Copper: ICMR-NIN Intake, Indian Food Sources, the Zinc Interaction and Copper Vessels

Copper is a trace mineral that the body needs in milligram amounts. It sits inside a group of enzymes, among them one that helps move iron into haemoglobin. ICMR-NIN's Nutrient Requirements for Indians recommends 1.7 mg a day for adults and gives no figures by age. Ordinary Indian meals built on dal, whole grains and a few nuts reach that amount, and both deficiency and excess are uncommon outside particular medical situations. This entry in the minerals section of the handbook covers the requirement, the foods, the zinc interaction and the copper pot.

What does copper do in the body?

It makes a set of enzymes work. WHO's review of copper lists them: ceruloplasmin, superoxide dismutase, cytochrome-c oxidase, tyrosinase, monoamine oxidase and lysyl oxidase among others. Ceruloplasmin carries most of the copper in blood and also acts as a ferroxidase that takes part in making haemoglobin, which is why a shortage of copper can show up as an anaemia that does not respond to iron, the subject of the handbook entry on iron.

The body controls its copper closely. Absorption happens in the upper gut through a regulated process, and the main exit route is bile: WHO notes that less than 3 per cent of daily intake leaves in urine, and that excretion in bile may matter even more than absorption in setting the body's total. In a healthy adult the liver holds 8 to 10 per cent of the body's copper and about half sits in muscle and bone.

How much copper do you need under the Indian values?

An adult needs about 1.7 mg a day on ICMR-NIN's figure. The expert group did not work out an average requirement and an allowance for copper as it did for iron or zinc. Its short report says copper, chromium and manganese were considered separately and given suggested adequate intakes for adults, and the summary table lists copper at 1.7 mg. There is no Indian value for children, pregnancy or lactation, so the table below adds the United States and Canadian values that WHO quotes, labelled as such.

The Indian adult figure is nearly double the American one, and the short report does not set out how it was derived. WHO's review puts usual adult intake from food at 1 to 3 mg a day across countries and records about 2 mg a day in Scandinavian lacto-vegetarians and 3.5 mg in vegans, since pulses, nuts and whole grains are the richer foods.

Which Indian foods supply the most copper?

Liver from goat or sheep is the richest common food, followed by oilseeds and nuts, then pulses and whole grains. Milk, eggs, milled rice and most fruit and vegetables carry very little. The portions below are worked out from the Indian Food Composition Tables 2017, with grains and pulses weighed raw. One surprise in the Indian tables is chicken liver, which holds far less copper than goat or sheep liver.

A vegetarian plate does well here. Two chapatis, a katori of toor dal and a handful of nuts (see the cashew nut page) already add up to 1.3 mg. The site has no ranked copper table yet, so the pages for nuts and seeds and pulses and legumes are the places to compare foods one by one. Because milk is so poor in copper, a diet that leans heavily on milk and polished rice with little dal is the pattern most likely to run low.

Why do zinc tablets lower copper?

Because the two metals compete in the gut. WHO's review states that copper uptake from the intestine is open to competitive inhibition by other transition metals, particularly zinc and iron. At the amounts found in food this does not matter. It matters when zinc is taken as a tablet in large amounts for months. ICMR-NIN sets the adult zinc allowance at 17 mg for men and 13 mg for women and the tolerable upper limit at 40 mg a day, a ceiling that the zinc entry explains.

A hospital audit published in the Journal of Clinical Pathology in 2015 shows how this goes wrong in practice. Of 70 patients prescribed zinc, 62 per cent were on amounts the authors judged sufficient to cause copper deficiency, plasma copper had been measured in only two, 9 per cent developed unexplained anaemia and 7 per cent developed neurological symptoms typical of copper deficiency. The authors warn that a missed diagnosis can end in nerve damage that does not reverse.

Copper vessels and drinking water: what is known

Two things have been measured. First, a copper pot does kill bacteria. A Bengaluru laboratory study contaminated drinking water with cholera, typhoid, Shigella and diarrhoea-causing E. coli at 500 organisms per millilitre and stored it in copper pots for 16 hours at room temperature; none could be recovered afterwards. Second, the water picked up little copper: 177 parts per billion, or about 0.18 mg in a litre, against WHO's guideline of 2 mg per litre. The same group had found about 420 parts per billion in slightly acidic distilled water.

What has not been shown is any benefit to the drinker beyond safer water. The study tested bacteria in the pot, not health in people, and it used one groundwater source for one length of time. Acidity changes the picture. ICMR-NIN's 2024 Dietary Guidelines say small amounts of metal leaching from cookware need not cause concern, but that storing acidic foods such as pickles, chutneys, sambar or khatta dal for long in aluminium, iron, untinned brass or copper vessels can make them unsafe. Plain water is one thing; nimbu pani, buttermilk or juice in a copper bottle is another.

Copper deficiency and the Indian evidence

There is little of it. The national survey figures this handbook quotes for iron, zinc and vitamins have no counterpart for copper in the sources read here. One Indian figure comes from a pilot survey of 995 tribal adults aged 18 to 75 in Sahibganj district, Jharkhand, published in 2005: the mean serum copper was 91.18 mcg per decilitre and 34 per cent were below 80. The authors asked for larger studies to learn what the finding means for health.

Serum copper is also an imperfect test. WHO's review says serum copper, ceruloplasmin and superoxide dismutase activity are used to assess status but that more sensitive markers are still being evaluated. Outside surveys, the people in whom doctors look for deficiency are those on long-term high zinc, and infants with the rare inherited Menkes syndrome, in which the gut absorbs almost no copper. WHO's summary is that clinical dietary deficiency of copper is rare.

What does the evidence say about copper supplements?

For healthy people, the sources read for this entry turned up no proven benefit. A 2021 systematic review pooled the randomised trials of copper supplements and blood lipids: five trials with 176 participants, and no significant change in total, LDL or HDL cholesterol. The evidence is small, but it gives no support to copper sold for the heart.

On safety the evidence has tightened. The European Food Safety Authority re-examined copper in 2023, using retention in the liver as the early warning sign instead of waiting for illness. It concluded that no retention is expected at an intake of 5 mg a day and set an acceptable daily intake of 0.07 mg per kg of body weight, which is 4.2 mg for a 60 kg adult. The older United States upper level of 10 mg a day is therefore the more permissive of the two.

A worked example: one vegetarian day and a copper bottle

This is an illustration, not a real person. Take a 32-year-old vegetarian bank officer in Pune. His day holds four chapatis (120 g atta, 0.58 mg of copper), rice at lunch (75 g raw, 0.17 mg), toor dal (30 g, 0.34 mg), rajma at dinner (30 g, 0.23 mg), a handful of groundnuts (30 g, 0.28 mg) and two glasses of milk (0.12 mg). The total is 1.72 mg, which meets ICMR-NIN's 1.7 mg without any special food.

He also drinks two litres from a copper bottle filled the night before. At the 0.18 mg per litre measured in the Bengaluru study that adds about 0.35 mg, taking the day to roughly 2.1 mg: under half of the 5 mg at which the European authority expects no retention. The bottle is neither needed nor harmful at that level. What would change the picture is a high-strength zinc tablet taken for months without advice: intake would look the same while absorption fell.

Common mistakes and myths about copper

The second mistake is to think of zinc and copper separately, taking a zinc tablet for immunity or hair for months without knowing it works against copper. The third is to treat liver as an everyday health food: 50 g of sheep liver alone carries 2.85 mg, so a frequent large serving is the one food route to a high intake. The fourth is to read tiredness as copper deficiency and buy a supplement, when the Indian data are too thin to assume a shortage.

Too much copper, Wilson disease and when to see a doctor

Swallowed in quantity, copper salts irritate the gut first. WHO's review describes headache, nausea, vomiting and diarrhoea, usually within 15 to 60 minutes of contaminated water or drinks, and far graver harm to blood, liver and kidneys after large doses of copper sulphate. India has its own history of chronic excess. Indian childhood cirrhosis, a fatal liver disease of infants with heavy copper deposits, was linked to milk boiled or stored in brass vessels, and reviews in 1998 and 2002 record that it largely disappeared as feeding vessels changed.

Wilson disease is a separate matter. It is an inherited condition in which the liver cannot move copper into bile, so copper builds up in the liver, brain and eyes, often from late childhood. Indian specialist societies published clinical guidelines in 2019 that rest diagnosis on serum ceruloplasmin and 24-hour urine copper, with a limited role for serum copper. WHO's review states that restricting copper in food alone cannot alter the course of the disease. Diagnosis, medicines and diet in Wilson disease belong to a hepatologist or neurologist, not to a handbook or a coach.

What does FSSAI allow in a copper supplement?

FSSAI's regulations on health supplements and nutraceuticals name the forms of copper that may be added: cupric carbonate, cupric citrate, cupric gluconate, cupric sulphate, copper lysine complex and, since an amendment in force from September 2021, copper oxide. The same regulations say the quantity of a nutrient added must not exceed the recommended daily allowance specified by the Indian Council of Medical Research. A health supplement's label must declare the amount of each nutrient, state it as a percentage of that allowance where applicable, and carry the words NOT FOR MEDICINAL USE and a warning not to exceed the recommended daily usage.

Learning this properly

Trace minerals and their interactions are taught in NNWA's courses under requirements and diet planning. The academy is private, sits in Kolkata and teaches online in Hindi and English. What it offers are skill courses for coaching healthy clients and referring medical cases onward, and none of them is a degree or a dietitian qualification. The Clinical Nutrition course deals with nutrients alongside illness and medicines, and the Diploma in Nutrition, Dietetics and Public Health covers requirements and food composition.