The highest diet rich sources of copper include organ meats, shellfish, nuts and seeds like sesame seeds, cashew, sunflower seeds, walnuts, pumpkin seeds, peanuts, almonds, flax seeds, chocolate soy beans, shiitake mushroom, crimini mushroom, spinach, kale, summer squash, tempeh, tofu, kidney beans, sweet potatoes, grapes, pineapple, tomatoes and egg plant.

Despite the lack of consensus concerning supplementation dosing, routine copper supplementation is recommended. At least 2 mg of copper per day is advised in the form of copper gluconate or sulfate as part of a vitamin and mineral supplement for BPD-DS and RYGB patients. Patients being treated for zinc deficiency or using supplemental zinc for hair loss should receive 1 mg of copper for each 8–15 mg of zinc as zinc replacement can cause copper deficiency. Copper levels are not routinely monitored but need to be evaluated in patients with neuropathy and normal vitamin B12 levels [16, 17]. The literature reports the use of oral copper gluconate in mild to moderate deficiency and IV copper infusion in severe deficiency [18–22]. For mild to moderate deficiency, the recommended oral administration is of 3–8 mg/d of copper gluconate until copper indices return to normal. Severe deficiency should be treated with 2–4 mg/d IV copper for 6 days or until neurological symptoms resolve and serum levels return to normal. Continuous monitoring of copper status is necessary every 3 months after deficiency is treated [23].

Plant foods are the major sources of selenium and it varies tremendously according to its concentrations in soil which varies regionally. Animals that eat grains or plants that were grown in selenium rich soil have higher levels of selenium in their muscle and is widely distributed in all tissues. Selenium is present in foods like brazil nuts, walnuts, almonds, peanuts, cashew nuts, pistachios, pine nuts, hazelnuts, sunflower seeds, grains (wheat germ, barley, brown rice, oats), fresh water and salt water fish (tuna, halibut, sardines, flounder, salmon), shellfish (oysters, mussels, shrimp, clams, scallops), meat (beef, lamb, pork, liver), poultry (chicken, turkey), eggs andmushroom (button, crimini, shiitake) [45].

A prospective pilot study (n = 39) showed that RYGB and laparoscopic adjustable gastric banding (LAGB) procedures increase the risk for disturbances of selenium and GTP homeostasis and suggested that consideration of selenium supplementation at higher levels of current RDA (i.e. 55 mcg) during the first 3 months and perhaps longer may be needed [26].

However, there is insufficient evidence for routine selenium screening or supplementation but patients with malabsorptive bariatric surgeries who have unexplained anemia or fatigue, persistent diarrhea, cardiomyopathy or bone metabolic diseases, selenium levels should be checked.

Zinc deficiency is common after bariatric surgery as the main absorption sites such as duodenum and proximal jejunum are being bypassed and also the deficiency rates may vary depending on the type of surgery. After surgery, reduced stomach acid which is essential for zinc bioavailability, reduced protein intake, food intolerance and impaired zinc absorption may worsen the situation and may lead to zinc deficiency [30, 31]. In addition, regular iron and calcium supplementation can also contribute to insufficient zinc absorption [32, 33]. Zinc deficiency can also be associated with pregnancy and can lead to reduced birth weight, preterm delivery and congenital abnormalities and can induce hypertension in the mother [34–36].

A recent retrospective study showed that patients (n = 272) who underwent RYGB, LSG and BPD-DS, 99 % had zinc deficiency preoperatively [31]. Studies at 2 years follow up after RYGB reported 20–35 % and Sleeve with 18–34 % and higher deficiency rates were found with BPD (74–91 %) with serum or plasma zinc levels [15, 37, 38]. It was found that, zinc deficiency persisted in patients even after 5 years follow up with 12.5 % after sleeve, 21–33 % after RYGB and 45 % after BPD. Rojas et al. stated that at 6 months, post bariatric surgery patients have an increased hair loss with lower intakes of zinc and iron requiring monitoring and supplementation [39].

Liver (beef, chicken, lamb, pork), red meat (beef, lamb, pork), sea foods like crab, lobsters, oysters and scallops, wheat germ, spinach, pumpkin, sesame and squash seeds, cashew nuts, mushrooms, chick peas, lentils, black beans, tofu, and whole grains are good dietary sources of zinc.

Copper and zinc compete for the same transport mechanism, so the excess of one might determine the deficiency of the other. Hence post bariatric patients should be advised oral zinc gluconate or acetate to provide 8–15 mg of zinc and 1 mg of copper for each 8–15 mg of zinc given.