This page discusses the effects of copper toxicity on the gut and digestion, as well as how a plant based diet contributes to copper toxicity. This discussion should not be taken in any way to knock the virtues of veganism / vegetarianism, as copper's affect on gut health affects everyone, regardless of dietary preference. The information here is presented with evidence from a nutritional / mineral perspective, further backed up by HTMA data, to inform, educate, and serve. Remember that, even diet aside, excess copper can build up for everyone from drinking water through copper piping (discussed at the bottom of this page), as well as from glyphosate sprayed on crops (which tends to chelate zinc), fungicides such as copper sulphates also used on crops (as also discussed further below, and which contain oxidized copper that cannot be used by the mitochondria and is toxic to the body), congenitally, birth control methods, and a number of other sources. Diet, however, is a key contributor that needs to be acknowledged as part of a complete discussion. For the vegan reader, this section is not to dissuade from the plant based diet, but rather is offered as a source of further empowerment for the individual by providing a greater understanding of the biochemical effects of minerals, while encouraging proactive action through proper testing and added supplementation.
The vegetarian diet, and even more so the vegan diet, puts one at significantly higher risk of having elevated levels of copper. How 'toxic' the copper accumulation becomes on your body depends on how long you've been following a plant based diet, the strength of your detox pathways, stressors in your life, and if other sources of copper (such as the birth control pill or IUD) are also contributing. Everyone reacts differently, and elevated copper levels do not necessarily translate into symptoms, initially. However, almost across the board, through HTMA data looking at the tissue level of copper, we see the copper toxic pattern as typical in the long-term vegan/vegetarian person.
"We have observed through TMA studies that vegetarians appear to have a greater tendency to retain copper than non-vegetarians." 
~Trace Elements Inc
"Once digestive vigor has been reduced and copper buildup has affected liver function, foods high in copper, or those that interfere with zinc, can be troublesome. Gittleman states that vegans, who often combine plant protein sources to increase protein intake, can be especially susceptible to copper toxicity."
Zinc is required to keep copper in check; without enough zinc copper will accumulate. The best zinc sources in terms of absorption are found in meats. Without this zinc, excess copper builds up in tissues which then interferes particularly with the liver and digestion, among other systems as well. A vicious cycle is then created, because as liver / bile function and digestive processes decline, meat protein becomes less tolerable, solidifying the belief that one feels better eating plant foods.
Zinc is also very important for metallothionein (MT) synthesis. One of MTs vital roles is to bind to copper for enhancement of utilization or for removal and excretion. Without adequately absorbed dietary zinc, MT synthesis is impaired, further allowing copper (along with other toxins and metals) to build up. 
Phytates, common in plant foods, further compound the problem by interfering with zinc absorption. The copper zinc ratio in plant foods is already high to begin with, and the phytates (and oxalates) just make it worse. Without adequate 'high-absorption' zinc, the individual lacks the ability to retain potassium. Adequate potassium is necessary for hydrochloric acid secretion in the stomach - a deficiency of which can then lead to developing a distaste for animal protein (not to mention the inherent slowing of metabolism which further makes higher fat foods (ie: meat) more difficult to digest. No matter how much potassium the individual eats through vegetables and fruit, it is not being retained. This lack of available potassium is a common cause behind many vegetarian complaints including apathy, underweight, digestive issues, and depression. The answer is not to simply eat more potassium, but rather help the body make it usable by strengthening the adrenals and metabolism. Otherwise, the vegetarian will continue to crave stimulants such as chocolate (high in sugar, copper, and oxalic acid) or running/jogging which temporarily whips up the adrenal glands making the person feel temporarily 'more alive'...all the while depleting their energy reserves further and allowing copper to rise. These are just some of the dangers of veganism (and to a slightly lesser extent vegetarianism) that are often over-looked but should at least be understood.
Two additional problems the vegan/vegetarian faces is potential sulfur deficiency and taurine deficiency, both of which then make proper detoxing even more difficult. Sulfur is found in certain vegetables (i.e.: garlic, onions, beans) as well as in meats. It is most abundant however and in a more usable form in meat. This creates a serious problem for many vegetarians and vegans as sulfur is essential for liver detoxification and removing heavy metals. Without enough meat-based sulfur sources in the diet, vegetarians will be even more prone to the build-up of heavy metals (and copper), as well as experience a much harder time chelating those metals. The case with Taurine is similar, especially as Taurine is also sulfur-containing. Taurine is a meat-sourced amino acid not found in plant foods which is critical for the production of bile. Bile is the primary means through which the body eliminates excess copper. Taurine (and sulfur) deficiency means bile production is impaired, hindering the natural detox process and further allowing copper (and other toxins) to build up.
"Disruption of the copper-zinc ratio is an overlooked contributor to intractable fatigue that follows excessive reliance on a plant-based diet. The result is toxic accumulation of copper in tissues and critical depletion of zinc through excretion. This condition usually goes unrecognized because copper levels in the blood can remain normal. Also, most doctors are unprepared to meet with extreme zinc deficiency and its baffling effects on many systems of the body. Hair mineral analysis, competently used, is the tool which can unravel the complexities of this growing problem. In particular, it is becoming clear that plant-based diets, and lighter diets generally, cause serious nutrient imbalances and long-term damage to digestion and cellular metabolism that are not easily corrected." 
"Ironically, animal meat is the main food high in zinc which could correct the excess copper. But a person like me, who stayed away from red meat for the past 10 years and leaned into a vegetarian diet, tends to accumulate more and more copper unbalanced by zinc. Then, to make us extra crazy, our body begins to crave high copper foods, so we eat more of them. I was inhaling avocado, nuts, beans, chocolate, sugar and tea every day. Growing just a tad more coppery, zippy and fatigued as I munched along, oblivious."
~Diane Stallings RN, Nutritionist
Of course much of this imbalance won't show up in a blood test. Unless there is a current and direct exposure to copper (such as an IUD), most vegetarians / vegans have too low a metabolic rate for the elevated copper to show up high in a blood test. At times, when metabolism is low and the body is exhausted, it won't show up in a hair test either (though other indirect indicators can be used in the HTMA to determine the copper status).
However, a quick search through online forums will turn up a large percentage of vegetarians/vegans (and ex-vegetarians/vegans) sharing stories of their battles with copper toxicity, many of them eventually realizing their health was more important than their principles, however virtuous. Many too, about 50%, drop out of the vegan diet due to declining health, though this mineral connection to the cause of their health decline is rarely made. Though veganism is thought to be healthy, unlike vegetarianism it has no historical basis and is founded on ideology, not on human physiology. Vegetarianism on the other hand does have a much longer history, and can be considered slightly more healthy. However when the underlying mineral patterns are analyzed, we quickly see that both diets are deplete in key nutrients. DHA for example, essential for good health, energy, and neurological function, is non-existent in the vegan diet. As Mara J Kahn points out in her deeply researched book 'Vegan Betrayal: Love, Lies, and Hunger in a Plants-Only World', "DHA is really a problem with vegans … In fact, two of the founders of veganism, as they became older, suffered from Parkinson’s disease. They had their DHA tested and it was zero." B12 deficiency is a huge problem among vegans, as is the lack of retinol. Animal source retinol is essential for the liver and the production of ceruloplasmin which is the key protein that binds to copper to make it bioavailable. Many vegetarians and vegans who have been diagnosed as copper toxic have returned to a meat diet, as taking that step becomes almost essential in order to properly heal and re-balance minerals.
"Restoring and maintaining liver detoxification is one of the most important aspects of healing. Sulfur, mainly in the form of sulfur-containing amino acids - mainly taurine, methionine and cysteine - are absolutely needed for the detoxification pathways in the liver. We find that most vegetarians…cannot remove toxic metals as well because they are low in the sulfur-containing amino acids." ~ Dr. Lawrence Wilson
"The great majority of vegetarians suffer from long-term copper toxicity. This is true even if all tests indicate a low copper level. The vegetarian’s metabolic rate is too low to cause a proper elimination of copper. Not enough copper may be released on a regular basis to show up in a blood test or even in a hair analysis test. Of course, sometimes the copper level in the hair will be high, but it doesn’t have to be. In some of the worst cases I have seen, the copper is tightly-bound in tissue storage sites. It may take three years on a nutritional correction program before the person will even start releasing his excess copper”
~ Dr. Paul Eck
Copper toxic individuals very often will also have gut concerns, including candida and yeast, low HCl, poor nutrient absorption, gluten sensitivity, even leaky gut. One of copper's roles is that of an anti-fungal, and when in balance, helps to control fungi and yeast / candida in the gut. However, with toxic levels of copper, much of this copper is in a bio-unavailable form stored in tissues, and is not serving it's role in controlling the candida / yeast, or other parasites. This, along with the anaerobic GI environment that's created, allows candida, fungi, yeast, parasites and bacteria to flourish. Meanwhile, as mentioned above, copper toxicity (by way of lowering zinc) also reduces hydrochloric acid production. When hydrochloric acid (HCl) is low, the healthy gut flora are weakened (and zinc is lowered further - a vicious cycle). HCl helps kill off pathogens and is required for the absorption of nutrients such as calcium, iron, and various vitamins. Reduced digestive enzyme production occurs and the intestine becomes overly alkaline, giving a nice home to pathogenic bacteria. Copper toxicity leads to low HCl by way of slowing metabolism and reducing sodium and potassium levels, two minerals which are required in the production of HCl. The destruction of gut function and the collapse of one's metabolism are hallmarks of copper toxicity.
Long term copper-induced zinc deficiency will increase the permeability of the gut lining, contributing to leaky gut and food intolerances. "Research has shown that both metallothionein and zinc play powerful roles in preventing and restoring the damage in the gut barrier. Damage to the intestinal barrier can lead to serious conditions, such as leaky gut, colitis and Crohn's Disease.". We already know that copper lowers zinc, and zinc is important for metallothionein synthesis. For the vegan / vegetarian, they do require extra zinc supplementation. However, it alone may not be enough. This is because, when the body is under stress or suffering from adrenal weakness, the zinc level can drop further even when supplementing - allowing copper to accumulate further. A whole body / endocrine system approach is required to understand which supplements (and in what amounts) are optimal.
It's becoming increasingly difficult for people to get unbiased and scientifically founded facts on nutritional choices, especially when some of the most widely referenced 'nutrition facts' websites are run by vegan organizations with a clear bias toward pushing the plant-based diet. To be clear, the author here is not suggesting any one diet over another, but rather is an advocate for people having informed choice and receiving full disclosure. The goal here is to support vegans and vegetarians by providing awareness into potential pitfalls so that those pitfalls can be avoided down the road. With awareness, intelligent supplementation, and some flexibility, the risk of copper toxicity can be reduced. For those truly interested in understanding the mineral imbalances inherent in the vegan diet and the role copper has to play in the regard, click to read this article.
"It is tragic that Americans who have been inspired to adopt healthier diets have been so harmfully misled by the anti-animal foods dogma, often against their better instincts. I myself was led into this trap in the mid 1970s, and have only found my way out of it in the last few years. Although I found the Weston A. Price Foundation material when it first appeared, and benefited from many of its suggestions, I was unable to consistently expand my diet, or even tolerate any fat, until I learned to recognize and apply the lessons of the copper-zinc imbalance. In fact, this imbalance could very well have killed me. . ~Laurie Warner, MA, CNC
"There is a predisposition in this country to kinds of virtuous extremes, and I lived this life myself. I was a vegan, I was a vegetarian, I was non-fat, I was low-fat, I was anorexic, in short I thought that if animal foods would kill you and fats would kill you, the less the better and zero must be ideal. This is obviously nonsensical thinking. It's black its white. It's rigid. It's extreme. And it's not virtuous... Little by little I started to eat these foods (traditional - meat, poultry, raw milk, etc) again and in time came back to being a moderate omnivore, a conscientious carnivore, a traditional foods person, and restored my health along the way.... ... I was...gloomy and irritable, I was depressed in the winter, in short I was a sickly person with a big personality and I had no idea that my virtuous diets were making me sick until little by little I added traditional foods back." ~Nina Planck (Food Writer)
Copper sulfate is a fungicide which is used against bacterial and fungal diseases on a wide variety of fruit, vegetable, nut and field crops. (It’s also added in some pools, hot tubs, and municipal drinking water supplies to control yeast, bacterial or algae growth). Focusing here on crops, copper sulfate, though numerous studies show it is toxic to humans and the environment, is approved as a pesticide under the USDA National Organic Program . While the official pesticide information website on copper sulfate tries to paint it as being harmless (suggesting that ‘excess copper is excreted and not often stored in the body)’, this site , though somewhat dated, offers a somewhat more telling perspective . Since copper sulfate is derived from ‘natural sources’, it's allowed to be used on organic produce, even if it’s no less harmful than synthetic pesticides. In fact, the Committee on European Communities noted in their recommendations to Parliament in 1999 that copper sulfate was even more dangerous than the synthetic alternative. Some wineries in France (and other countries) have even stopped growing organic wine because of copper in the soil. Even though much of the spray is usually washed off the produce, it then ends up going into the soil, affecting the next batch of crops. “Typically, each spray with a copper-based fungicide results in an application of 1 to 4 lb. of copper per acre (raising the topsoil concentration from 0.5 to 2 ppm), and often several copper sprays are made per season. Thus, under a heavy copper spray program, toxic topsoil levels could be reached in a matter of decades.”  In other words, even those of us who try to live healthy and clean by eating organic fruits and vegetables are at risk of toxic copper accumulation from even just this one source alone, especially in places where soil levels are not properly monitored.
With no proteins to bind to in water, the drinking water flowing through copper piping in homes leaches copper off from the pipes. This copper then combines with sulfates, carbonates and phosphates to form copper sulfate, copper carbonate, or copper phosphate. This inorganic copper is at its highest level during the first run of the tap in the morning. If your home has copper piping (aged piping being the worst), it would be wise to test your water, and also to run the water for a minute before using the water for your morning drink or coffee maker. Not doing so could be exposing you to high levels of inorganic copper. The use of copper piping in homes of developed countries, along with increasing use of The Pill, both gaining mainstream and widespread use in the 1950s/1960s, are perhaps the two biggest causes of the copper epidemic that has been increasing over this past century. Just how dangerous is this increased inorganic copper? Well, in addition to everything else explained throughout this site, there is also a very strong link between the use of copper piping for drinking water and the rising prevalence of Alzheimer's disease. This connection is discussed further in the Alzheimer's section at the bottom of this page.
It's one thing to ingest copper through diet, it's another to be exposed to copper through copper sulfates and other sources. Food source copper is organic copper, bound to organic protein molecules, and not exhibiting as severe side effects as inorganic copper. This does not invalidate the above discussion of the vegan diet contributing to copper overload. Even though the copper is of a healthy organic kind, the lack of taurine and/or high quality absorbable zinc contributes to the accumulation of copper, which then eventually takes a toll on the adrenals and liver and eventually, due to lowered Cp, lowers the bioavailability of the copper. Also, due to the vegan's higher crop consumption, they are generally more prone to inorganic copper sulfate exposure as discussed above.
Inorganic copper (the kind found in drinking water, most copper-containing supplement pills, or the copper IUD) is not bound to anything. Unlike organic copper, inorganic copper largely bypasses the liver and enters the free copper pool of the blood directly. This copper is potentially toxic because it can penetrate the blood/brain barrier .