Leafy greens, we all know are one of the healthiest foods on the earth. It offers so much, the benefits are countless, whether it is brain health, heart health or to control your blood sugar levels. But there is always a debate between which one is better. Spinach or kale?

So let's get into it!

Kale, we often must have heard its name listed as a "superfood". The reason is because of the rich nutrients it has to offer. However, both, spinach and kale are powerhouse leafy greens, rich in various nutrients.

If one must break down its nutrients, then we can broadly divide it between the fiber content, vitamin K, vitamin C, vitamin A, calcium, and folate.

Fiber

All leafy greens are rich in dietary fiber and thus is essential for feeding your gut microbiome. This is the community of good bacteria that lives in your gut and supports your digestive health. The recommended daily amount or the RDA of fiber is 25 grams per day. So, if you go for a cup of raw spinach, this gives you around .7 grams of dietary fiber, whereas one cup of raw kale gives you a bit more. It has .9 grams of fiber.

A study published in M J Lifestyle Med titled . Closing America's fiber intake gap: Communication strategies from a food and fiber summit, found that most Americans actually do not get their RDA for fiber met. So, adding spinach and kale could be a great way to give your RDA fiber a start!

Vitamin K

Vitamin K is necessary for blood clotting or lowering blood flow following an injury so that the wound can heal. In addition to calcium and vitamin D, it also supports healthy bones. While some animal products and fermented foods include vitamin K2, a 2020 study titled Vitamin K2 needs an RDI separate from vitamin K1, notes that lush greens like spinach and kale have vitamin K1.

The recommended daily intake of vitamin K is 120 microgrammes (mcg). A cup of raw kale has 82 microgrammes of vitamin K, while a cup of raw spinach contains 145 microgrammes.

Vitamin C

It is a water-soluble vitamin and antioxidant that protect cells from damage and supports immune health. While it is often attributed to citrus fruits like oranges, vitamin C can also be found in leafy greens and both kale and spinach could be a great source. US Food and Drug Administration (FDA) recommends around 80 milligram of daily vitamin C. In one cup of raw spinach, you can get 8.5 milligrams, while kale provides 20 milligrams of daily vitamin C.

Vitamin A

As per the FDA, vitamin A is important not only for your immune system, but also for your eye health. One must have at least 3,000 international units daily. The Office of Dietary Supplements notes that spinach and kale contain compounds called carotenoids, which our bodies convert to a usable form of vitamin A. This way you can have these leafy greens in your diet to fulfill your requirement of vitamin A. In one cup of spinach, you can get 2,810 international units of vitamin A, whereas in one cup of kale, you will find 1,010 international units of vitamin A.

Calcium

Leafy greens are a rich source of calcium, an important nutrient which supports healthy bones and teeth, nerve communication, and muscle movement. The RDA for calcium in adults is 1,300 milligrams and one cup of raw spinach contains 30 milligrams of calcium, whereas in kale, it has 53 milligrams.

Folate

It is a B vitamin which is best known for its important in pregnancy and that provides neural tube defects like spina bifida in fetuses. The RDA for folate is 400 micrograms in pregnant mothers and 600 for those who are lactating. In one cup of spinach, one can get 58.2 micrograms of folate, whereas kale contains 13 micrograms of folate.

How to Decide Your Diet?

Now that you know the nutrients that kale and spinach contain, you make your own decision. This could be decided based on your requirement. The best way to do this is by talking to a healthcare expert, or a nutritionist who can recommend you better based on your body's need.

Walk through a grocery store today and even chips and pastries come in "protein-boosted" versions. Nutrition experts at Stanford Medicine say this trend, often called "protein-maxxing," has outrun the science behind it.

The real picture is more nuanced. Some people do need more protein than official guidelines once suggested, but for most, the bigger problem lies elsewhere in the diet, not in a shortage of protein. Here's what the research actually shows.

1. Your body does need protein

Protein is one of three macronutrients, along with carbs and fat, and your body can't skip it. Dietary protein breaks down into amino acids, the building blocks used to make your own body's proteins.

"Protein can take the form of your muscles, your hair, your skin, everything has protein in it," said Jonathan Long, an associate professor of pathology at Stanford. Of the 20 amino acids your body needs, nine can only come from food.

2. The official recommendation just changed, and the old number was debated for decades

Until early 2026, the US RDA for protein was 0.8 grams per kilogram of body weight, a figure that had stood for over 80 years, according to nutrition writer Shannon Keefe.

New federal dietary guidelines released in January 2026 raised that to 1.2 to 1.6 grams per kilogram. For a 150-pound adult, that moves the daily target from about 55 grams, roughly an 8-ounce steak, up to 80-110 grams.

Also Read: New Experimental Drug May Preserve Muscle Mass During Weight Loss From Ozempic

Whether this matters for you depends on who you are. Christopher Gardner, Stanford's director of nutrition studies, says the old RDA already covers most healthy adults.

But other experts interviewed by Today's Dietitian, including sports dietitian Angie Asche, argue the 0.8g figure is too low for people trying to build muscle, adults over 65, and anyone on a weight-loss diet. The gap is partly because the original RDA was built on decades-old nitrogen-balance studies that may underestimate real needs, Keefe writes.

3. Protein matters most when you're cutting calories

Stanford Medicine notes protein becomes more important specifically when someone eats fewer calories, since a calorie deficit raises the risk of losing muscle along with fat.

This is especially relevant now, given rising use of weight-loss medications. Outside a calorie deficit, piling on extra protein doesn't offer the same payoff.

4. Fiber is the real gap in most diets

While protein gets the spotlight, fiber doesn't. Gardner points out that antioxidants which lower inflammation and help prevent cancer "don't come in meat and cheese and protein bars," per Stanford Medicine.

Only 5% of Americans meet recommended fiber intake, despite its role in gut and heart health. Beans, legumes and whole grains deliver both fiber and protein, but Americans eat less than 10 grams of legumes a day on average, Gardner says.

5. "Incomplete protein" is a myth

The old claim that plant proteins are 'incomplete' and must be paired with specific grains doesn't hold up, Gardner says. Plant proteins contain all 20 amino acids. Legumes run only slightly lower in one of them. Gardner co-authored a 2019 paper comparing amino acid profiles across animal and plant foods and found them nearly identical.

Other myths don't hold up either. There's no need to spread protein evenly across meals, says Stanford dietitian Marily Oppezzo, though older adults may need more per meal to trigger muscle growth. The post-workout 'anabolic window' is also longer than assumed, closer to 24 hours, so a protein shake right after the gym isn't essential.

More isn't automatically better. "I don't think a high-protein diet is necessarily bad, but what are you not eating?" Oppezzo asked. Chasing protein can crowd out the fiber, vitamins and antioxidants in vegetables, fruits, whole grains and nuts.

A compound your body makes after eating pomegranates, walnuts and some berries has improved heart function by up to 80% in lab models of a form of heart failure that's notoriously hard to treat. The finding comes from King's College London, and it's early, but it points at a problem doctors have struggled with for years.

The Condition With Few Treatments

The heart failure in question is called heart failure with preserved ejection fraction, or HFpEF. Here, the heart still pumps blood normally, but becomes too stiff to relax and fill properly between beats. It causes breathlessness, fatigue and a poorer quality of life, and accounts for roughly half of all heart failure cases in the UK, affecting nearly half a million people, according to King's College London's release, carried by ScienceDaily.

HFpEF has long resisted treatment because it's driven by many overlapping factors, including ageing, high blood pressure and diabetes, King's College London says. One class of diabetes drugs, called SGLT2 inhibitors, has recently changed that picture. Large trials named EMPEROR-Preserved and DELIVER found that the drugs empagliflozin and dapagliflozin cut deaths and hospital visits in HFpEF patients, and empagliflozin became the first SGLT2 inhibitor approved in the US specifically for HFpEF, according to TCTMD. But researchers still call the field wide open.

Also Read: Heart Valve Clips Explained: How a Tiny Clip Can Help Repair a Leaking Valve

What The New Study Found

Researchers led by Dr. Joseph Burgoyne found that a compound called urolithin A activates a protein named PKGIα, which helps blood vessels and heart muscle relax, King's says. In animal models of HFpEF, urolithin A improved heart function measures by as much as 80%, helped heart tissue relax better, and reduced fibrosis, the scarring that interferes with normal heart function. It also limited harmful enlargement of heart muscle cells.

The team then tested the compound in engineered human heart tissue grown from stem cells, a lab model that closely mimics real heart muscle. Urolithin A significantly improved relaxation there too, according to King's, suggesting the animal results might carry over to humans.

Notably, urolithin A has already been studied in people and has shown a good safety record, King's says. But your body doesn't get it directly from food. Instead, gut bacteria produce it by fermenting compounds found in pomegranates, walnuts and berries, according to the Global Prebiotic Association, a nutrition industry group. That means how much urolithin A a person makes can depend on which gut bacteria they have, not just what they eat.

Not A Reason To Stock Up On Pomegranates Yet

Burgoyne was careful about what the findings mean. "While there isn't enough evidence to suggest that people should eat pomegranates to treat heart failure, these findings raise the possibility that dietary approaches that enhance urolithin A production may help alleviate this condition," he said, per King's.

Professor James Leiper of the British Heart Foundation, which funded the study, struck the same note: "These findings are promising, but the benefits have so far been seen in animals and engineered human tissue, so clinical trials involving people are needed." He added that a healthy, balanced diet is still one of the best ways to protect the heart, but "no single food can prevent or treat heart disease on its own."

There is a reason why when we think about coffee, we only see ‘caffeine’ in big, bold letters. It helps up wake up, stay energetic, alert, sharpens our attention and helps us fight the midday grogginess at work. So, little attention has been paid to other components of coffee.

But new research suggests some of coffee’s effects on the brain may have little to do with caffeine.

A study published in Nature Communications found that both caffeinated and decaffeinated coffee were linked to changes in the gut microbiome, mood and stress. But improvements in learning and memory were seen specifically among people who drank decaffeinated coffee.

The findings suggest that coffee’s effects on the brain could involve its many other compounds and the gut-brain connection, rather than caffeine alone.

How Was The Study Conducted

Researchers from APC Microbiome Ireland at University College Cork studied 62 people. Thirty-one were regular coffee drinkers, while 31 did not normally drink coffee.

The regular coffee drinkers first stopped consuming coffee for two weeks. Researchers then collected stool and urine samples and monitored their mood, stress, cognition and other measures.

Coffee was subsequently reintroduced, with participants receiving either caffeinated or decaffeinated coffee for three weeks. The researchers found that both forms of coffee were associated with changes in gut bacteria and metabolites. But when it came to cognitive effects, there was a striking finding.

Also read: Andrew Huberman’s Sleep Trick: Can Eye Movements Help You Fall Back Asleep?

Decaffeinated Coffee Improved Memory

Participants who drank decaffeinated coffee showed significant improvements in learning and memory. For example, they made fewer errors on a test examining learning and memory. They also showed improvements in episodic memory, which involves remembering information and experiences.

The caffeinated group did not show the same results. This helped researchers find out that the non-caffeine components of coffee may have some positive cognitive effects.

But the researchers also acknowledge that some of the improvement could have happened due to participants becoming more familiar with the tests over time.

Also read: Gut Microbiome Linked To 3x Higher Type 1 Diabetes Risk In Children

Decaf Coffee's Effect On Brain

Coffee contains thousands of chemical compounds, including polyphenols. These compounds can interact with gut microbes and influence the production of metabolites, which can then affect the body and brain. This is where the gut-brain axis comes into the picture.

The gut and brain are in constant communication through several processes involving the nervous system, immune system, hormones and chemicals produced by gut bacteria.

The study found that coffee consumption altered the composition and activity of gut microbes and changed certain metabolites. Some bacteria, including Eggerthella species and Cryptobacterium curtum, were more found in more quantity among coffee drinkers.

Researchers believe these microbial changes could help explain some of coffee’s effects on mood and cognition.

Effects Of Caffeinated Coffee

Participants drinking caffeinated coffee experienced reduced anxiety and other psychological effects, while some measures of attention and cognitive performance also improved.

Both caffeinated and decaffeinated coffee showed lower signs of stress, depression and impulsivity.

So the study does not suggest that decaf is universally better for the brain. Instead, it shows that different components of coffee may produce different effects.

It also adds another layer to the increasingly complicated story of coffee and health. Coffee may be more than a delivery system for caffeine. Its polyphenols and other compounds may interact with gut bacteria, influencing metabolism, inflammation, mood and brain function.