Are Nightshades Good for You?

Nightshades are a family of plants many of which are staples in human diets around the world. The Nightshade family include among others potatoes, tomatoes, Eggplant and Peppers. Despite the prevalence of these food crops in the human diet in many parts of the world, nightshades are often the subject of food controversy. On one side of the argument, they are touted for their tremendous health benefits, while the other side claims nightshades promote inflammation, are high in dangerous antinutrients, and may be damaging to your gut and overall health.

What’s the truth about nightshades? Are they good for you and is there any reason they  should be avoided?

What Are Nightshades in Food?

Nightshades actually belong to a scientific family of plants called Solanaceae, which includes thousands of species, such as fruits, vegetables, herbs, shrubs, and weeds. Nightshades are unique in that they all grow five petal flowers and alternate leaves that grow in a staggered fashion on the stems.

Most nightshades are toxic to humans, insects, and animals on some level, such as tobacco and the belladonna plant (ominously and accurately known as deadly nightshade). One of the biggest reasons these plants are not ingested is because of compounds called tropane alkaloids. These substances can have hallucinogenic effects, damage organs, and negatively impact the functioning of the central nervous system and digestive system.

Only a handful of nightshades are actually safe for humans to eat, which may be part of the reason many people are sceptical about nightshades in the first place.

Nightshade Vegetables

It’s likely that edible nightshades are already a regular part of your diet. Some of the most popular types of nightshade vegetables include:

·         Bell peppers, hot peppers, sweet peppers

·         Spices that come from peppers, such as cayenne and paprika

·         Eggplant

·         Potatoes (excluding sweet potatoes)

·         Tomatoes

·         Tomatillos

Like all whole plant foods, vegetables that also happen to be nightshades are still great sources of nutrients such as vitamins, minerals, and fibre. And eating more fruits and vegetables is associated with a reduced risk of chronic disease and mortality.

Let’s examine what we know about nightshade foods and their benefits.

Peppers

As you no doubt are aware peppers present in three colours, green, red and yellow. Research shows the different colours of fruits and vegetables are linked to specific phytonutrients, each with its own health-promoting superpowers.

Nutritionally, peppers are also a great source of vitamins A, C, E, K, and B6, along with potassium and folic acid. And they’re high in antioxidants that can help prevent and perhaps even reverse a number of diseases, like heart disease and cancer.

One of the most beneficial compounds found in hot peppers, specifically, is capsaicin. Although we know it as the spiciness factor in peppers, capsaicin also has applications that range from pain relief to improving cardiovascular health.

Eggplants

Eggplants are rich in fibre, potassium, and vitamins B1, B6, and K. Although eggplants come in a variety of colours, the most common is purple. Eggplants’ purple colour comes from their anthocyanin content, an antioxidant and phytochemical that may protect against inflammation, cancer, heart disease, and type 2 diabetes. In fact, eggplant consumption may be a valuable tool in treating metabolic syndrome, a condition involving type 2 diabetes, obesity, high cholesterol, and high blood pressure.

Tomatoes

Tomatoes are an excellent source of vitamin C and potassium, along with the powerful eye-health-promoting antioxidants lutein and zeaxanthin. They’re also one of the best sources of lycopene, an antioxidant that reduces inflammation as well as conditions related to oxidative stress.

To enhance your absorption of lycopene from tomatoes, cook them and eat them with fat. Traditional cultures seem to have known this intuitively — classic Italian dishes pair olives with stewed tomatoes, and Mexican cuisine combines avocados and various tomato-based sauces and spreads.

A 2016 meta-analysis found that tomatoes may be protective against cancer, especially that of the prostate. This likely has something to do with their lycopene content, which has been shown to slow the progression of cancer cells. Tomatoes also appear to benefit heart health by lowering both your LDL cholesterol and blood pressure, among other cardioprotective effects.

Potatoes

Different colours of potatoes offer different health benefits, but they’re typically all good sources of fibre, potassium, vitamin C, and vitamin B6. Potatoes are an abundant source of resistant starch, which is good for digestion and may even play a role in reducing the risk of colon cancer. Their peels are also rich in nutrients important for bone health, like iron, phosphorus, calcium, magnesium, and zinc. Red and purple potatoes are a source of antioxidants, especially carotenoids, which have been widely researched for their protective effects against chronic diseases and inflammation. Purple and blue potatoes have been shown to reduce oxidative damage and inflammation.

Why Do People Think Nightshades Are Bad?

Nightshades’ bad reputation likely stems from the infamy of one plant, in particular: deadly nightshade or Atropa belladonna. Its botanical name comes from Atropos, one of the three fates in Greek mythology who is in charge of ending a life, and belladonna, which means “beautiful woman” in Italian. As its name suggests, it’s a beautiful but deadly plant that’s toxic when ingested. Nevertheless, that didn’t stop people from using it for both good and nefarious reasons.

Some of its more nefarious uses were to induce hallucinations in ancient Grecian cults. It was also the poison of choice in ancient Rome, and many people speculate that the sleeping draught Juliet takes in William Shakespeare’s Romeo & Juliet was derived from deadly nightshade.

But Atropa belladonna also had cosmetic and medicinal purposes as well. During the Renaissance period in Europe, women allegedly used it to dilate their pupils, making their eyes appear larger and more doll-like. Atropine sulfate eye drops (originally derived from the deadly nightshade plant) are still used by eye doctors to dilate pupils before an eye exam. And atropine is commonly used to treat bradycardia (slow heart rate) as well as organophosphate poisoning (a pesticide and nerve agent that can affect the heart, excretory glands, and muscles).

The New Myth of Nightshade Foods Being Bad for You

Nowadays, there’s a new spokesperson for the “all nightshades are dangerous” perspective: Dr. Stephen Gundry, the physician behind the “Gundry Way” eating plan and The Plant Paradox book. A quick Google search will unveil the many claims he has emphasised about nightshades causing inflammation and generally being unhealthy and disastrous to your body, especially your digestive system.

According to Dr. Gundry, there are two main reasons to avoid nightshades: lectins and alkaloids. You may have heard of these being referred to as “antinutrients,” meaning that they may compete with nutrient absorption in the body.

Lectins are proteins found most densely in nightshade peels and edible seeds like cereal grains and legumes. Gundry claims that lectins are toxic and inflammatory and that they are resistant to your digestive enzymes, making them impossible to properly break down in the body. If you eat a lot of lectins, he says, you will experience major discomfort. Therefore, he advocates for a lectin-free diet.

Alkaloids include plant compounds such as solanine, nicotine, and capsaicin. Gundry claims that some people may not be able to digest these properly, either, and that they may cause vomiting, diarrhoea, and abdominal pain.

Dr. Gundry also notes that some people have nightshade sensitivity and may not realise it due to its similarity to other conditions. For instance, he says nightshade sensitivity may present itself as diarrhoea, heartburn and acid reflux, nausea, irritable bowel, joint pain, and swelling.

So What’s the Truth About the Compounds in Nightshades?

This all brings us to the most important question: What does the research actually say about the compounds found in nightshade vegetables? Are lectins and alkaloids truly dangerous to your health? Should we all be avoiding tomatoes and potatoes from here on out? Let’s see what the research tells us.

Lectins

Lectins are proteins present in many plants and concentrated in beans, whole grains, and certain fruits and vegetables. Excessive amounts of certain kinds of lectins can, indeed, be problematic. For example, one of the lectins found in kidney beans, phytohaemagglutinin, can make people sick if it’s consumed raw.

I don’t know anyone who’s actually in the habit of eating raw kidney beans. But some people don’t cook them properly, and this can allow a small amount of dangerous lectins to remain. For all legumes, it’s best to cook them well (in a pressure cooker if you have one) until they are fork-tender. (Lectins aren’t a concern with canned beans because all canned beans are thoroughly pressure cooked.)

Some research indicates that ingesting large amounts of raw lectins can cause harm. However, soaking, processing, and cooking lectins breaks them down and minimizes any risk.

Alkaloids

Alkaloids are, in fact, toxins that can be dangerous to humans and animals when eaten in very large doses. In vegetables, the primary toxic alkaloid is solanine, which is found in high levels in certain foliage. Some fruits also contain trace amounts of solanine.

How much solanine would you have to eat for it to be risky? For the average adult, potentially life-threatening, toxic intakes would be around 400 mg. But since nightshade vegetables typically contain from 2–13 mg of solanine each, you would have to eat over 35 raw eggplants to pose any risk to your well-being. 

As to Gundry’s claims that alkaloids cause joint pain, arthritis, and gastrointestinal effects, there are no scientific studies to back up these claims, nor does the Arthritis Foundation agree.

That’s not to say that some nightshades can’t have excessive alkaloid content. Have you ever seen a potato that looks slightly green? This can happen due to light exposure and may show up in certain areas of the potato or in patches that you can typically see on the skin. Potatoes that have turned green for this reason should be avoided, as they contain high levels of the glycoalkaloids chaconine and solanine, which can be dangerous for humans to eat. The concentration of solanine in green or blighted potatoes has been shown to increase sevenfold. Studies have found that doses of glycoalkaloids as low as 1–5 mg per kilogram of human body weight can be acutely toxic. But unless you eat green potatoes, this is unlikely to be a concern.

Who (if Anyone) Should Avoid Nightshades?

Nightshade vegetables aren’t bad for you and do offer many health benefits for most people, however, as with many foods there are some people who may want to steer clear of them.

For instance, if you have a food allergy or sensitivity to specific nightshade foods, you’ll want to limit or avoid these in your diet. It is possible to have an acute allergic reaction to a nightshade like tomato or eggplant, so if that’s you, then, by all means, exclude nightshades from your diet.

There are also anecdotal reports claiming that when people eliminate nightshades from their diet, they stop experiencing painful inflammatory symptoms. People with inflammatory bowel diseases like Crohn’s disease or ulcerative colitis may find that they do better when they avoid nightshades. Some of these conditions can cause intestinal permeability. And a number of test-tube and animal studies suggest that excessive intake of the alkaloids in potatoes, fiber in tomatoes, and capsaicin in peppers can negatively impact intestinal permeability.

Although primarily anecdotal, some people with autoimmune diseases report feeling fewer symptoms when they eliminate nightshades from their diet. Whether it’s from the placebo effect or not, paying attention to how particular foods make you feel is always a wise approach.

Information and statements made in this article are for education purposes only and are not intended to replace the advice of your doctor. Whole Life Wellness does not dispense medical advice or diagnose illness. The views and nutritional advice expressed by Whole Life Wellness are not intended to be a substitute for conventional medical service. If you have a medical condition or health concern, see your physician.