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Changes in Bone Density

Changes in Bone Density

Introduction: (Initial Observation)

Osteoporosis is a disease of bone in which the bone mineral density is reduced and the bones are more susceptible to fracture. Osteoporosis is best described as “porous bones”.

Bones are living tissue, constantly being rebuilt. With osteoporosis, the rate of bone loss is greater than that of bone rebuilding, causing thin, porous bones that break easily.

More than 28 million Americans have osteoporosis or are at high risk of developing it.

One in every 2 women and 1 in every 8 men will suffer osteoporosis-related fractures some time in their life. The national cost of osteoporosis and associated fractures is estimated at $10 billion and rising. Osteoporosis causes pain, disability, and loss of independence.

I am wondering if osteoporosis is treatable and if the bone loss can be prevented.

My initiative for this project

My mom had a bone density test and she has mild osteoporosis. After hearing about osteoporosis I learned that osteoporotic bones are normal bones with reduced bone minerals. Such bones are more prone to fractures with trauma, even minor trauma. I am wondering what conditions may cause this and if we can cure osteoporosis by providing additional minerals to the bone.

My initial project plan:

I thought I would take 3 chicken leg bones and clean all the meat off. Then I would weigh each bone and note the appearance. Place each bone the a jar and cover with white vinegar. Every 24 hours for 7 days I would remove the bones and weigh them one at a time. Also noting any changes. After a week I would remove from the vinegar and rinse with water. Then I would put the three bones in jars containing solutions as follows one with calcium citrate and distilled water, one with calcium carbonate and distilled water and a third would have only distilled water. I would put one bone in each solution. Every 24 hours for an additional seven days I would remove the bones one at a time and weigh them noting any changes in appearance or flexibility.

I am thinking that if the bones weigh more then they are absorbing calcium.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

Find out about bone structure and how it gets hard by absorbing calcium from different minerals. Read books, magazines or ask professionals who might know in order to learn about the factors that affect proper calcification of the bone. Keep track of where you got your information from.

Following are samples of information you may find.

Note: I am cautious in using the term “Bone Calcification” in this project. In medicine the term calcification is often used to describe improper accumulation of calcium minerals in soft tissue or in body fluid. Such conditions are often disease or symptoms of some diseases. To avoid confusion or misunderstanding, I will call it “Proper bone calcification” or “Increase in bone density”.

Calcium and Bone

Calcium is a mineral found in many foods. Getting enough of this nutrient is important because the human body cannot make it. Even after you are fully grown, adequate calcium intake is important because the body loses calcium every day through the skin, nails, hair, and sweat, as well as through urine and feces. This lost calcium must be replaced daily through the diet. Otherwise, the body takes calcium out of the bones to perform other functions, which makes the bones weaker and more likely to break over time.

Experts recommend that adults get 1,000 to 1,200 mg (milligrams) of calcium each day. Although food is the best source of calcium, most Americans do not get enough of it from food sources. Calcium-fortified foods (like orange juice, bread, cereals, and many others on your grocer’s shelves) and calcium supplements can fill the gap by ensuring that you meet your daily calcium requirement.

What to Look for in a Calcium Supplement

Calcium exists in nature only in combination with other substances. These substances are called compounds. Several different calcium compounds are used in supplements, including:

  • calcium carbonate
  • calcium phosphate
  • calcium citrate.

These compounds contain different amounts of elemental calcium, which is the actual amount of calcium in the supplement. It is important to read the label carefully to determine how much elemental calcium is in the supplement and how many doses or pills to take.

Vitamin D dilemma
Consuming calcium alone is not enough, though. To absorb calcium from the intestines into the blood stream, the body needs vitamin D.

Fortunately, vitamin D comes from sunlight. Spending 20 to 30 minutes in mid-day sunlight three times a week usually create enough vitamin D—400 international units —through the skin.

You can also get vitamin D through diet. Check nutritional information on milk cartons to make sure the milk contains the vitamin, he says. Multivitamin supplements also can help.

What is Osteoporosis?

Bone is living tissue. To keep bones strong, your body is always breaking down old bone and replacing it with new bone tissue. As people enter their forties and fifties, more bone is broken down than is replaced. A close look at the inside of bone shows something like a honeycomb. When you have osteoporosis, the spaces in this honeycomb grow larger. And the bone that forms the honeycomb gets smaller. The outer shell of your bones also gets thinner. All this loss makes your bones weaker.

Who Has Osteoporosis?

Millions of Americans have osteoporosis. They are mostly women, but more than 2 million men also have this disease. White and Asian women are most likely to have osteoporosis. Other women at great risk include those who:

  • have a family history of the disease,
  • have broken a bone while an adult,
  • had surgery to remove their ovaries before their periods stopped,
  • had early menopause,
  • have not gotten enough calcium throughout their lives,
  • had extended bed rest,
  • used certain medicines for a long time, or
  • have a small body frame.

The risk of osteoporosis grows as you get older. At the time of menopause women may lose bone quickly for several years. After that, the loss slows down, but continues. In men the loss of bone mass is slower. But, by age 65 or 70 men and women are losing bone at the same rate.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement. Following are two examples:

  • Can decalcified bones reabsorb calcium from solution?
  • Does bone density increase if solutions of calcium salts are freely available to the bone?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Bones inside an acidic solution such as vinegar may gradually lose their calcium and transform to low density bones. Also bones inside a solution of calcium salt (such as calcium acetate) may gradually absorb calcium and transform to the high density bones. Obviously time is factor because such changes and transformation may not happen instantly. This is a sample of how you can define variables:

For experiment of decalcification:

Independent variable (also known as manipulated variable) is the length of time a bone sample is inserted into an acidic solution.

Dependent variable (also known as responding variable) is the density of the bone or the hardness of the bone.

Controlled variable is the temperature.

Constants are the type of solution and the type of bone.

For experiment of Calcification:

Independent variable (also known as manipulated variable) is the length of time a bone sample is inserted into a s solution of calcium salt.

Dependent variable (also known as responding variable) is the density of the bone or the hardness of the bone.

Controlled variable is the temperature.

Constants are the type of solution and the type of bone.

Note: Low density bone is also softer. So the softness can be an indication of low bone density.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. This is a sample hypothesis:

My hypothesis is that bones will lose calcium in acidic environment and absorb calcium when plenty of calcium salts are available.

This is another sample hypothesis:

My hypothesis is that bones will lose calcium in acidic environment; however, they only absorb calcium from solutions if the bone is live. In other words cooked bones or very old bones will not absorb calcium again.

Yet another example:

My hypothesis is that bones lose calcium in acidic environment but they don’t absorb calcium again.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

In the following experiments we assume that you want to try 3 different calcium source to see if they can increase the bone density. You will also use a total of 6 similar chicken bones. (Leg bones if possible)

Osteoporosis or low bone density is caused when the loss of bone calcium happens at a faster rate than the absorption of calcium by the bone. In order to test the calcification of the bone, first we need to have bone samples that have lost their calcium or are decalcified.

Experiment 1: Bone decalcification

Introduction: In this experiment, we shall have vinegar to represent our bloodstream, and the chicken bone represents our bone of course! If you have read our background info earlier, calcium level in our bloodstream must be maintained, hence, when our calcium level in the blood is low, calcium will be taken from our bones. This experiment will show what actually happens to our bones when calcium is removed from it, and we do not replenish them.

PS. The vinegar does not actually take calcium away from the bone. It just reacts with the calcium compound (calcium phosphate) and converts it to another compound that is not hard. This will certainly reduce the hardness of the bone, but it may not necessarily reduce the mass of the bone. This method can never simulate dissolving calcium in blood that will really reduce the bone mass and bone density.

Materials needed:

  • steak knife
  • 6 identical uncooked chicken bone (leg or wing)
  • pure white vinegar: acetic acid(4 mol/dm3)
  • hydrogen peroxide
  • gloves (optional)
  • Digital Scale (0.1g precision)
  • Paper towels
  • 3 glass jars

Safety Notes:

  • If not wearing gloves, always remember to wash your hands thoroughly with soap after handling the raw chicken bone as salmonella bacteria may be present.
  • Have an adult present when handling the steak knife.


1. Remove meat away from bone as much as possible.

2. Treat bone by removing unwanted tissues (if any) and soak it in hydrogen peroxide to remove bloody color of bone.

  • Soak it for as long as it takes for bloody color to be removed.
  • This prevents the vinegar from being too murky by the end of the experiment.

3. Bend bones to check flexibility and weigh them (all together). Make sure to dry the bones with paper towel before weighing them.

4. Immerse bone completely in pure white vinegar in a glass jar.

5. Cover jar with a lid.

6. After 1 day, check bones for flexibility and weigh them.

7. Record results.

8. Repeat steps 6 and 7 for the next four days.

Your results table may look like this:

Observation days Weight of all 6 bones together
Day 1 (Before vinegar exposure)
Day 2
Day 3
Day 4
Day 5

Experiment 2: Returning calcium back to the bone

Introduction: In this experiment we try to absorb calcium into the decalcified bones to see if the bones become as rigid as before or if the bone mass will increase.

Materials needed:

  • Calcium hydroxide and other calcium solutions such as calcium citrate, calcium acetate, calcium lactate. (See “How to get them? How to make them?” following the experiment procedures.
  • Decalcified bone (from the previous experiment)
  • Three jars. One Jar for each calcium solution you want to test.


  1. Get 3 jars filled with calcium salts you want to test. Label the jars with the name of salt solution in it. For example you may label the jars as Calcium Hydroxide solution, Calcium acetate solution and calcium lactate solution.
  2. Weigh and then place 2 decalcified bones in each jar and cover the jars.
  3. Leave them to soak for 5 days.
  4. Remove the bones from each jar, dry them with paper towel, weigh them and then examine their hardness.

Record your results in a table like this:

Calcium Solution Initial Mass of 2 bones Final mass of 2 bones Initial hardness of bones Final Hardness of bones
Calcium Hydroxide
Calcium Acetate
Calcium Citrate

This results table may later be compiled to another results table like this:

Calcium Solution %Increase in mass %increase in hardness
Calcium Hydroxide
Calcium Acetate
Calcium Citrate

Make a graph

Use your latest results table to make a bar graph and visually display your results. Make one vertical bar for each calcium solution you are testing. Label each bar with the name of the calcium solution it represents. The height of each bar will show the percent of mass increase or the increase in the hardness occurred in one specific calcium solution.

Can I just feel the hardness?

Can one just feel the hardness of the bones and estimate the change? Although this is possible to feel the hardness, it is best if you somehow measure it to reduce any errors. This is one way you may do it.

On a flat wooden board insert 2 strong nails or screws about 7 cm (3 inches) apart. The distance between the nails must be less than your smallest bone so they can hold the bones. place and secure a ruler between the nails as shown in the diagram.

To test the hardness of each bone place it over the two nails and use the spring scale to pull it down 1/2 centimeter (1/5 of an inch). Read the force on the spring scale.

Since each spring scale has a limited range and limited sensitivity, you may need more than one spring scale for higher accuracy of results. The spring scales show the force in grams so you may report your results in grams per 1/2 centimeter.

Use this test only for your second experiment. Trying it for the first experiment may damage the bones and reduce the accuracy of your results.

Since you have 2 bones in each jar, you must measure the hardness of both of them and then calculate and report the average.

How to get them? How to make them?

Calcium Hydroxide also known as hydrated lime is a white powder. It may be available for sale in some garden suppliers. Farmers use that to increase to pH of the soil (reduce the acidity of the soil). It is also available at ChemicalStore.com online store. This is what you need to buy. You cannot make it at home. Calcium hydroxide may also be used to make other calcium compounds; however I often suggest to use calcium carbonate to make other calcium compounds. To make the calcium hydroxide solution you can mix it with water. Start adding calcium hydroxide to water with a small spoon and stir it. Continue this until no more calcium hydroxide will dissolve and the solution becomes milky. Then let it precipitate (takes a few hours) and then use the clear solution on top for your experiment. You must transfer this clear solution to your experiment jar slowly and carefully. Any agitation may mix the solution and make it milky again. (It is OK to use the solution that is milky. Separating the clear solution is optional)

Calcium citrate, calcium lactate and calcium acetate may be purchased from chemical suppliers but I prefer to make them at home using some calcium carbonate. This is how I do it and I recommend you to do the same.

To make calcium acetate get a jar of vinegar (Vinegar is a 5% solution of acetic acid in water) and with a small spoon gradually sprinkle calcium carbonate on it. As calcium carbonate gets in contact with vinegar it will react and release carbon dioxide gas (Carbon dioxide or CO2 is the same gas used in soft drinks) and you will see bubbles. Stir the vinegar slowly until the bubbles go away and continue adding calcium carbonate. Continue this until the addition of calcium carbonate does not create any new bubbles. That is when your calcium acetate is ready. You may want to filter it and get a clear solution; however, you don’t have to. To make calcium acetate you may buy white vinegar from a local store and calcium carbonate from ChemicalStore.com or any other chemical supplier.

To make calcium citrate you may use the same procedure of making calcium acetate. The only difference is that instead of vinegar you will use lemon juice or a 5% solution of citric acid. Pure citric acid is a white powder or crystal and is sold at bakery suppliers and at chemical Stores.

To make calcium lactate you may use the same procedure of making calcium acetate. The only difference is that instead of vinegar you will use lactic acid. Pure lactic acid is a food additive so it may be available at some food suppliers. Lactic acid is mostly added to beverages such as beer and wine. Sourness of sour cream is from the lactic acid.

Materials and Equipment:

List the materials you use for your experiments. This is a sample:

  • steak knife
  • uncooked chicken wing bone
  • pure white vinegar: acetic acid(4 mol/dm3)
  • hydrogen peroxide
  • titration materials
  • gloves (optional)
  • Calcium hydroxide and other calcium solutions such as calcium citrate, calcium acetate.
    Decalcified bone
  • One Jar for each calcium solution.
  • Nails
  • Spring Scales

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

What did you find out in the experiment 1, Bone decalcification?

When you bent the bone each day, did you realize that the bone is getting more and more flexible? This is because there is less calcium phosphate in the bone each day.

Possible Re-Calcification results

What are the possible results and how do we analyze them?

Possibility 1: the bone still remained soft & flexible

If this happens, we can explain that the chicken bone is no longer “active” (because it is dead). As a result, the chicken bone cannot absorb calcium anymore.

This is likewise with our bone. Before 35, our bones are growing and constantly need calcium to be firm and rigid. However, after the age of 35, our bones can no longer take in calcium.

This is, however, not an excuse to stop taking in calcium. Why? When we do not take in calcium, our calcium level in the blood goes down. To maintain the calcium levels, our body has no choice but to take calcium from our bones. However, after 35, our bones can no longer take in calcium to replace the lost calcium. As a result, we can suffer from diseases like osteoporosis.

Hence, in order to make sure our body is not ‘forced’ into taking calcium from our bones, we must take in enough calcium everyday.

Possibility 2: the bone becomes hard again and it may also gain some weight

If this happens, we can explain that certain types of calcium compounds are able to provide the necessary calcium back to the bone and increase the bone density.

It is then important to identify such compounds and the conditions in which they are effective. It is also important to do bone density tests and consume additional calcium when needed.


Write your calculations in this section of your project guide. For example you will need to calculate the average of hardness or strength for the two bones in each jar.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.


Visit your local library and find some related books in the biology section. You are looking for the books that discuss the structure of the bone, compounds of the bone and the bone growth. You may also review some nutrition books that discuss the bone minerals.

Following are some helpful links:

Experiment: Effect of soda drinks on the bone minerals

Healthy Bones

Calcium supplements

USC Health Magazine

National Osteoporosis Foundation
1232 22nd Street, NW
Washington, DC 20037-1292

National Institutes of Health
Osteoporosis and Related Bone Diseases~National Resource Center
2 AMS Circle
Bethesda, MD 20892-3676
1-800-624-BONE (1-800-624-2663)
202-466-4315 (TTY)

National Library of Medicine
In Health Topics, go to:

The National Institute on Aging has information on health and aging, including a booklet and video about exercise for older people and several helpful Age Pages. Contact:

National Institute on Aging Information Center
P.O. Box 8057
Gaithersburg, MD 20898-8057
1-800-222-4225 (TTY)

To order publications (in English or Spanish) online, visit www.niapublications.org

The National Institute on Aging website is www.nia.nih.gov

Visit NIHSeniorHealth.gov (www.nihseniorhealth.gov), a senior-friendly website from the National Institute on Aging and the National Library of Medicine. This simple-to-use website features popular health topics, including exercise, for older adults. It has large type and a “talking” function that reads text aloud.