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Harvard Commentaries
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Reviewed by the Faculty of Harvard Medical School

Food for Thought Food for Thought

Phosphorus -- Backbone to Healthy Bones

January 16, 2013

By Rebecca Lynch, M.S., R.D., L.D.N.
Brigham and Women's Hospital

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What Is Phosphorus?

Phosphorus is a mineral that works with calcium to keep bones strong and healthy. This depends on a good balance between calcium and phosphorus in your diet. Eating too much phosphorus can disrupt the balance.

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How Much Do I Need?

The amount of calcium and phosphorus you need depends on your age, and whether you are pregnant or breastfeeding.

The recommendations below are for healthy people. People with chronic health conditions, such as kidney disease, should speak with their doctors or a dietitian regarding the amount that is right for them.

Age (years)

Milligrams of calcium per day

Milligrams of phosphorus per day

1 – 3
4 – 8
9 – 18
19 – 50
Pregnancy and breastfeeding
1,000 – 1,300
700 –1,250

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Food Sources of Phosphorus

Amount (milligrams)
Yogurt (1 cup)
Milk (1 cup)
Cheddar cheese (1 oz)
Soy products
Soy milk enriched with calcium (1 cup)
Tofu, firm or extra firm (¼ cup)
Ground beef (3 ounces)
Chicken breast (3 ounces)
Pink salmon, cooked (3 ounces)
Seeds, Nuts, Beans
Sunflower seeds, dry roasted (1 ounce)
Peanut butter, smooth (2 tablespoons)
Peanuts, dry roasted (1 ounce)
Black, navy or kidney beans, cooked (1/2 cup)
Whole grains
Shredded wheat (1 cup)
Whole wheat bread (1 ounce)
Instant oatmeal (1 packet)
Regular cola (12 ounces)
50 – 60
Flavored water (12 ounces)
0 – 120
Bottled iced tea, most flavors (12 ounces)
50 – 100

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The Calcium-Phosphorus Balance

Americans, on average, tend to get too little calcium and too much phosphorus in their diets.

Average calcium intake: 925 milligrams (recommendation: 1,000-1,200)
Average phosphorus intake: 1,495 milligrams (recommendation: 700)

Average calcium intake: 675 milligrams (recommendation: 1,000-1,200)
Average phosphorus intake: 1,024 milligram (recommendation: 700)

Some studies suggest that consuming a high-phosphorus, low-calcium diet can be harmful to bones. At most, you shouldn't consume more than three to four grams (3,000 - 4,000 milligrams) of phosphorus a day, depending on age.

Over the past 20 years, however, we have increased our phosphorus intake 10% to 15% because more phosphorus salts have been added to the food supply. They:

  • Add texture, retain moisture, maintain color, emulsify, enhance flavor and increase shelf life
  • Are in frozen dinners, canned entrees, snack foods, soups, toaster pastries, cereal bars, flavored beverages and fast food meat and chicken

Phosphorus salts are more easily absorbed into the bloodstream, compared with phosphorus found naturally in food. People with kidney disease are more susceptible to a build-up of phosphorus in the blood.

A diet high in processed or convenience foods may disturb the calcium and phosphorus balance that maintains bone health. Unfortunately, food companies are not required to provide information about phosphorus content on the nutrition fact label. This makes it difficult for consumers to make good choices. To identify phosphorus salts in foods, look for "phos" in the ingredient list.

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The Bottom Line

Aim for two to three servings of dairy a day. If you can't tolerate dairy, choose other foods high in calcium, or take a calcium supplement to meet your daily calcium requirement.

To avoid eating too much phosphorus, choose whole, fresh foods, when possible. Processed, convenience and fast foods can be high in phosphorus and sodium. So eat them in moderation.

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Rebecca Lynch, M.S., R.D., L.D.N, completed her dietetic internship at the Brigham and Women's Hospital, Boston and received her master's degree in nutrition at the University of Vermont. She is currently a senior clinical dietitian working with people with kidney problems at Brigham and Women's Hospital.

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