full of omega-6 seed oils (e.g. sunflower oil), flour (e.g. wheat flour) and added sugars (e.g. soda). Those items are in nearly every meal nowadays.
So the two-part check-list for ensuring your diet is nutrient-dense is pretty simple:
- No omega-6 seed oils (e.g. sunflower oil)
- No flour products (e.g. bread)
- No added sugars (e.g. soda)
- Lots of animal-sourced foods dominating your plate (e.g. pork, lamb and dairy food). And opt for fats like butter, lard, tallow, and olive oil.
- If you’re having plant-based foods then opt for avocados, berries, and beans rather than bagels, pasta and fruit juice.
All essential macro and micronutrients are de facto important. But there are a few stand-out ones worth highlighting, especially for anyone interested in ketogenic or plant-based diets.
Vitamin C is abundant in fruit and vegetables. A standard ketogenic diet containing generous portions of plants and animals will supply plenty of vitamin C.
Major food sources might come from low-sugar berries (9.7 mg/100 g), parsley (125 mg/100 g) or red peppers (1,900 mg/100 g). People on a more carnivore-like ketogenic diet will have limited sources of vitamin C, but their need is likely lower due to increased collagen and carnitine intake, or even a compensatory upregulation of other antioxidants like glutathione[*].
But for total peace of mind, the carnivorous types may want to focus on fresh muscle meat and the occasional serving of chicken liver (17.9 mg/100 g)!
Most people are scared of eating too much salt. It has been successfully, unfairly demonized. But salt is actually a super important electrolyte. For instance, when someone goes from a standard American diet to a keto diet they will first lose water weight and some electrolytes.
This is normal when you’re depleting your glycogen stores. It can cause the notorious keto flu, the worst of which you can get over easily by supplementing with a few extra grams of salt a day (say between 3 to 9 grams).
For convenient electrolyte replenishment, check out Perfect Keto’s electrolyte supplement.
Manganese is an essential mineral you need for the enzyme called MnSOD, whose job it is to mop up the reactive oxygen species given off by your mitochondria.
Plants like dried parsley (9.8 mg/100 g) and seaweed (6.2 mg/100 g) can provide decent amounts of manganese. Animal sources have a little less, but they still provide some. Muscles have about 1.6 mg/100 g and old school recipes like boiled tripe have 6.1 mg/100 g.
Riboflavin, also known as vitamin B2, is predominantly found in animal-sourced foods like turkey (2.2 mg/100 g) and lamb’s liver (5.2 mg/100 g). It can also be found in plants like seaweed (2.8 mg/100 g). Riboflavin is a crucial precursor for the enzyme called succinate dehydrogenase that helps your cells produce ATP in the presence of oxygen.
Choline is an essential nutrient that serves as a precursor to two important phospholipids that give your cell membrane their proper structure and function. It’s also involved it in critical functions like handling lipids and the synthesis of neurotransmitters. It may also help protect from fatty liver disease[*]. Choline is most easily found in animal-sourced foods like eggs — especially the yolk!
DHA is the active and essential form of dietary omega-3 fats. ALA is the inactive plant form that can get converted to DHA by a series of enzymes. Humans, however, are very limited in their capacity to do so, as only 4% of ALA can get turned into DHA[*].
Seafood is a particularly rich source of DHA, such as salmon (2.2 g/100 g), mackerel (5.1 g/100 g) and oysters (672 mg/100 g). In comparison, 100 g of ground flax seeds will only yield 680 mg of actual DHA from 17.1 g of the ALA plant precursor form – that’s merely 4% efficiency.
The Takeaway: Eat for Nutrient Density
Understanding what makes food truly nourishing is like a diet superpower. No matter how your diet evolves you’ll always be able to pick nutrient-dense options.
People trying to follow a well-formulated ketogenic diet can benefit from learning more about nutrient foods and getting inspired by some recipes. One tool you can try is this handy keto food search engine and tracking app — Nutrita Pro. Nutria Pro has over 18,000 items scored with a nutrient density score, keto score and insulin index.
So, if you’re not sure whether a food is considered nutrient-dense or keto, this app can help. Happy eating!