How Much Potassium & Phosphorus Is in a Cup of Milk?
Milk is primarily known for its protein, vitamin D and calcium content. Although not particularly high in many other nutrients, milk is also an excellent source of phosphorus and good source of potassium. Despite their important physiological functions, these minerals can be toxic in excess. In addition, too much phosphorus can deplete your body's stores of calcium and contribute to osteoporosis. As such, you should be careful when consuming large amounts of milk and other significant sources of these minerals, which include meat, fish, seafood, legumes and fresh and dried fruit.
Your recommended dietary allowance for phosphorus is 700 milligrams per day. The Institute of Medicine estimates that 4.7 grams -- or 4,700 milligrams -- of potassium is adequate to meet most people's daily needs. As such, your potassium needs may exceed 4.7 grams per day, particularly if you are breastfeeding.
The amount of potassium and sodium in milk decreases as its fat percentage increases. For example, a 1-cup serving of 2 percent milk contains 224 milligrams of phosphorus and 342 milligrams of potassium. Using the above recommendations of 700 milligrams for phosphorus and 4,700 milligrams for potassium, this amounts to 32 percent and 7 percent of your respective daily intakes for these nutrients. In comparison, 1 cup of skim milk contains 247 milligrams of phosphorus and 382 milligrams of potassium, or 35 percent and 8 percent of your respective daily intakes. As skim milk contains approximately 2/3 the calories of 2 percent milk, it is a much less fattening option for helping you meet your daily phosphorus and potassium needs.
Potassium is one of the most important minerals in your body. It serves as an electrolyte, helping to conduct electricity and maintain the healthy functioning of your body's cells, organs and tissues. Because of its impact on muscular functions, potassium is particularly important for digestive and heart health. A regular intake of high-potassium foods also contributes to bone health and may decrease your risk of osteoporosis. In addition, potassium helps to regulate your blood pressure. Although there is a link between low potassium intake and both high blood pressure and cardiovascular disease, eating more than an adequate intake of potassium does not necessarily reduce your risk of these health issues.
After calcium, phosphorus is the most abundant mineral in your body. The majority of this is stored in your bones and teeth, as phosphorus is vital to their development and maintenance. As such, adequate intakes of phosphorus and potassium add to the bone health benefits of milk's vitamin D and calcium content. Phosphorus is also important for your kidneys' ability to filter wastes and for energy storage and usage. Because of its role in the growth, maintenance and repair of your body's tissues and cells, eating adequate amounts of phosphorus can help to reduce muscle pain after an intense bout of physical activity.
Matthew Lee has been writing professionally since 2007. Past and current research projects have explored the effect of a diagnosis of breast cancer on lifestyle and mental health and adherence to lifestyle-based (i.e. nutrition and exercise) and drug therapy treatment programs. He holds a Master of Arts in psychology from Carleton University and is working toward his doctorate in health psychology.