Some tid-bits (more in the link above).
Copper-Zinc Imbalance: Unrecognized Consequence of Plant-Based Diets and a Contributor to Chronic Fatigue
A commonly reported consequence of vegetarian or vegan diets, or even diets that rely too heavily on plant foods, is chronic fatigue. Many sufferers subsequently embrace the principles enumerated by Weston Price, adopting a diet containing more nutrient-dense animal foods and fat; however, the fatigue often persists, even after considerable time on the new diet.
The fact is that the micronutrient copper is widely available in unrefined foods, but the mineral zinc, needed in larger amounts to balance copper, can only reliably be obtained in optimum amounts from land-based animal foods, in particular eggs and red meats.
In lighter diets generally, and in heavily plant-based diets in particular, zinc is sharply reduced relative to copper, protein is curtailed, and fat is provided scantily at best. The excess copper that builds up in tissues is in unbound, inorganic form, highly immobile and creates a low-level toxicity that interferes with many body systems. Particularly affected are the liver and digestion, which are already hampered by increasing deficiency of zinc. As bile function and digestive vigor decline, difficulty with meat and fat develops. Legions of light-diet and vegetarian adherents feel justified in their choices because heavier food becomes unpalatable to them.
Even in 1975, Pfeiffer considered zinc status in most Americans to be borderline at best. After twenty-five years of vegetarianism and plant-based diets, it is doubtful our status today is even that optimistic. Too many other factors also work to increase copper and work against zinc. Zinc galvanized pipes have been replaced by copper pipes in many areas, which can be etched by slightly acidic water supplies. Birth control pills and other medications increase the retention of copper. Blanching of vegetables before commercial freezing removes zinc and many trace minerals, while copper is added to many multivitamins.
There are numerous other factors contributing to this imbalance, but most devastatingly zinc is lost from our bodies every day when we are under stress. The more stress, the higher the losses, and yet zinc is needed in large amounts by our stress-resisting adrenal glands. When we are zinc-deficient our innate coping resources can start to unravel, and the grind of everyday stress can seem overwhelming.