Macrominerals

These are the minerals that are found in larger amounts in the body and include; calcium, phosphorus, magnesium, potassium, chloride and iron.

Calcium

The amount of calcium which adults are advised to take every day is at least 700mg, though in certain circumstances (e.g. adolescence, pregnancy, and osteoporosis) the level should be at least 1,000mg.

The following foods are valuable sources of calcium in our diets:

Glass of whole milk (190ml) - 226mg
Glass of semi- skimmed milk (190ml) - 232mg
Glass of skimmed milk (190ml) - 236mg
Pot of yoghurt (150g) - 225mg
Small pot of fromage frais (100g) - 86mg
1oz (28g) cheddar type cheese - 210mg
2tbsp (20g) grated hard cheese - 148mg
Cheese spread triangle (25g) - 150mg
Small pot cottage cheese (115g) - 90mg
Cream cheese (in sandwich – 30g) - 29mg
Scoop ice cream (60g) - 66mg
Thick slice white bread - 37mg
Thick slice wholemeal bread - 20mg
Crumpet (40g) - 60mg
Scone (48g) - 90mg
Bowl muesli (50g) - 55mg
Kellogg's Nutri-Grain bars (37g) - 200mg
2oz (57g) drained sardines - 310mg
Shelled prawns (60g) - 90mg
1 egg - 32mg
4oz (110g) green vegetables - 35mg
Small can baked beans (150g) - 80mg
2 tbsp red kidney beans (70g) - 50mg
Large orange (210g) - 70mg
7 dried apricots (56g) - 52mg
1 tbsp sesame / sunflower seeds (12g) - 80mg

Although dairy products may contain higher amounts of calcium, beans and seeds may have amounts which are more bioavailable, i.e. we absorb a higher percentage of the calcium from these foods.

Iron

Foods rich in iron fall into two main groups:

Animal sources - haem iron
Plant sources - non-haem iron

Animal sources tend to be better absorbed than plant sources, but try to consume a variety of foods from both sources

Animal sources

All red meat, game, liver, kidney, sausages, beef burgers
Egg yolk
Fish (not as high as red meat), but reasonable sources are pilchards and sardines, especially those canned in tomato sauce
Poultry (not as high as red meat)

Plant sources

Pulses – butter beans, broad beans, haricot (baked) beans, lentils, red kidney beans, chick peas
Green leafy vegetables e.g. brussel sprouts, spinach, cabbage, lettuce, etc – but a large portion needs to be eaten for a good iron intake
Flour products – bread, pasta, biscuits, cakes – wholemeal varieties are higher in iron
Breakfast cereals – many are fortified with iron, check the packet. Especially good are Branflakes, Weetabix, All-bran, Shredded wheat

Miscellaneous
The following contain some iron but in smaller amounts:

Dried fruits - apricots, figs, prunes
Dark chocolate, cocoa, liquorice, black treacle, gingerbread

Vitamin C and Iron
Vitamin C can help iron be more easily absorbed by the body, by changing it into a form more easily used. Therefore eat foods rich in vitamin C with foods rich in iron:

Fresh fruit - especially citrus fruit, strawberries, blackcurrants; including fruit juice and tinned fruit
Fruit squashes - vitamin C enriched cordials including orange squash, blackcurrant
Vegetables - especially tomatoes, green leafy vegetables and potatoes. Most vitamin C is found just under the skin so is lost in peeling. Some is also lost in cooking and letting food stand for a long while. To minimise losses avoid peeling where possible, prepare foods just before meal times and cook in minimal water with the lid on

Calcium and Iron
Calcium can inhibit iron absorption. It is recommended to consume calcium-rich foods, especially dairy products, away from iron rich foods. But, do not omit calcium-rich foods from your diet, as they are needed for healthy bones and teeth.

Bran and Iron
The use of raw bran is not recommended, as it contains phytate which 'binds' dietary iron, making it unavailable for absorption. You still need to have a good fibre intake, so continue to consume wholemeal products, fruit and green vegetables, which are high in iron.

Magnesium

Magnesium is the fourth most abundant mineral in the body. Most is found in bone, but there are also high amount in cells of tissues and organs. Magnesium is involved in a huge amount of biochemical reactions in the body, including helping to maintain normal muscle and nerve function, keeping heart rhythm steady, supporting a healthy immune system and keeping bones strong. Magnesium also helps to regulate blood sugar levels, promotes normal blood pressure, and is known to be involved in energy metabolism and protein synthesis.

Dietary magnesium is absorbed in the small intestines and its metabolism is closely linked to calcium. Magnesium is excreted through the kidneys.

Magnesium deficiency is characterised by progressive muscle weakness, neuromuscular problems, heart problems and eventual death. Adult males should aim for 300mg per day, females 270mg per day.

Green vegetables contribute a good proportion to magnesium intake because the chlorophyll, which gives greens their green colour, contains magnesium. Wholegrain cereals are also great sources, but refined grains are low in magnesium as refining removed the magnesium rich germ and bran, so some cereal products are fortified with magnesium. Tap water can also be a source of magnesium but the amount varied according to supply; 'hard' water contains more magnesium than 'soft' water.

Spinach (130g) – 45mg
Muesli (95g) – 95mg
All-bran (45g) – 95mg
Bran Flakes (45g) – 60mg
Shredded Wheat (2 biscuits) – 55mg
Weetabix (2 biscuits) – 48mg
Special K (35g) – 19mg
Porridge oats (100g) – 18mg
Wheatgerm (2 tbsp) – 35mg
Wheat bran (2 tbsp) – 45mg
Wholemeal bread (1 slice) – 55mg
Granary bread (1 slice) – 40mg
Brown rice (50g) – 55mg
Almonds (25g) – 80mg
Cashew nuts (25g) – 75mg
Peanuts (25g) – 50mg
Peanut butter (25g) – 50mg
Mixed nuts (25g) – 65mg
Soya beans, cooked (100g) – 63mg
Kidney beans (50g) – 75mg
Chick peas (50g) – 65mg
Baked beans (200g) – 62mg
Potatoes, baked with skin (150g) – 48mg
Banana – 45mg
Avocado – 25mg
Halibut (85g) – 90mg
Natural yoghurt, low fat (150g) – 45mg
Plain dark chocolate (100g) – 100mg
Milk chocolate (100g) – 100mg

Phosphorous

Most phosphorous in the body is present in the bones helping provide rigidity to the skeleton. It is also present in soft tissues as inorganic phosphate. It is involved in metabolism in high energy phosphate compounds, eg as adenosine triphosphate (ATP).

Around 80% of dietary phosphorous is absorbed. Requirements are set equal to dietary calcium, and adults should aim for 800mg per day. Symptoms of phosphorous deficiency include progressive muscle weakness, fatigue, arthritis, tooth decay, fragile bones and stunted growth.

Phosphorous is a major constituent of plant and animal cells, therefore is abundant in the diet and present in all natural foods. It is also present in many food additives. Especially good sources include:

Tuna
Mackerel
Salmon
Sardines
White fish eg cod, plaice
Liver
Kidney
Chicken
Turkey
Eggs
Pine nuts
Pistachios
Pumpkin seeds
Sesame seeds
Sunflower seeds
Walnuts
Almonds
Brazil nuts
Cashews
Peanuts
Pecan nuts
Chickpeas
Lentils
Soya beans
Garlic
Popcorn
Cheese
Wheat bran
Wheatgerm
Brown rice
Buckwheat
Oats
Rye
Wheat
Chocolate
Kelp
Yeast

Zinc

Zinc is an essential mineral present in small amounts in all tissues. Bones and teeth contain more, as does the pancreas and there is around 0.7mg/100ml blood. It is however, only needed in small amounts from the diet. Even though we only need small amounts, some people do not have high zinc levels because only 20-30% of the zinc we consume is actually absorbed in the intestine. Absorption is decreased by dietary fibre, calcium, copper, phytate (from raw unprocessed bran), and phosphate. The presence of amino acids and peptides in the gut increase zinc absorption. Adult males require 9.5mg of dietary zinc per day, females 7mg per day.

The following foods are significant sources of zinc:

Fortified breakfast cereals
Brazil nuts
Pumpkin seeds
Almonds
Other nuts and seeds
Red meat
Poultry
Pork
Dairy products (especially yoghurt and hard cheese)
Beans
Lentils
Chickpeas
Peas
Wholegrain foods
Wholewheat flour
Rye, rye flour and rye bread
Oats and oat flour
Free range eggs
Wheatgerm