How Humans Benefit From Stressed Plants

Appropriating Plant Defenses

Plants live the ultimate sedentary lifestyle—most of us usually think of plants more as objects than as organisms. Because plants can’t move, they’ve had to evolve a whole other way to escape threats to their well-being. Plants can “sense and respond dynamically to all sorts of stimuli: chemical concentrations in the air and soil, water, touch, motion, vibration, pathogens, predators, and, of course, light.” How do they respond? Biochemically. They manufacture, from scratch, a dizzying array of compounds to deal with specific threats.

If we get too hot, we can move into the shade. If plants get too hot, they’re stuck—they are the shade! As a result, “the complexity of the plant stress response humbles that of animals. Plants and their stress response have been evolving for almost a billion years.” And in that time they’ve created a whole chemistry lab of protective substances, some of which can induce similarly protective responses in those of us who eat them.

The “best grapes in terms of health benefit often grow in relatively dry, sun-exposed, infertile soil. Similarly, drought-stressed strawberries have more antioxidants and phytonutrients. Indeed, commonly consumed foods like lettuce and fruits can be nutritionally enhanced by cold stress, light stress, water deficit, or nutrient deficit stress.” Why are stressed plants often the healthiest?

Studies (such as those highlighted in my video, Appropriating Plant Defenses) suggest that plants and animals largely share the same molecular pathways in order to respond to stress, so it’s conceivable that a molecule produced in plants can also be effective in people. Plants have DNA; humans have DNA. The UV rays in sunlight can damage the DNA in plants in the same way it can damage our DNA (by creating free radicals). Plants figured out how to cook up all these complex antioxidants, and instead of reinventing the wheel, animals can just expropriate those antioxidants from plants and commandeer them for the same purpose.

We get attacked by bacteria; plants and fungi get attacked by bacteria. When a particular fungus is getting muscled in on by bacteria, it creates a molecule called penicillin–provided free for us.

When plants get infected, they produce aspirin (See Aspirin Levels in Plant Foods), which can come in handy when we get infected. Plants heal wounds; we heal wounds, using similar fatty-acid signaling systems. It is “increasingly evident that plants and animals differ less than we thought in how we respond to stimuli, sharing elements of fatty acid, protein, steroidal, neurotransmitter, free radical, nitric oxide, and even plant growth hormone signaling systems.” So in a sense, we’re just opening up nature’s drug store when we pull out the crisper in our fridge.

This whole co-evolution concept reminds me of Human Neurotransmitters In Plants and The Broccoli Receptor: Our First Line of Defense.

More on the power of plants in Power Plants.

Some of the wilder things that Phytochemicals: The Nutrition Facts Missing from the Label can do are explored in:

We evolved eating a lot of plants: Paleolithic Lessons.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Hernan Pinera / Flickr




    Be aware that also there can be high levels of heavy metals in some chocolates. Cadmium and lead are found in many types of chocolate due to either the contaminants in the soil or due to the equipment which is used to process the chocolate. The heavy metals accumulate in the body and can create a health crisis, often unrecognized. Chocolate often exceeds the safe limits for lead and/or cadmium.)…/warning-sounded-heavy…/ and

    • Joseph Gonzales R.D.

      Thanks “Chocolate Safe” :-) Consumer lab did extensive cocoa testing and indeed found problems with cadmium, lead or both. They continue to test brands. As soon as they come up with one that’s clean we’ll let everyone know…

      • Leonid Kalichkin

        Sunflower seeds are high in cadmium too, but it doesn’t get absorbed by body. Any studies on absorption of cadmium and lead from cocoa powder?

        • guest

          how do you know the cadmium doesn’t get absorbed?

          And, sunflower seeds are known to have a strong ability
          to suck LEAD out the soil.

          • Leonid Kalichkin

            Because studies I have seen show that you excrete the same amount you consumed. If you have something on the contrary, I’d appreciate it.

        • Joseph Gonzales R.D.

          Yes a few exist. Another user posted some here and 13 studies more to browse thru here.
          Dr. Greger talks about what we absorb in this video on cadmium and cancer.

      • largelytrue

        Cadmium is also apparently a concern with stoneware and glass, too. Like many metals in ceramics, it is used for coloring. Cadmium is often incorporated into glazes ranging from red to yellow. When stoneware is improperly fired, the cadmium can leach out in appreciable quantities, particularly with the help of an acidic food. The US, like many postindustrial nations, has introduced a degree of surveillance to help address this issue.

  • Darnell

    Just shows that ethically, vegans are on the same level as meat eaters..,

    • largelytrue

      Yeah, and that cannibals are on the same level as plant eaters. And owning a petunia is on the same level as owning a human being. Nothing in the article discussed the ethics of food at all; you are the one who is importing some sort of ethical standard into the discussion, though you haven’t been explicit about what that standard is.

      • Darnell

        Your right. I apologize…


    • John

      I eat almost all plants and a little meat, and I can’t understand what you mean by that , Darnell. John

  • Plantstrongdoc M.D.

    That’s why I yell at my broccoli and kale before I eat them !! :-)

  • LG King

    WOW…I like the ‘new look’ of Dr. Michael Greger…!

  • Matthew Smith

    Matcha tea leaves are covered progressively to screen out the light putting the plant under stress, perhaps in order to culture higher levels of antioxidants.

  • Rodrigo Cardoso

    Very interesting this wider view on how we co-evolved with plants. Shared in Portuguese:

  • vegank

    Does it make a difference (the Aluminium) if it is Organic Tea?

  • Megan Denman

    I’ve been reading about rhodiola supplement for stress reduction and general well-being, but can’t find anything about it here. I’m curious what the facts – checkers can find.