Overview of vitamin, mineral and trace element deficiencies

People with a medical condition affecting the gastrointestinal tract are at high risk of micronutrient (vitamin, mineral and trace element) deficiencies and malnutrition resulting from malabsorption or inadequate intake. Such conditions include short bowel syndrome, pancreatic insufficiency, inflammatory bowel disease, untreated coeliac disease, chronic vomiting, gastroparesis, bariatric surgery or other surgery to the small bowel or stomach. Other groups at high risk of deficiencies due to inadequate intake or increased requirements include pregnant people, elderly people, vegans, people with a high alcohol intake (see Alcoholic hepatitis), people with chronic liver disease, people with eating disorders and people on a restrictive diet (eg if whole food groups are excluded).

The decision to test for a micronutrient deficiency depends on the clinical situation and should be individualised based on the patient’s risk factors. Iron and vitamin B₁₂ are nutrients that are at high-risk of deficiency. Caution is advised when interpreting micronutrient test results in patients with acute or chronic systemic inflammation—inflammation can significantly impact test resultsMcMillan, 2019.

Micronutrient deficiencies are unlikely in people who consume a varied diet, are well-nourished and have no medical conditions. Despite this, many Australians regularly take over-the-counter vitamin and mineral supplements. There is little evidence for or against this practice; however, there is evidence of harm if these supplements are taken in high doses without an indication. Over-the-counter multivitamins contain varying amounts of vitamins and minerals; they are not adequate to treat individual vitamin deficiencies, but can prevent deficiencies developing in people with poor oral intake or those on a restrictive diet.

Dietary sources of the vitamins, minerals and trace elements discussed in this topic are given in Dietary sources of key vitamins, minerals and trace elements. Micronutrient deficiencies are often treated with supplementation; however, depending on the cause of the deficiency, increasing dietary sources of the micronutrient may be sufficient for long-term maintenance.

Nutrient reference values for Australia and New Zealand and recommended daily intake of vitamins and minerals are available from the National Health and Medical Research Council website.

Table 1. Dietary sources of key vitamins, minerals and trace elements
Nutrient	Dietary sources
vitamins [NB1]
vitamin A	preformed vitamin A (retinol): animal-derived foods (eg liver, butter, cheese, milk, egg yolk, fish, fish oil) provitamin A carotenoids (including beta-carotene): green leafy vegetables, orange/yellow-coloured fruit and vegetables, margarine
thiamine (vitamin B₁)	yeast extract, fortified breads and cereals, wheat germ, kidney beans, soybeans, offal (eg liver, kidney, heart), pork, nuts
pyridoxine (vitamin B₆)	meat, liver, poultry, fish, yeast, soybeans, nuts, whole grains (eg brown rice, rice bran, wheat bran, barley), green leafy vegetables, eggplant
vitamin B₁₂	animal-derived foods (eg offal [eg liver, kidney, heart], meat, fish and seafood, eggs, milk, cheese), fortified soy milk
folate	yeast extract, green leafy vegetables, whole grains, legumes and peas, nuts, avocado, offal (eg liver, kidney, heart)
vitamin C	citrus fruit, guava, strawberries, kiwi fruit, cantaloupe, lychee, pawpaw, broccoli, brussels sprouts, red cabbage, capsicum, cauliflower, snow peas
vitamin D	cod liver oil, oily fish, eggs, margarine, butter, cheese
vitamin E	almonds, peanuts, seeds, vegetable oils, margarine, butter, egg yolk, wheat germ
vitamin K	green leafy vegetables, liver, eggs
minerals and trace elements
calcium	best sources: milk, cheese, yoghurt, fortified beverages (eg soy milk) alternative sources: canned salmon and sardines, fortified breads and cereals, firm tofu, prawns, oysters, broccoli, nuts (particularly almonds and brazil nuts), dried figs
iron	best sources: lean red meat, offal (eg liver, kidney, heart), chicken, fish, eggs nonhaem sources (poorly absorbed; improved with concomitant vitamin C): green leafy vegetables, fortified breakfast cereals, wholemeal bread, legumes, cocoa, dried fruit
selenium	offal (eg liver, kidney, heart), seafood, meat, eggs, brazil nuts, whole grains (particularly wheat and oat bran)
zinc	best sources: meat, chicken, seafood (particularly oysters), offal (eg liver, kidney, heart), fortified breads and cereals alternative sources: eggs, milk, cheese, fish, whole grains, legumes, nuts and seeds
Note: NB1: Many vitamins (particularly water-soluble vitamins) are heat sensitive and can be destroyed by overcooking and exposure to sunlight. Consumption of fresh foods is recommended if possible.