Bone Health: A Review

The trend in western medicine has been to use supplements to fix nutritional deficiencies. When it comes to improving bone health, it was claimed that calcium would do the job, then magnesium, then Vitamin D, and now vitamin K.  Though all of these are integral to the human body, supplementing them is like giving a car an oil change when it is out of gas. Fortunately, there is a new holistic trend focused on blending nutrition and medicine.  It is becoming more widely accepted that broader lifestyle choices, including exercise and a balanced diet, provide a healthier framework than supplementation. Supplements can be beneficial at times, but it is important to understand when and why they are used.

How is calcium related to bone health?

It is widely accepted that calcium supplementation is directly responsible for improved bone health.  However, despite the numerous research studies showing improvements of bone density with calcium and vitamin D supplementation, rates of osteoporosis have not improved.  In fact, the United States has the highest rate of dairy and calcium consumption in the world and yet, according to the National Osteoporosis Foundation, the United states represents 44 million people, or nearly 1/4 the cases of osteoporosis in the entire world. 

How can this be?  The problem we run into is that one research study shows that calcium improves bone density and the next claims that calcium causes heart attacks, without improving bone health.  As a general rule, there will always be ''studies'' to support any theory.  The truth is that many foods provide calcium and many interact with calcium. Consuming dairy and calcium supplements for bone health is not enough. On the other hand, avoiding dairy based on one research study is not valid either.  Given the complexity of the human body and food, it is impractical to attempt to improve health through only a few variables.  Our bodies need innumerable nutrients from a variety of sources.

The only real solution to bone health comes from a balanced diet of whole foods.  If you are still worried about calcium intake, consider the following list of whole foods which provide ample amounts, as well as hundreds, if not thousands of other micro-nutrients needed by our bodies.

Calcium Per Serving of Various Foods

Produce	Serving Size	Estimated Calcium*
Collard greens, frozen	8 oz	360 mg
Broccoli rabe	8 oz	200 mg
Kale, frozen	8 oz	180 mg
Soy Beans, green, boiled	8 oz	175 mg
Bok Choy, cooked, boiled	8 oz	160 mg
Figs, dried	2 figs	65 mg
Broccoli, fresh, cooked	8 oz	60 mg
Oranges	1 whole	55 mg
Seafood	Serving Size	Estimated Calcium*
Sardines, canned with bones	3 oz	325 mg
Salmon, canned with bones	3 oz	180 mg
Shrimp, canned	3 oz	125 mg
Dairy	Serving Size	Estimated Calcium*
Ricotta, part-skim	4 oz	335 mg
Yogurt, plain, low-fat	6 oz	310 mg
Milk, skim, low-fat, whole	8 oz	300 mg
Yogurt with fruit, low-fat	6 oz	260 mg
Mozzarella, part-skim	1 oz	210 mg
Cheddar	1 oz	205 mg
Yogurt, Greek	6 oz	200 mg
American Cheese	1 oz	195 mg
Feta Cheese	4 oz	140 mg
Cottage Cheese, 2%	4 oz	105 mg
Frozen yogurt, vanilla	8 oz	105 mg
Ice Cream, vanilla	8 oz	85 mg
Parmesan	1 tbsp	55 mg

How does acidity affect bone health?

Bones are more than just repositories for calcium.  In fact, calcium exists all throughout our body as a catalyst/signal for numerous life-dependent chemical reactions.  Much of this calcium is stored in the bones and kidneys and without proper nutrition; some of these stores are tapped.  One of the theories explaining the decrease in bone density is that acidic food from high protein (animal/grain) causes a net acidic load to the body.  Others propose that this is caused by high phosphate levels.  To balance pH, the body reabsorbs calcium from the bones and kidneys. Proponents of this theory suggest eating a diet with a net alkaline load to the body, high in vegetables and low on animal protein.

The theory has sparked controversy and numerous studies.  The main counter argument maintains that pH is balanced through respiration of CO2 and reabsorption of calcium from the kidneys.  However, studies have shown that an acidic diet causes a net calcium loss from the body (through urination).  Whether from the kidneys or bones, one fact is clear; calcium is leaving the body. With this in mind, maybe we should focus on retaining calcium more than supplementing it.   

To limit the amount of acidic foods in your diet, use the ''Potential Acid Renal Load'' scale, or PRAL. PRAL lists the major foods and their net acidic or alkaline load to the body.  The following chart shows the PRAL of many foods.  Interestingly, even those who counter the acid-base theory admit that a high alkalinity diet will necessarily mean eating more fruits and vegetables, which will thus improve health.

Major Food Groups	Avg PRAL (per 3.5 oz /100 g)
Fruits	-4.44
Vegetables	-2.78
Beverages	-1.23
Fats and Oils	0
Milk and Non-Cheese Dairy	0.95
Bread, Grains	5.73
Eggs	8.21
Fowl and Fish	8.45
Meat	8.38
Meat, Processed	11.42
Cheese, Soft	4.51
Cheese, Hard	19.22

Conclusion

Bones are composed of more than just calcium.  The connective tissue that stores calcium and other minerals is known as the ''matrix''.  When the matrix is unhealthy, osteoporosis occurs.  This is shown in the fact that countries such as Bhutan and China with populations who consume as little as 200 mg of calcium per day often have greater bone density/health than western societies consuming 1000-3000 mg/day.  Statistics like these prove that bone health is regulated by more than just calcium.

Secondly, an acidic diet (PRAL) erodes bones by chronically stealing calcium from the body to balance the pH of the bloodstream. To neutralize this potential threat, the solution is to eat alkaline foods. Though this theory is contested, an increase in alkaline vegetable and fruit intake would improve bone health by providing calcium as well as numerous other minerals and enzymes necessary for the optimal health of the bone matrix.

Lastly, it is important to recognize the physical activity may be even more important to bone health than either of the above two conflicts.  It has been shown numerous times that the physically active have a much lower chance of developing osteoporosis. So go for a walk and get creative with your meals! 

Blog post by J.T. Thompson.