Most people can recall being told to “eat your vegetables” frequently as a child.
Some people learn to love vegetables and others never acquire a taste for them, but the idea that vegetables are good for you is a deeply ingrained dietary dogma.
But recently, in the keto and carnivore diet communities, vegetables have been at the center of a controversial debate. Is the heretical idea that you don’t need to eat vegetables to be healthy–or that they might even be bad for some people–true?
Do You Need Vegetables To Be Healthy?
Short answer: it’s complicated, but mostly yes.
Here are some claims you may have heard about vegetables:
- Everyone needs to eat a lot of vegetables to be healthy!
- You can be healthy without vegetables if you get your micronutrients from other sources.
- Vegetables are harmful to some people.
- Excessive intake of plant foods is unhealthy!
Obviously, all of these statements can’t be 100% true all at once. But surprisingly, each perspective is at least partially supported by evidence.
In support of the “vegetables are good for you” argument, two large reviews including hundreds of thousands of participants recently found that eating more fruits and vegetables reduces all-cause mortality as well as deaths by heart disease and cancer[*][*].
On the other hand, these are not randomized controlled trials, and they only tell you what happens on average. If a minority of people are healthy without eating any veggies, or if some people who eat a lot of vegetables are adversely affected, it wouldn’t show up in the data.
Those studies also can’t control entirely for other factors. For example, if people who eat fewer veggies are more likely to smoke and eat unhealthy foods, the vegetables might not be the key factor.
The idea that vegetables are harmful to some people or unhealthy in excess is also supported by the facts that people can develop food sensitivities to veggies, and that many plant foods contain anti-nutrients like phytins and lectins that can cause inflammation in your body and interfere with nutrient absorption[*][*].
As you can see, this is a complex debate without a universal answer.
However, that doesn’t make it impossible to figure out what’s best for your body. Read on to learn how to solve the veggie puzzle for yourself.
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What About the Traditional Inuits? They Didn’t Need Veggies
Traditional Inuit people (or Eskimos) are one reason why people say you don’t need vegetables to be healthy, as long as you get nutrients from other sources.
It comes down to the fact that vegetables and other edible plants don’t grow well far from the equator. In the far, cold north, indigenous peoples like the Inuit developed traditional diets that relied almost exclusively on animal products[*]. However, they still ate berries, roots, and marine plants–when those foods were available.
By eating a high-fat diet rich in seafood, without many veggies, Inuit people enjoyed excellent health. But after colonization and more interaction with other cultures, their diet shifted away from the traditional pattern and their health suffered[*][*].
In Inuit people today, eating the traditional diet is associated with a lower risk of heart disease and better health[*].
While the Inuit are a fascinating example of human dietary diversity, they don’t singlehandedly prove that no one needs vegetables to be healthy. They ate their ancestral diet for thousands of years, and living at a far northern latitude also caused some unique genetic adaptations[*].
What Does Evolutionary Biology Say?
Zooming out from the Inuit people, scientific disciplines like evolutionary biology and paleoanthropology (the study of human ancestors) are extremely helpful to put the vegetable debate into perspective.
In general, aboriginal and hunter-gatherer humans eat what grows in their local environment. They thrive on a combination of hunted animals and foraged plants, and in some cases they rely partially on agriculture[*].
Here are some key takeaways from evolutionary biology:
- Humans evolved as omnivores who sought to maximize their dietary diversity[*]
- Cooking and the use of fire are ancient and essential to human evolution[*][*]
- Vegetables and other plants often played an essential medicinal role[*]
- Traditional human diets vary greatly depending on the region[*]
- Until recently, people were forced to eat seasonally and locally, which meant few carbs during the winter (no UV from sunlight = no carbs)
With some exceptions like the Inuit and other peoples like the Maasai and Sami, most ancient and modern hunter-gatherers derive between 20 and 55 percent of their calories from plants[*].
And while there are a few examples of diets that mostly lack vegetables found in paleoanthropology, there are no examples of ancient vegan or raw vegan diets.
Score one for low-carb and carnivore diets, zero for vegan and raw vegan.
Aboriginal people tend to eat as much of their calories from animal products as possible, but are limited in doing so by their environments[*]. That said, they don’t shun vegetables and other plant foods, which are a secondary source of calories and very important medicinally[*].
Overall, humans evolved to eat vegetables as part of their diet most of the time, with a few exceptions. Keep reading to learn how vegetables can benefit your health and why you should consider including them.
7 Health Benefits of Vegetables
#1: Rich in Fermentable Fiber
As opposed to the insoluble fiber found in grains, vegetables are high in soluble or fermentable fiber. This form of fiber acts as a prebiotic, nourishing your gut microbiome.
Your gut bacteria (and other microorganisms like fungi and archaea) play many essential roles in your body:
- Production of neurotransmitters[*]
- Gut-brain signaling[*]
- Immune function[*]
- Control of inflammation[*]
- Gene expression[*]
Thanks to fermentable fiber, a diverse diet rich in vegetables results in a high-quality, diverse microbiome that supports your health[*][*][*][*].
#2: Packed With Micronutrients
While it’s possible to get many essential micronutrients from animal products, vegetables are an easier way to get magnesium, betaine, and potassium.
According to research, increasing your veggie intake is also an excellent way to get more vitamin C and carotene and improve your overall micronutrient profile[*][*].
#3: Better Colon Health
Vegetables can enhance the health of your colon and gut through their fiber content, as well as the phytonutrients they offer.
Polyphenols like resveratrol, curcumin, chlorogenic acid, quercetin, and piperine reduce your risk of colon cancer and can increase the effectiveness of cancer therapies in people who already have colon cancer[*].
A 2016 scientific review concluded eating more vegetables may also prevent dysbiosis and improve or reverse irritable bowel syndrome (IBS)[*].
#4: Improved Heart Health
According to several large reviews of published scientific papers, eating more vegetables reduces your risk of heart disease and death by cardiovascular issues[*][*][*].
Plant foods contribute to your heart health because they contain fiber, vitamins, minerals, and phytonutrients[*].
But the benefits of veggies for heart health don’t come down to one specific nutrient–they’re likely due to combined effects of various components within plants[*].
That’s why it’s key to focus on eating a diverse array of vegetables and other whole foods to preserve your heart health.
#5: Cancer Prevention
Multiple large studies show that eating more vegetables than the average person helps prevent cancer, and reduces your overall risk of dying of cancer[*][*][*]. One study concluded that if everyone ate 800 grams of vegetables per day, it might prevent up to 8 million premature deaths per year[*].
A Korean study found that high vegetable intake decreases the risk of cancer and death by cancer, but fruit does not[*].
The benefits for cancer prevention are partly due to phytonutrients in vegetables, and partly due to their fiber.
Broccoli and other cruciferous veggies appear to be the star players for preventing cancer. They can protect your gastrointestinal tract, lungs, prostate, or breasts against cancer thanks to chemicals called glucosinolates[*].
However, the risk of certain cancers, including pancreatic, cervical, kidney, and bladder cancer, does not appear to be lowered by vegetables[*].
#6: Brain Health
While it may seem intuitively obvious that vegetables are good for your brain, most people don’t stop to think about why.
The fact that hunter-gatherers tend to view plants as both food and medicine is a major hint, though. In the case of brain health, and cognition, vegetables exhibit medicinal properties beyond most other foods.
One study found that for every 100 gram increase in daily plant food intake, senior citizens’ risk of dementia and cognitive decline decreased by 13%[*]. And a majority of studies find a cognitive performance benefit from eating these foods, likely due to polyphenols[*].
The bottom line: eating more vegetables increases your antioxidant capacity, decreases your risk of cognitive decline, and reduces your risk of neurodegenerative diseases[*]. Scientists attribute these benefits to flavonoids, carotenoids, and other bioactive substances found in plants[*].
While it may be tempting to take a multivitamin or other supplement to achieve the same benefits, you’d be missing out on phytonutrients and other currently undiscovered bioactive compounds that veggies offer.
#7: Phytonutrients and Hormesis
Believe it or not, vegetables and other plants don’t just make beneficial compounds like phytonutrients to feed humans. The naturally-occurring chemicals found in plants exist primarily for the plant’s life cycle and survival, and in some cases for self-defense purposes.
Plants make chemicals like sulforaphane, capsaicin, and resveratrol to protect themselves from insects and other predators, including humans[*][*][*][*][*]. These types of compounds can have harmful effects in high doses, but in the proper amount, many of them can benefit your health.
Hormesis is a process that occurs when your body experiences a stressor and becomes stronger as a result. Scientists think that some of the health benefits of vegetables occur due to hormesis[*].
Essentially, low or moderate intake of polyphenols and other plant compounds activates a controlled stress response in your body that leads to better function and protects your cells in the long run[*].
This phenomenon also explains why some people respond poorly to vegetables. If you eat too many plant foods, or if your body is weakened or compromised and you’re sensitive to the biochemical effects of plant chemicals, they could have an adverse impact on your health.
Vitamins and Minerals: The 8 Best Plant Sources
#1: Kale for Vitamin A and Vitamin K
Kale is delicious and nutritious, raw or cooked. When it comes to vitamins and minerals, kale offers a lot of bang for your buck.
Your nutritional reward for eating a cup of cooked kale is an incredible 17700 IU of vitamin A, 53 mg vitamin C, 1060 mg vitamin K, 17 mcg folate, 94 mg calcium, 23 mg magnesium, 36 mg phosphorus, and 500 mcg manganese.
Leafy greens (including kale, spinach, and chard) also contain natural nitrates, which can boost your nitric oxide production. Nitric oxide is great for your heart health–it can lower your blood pressure and improve your cardiovascular function[*][*][*][*].
#2: Chard for Choline, Vitamin A, Vitamin K, and Minerals
If kale isn’t your jam, chard is a delicious alternative that is worth a try, for both its flavor and nutritional profile.
Just one cup of chopped, cooked Swiss chard contains a mind-blowing 10720 IU of vitamin A, 570 mcg vitamin K, 3 mg vitamin E, 32 mg vitamin C, 50 mg choline, 101 mg calcium, 150 mg magnesium, 58 mg phosphorus, 960 mg potassium, 300 mcg copper, and 600 mcg of manganese.
#3: Avocado for Potassium and Healthy Fats
Avocado is technically a fruit, but unlike a lot of fruits it’s green, fibrous, and packed with minerals. It’s a keto staple because of its healthy fat content and nutrient density.
A whole avocado has an astounding 975 mg of potassium, 14 grams of fiber, 290 IU of vitamin A, 20 mg of vitamin C, 42 mcg of vitamin K, 163 mcg of folate, 29 mg of choline, 58 mg of potassium, 105 mg of phosphorus, 1300 mcg of zinc, and 300 mcg of manganese.
#4: Seaweed and Kelp for Iodine
Most people in Western cultures don’t eat seaweed, but they should. Kelp and other seaweeds are a rich source of iodine. You can eat seaweed a few times a month to maintain adequate iodine levels and support healthy thyroid function.
A 1 gram serving of kombu kelp contains up to 3000 mcg iodine per gram, which is around 2000% of the recommended daily value. You won’t find a better source of iodine than seaweed.
#5: Cruciferous Veggies for Sulfur Compounds, Vitamins, and Minerals
Cruciferous vegetables like broccoli and cauliflower provide cancer-fighting sulfur compounds, but they’re also an excellent source of vitamins and minerals.
A cup of raw broccoli florets has 2130 IU of vitamin A, 66 mg of vitamin C, 50 mcg of folate, 0.4 mg pantothenic acid, 34 mg calcium, 0.6 mg iron, 18 mg magnesium, 47 mg phosphorus, 231 mg of potassium, and still contains under 20 calories and less than 4 g net carbs.
#6: Spinach for Betaine and Vitamins
If spinach triggers childhood memories of being forced to clean your plate, it’s time to reassess your relationship with this leafy green. Not only is spinach rich in betaine, which aids digestion and promotes liver health, it’s also packed with other nutrients[*][*].
A cup of keto-friendly raw spinach packs a whopping 2800 IU of vitamin 8, 145 mcg of vitamin K, 165 mg betaine, 30 mg of calcium, 24 mg of magnesium, 170 mg of potassium, and 0.3 mg of manganese.
#7: Onions for Vitamin C, Folate, and Manganese
Raw or cooked onions are a delicious addition to your plate, but they also provide surprisingly high quantities of vitamins and minerals.
A 100-gram serving of onions offers 7.4 mg vitamin C, 19 mg folate, 23 mg calcium, 10 mg magnesium, 29 mg phosphorus, 146 mg potassium, and 100 mcg of manganese.
#8: Garlic for Allicin and Minerals
Garlic isn’t just a fantastic ingredient to add flavor to your dishes–it’s also high in the beneficial sulfur compound allicin. Allicin is anti-inflammatory and reduces inflammation in your body[*].
Eat garlic for minerals like calcium, iron, magnesium, phosphorus, potassium, selenium, as well as vitamins A, C, K, B6, B12, and choline.
Sure, vegetables are generally good for you, but what if they make you feel worse?
If you experience issues from eating vegetables, you may be sensitive to certain phytochemicals found in them, or you may have underlying gut issues.
Should that be the case, you can try the carnivore diet for 2-4 weeks, then gradually add back in one vegetable at a time, waiting a few days each time to gauge your response. Make sure to pay attention to your symptoms as you switch to the carnivore diet, and as you add veggies back in.
If you use this approach, be sure to eat plenty of nutritious animal foods like shellfish, salmon, sardines, egg yolks, liver, and other organ meats to ensure you get enough micronutrients.
Gut dysbiosis and leaky gut can allow food particles to enter your bloodstream, triggering an immune response, so it’s essential to allow your GI tract to heal[*]. Taking a break from problem foods allows your body to repair itself.
If you suspect your problems are related to leaky gut, here are some more tips:
- Eliminate dairy, preservatives, and other artificial food additives from your diet.
- Eat lacto-fermented vegetables instead of cooked or raw veggies to heal your gut.
Homemade, probiotic lacto-fermented vegetables are easy–just rinse and chop the veggies, put them in a container with water, and add 2-2.5% sea salt by weight. You can let them ferment anywhere from one week to six weeks or longer.
Fixing Vegetable Sensitivities
Whether or not you try out the carnivore diet, here are some effective solutions to address vegetable sensitivities:
- Limit yourself to one or two servings of veggies per meal.
- Cook plant foods thoroughly (which reduces anti-nutrients and hormetic phytochemicals while making micronutrients more absorbable).
- Chew thoroughly.
- Eat local and seasonal plant foods.
- Get more sunlight and ultraviolet (UV) light on your whole body, including your abdomen.
What does sunlight have to do with vegetable sensitivities, you ask?
Your body evolved to eat local foods that are in season. The amount of UV in sunlight at any given time not only controls what plants grow in your area; it also affects your gene expression[*][*].
Insufficient UV light increases your risk of inflammatory and autoimmune diseases, while plenty of sun exposure improves your insulin sensitivity and helps you stay lean[*][*][*][*][*]
Recent data from the Hadza hunter-gatherers as well as studies of mice demonstrate that UV on your belly can even change your microbiome on a seasonal basis[*][*].
If you eat foods that are out of season in your area, you may be more likely to suffer from food sensitivities[*].
The moral is this: if your body doesn’t tolerate plant foods, it’s best to try to get to the bottom of the issue. There may be some people out there who are better off altogether with no vegetables, but there’s a good chance they have underlying gut or autoimmune issues.
Should You Worry About Anti-Nutrients?
Anti-nutrients like phytates, phytic acid, and lectins can block the nutrients you’d otherwise obtain from food, and they may be behind some plant food sensitivities[*][*].
Luckily for paleo diet followers, most of the foods high in lectins and other anti-nutrients–like legumes and grains–are already off the keto foods list.
Some nuts have lectins and phytates, but you can reduce their content by peeling them and then soaking or roasting them.
You can also decrease anti-nutrient content by cooking, sprouting, or fermenting your food.
How to Choose the Best Vegetables for Your Keto Diet
Contrary to the myth that the ketogenic diet doesn’t allow you to eat enough vegetables, there’s plenty of room in your keto macros for leafy greens and other nutritious staples.
Just remember to stick with keto-friendly low-carb vegetables. Try to get at least one or two servings of vegetables per meal whenever possible.
And just as importantly, eat organic and local whenever possible. Organic vegetables grown by small-scale farmers are better for you and the planet.
If you suspect you may be sensitive to vegetables, go on the carnivore diet for 2-4 weeks, then slowly incorporate veggies back into your diet. That way you can gauge where the problem lies.