Calcium and trace elements Calcium carbonate is present in a range of foods, primarily dairy products, fish (salmon, sardines, shrimp), nuts (Brazil nuts, almonds), soybean, molasses, and chicory. Concomitant ingestion of certain foods, such as spinach, rhubarb, bran, wholegrain cereals, fruit, and fresh vegetables, may lower calcium absorption.
Hypomagnesemia may occur with diuretics. It is reported in up to 30% of heart failure patients, in whom it is associated with muscle weakness and fatigue. It increases ventricular arrhythmia, precipitates digoxin toxicity, and is associated with a poor prognosis. Magnesium is present in fish (herring, cod, mackerel, swordfish, sea-bass, shrimp, carp), nuts, green leaf vegetables, wheat germ, sunflower seeds, and soybean.
Zinc deficiency is common in the elderly, in particular in those on diuretic therapy. High zinc levels are found in urine. Deficiency aggravates oxidative stress, indicating that zinc acts as an antioxidant. Sources include meat (lamb, pork, turkey, lean beef, chicken), fish and shellfish (notably oysters), wheat germ, sunflower seeds, bran, sesame seeds, wholegrain cereals, soybean, yeast, milk, and egg yolk.
Manganese occurs at high levels in heart failure. Sources include cereals (bulgur, oats, bran, barley), pulses (peas, dry beans), nuts, avocado, coffee, and spinach.
Copper deficiency may contribute to cardiomyopathy, probably on a genetic basis. In mice, a low copper diet causes myofibrillary disarray, mitochondrial fragmentation, and ventricular dysfunction. Sources include honey, nuts, grains (oats, barley, wheat germ), lentils, salmon, shellfish, and brown sugar.
Selenium deficiency has caused cardiomyopathy in patients on long-term parenteral therapy. Selenium protects tissues from oxidative damage and enables cells to produce ubiquinone (coenzyme Q10). Selenium deficiency increases oxidative stress. Sources include vegetables (garlic, onion, mushrooms, celery, broccoli, cabbage, cucumber), wheat germ, milk, meat (chicken, liver, kidney),egg yolk, and seafood (tuna).