You try to eat a healthy, calcium-rich diet. You watch your weight. You exercise. You do everything in your power to maintain strong bones because you want to be active well into your 70s and 80s.

You even make sure you have a nutritious breakfast of natural whole wheat squares topped cold, vitamin-D-fortified milk.

It sounds like a nutritious way to your day. But eating whole-wheat cereal and milk together may not be the best menu choice if you are trying to increase your bone mass. There are certain foods, like wheat, that block calcium absorption.

Phytates bind calcium.

High-fiber foods contain phytates, which prevent the body from absorbing calcium in other foods. Eating a high-fiber, whole-wheat cereal with milk, macaroni and cheese, or drinking a tall, cold glass of milk with Boston baked beans and hot dogs may be great-tasting combinations, but they do not boost bone-building nutrition.

Phytates found in whole-grains, legumes (dried beans), nuts and soy products bind the calcium of other foods eaten when they are eaten at the same time. When calcium is bound, the body cannot use it.

Oxalic acid hinders calcium absorption.

Foods high in oxalic acid also impede the absorption of calcium by binding the mineral.

Spinach is naturally high in calcium, but it is also high in oxalic acid. The body is unable to process the calcium it provides. Other foods that contain oxalic acid include beet greens, rhubarb and sweet potatoes.

Though these foods should not be considered for their calcium value, they do provide other nutrients and minerals that help the body stay healthy.

Does protein interfere with calcium absorption?

Historically, nutritionists have warned that eating large amounts of protein causes the kidneys to flush calcium out of the body. But recent studies show protein also may increase intestinal calcium absorption.

More study is needed to determine protein’s effect on the body’s ability to process calcium. To make the most of your calcium intake, don’t drink milk with your beef stew, chili or steak dinner. Eat your meal and then drink your milk later.

Beer, cheese and snacks are a trifecta for calcium loss.

Alcohol and salty foods are catalysts for calcium flushing. As calcium levels in the blood decrease, the body extracts (resorbing) calcium from the bones to obtain the calcium it needs to function properly. Calcium flushing can make the bones porous, which can lead to the development of osteoporosis.


To minimize calcium flushing:

  • Avoid eating foods that have a sodium content higher than 20 percent of the daily recommended value.
  • Don’t drink more than two or three alcoholic drinks a day.

You can eat your spinach and build your calcium, too.

Wheat and other “bad-to-the-bone” foods provide many other vitamins and minerals vital to your health. You should still eat these types of foods, just not at the same time that you drink milk or eat calcium-rich foods.

The best way to maximize the nutrition from foods that bind or flush calcium and continue to boost your calcium levels is just a matter of scheduling. Eat calcium-binding foods at least two hours before or after you eat calcium-rich foods. This timing allows your body to maximize the vitamins and minerals of all food types. By making this timely adjustment to your meals, you gain all the nutritional benefits without interfering with your body’s ability to absorb the calcium it needs every day.

The National Institutes of Health Office of Dietary Supplements