Milk and milk products can be a source of a variety of minerals. Most notably present are potassium, calcium and phosphorus. Dairy can therefore help to meet our body’s mineral requirements.

Milk contains many different minerals. Potassium, calcium and phosphorus are present in relatively high levels.

A sufficient potassium intake helps to maintain a normal blood pressure.

Calcium is present in many foods, with milk as one of the best natural sources of bioavailable calcium.

A calcium:phosphorus ratio (Ca:P-ratio) of 1:1 to 1.5:1 is considered optimal for good bone health.

Potassium

Potassium is an essential nutrient for the proper functioning of muscles and the nervous system.1  A sufficient potassium intake also helps to maintain a normal blood pressure, an important benefit in light of the WHO estimate that worldwide, approximately 40% of people over twenty-five suffer from elevated blood pressure levels.1,2

This mineral is present in food sources such as vegetables, fruits, potatoes, wheat products and nuts.3  Milk and many milk products are also a valuable source of potassium, see annex I. One cup of milk (240 ml) supplies approximately 375 mg of potassium (8% of an adult’s RDA established in the USA – see annex I – or 19% of the European Reference Values.4 The presence of potassium in milk products is one of the reasons why low fat dairy products – along with plenty of fruits and vegetables – form an integral part of the DASH (Dietary Action Against Hypertension) diet. This diet is known to help in lowering blood pressure.4-7

Calcium

Milk is well-known for its high calcium content. Approximately 1% to 2% of the human body is made up of calcium, of which 99% is contained in the bones and teeth. An adequate intake of dietary calcium is therefore vital for maintaining healthy bones and teeth. One serving of milk (240 ml) supplies around 290 mg calcium (29% of an adult’s RDA established in the US), of which one third is bioavailable. This is relatively high compared to other foods, see annex II.8,9

Unique casein micelles explain high calcium content

Milk would not provide such a high concentration of calcium, if calcium was not bound to phosphate and caseins (milk-specific proteins). Caseins contain amino acids that bind phosphates. In turn, these phosphates bind high amounts of calcium. These complex casein-phosphate-calcium clusters are known as casein micelles. Due to this unique binding in micelles, calcium is highly available for absorption from dairy compared to, for example, plant-based products. Milk is therefore one of the best natural sources of bioavailable calcium.

Phosphorus

Phosphorus is a mineral present in every cell of the body, but 85% of phosphorus reserves are found in the skeleton. Phosphorus is abundant in milk, as well as many other protein sources including soy, meat and eggs, see also annex I. While whole wheat products, nuts and legumes are also a source of phosphorus, the bioavailability of phosphorus from some plant sources is rather low, due to a different storage form of phosphate. Phosphorus is involved in several physiological processes and, for example, contributes to a normal energy-metabolism.10

Calcium & phosphorus for bone health

Calcium and phosphorus jointly contribute to the growth, development and maintenance of bones and teeth. Sufficient intake of both minerals is therefore important at all stages of life. Studies link an adequate phosphorus intake to calcium retention in the body and suggest that a calcium:phosphorus ratio (Ca:P-ratio) of 1:1 to 1.5:1 is probably optimal for bone health.11,12


Annex I

Table 2: Dairy and other products that contain phosphorus and potassium 13-15

Food sources Phosphorus

(mg/100 g) | %RDA

Potassium
(mg/100g) | %AI
Milk, semi skimmed 94    | 13 156   | 3
Yoghurt, low fat 143  | 20 228   | 5
Cheese, Gouda 498  | 71 82     | 2
Chicken average, raw 160  | 23 380   | 8
Egg, raw 200  | 29 130   | 3
Bread, brown 157  | 22 216   | 5
Orange 21    | 3 150   | 3
Tomato 24    | 3 250   | 5

Note: The US Recommended Dietary Allowances (RDAs), which are used in this table, are set to meet the needs of almost all (97 to 98 percent) individuals in a group. Adequate Intake (AI) is believed to cover the needs of all individuals in the group, but lack of data prevent being able to specify with confidence the percentage of individuals covered by this intake; therefore, no Recommended Dietary Allowance (RDA) was set. The RDA and AI are based on adults, aged 19-70 years.

References

  1. European Commission. EU Register on nutrition and health claims: Potassium. 2013 16/06/2013 [cited 2014 19 May]; Available from: http://ec.europa.eu/.
  2. World Health Organization. Global Health Observatory (GHO): Blood Pressure. 2014 [cited 2014 19 May]; Available from: http://www.who.int/.
  3. Weaver, C.M., Potassium and health. Adv Nutr., 2013. 4(3): p. 368S-77S.
  4. European Parliament and the Council, Regulation (EU) No 1169/2011 Official Journal of the European Union, 2011. 304(18).
  5. J.K. Etherton PM, et al., Milk products, dietary patterns and blood pressure management. Am Coll Nutr. , 2009. 1(10): p. 3S-19S.
  6. L.J. Appel, et al., A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med., 1997. 336(16): p. 1117-24.
  7. M. M. McGrane, et al., Dairy Consumption, Blood Pressure, and Risk of Hypertension: An Evidence-Based Review of Recent Literature. Curr Cardiovasc Risk Rep., 2011. 5(4): p. 287–298.
  8. C.M. Weaver and R.P. Heaney, Calcium in Human Health. 2006: Humana Press Totawa. 137.
  9. Institute Of Medicine, Dietary Reference Intakes for Calcium and Vitamin D/DRI Values. 2010.
  10. European Food Safety Authority, Scientific Opinion on the substantiation of health claims related to phosphorus and function of cell membranes (ID 328), energy-yielding metabolism (ID 329, 373) and maintenance of bone and teeth (ID 324, 327) pursuant to Article 13(1) of Regulation (EC) No 1924/20061 EFSA Journal 2009. 7(9): p. 1219.
  11. T.R. Fenton, et al., Phosphate decreases urine calcium and increases calcium balance: A meta-analysis of the osteoporosis acid-ash diet hypothesis. Nutrition Journal, 2009. 8(41).
  12. M.S. Calvo and K.L. Tucker, Is phosphorus intake that exceeds dietary requirements a risk factor in bone health? Ann. N.Y. Acad. Sci. , 2013. 1301(1): p. 29–35.
  13. R.A. McCance and E.M. Widdowson, McCance and Widdowson’s The composition of Foods. Sixth summary ed. 2002: Cambridge: Royal Society of Chemistry.
  14. Institute Of Medicine, Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. 1997.
  15. Institute Of Medicine, Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate. 2004.