This Is What Happens To Your Body When You Eat Kale Every Day

For many years, kale has been the poster child for fashionable produce and at the center of countless memes at the expense of hipsters everywhere. According to a 2019 article in The Atlantic, however, the sun is setting on kale's popularity. Sales have been declining year-over-year, and dwindling searches for kale-related recipes suggest Americans' passionate love affair with this dark leafy green is fizzling. That's unfortunate, because kale is an extremely nutritious and versatile veggie.

Although kale might be a relative newcomer in the United States, it's been eaten since Roman times and is a commonly-consumed vegetable throughout much of Europe. Kale is a cruciferous veggie, which means it belongs to the same plant family that includes broccoli, Brussels sprouts, cauliflower, and cabbage. There are several types of kale. The curly variety is most prevalent in the U.S., but dinosaur, redbor, and Russian kale are other relatively easy-to-find options. 

Kale can be eaten in a number of ways, including raw, sautéed, blended or juiced, and baked into kale chips. Kale also offers a host of important micronutrients, and regularly consuming it and other dark leafy veggies has been shown to have numerous health benefits (via WebMD). But what happens to your body if you eat kale every day — and are there any risks to chowing down on this superfood?

You'll fight free radicals

Kale is an excellent source of antioxidants. In a 2010 paper published in Nutrition Journal, researchers established the total antioxidant content of more than 3,100 foods and beverages, including kale. According to their findings, kale contained between 1.62 and 4.09 millimoles (mmol) of antioxidants per 100-gram serving (and by comparison, kale's arch rival spinach contains only 0.89 to 1.35 millimoles per 100 grams). A 2012 study published in Acta Scientiarum Polonorum Technologia Alimentaria noted that vitamin C, beta-carotene, and polyphenolic compounds such as chlorogenic acid were among the chief antioxidants in kale. The authors also observed that cooking decreased the activity of these substances — choose raw kale if you want to maximize antioxidants.

But what exactly do antioxidants do, and why are they so important for good health? Antioxidants are chemicals that protect the body against damage from free radicals. Free radicals are highly unstable atoms of oxygen that try to "steal" electrons from other molecules in the body. This destabilizes the molecules and creates a chain reaction that leads to damage throughout the body, a process known as oxidative damage or oxidative stress. Substances that produce free radicals can be found in food, medicine, and our environment — and free radicals are also created as the byproduct of natural chemical processes in the body. Antioxidants are able to give free radicals the electrons they want "without becoming destabilized themselves" (via Live Science).

Keep chronic inflammation away

Kale is chock-full of quercetin, a flavonoid (plant pigment) found in vegetables, fruits, and grains. Quercetin is a powerful antioxidant that is believed to have anti-inflammatory properties. High levels of free radicals in the body can activate genes that promote inflammation, so by neutralizing these free radicals, quercetin reduces chronic inflammation (via Healthline). Although many plant foods contain quercetin, kale is a particularly good source. According to a 2019 study published in Nutrients, kale contains 22.6 milligrams of quercetin per 100 grams of fresh kale (by comparison, spinach has 27.2 milligrams and broccoli has 13.7 milligrams).

Although it often gets a bad rep, inflammation isn't always a negative thing. According to the Harvard Medical School, acute inflammation occurs immediately after an injury and produces warmth, redness, swelling, and pain. Problems arise if the inflammatory response becomes chronic. In these cases, the body can get confused and begin attacking healthy tissue. Chronic, low-grade inflammation is believed to cause or worsen a number of conditions, such as heart disease, diabetes, cancer, and arthritis. Chronic inflammation doesn't produce the telltale signs that acute inflammation causes, so it often goes unnoticed and unaddressed.

Better digestive health

Including lots of kale (and other fiber-rich foods) in your diet will ensure smooth sailing in the bathroom. According to the Mayo Clinic, "Dietary fiber, also known as roughage or bulk, includes the parts of plant foods your body can't digest or absorb." It comes in two forms: soluble and insoluble. Soluble fiber absorbs water as it passes through your digestive tract, while insoluble fiber doesn't. Although both types of fiber are beneficial, the insoluble kind is responsible for keeping you "regular." Adult women should aim to get 21 to 25 grams of fiber a day, depending on age, while men should shoot for 30 to 38 grams.

But the benefits of fiber don't stop at the bathroom. As Eating Well magazine explained, fiber can improve your health in a number of ways. It supports the beneficial bacteria in your digestive tract and can make it easier to lose weight and keep the pounds off over time. It also lowers your risk for heart disease (by reducing cholesterol levels) and type 2 diabetes (by preventing sudden spikes in blood sugar after you eat). Getting adequate fiber also reduces your risk of certain cancers and offers a natural way to "detox" your body of harmful compounds.

Because cooking removes a lot of the water in kale, it significantly increases the amount of fiber per serving. One cup of raw kale has 1.3 grams (via NutritionData), while the same volume of cooked kale has 2.6 grams (also via NutritionData).

It may prevent certain cancers

Cancer is the second leading cause of death in the United States, claiming the lives of 599,601 Americans in 2019 (via the Centers for Disease Control and Prevention). Breast cancer, lung cancer, and prostate cancer are the most frequently diagnosed cancers, while lung cancer, colorectal cancer, and pancreatic cancer account for the largest number of deaths each year (via the National Cancer Institute). The National Cancer Institute noted that approximately 39.5% of Americans will be diagnosed with some form of cancer during their lifetime.

There are many factors that can impact cancer risk, and eating kale every day may lower your risk for certain types of malignancies. According to the American Institute for Cancer Research, there are a number of micronutrients in kale that may make it a powerful ally against cancer, but more research is needed. There is "convincing" or "probable" evidence that high-fiber foods such as kale decrease colon cancer risk and rates of obesity — being overweight is a risk factor in and of itself for a number of cancers. There's also very strong evidence that non-starchy vegetables like kale decrease digestive tract cancers, as well as "limited suggestive" evidence that they decrease non-estrogen dependent breast cancer risk. The vitamin C and carotenoids in kale may also lower risk for lung cancer. Other noteworthy compounds in kale include lutein and zeaxanthin, glucosinolates, flavonols, and folate.

Lower your cholesterol

According to the Centers for Disease Control and Prevention (CDC), approximately 94 million American adults have a total cholesterol level higher than 200 mg/dL. If you need to get your cholesterol under control, kale may be able to help. As Everyday Health explained, your liver produces bile, which aids in digestion and elimination of waste products. The acids in bile break down cholesterol. Substances called bile acid sequestrants increase the action of these acids. "The sequestrants take cholesterol-containing bile acids and form them into an insoluble complex — meaning it can't be dissolved in the body — which then leaves your body through your stool." Bile acid sequestrants can lower LDL ("bad") cholesterol by 10–20%. Although bile acid sequestrants are available as prescription medications, kale contains naturally-occurring sequestrants.

In a 2007 study published in Food Chemistry, researchers compared the bile-acid-binding abilities of kale and a number of other dark leafy greens to those of cholestyramine, a prescription bile acid sequestrant. Cholestyramine was set as the control, and kale was found to be about 22% as effective. So while kale can't take the place of cholesterol-lowering medication, it appears that it can, as part of a healthy diet, play a role in lowering cholesterol. Be sure to steam your kale for best results, as a 2008 study in Nutrition Research found that this significantly increased its bile-acid-binding capabilities.

Lower your blood pressure

You've heard that nitrates are the ingredient that makes bacon so bad for you, but did you know that there are other nitrates you should be trying to get more of in your diet? Unlike the synthetic nitrates used as preservatives in bacon and other cured meats, the natural nitrates found in some fruits and vegetables appear to be beneficial for health (via Livestrong). Kale is high in these natural nitrates, although their concentration appears to vary based on when the kale is harvested. According to a 2017 study published in the African Journal of Traditional, Complementary, and Alternative Medicines, kale contains 603 milligrams of nitrates per kilogram in spring, but a whopping 1,181 milligrams in autumn.

WebMD reported on a study published in the New England Journal of Medicine in which researchers examined the effect nitrates had on participants' blood pressure. They found that "average diastolic blood pressure (the bottom number in a blood pressure measurement) was 3.7 mmHg lower after three days of nitrate supplementation than it was after taking the placebo for three days." Nitrates appear to help keep blood vessels healthy and adequately dilated, thus reducing blood pressure.

According to the Centers for Disease Control and Prevention (CDC), 47% of American adults have high blood pressure, which is a leading risk factor for both heart disease and stroke.

Kale may reduce risk for diabetes

Diabetes is a major public health issue in the United States. According to the American Diabetes Association (ADA), 34.2 million Americans (more than 10% of the population) have diabetes. Of these, 32.6 million have type 2 diabetes. Poorly managed diabetes can lead to a number of serious complications, and the condition is the seventh leading cause of death in the U.S. In addition, some 88 million Americans have prediabetes — a condition that, if not promptly and adequately addressed, can become full-blown diabetes.

WebMD noted that dark leafy greens can help fight diabetes in a variety of ways. Kale and other cruciferous veggies are "low in calories and carbs, and high in nutrition. They also have a low glycemic index, so they'll help keep your blood sugar under control." Dark leafy greens also contain magnesium, which is essential for proper insulin function. In a 2016 study published in Biomedical Reports, researchers investigated the effect kale had on blood glucose levels after a high-carb meal. They found that as little as 7 grams of kale significantly reduced post-meal blood sugar levels. This suggests that even a miniscule amount of kale could help keep your blood sugar in check.

Build strong bones

They say milk does a body good, but if you're not a fan of dairy and still want to keep your skeleton sturdy, try adding more kale to your diet. It contains significant amounts of two bone-building minerals: calcium and manganese. According to American Bone Health, "When your body makes new bone tissue, it first lays down a framework of collagen. Then, tiny crystals of calcium from your blood spread throughout the collagen framework." These calcium crystals fill in all the gaps in the "web" of collagen. Collagen makes bones flexible, while calcium makes them strong. 

Although calcium is also an important electrolyte that circulates through your body, the vast majority is found in your bones. In fact, the body uses your bones as a sort of calcium "bank," making "deposits" and "withdrawals" of this important micronutrient as needed to maintain stable circulating levels. Not getting enough dietary calcium means your bones must give up theirs, leading to brittle and fracture-prone bones (via the National Institutes of Health). Although not as well-known as calcium, the trace mineral manganese also plays an important role in bone health. Several enzymes involved in bone formation need manganese to function properly, and manganese deficiency can cause decreased bone "demineralization" (via the National Institutes of Health). One cup of raw kale contains 9% of your daily calcium needs and 26% of your manganese requirement (via NutritionData).

Eating kale every day is an easy way to load up on vitamin C

Although oranges are probably the first food that comes to mind when you think of vitamin C, kale is a phenomenal source of this micronutrient. A single cup of raw kale contains 80.4 milligrams of vitamin C — 134% of your daily needs (via NutritionData). Cooking significantly decreases vitamin C content, but a one-cup serving of cooked kale still packs 53.3 milligrams or 89% of the recommended intake (via NutritionData).

According to the National Institutes of Health, vitamin C is a water-soluble vitamin that plays a number of important roles in the body. It's essential for the production of collagen, a protein that gives skin and connective tissues their structure. Vitamin C is also needed to produce certain neurotransmitters, metabolize the protein we eat, and absorb iron from plant foods. As a powerful antioxidant, vitamin C fights free-radical damage in the body. It may even have the power to "regenerate" other antioxidants in the body. Adequate vitamin C is also needed for proper immune function. The recommended dietary allowance (RDA) for vitamin C is 90 milligrams for men, 75 milligrams for non-pregnant women, 80 to 85 milligrams during pregnancy, and 115 to 120 milligrams if breastfeeding. Smokers are advised to up their intake by an additional 35 milligrams a day. While true vitamin C deficiency is rare, 38.9% of American adults don't meet the estimated average requirement (EAR) for vitamin C (via Oregon State University).

You'll get tons of iron

Iron deficiency is extremely common, affecting approximately 20% of non-pregnant women, 50% of pregnant women, and 3% of men (via WebMD). In fact, according to the Iron Disorders Institute, iron deficiency is the most prevalent nutritional deficiency in the world. It can lead to anemia (low red blood cell count), which can cause fatigue, shortness of breath, dizziness, headaches, and weakness.

The good news for kale lovers is that this dark leafy green is a double threat when it comes to iron deficiency. First, kale is a solid source of iron — one cup of raw kale contains 1.1 milligrams, or 6% of your daily needs (via NutritionData). Second, the vitamin C in kale improves absorption of iron from plant-based sources. As the Harvard School of Public Health explained, there are two types of iron: heme (from animals) and non-heme (from plants). While heme iron is easily absorbed by the body, non-heme iron is much less bioavailable. According to a 2014 paper published in Free Radical Biology and Medicine, in addition to improving iron absorption in the digestive tract, vitamin C plays a number of other roles when it comes to iron, both heme and non-heme. These include influencing cells' uptake of iron from the blood and regulating how much iron is stored in the body.

Less bruising

If just lightly bumping into things leaves you black and blue for days, it could be a sign that you need more kale in your diet. The vitamin C and vitamin K it contains combat easy bruising. As a 2019 article in Prevention explained, vitamin C is essential for production of collagen, the protein that gives skin its strength and structure. "Without enough of it, your blood vessels are out in the open and more likely to rupture," noted Prevention. It's this rupturing of small blood vessels under the skin that causes unsightly bruises. 

Vitamin K may not be as well-known as other vitamins, but it's just as essential for good health. Your body uses vitamin K to produce proteins that oversee blood clotting. This process, also known as coagulation, prevents excessive bleeding both externally and internally. Easy bruising is an early sign of inadequate vitamin K levels. Although your body can produce one form of vitamin K, known as K2 (menaquinone), you get most of the vitamin K you need from food in the form of vitamin K1 (via Healthline).

As previously mentioned, kale is a great source of vitamin C, and it boasts an almost absurd amount of vitamin K. A one-cup serving of raw kale contains 547 micrograms, which is 684% of your daily needs (via NutritionData).

Protect your vision

When it comes to eye health, vitamin A is extremely important. According to Healthline, vitamin A is needed to produce rhodopsin, a protein that allows the eyes to function in low light. Vitamin A is also important for maintaining a clear cornea (the outside covering of the eye) and may reduce your risk for cataracts. Not getting enough vitamin A can lead to xerophthalmia, a progressive eye disease that "begins with night blindness" and if not corrected can cause irreversible blindness.

Lutein and zeaxanthin are two other substances crucial to vision. As a 2014 paper published in Nutrition Reviews explained that these carotenoids (plant pigments) are taken up by the eye, where they "may be protective against eye disease because they absorb damaging blue light that enters the eye." In addition to safeguarding the eyes from diseases such as macular degeneration, lutein and zeaxanthin also appear to play a role in visual development and proper functioning of the retina.

Kale is an excellent source of these micronutrients. One cup of cooked spinach contains 10,302 IU of vitamin A — 206% of your daily needs (via NutritionData). One cup of cooked kale contains 6,447 micrograms of lutein and zeaxanthin, making it (and other dark leafy veggies like collards and Swiss chard) among the richest sources of these carotenoids (via MyFoodData).

Is it bad for your thyroid?

If your metabolism is a factory, where workers (the body's cells) turn food into energy, then the thyroid gland is the foreman, supervising and regulating everything. It does this by producing two hormones: T3 (triiodothyronine) and T4 (thyroxine). These hormones affect every cell in the body and dictate how quickly or slowly that cell uses energy. Iodine is an essential component of these hormones, and the thyroid extracts and stores this mineral. Thyroid disorders most often occur when the thyroid makes either not enough thyroid hormones (hypothyroidism) or too much thyroid hormones (hyperthyroidism). Goiters are another common thyroid issue and can be caused by hyperthyroidism or iodine deficiency (via endocrineweb).

According to the Kresser Institute, some foods, including cruciferous vegetables like kale, are goitrogens, meaning they interfere with the thyroid's ability to take up the iodine it needs. This interference may be particularly problematic for individuals who have a preexisting thyroid disorder. The institute noted that "certain varieties of kale, collard greens, and Brussels sprouts [are] at the top of the list." So, if you have thyroid issues it's probably not a great idea to be eating lots of raw kale daily. Cooked kale is a better option. "Steaming crucifers until fully cooked reduces goitrogens by two-thirds. Boiling crucifers for 30 minutes destroys 90% of the goitrogens," noted the Kresser Institute. 

Kale could expose you to high levels of pesticides

If at all possible, spend the extra money to get organic kale. The reason? Conventionally-grown kale is packed with pesticides. According to the Environmental Working Group (EWG), roughly 60% of kale sold in the United States is contaminated with the pesticide DCPA (marketed under the brand name Dacthal). DCPA has been classified as a possible human carcinogen since 1995, with links to liver and thyroid cancer. It may also harm the lungs and kidneys. In the U.S., DCPA use on crops such as artichokes, beans, and cucumbers ended in 2005, but it's still used on kale, broccoli, sweet potatoes, eggplants, and turnips, among other produce items. The European Union (EU) banned the use of DCPA on all crops in 2009.

But DCPA isn't the only pesticide that may be contaminating your kale. According to the EWG, "Analysis of recent USDA data shows that on average, leafy green samples had detectable levels of 5.6 different pesticides, with a maximum of 20 different residues on a single sample." Traces of the insecticides bifenthrin and cypermethrin are also common on non-organic kale, and these have been linked to neurological issues in children.

For these reasons, conventionally-grown kale is ranked third on the EWG's "Dirty Dozen" list of the most contaminated fruits and vegetables. While it may not be financially feasible to buy the organic versions of all your favorite produce items, it's definitely worth springing for organic kale.