Calcium — how much is enough?

Originally Published: December 6, 1996 - Last Updated / Reviewed On: September 9, 2011
Share this

Hi Alice,

I drink about three cups of coffee and one cup of milk a day. I was wondering if one cup of milk contains enough calcium to keep my bones strong. I am twenty-three years old.

Dear Reader,

Regardless of your age, one cup (8oz) of milk a day, which provides about 300 mg of calcium, is not enough to keep your bones strong and healthy. It is recommended that people in their twenties get at least 1,000 mg of calcium each day which would be about 3-1/3 cups of milk.

Why do we need so much calcium? The short and sweet answer is: to maintain strong, healthy bones and good general nutrition, as well as to prevent osteoporosis (See Women, calcium, and osteoporosis? in Alice's Fitness & Nutrition archive). Calcium is an essential component in the life-long process of laying down new bone. Before you reach thirty, more bone is made than lost; after thirty, this trend reverses, and calcium can help our bodies maintain bone mass.

Women especially need to be vigilant about this important mineral. On average, women make less bone and lose it at a greater rate than men. A woman's calcium stores are drawn on during pregnancy and lactation. Adding to this, women generally live longer than men, giving their bones more time to become brittle, less dense, and prone to fracture (i.e., to develop osteoporosis). The two best things you can do now to prevent future osteoporosis are: (1) include enough calcium in your diet; and, (2) exercise often, and include weight-bearing activities in your exercise routine.

The Recommended Daily Allowances (RDAs) for calcium intake is

  • 9 to 18 years old — 1,300 mg/day
  • 19 to 50 years old — 1,000 mg/day
  • Over 50 — 1,200 mg/day

If this amount of lactose seems daunting, don't worry, there are many high calcium foods besides milk that you can consume to bulk up your calcium intake. The Linus Pauling Institute at Oregon State University provides the following table of common foods (some dairy, some not) and their relatively high calcium content:

Food

Serving

Calcium (mg)

Servings needed to equal the absorbable calcium in 8 oz of milk

Milk

8 ounces

300

1.0

Yogurt

8 ounces

300

1.0

Cheddar cheese

1.5 ounces 

303

1.0

Pinto beans

1/2 cup, cooked

45

8.1

Red beans

1/2 cup, cooked

41

9.7

White beans

1/2 cup, cooked

113

3.9

Tofu

1/2 cup

258

1.2

Bok choy

1/2 cup, cooked

79

2.3

Kale

1/2 cup, cooked

61

3.2

Chinese cabbage

1/2 cup, cooked

239

1.0

Broccoli

1/2 cup, cooked

35

4.5

Spinach

1/2 cup, cooked

115

16.3

Rhubarb

1/2 cup, cooked

174

9.5

A few other pointers on how to maximize the calcium in your diet: calcium is absorbed better in the presence of vitamins C and D and lactose (a sugar found in milk and dairy products), so squirting some lemon or orange juice on your greens, in addition to tasting great, can help make the calcium in them more bio-available. Dairy products are also an excellent choice for calcium because of the lactose they contain.

While there are many calcium supplements available to help you meet your intake goals, getting calcium through foods is preferable to supplementation because of a better absorption rate. However, if you simply cannot eat enough to get adequate calcium, which is the case for many, especially busy students in their twenties, turning to a food-based, calcium supplement could be useful to you. Calcium citrate, which is in the newer calcium supplements, tends to be more easily absorbed than calcium carbonate, which is used in the older supplements like chewable antacids.

It's great that you're keeping tabs on your calcium consumption as a young person. With an awareness of what you need and how you can get it, you are sure to keep your bones healthy and strong.

Alice

September 8, 2011

21622
Thank you to that person who made the comment about magnesium. Not enough people out there know that too much calcium depletes the amount of magnesium in a body which can cause serious problems. Some...
Thank you to that person who made the comment about magnesium. Not enough people out there know that too much calcium depletes the amount of magnesium in a body which can cause serious problems. Some of which are brittle bones and can also affect your nervous system as it has done to me. I suffered from head tremors for 12 years before finding out that all the milk I was drinking (about a litre a day) was causing a lot of damage. I cut down the amount of milk to a cup a day and started to take magnesium supplements 500 mg a day and in just over a month my tremors were almost completely gone. Please people, study this in more detail for your own health and benefit.

January 6, 2006

20992
Alice,

Did you forget to mention how important it is to also get enought magnesium in your body with the calcium? Although Americans drink more milk than most countries in the world, we also have...

Alice,

Did you forget to mention how important it is to also get enought magnesium in your body with the calcium? Although Americans drink more milk than most countries in the world, we also have a higher rate of brittle bones or osteoporosis. Magnesium is not stressed enough when taking calcium, and can help absorb the calcium into your body, therefore reducing risks of bone loss.