by Dr. Frank Jackson

Prebiotin Academy

Medical Concerns, Scientific Research and Diets

Calcium and Bone Density

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Dr. Jackson certainly was aware of the importance of proper gut health and the relationship between prebiotic fiber for that good gut health, and the absorption of calcium as it impacts bone density.

Read more about this topic: 

"Gut Microbiome and Bone Density Connection Found"
from September 24, 2023 for 


Scientific Research

The major actors in the gut microbiome are called short-chain fatty acids (SCFA). These substances are made in large quantities in the colon when the right bacteria, the Bifidus, and Lactose, are growing prodigiously. One of these SCFAs is called proportionate. This substance has been shown to reduce cholesterol. However, by far the star SCFA is butyrate. This is the substance that does many good things in the colon and beyond. It is the nutrient for the colon cells themselves. It heals the colon wall and may reduce a leaky gut. A leaky gut allows unhealthy substances and inflammatory factors to slide through and into the blood stream. Some of these end up in the wall of the coronary arteries where they do not belong. The article below reviews these facts.

A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents.

The next question of where in humans the calcium was absorbed and this was answered in 2007 in the following article. It is in the colon and prebiotics were the reason it occurred.

An inulin-type fructan enhances calcium absorption primarily via an effect on colonic absorption in humans.

Of course, a most important question to be answered would be what happens to post-menopausal females who are prone to osteopenia and osteoporosis. The following article answeres this question. These older females did increase their calcium absorption when they took the prebiotic oligofructose-enriched inulin.

Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women.

This very solid research means that this specific prebiotic, oligofructose-enriched inulin can be recommended to both the young when their bones are actively growing and to the postmenopausal females to enhance bone health.


Osteoporosis Dietary Therapy


Calcium is essential to the body.  It is the most common mineral in the body and is needed in tiny amounts for the function of most vital organs such as heart and brain.  However, the vast majority of calcium is used by the bones and teeth.  During early childhood and adolescence, vigorous bone growth occurs.  However, bone is a living tissue and calcium leaves the bone as new bone is being created.  By the mid 30’s, a shift occurs whereby more calcium begins to leave bone than is deposited.  Bones begin to weaken.  In the earliest stages, this is called osteopenia.  As it worsens, it becomes osteoporosis.  This is when bone fractures of the hip and spine begin to occur.  It is never too late to reverse this process, though starting early in life and when young will give you the best chance of having strong bones later in life.

Vitamin D

Vitamin D is also essential to bone health. It encourages absorption of calcium. You get vitamin D from exposure of the skin to the sun, from a limited number of foods, and from dietary supplements. A remarkable recent finding is that there are receptors for vitamin D in many tissues other than the small intestine, where calcium from food is absorbed. These include muscles, brain, prostate, breast, colon, and immune cells. We have to believe that these vitamin D receptors serve a function since diseases in these organs have been associated with vitamin D deficiency.

Additionally, vitamin D levels have recently been found to be significantly low in many age groups. The previous recommendation of 400 IU per day is too low. The new recommendation is 800-1200 IU daily, especially for people who do not have significant skin sun exposure like the elderly or those who are inactive. Vitamin D is found in a limited number of foods such as cheese, butter, vitamin D fortified milk, oily fish, and eggs.

Vitamin D and calcium are intimately connected.  You need to have a good level of vitamin D in your blood to absorb and use calcium.  In Caucasian and light-skinned people, the sun’s rays will make vitamin D in the skin. Dark-skinned people and African-Americans need to get their vitamin D from foods and vitamin D pills.  This is important as vitamin D deficiency is very common.  For detailed information on vitamin D from the National Institutes of Health, Google search: Dietary Supplement Fact Sheet: Vitamin D.

Selected Foods High in Vitamin D

  • Cod liver oil
  • Salmon, Mackerel, Sardines, Tuna
  • Vitamin D enriched milk, fruit juices, yogurt

What To Do – The Good Things

  • Consume 1000-1500 mg of calcium per day in food and/or a supplement
  • Active lifestyle – walking, bicycling, gym workout, etc.  You want to stress your bones.  Weightlifting by itself does not do this very well.
  • Eat soluble plant fiber or take a prebiotic supplement.
  • No cigarettes
  • Moderate alcohol only
  • Check your medications with your physicians.
  • Moderate caffeine intake – coffee and sodas

Calcium Intake

By far, the most important consideration is to get enough calcium into your body every day.  A minimum of 1000 mg a day is recommended going up to 1500 mg a day when needs are high, such as in recovery from fractures, athletics, and pregnancy.  The chart below provides information on calcium content in various common foods.

Calcium Content of Foods

Food Serving Size mg of Calcium
Almonds 1/4 cup 94
Apple, Medium 1 10
Banana, Medium 1 7
Beef, Lean Ground 3 oz 9
Bok Choy, Cooked or Fresh 1/2 cup 80
Bread, White 2 slices 70
Bread, Whole Wheat 2 slices 40
Broccoli, Cooked or Fresh 1 cup 90
Cheese, American 1 oz 174
Cheese, Cheddar 1 1/2 oz 305
Cheese, Grilled Sandwich 1 371
Cheese, Gruyere 1 cup 287
Cheese, Mozzarella 1 ounce 207
Cheese, Ricotta 1/2 cup 337
Chicken Breast, Baked 3 oz 14
Collard Greens, Frozen/Boiled 1/2 cup 179
Cottage Cheese, 2% 1 cup 163
Cream Cheese 2 Tbsp 23
Cream, Half and Half 1 Tbsp 16
Custard, Baked 1/2 cup 149
English Muffin, Whole Wheat 1 175
Fig Bar Cookie 4 40
French Toast 1 slice 65
Halibut, Baked 3 oz 51
Hot Dog, Turkey 1 58
Ice Cream, Vanilla 1 cup 176
Kale, Cooked 1/2 cup 90
Macaroni and Cheese 1/2 cup 179
Milk, Instant (Dry/Nonfat) 2 Tbsp 105
Milk, Skim or 2% 1 cup 300
Molasses, Blackstrap 1 Tbsp 137
Mustard Greens, Cooked 1/2 cup 75
Oatmeal, Instant 3/4 cup 163
Orange Juice with Calcium 1 cup 300
Orange, Medium 1 52
Pasta, Cooked 1 cup 10
Pizza, Cheese 1 slice 111-147
Pudding Maded with Milk 1/2 cup 147-160
Rhubarb, Cooked 1/2 cup 167
Rice Beverage with Calcium 1 cup 150-300
Salmon 5 oz 278
Sardines 7 322
Sesame Seeds, Dried 1 Tbsp 88
Soy Beverage with Calcium 1 cup 250-300
Spinach, Cooked or Frozen 1/2 cup 122
Taco, Chicken 1 87
Tofu, Firm 1/2 cup 240
Tofu, Regular 1/2 cup 108
Tofu, with Calcium 1/2 cup 204
Waffle, Homemade 1 179
Yogurt, Frozen (Fat Free/Low Fat) 1/2 cup 105
Yogurt, Fruit 1 cup 315
Yogurt, Low Fat 1 cup 450

Sample Menu

 Breakfast Lunch Dinner

grapefruit, 1/2
high fiber cereal (5-10 gm/serving)
banana, 1/2 cup
whole wheat toast, 2 slices
low saturated fat spread, 2 tsp
jelly or jam, 1 Tbsp
skim milk, 1 cup
decaffeinated coffee/tea

vegetable soup, 1 cup
lean hamburger patty, 2 oz
whole wheat hamburger bun
sliced tomato, 2 oz
lettuce with dressing, 1 Tbsp
fresh fruit salad, 1/2 cup
oatmeal cookie, 1
non-calorie beverage

tomato juice, 1 cup
broiled chicken breast, 2 oz
herbed brown rice, 1/2 cup
broccoli spears, 2
cheese sauce, 1/4 cup
hard dinner roll, 1
low saturated fat spread, 1 tsp
carrot/raisin salad made with lite mayonnaise, 1/2 cup
frozen strawberry yogurt, 1/2 cup
skim milk, 1 cup

This Sample Menu Provides the Following:

  • Calcium - 1200 mg
  • Calories - 2120 Kcal
  • Protein - 84 gm
  • Fat - 54 gm
  • Carbohydrates- 326 gm
  • Sodium - 3130 mg

Calcium Supplements

There are many different forms of calcium preparations sitting on the pharmacy shelf. How do you decide which is best for you?  If you are getting, on average, 1000-1500 mg of calcium a day in your foods, you likely do not need a supplement.  However, to get this much calcium, the diet must be rich in dairy products such as milk, yogurt, some cheeses, and fish.  If you select a calcium supplement, below are some key facts to consider.

There are two main preparations of calcium:

  • Calcium Carbonate
  • Calcium Citrate

Calcium is also available as calcium lactate and calcium gluconate.

Elemental Calcium – This is an important term.  The label may say calcium 1000 mg, but the important term is “elemental calcium“.  This is the amount of calcium that is actually available from the preparation.  For instance:

  Weight Elemental Calcium
Calcium Carbonate 1000 mg 400 mg (40%)
Calcium Citrate 1000mg 210 mg (21%)


If you do not find the two words “elemental calcium” on the label, assume you must multiply the calcium weight listed by 40% for calcium carbonate and 21% for calcium citrate to get the true amount of elemental calcium.

  • Expense – Calcium carbonate is the least expensive.  Calcium citrate is more expensive per pill while providing only half the elemental calcium that carbonate preparation does.
  • When and how to take it – Take calcium carbonate with meals, no more than 500 mg at a time.  Twice a day is a reasonable dosing.  Calcium citrate can generally be taken with or without food.

Calcium and Vitamin D

Calcium is one of the most common elements in the body. Yet, we still need a regular ingestion of at least 1200 mg of calcium a day. Milk can provide much of this. The calcium in vegetables is not as readily available to the body. Colon cancer risk seems to be greater when a low amount of calcium is ingested. So, adequate calcium intake in the form of milk, dairy products, shellfish, and vegetables is recommended. Many physicians are now recommending calcium carbonate supplements up to 1200 mg a day to keep calcium intake at a good level.

Vitamin D has always been associated with calcium and strong bones. However, considerable new research on this vitamin has uncovered some remarkable findings.

  • Most tissues in the body, including colon cells, have receptors or attachment points for vitamin D. Hmm, that’s interesting. Why should there be vitamin D receptors on so many cells in the body beyond bone cells?
  • Vitamin D controls, either directly or indirectly, over 200 genes responsible for healthy cell growth. If enough vitamin D is not present, some of these cells may get a bit disorganized.
  • There is now significant research to suggest an anti-cancer effect with vitamin D.
  • There is recognition that vitamin D deficiency is widespread, especially in the temperate weather zones where sun exposure is variable. Sunlight makes vitamin D in the skin.

This is startling information. The blood level of vitamin D should be above 30 ng/ml. National experts are not in agreement on the amount of vitamin D needed to reach this level. Many experts think that 400 IU a day is too low and that at least 800-1200 IU a day should be taken. Toxicity from too much vitamin D is very rare. Check with your physician.