Yes, you can eat wild weeds for a healthy lifestyle, but C A R E F U L L Y! Most weeds have at least minimal medicinal qualities, but do not expect major effects on your health unless you eat the poisonous ones. “Foraging The Weeds For Wild, Healthy Greens” was broadcast on NPR’s Morning Edition for 18 April 2011, but is a great Introduction for a discussion on medicinal herbs. Shouldn’t we avoid collecting herbs near polluted roads and highways? Most of the herbs we would collect for food also have medicinal qualities.
Updated 15 Oct 2011
NPR reporter Nancy Shute interviewed Sam Thayer, writer of food guides to edible plants who took the reporter on a foraging trip for edible plants growing near the downtown office of NPR in Washington, D.C. Some examples of edible plants he found include chickweed, prickly lettuce, mallow, dandelion, shepherd’s purse, sow thistle, and Siberian elm seeds. Nancy Shute also talked with John Kallas (Edible Wild Plants) about nutrition of wild plants. He attributed the great health of Greeks on the island of Crete to the large amounts of greens they ate (Mediterranean diet). An example of the foods he prepares with wild greens is on the web page for this report, Frittata With Wild Garlic Mustard. He also warns us to eat only plants that we have fully identified, since wild carrot looks a lot like poison hemlock.
Comments on Comments
In this report, there are comments by several people at the bottom of the page. The post by Eastern Branch is correct to warn against picking plants in toxic areas of the city. I cannot imagine picking greens from an abandoned lot in the city of DC (and most homes are built on what once was the dumping ground of the city when it was smaller). These lots are notorious for becoming garbage dumps. Even if it is not covered with rotting garbage, they will clearly have “drier” throw aways, like bottles, old rusty cars, lawnmowers, etc. Furthermore, something about these places attracts people who pour out chemicals (or dump the containers of these chemicals) there that are too dangerous to pour down their own drains (as if it is less dangerous on these dumping areas?), things like old transmission fluid, oil, cleaning fluids, turpentine, solvents, bug repellents, insecticides, fungicides, pesticides, asphalt/concrete/roof cleaning fluids, etc. Even if you can’t smell it, it is still dangerous to breathe.
Also don’t eat or give to your pets foods you’ve picked from areas next to a road, either, because they will most likely have a lot of vehicle exhaust on them. The pollution on most of these edible weeds is nearly impossible to remove completely. Most neighborhood greens also have a lot of pesticide, herbicide and fungicide on or inside them. Not a good choice for harvesting. It is difficult to find wild greens that are not so polluted in a city. You have to be willing to hike a distance from where you park your car. Or just collect the seeds in the Fall or late summer and grow your own. You can’t if you live in those areas with the ground too hard to dig. Contractors who cannot dig to bedrock (like in the southern half of the US) usually stabilize the ground with an injected chemical that is dangerous, before putting up a building.
Joy Jacques stated that her blood pressure dropped suddenly when she ate a lot of the nettles she collected. She suggested to listeners to eat only a few bites at first to test the food. I suggest that people who want to forage for wild greens should identify all foods with herbal medicine books. Most species of nettles are very benign, but there are several that are not. The common nettle found in the Northwest is benign, given the name of “bedstraw” by the pioneers for its other uses.
[I was mistaken when I said this in the NPR comments. Bedstraw (Galium aparine) is a different plant entirely, with similar properties. However, it is far milder and safer to use as a diuretic than nettles and very safe as a salad green. The photo here is deceiving. It is more "stemmy" than "leafy". It was collected to use in homemade mattresses by the pioneers, thus its name.]
Probably 80% of all spices have medicinal qualities. About 30% of all weeds have medicinal effects, from rather mild (as in the shepherd’s purse, Capsella bursa-pastons, mentioned in this report–relieves inflammation in non-serious bladder infections–see Moore 1989) to rather potent (as in particular species of nettles, sage, astragalus, bloodroot, etc.). About 60% are very slightly diuretic. Just because the books may say that, for instance, shepherd’s purse stops diarrhea, you cannot assume that it does this by causing an opposite response, constipation, if you don’t have diarrhea.
Even nettles (Urtica spp, mentioned in the report) is a “widely used diuretic” (Moore, 1979), to ease water retention. It is high in phosphates, so can render urine more acidic. Moore mentions that nettles are commonly used as a “Spring tonic”, but only where there is a strong difference in weather between winter and spring, reflecting changes in diet. He cautions using/eating a lot of it, too often, or in too strong a tea because it can irritate the kidneys.
Stinging nettles (Urtica dioica) can have acid in the barbs which can cause harm, so Moore (1979) suggests collecting them with gloves. The acid is lost upon drying or cooking of the herb, so even stinging nettles is a safe “Spring tonic” or salad green.
Most of these herbal medicines do not act in a dose-dependent way that we are used to experiencing with pharmaceuticals. Sometimes their medicinal properties are the same whether you eat 1/2 tsp or a whole plate. Some of these herbs will cause different physiological responses by different people. However, the same is true of agriculturally grown foods and of pharmaceuticals. I strongly suspect that these differences depend upon your own internal chemistry. People who have either or both a lot of toxic chemicals inside and/or damage from them will most certainly respond differently to foods high in phosphate, sulfur, calcium, boron, and bromine, gluten, and certain plant proteins (e.g. chiles, ginger, onions, garlic, leeks, tomatoes, corn, asparagus, fiddle fern, wheat).
Often herbal medicines act on the body in a way similar to how the normal inflammatory response works–homeopathically*. For instance, the homeopathic treatment for poison ivy is poison ivy (Rhus toxicodendron or Toxicodendron radicans). You take a few drops of tincture or a few very tiny pills of the stuff internally. The dosage is determined by diluting the substance to a level that the body can tolerate without having any deleterious response. A little taken into the body by mouth or rubbed on the skin alerts the nervous system that the problem is now found in many other places, triggering it to send in the heavy artillery (as in the inflammatory response of neutrophil signalling basophils).
There is a principle that can be applied to those medicinal herbs that do not act in a dose-dependent way–“use it or lose it” (see my blog post “Medicinal Herbs”). If it is not needed by the body for medicinal purposes, it gets metabolized and lost from the body without any ill effects. If it is needed, then it gets metabolized and sent to that tissue. The tissue needing it is already sending signals to the nervous system and to local blood capillaries so that certain ions or proteins cross those capillary boundaries preferentially in those areas. The “use it or lose it” principle cannot be applied to pharmaceuticals, which have not co-evolved with human physiology for millions of years as medicinal herbs have.
Other examples for the “use it or lose it” principle can be found with common agriculturally grown food, e.g. cranberry. We know that its diuretic properties will be felt regardless of whether you need it or not, but it also is known to kill urinary tract infections. If you do not have one there, it doesn’t kill anything. Eating prunes will not cause diarrhea if you do not have constipation, but will soften the stool if you did need it. Apples help to soften the stool if needed and help get rid of diarrhea if needed, and does neither if you don’t.
Certain herbs need to be addressed differently. Ephedra (Mormon Tea, ma huang) is an herb prescribed by Chinese Medical Doctors (practicing TCM, Traditional Chinese Medicine, see refs below) for specific conditions that involve blockage of the lung meridians, causing pulmonary edema and congestion. The symptoms are actually more than what I have stated, since Chinese Medicine is much more of an observational practice than what an M.D. does. TCM requires observations on the stool, urine, eyes, skin, 6 different pulses, body position, voice quality, etc. Ephedra is very helpful in relieving these symptoms. However, some athletes were also taking it for its epinephrine-like qualities (increasing alertness, rapid reflexes, etc.) which are not considered acceptable uses for this herb in the Chinese Medical tradition, since they generally do not accompany the other symptoms mentioned above. There are better ways to increase alertness and rapid reflexes.
You cannot assume that Ephedra‘s epinephrine-like qualities belong in the “use it or lose it” principle because they persist for long after the primary symptoms, for which the herb is acceptable, are gone. Thus there is an acceptable dosage for Ephedra, which is ignored by the formulas concocted in the nutritional supplements made for athletes. More is not always better, and in this case, is much worse. With Ephedra, it is better to go the homeopathic route, where you take the absolute minimum needed to relieve the symptoms, with doses separated by several hours. Furthermore, there is no such thing as a safe dose for children. See my blog post “Medicinal Herbs” for more discussion about Ephedra.
Moore, Michael. 1979. Medicinal Plants of the Mountain West. Santa Fe: Museum of New Mexico Press.
Moore, Michael. 1989. Medicinal Plants of the Desert and Canyon West. Santa Fe: Museum of New Mexico Press.
Moore, Michael. 1993. Medicinal Plants of the Pacific West. Santa Fe: Red Crane Books.
“Traditional Chinese Medicine: An Introduction“. National Institutes of Health, National Center for Complementary and Alternative Medicine.
*There is no doubt that many homeopathic medicines are diluted to the point that some pills/drops of tincture will have no substance from the plant in them at all. Rarely are homeopathic medicines taken as one pill/drop in a dose, however, and at some point in the medication taken a person will take in a very tiny bit of the medicine. However, there is also a high likelihood for some homeopathic medicines, that the patient will get no medicine at all, ever. In these cases, homeopathic medicines treat as placebo. Placebo treats? Yes, in a later post I will present the scientific evidence that shows that even some pharmaceuticals have been shown to treat only as a placebo, that placebos affect the satiety center in the neocortex (septal nucleus) that can trigger a response by the patient that could show that a “cure” has been effected by the brain, shown by a remission or complete loss of the symptoms being treated, thus rendering much of scientific testing of drugs with placebos questionable, since the researchers did not take into account the all centers of the brain involved in treatment.
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