Parathyroid hormone and magnesium: when “normal” is not always a good thing

This week, I’m at the 2009 national meeting of the American Society for Bone and Mineral Research in Denver, Colorado, learning about the most recent findings in bone research. I wanted to pass along an intriguing bit of information about magnesium deficiency and bone health.

If you’ve been following our work at the Center for Better Bones, you know that I often suggest clients be tested for both vitamin D and parathyroid hormone (PTH) levels. This is because low vitamin D levels can lead to high PTH, a condition that depletes bone.

Here’s how it works: when vitamin D is deficient, we cannot absorb enough calcium from our food to keep our blood calcium levels high enough to support our health. To achieve the necessary blood calcium level, the parathyroid gland releases PTH, which breaks down bone to release stored calcium for transfer into the blood. If this bone breakdown action continues over time, excessive bone loss can occur. In these cases, appropriate supplementation with vitamin D increases calcium absorption from food, which reduces the production of PTH. Normal PTH levels prevent excessive bone loss.

So when can a normal PTH level be a bad thing? When it’s caused by magnesium deficiency! People who are deficient in magnesium do not produce parathyroid normally even if their vitamin D levels are very low. I have seen such cases at the Center for Better Bones, where a person comes to me with low vitamin D status and yet has normal PTH.

In these cases, supplementing with vitamin D will help, but the magnesium deficiency needs to be addressed, too. Magnesium supports bone health on many levels, including stimulating the production of the bone-preserving hormone calcitonin and properly forming calcium crystals in bone. The best way to regulate production of PTH is by providing the body with the nutrients it needs to function well — especially vitamin D and magnesium. With ample nutrition, your body will naturally maintain healthy blood calcium levels while building strong bone — and your PTH will stay at a normal level for the right reasons!

Update on prunes reversing bone loss

It is September 13, 2009, and I am at the largest U.S. meeting of bone researchers (the American Society for Bone and Mineral Research meetings in Denver), and I am pleased to give you a follow-up report on prunes and their amazing ability to reverse bone loss.


At this year’s meeting, Professor Bahram Arjmandi and colleagues presented hot-breaking research findings on their one-year human trial testing the potential of prunes to reverse bone loss in postmenopausal women. As you might recall from earlier blogs, Dr. Arjmandi is studying 144 osteopenic postmenopausal women, simply giving them 100 grams of dried prunes daily (10-12 prunes each day) and looking for changes in bone mineral density.


The early data is in, and it looks good! The first data from the year-long trial was presented today at the ASBMR Meeting, and the findings include a significant increase in ulna and spine bone mineral density in the women who ate the prunes. As Dr. Arjmandi and colleagues write, “The findings of this one-year study confirm our earlier observation that dried plum has the ability to reverse bone loss.”


While the prune-associated hip bone density changes are not yet tabulated, Dr. Arjmandi has high expectations. Previously, he reported several cases showing hip bone density increases from prunes to be even greater than the spinal density gains.


Needless to say, I will keep you posted on the hip density increases as they are published. In the meantime, why not share with me and all readers your favorite recipes for adding 10-12 prunes to your daily diet?


Vitamin D is more important than calcium

Recently, data from a study of 10,000 Americans supported once again our contention that vitamin D is more important to bone health than is calcium. Even more, this new research suggests that high calcium intakes only aid bone density in those with very low vitamin D status.

Data from the U.S. National Health and Nutrition Examination Survey (NHANES III) published in early 2009, found that calcium intakes of 566 mg per day among women and 626 mg per day among men are likely adequate for those not burdened with low vitamin D levels. Among women only in those very low vitamin D levels (20 ng/mL or less) was there a positive association between calcium intake and bone density. Among women with a greater than 20 ng/mL vitamin D level, a calcium intake of over 566 mg per day was not associated with better bone density than that of women on just 566 mg calcium. Among men, calcium intake was not associated with bone density at any level of vitamin D studied.

So, if we need less calcium than previously thought, a good next question is, “Does higher calcium intake really prevent fractures, anyway?” The authors of this study answer that very question — and their answer is no. Summarizing the findings of more than a dozen large studies, they note the clear lack of association between calcium intake and osteoporosis fracture risk. In fact, a recent, large meta-analysis found higher calcium intakes to actually increase hip fracture risk. For further discussion of these recent findings on calcium intake and fracture see my blog post, “Higher calcium intake does not prevent fractures.”



Bischoff-Ferrari, HA, et al. 2009. Dietary calcium and serum 25-hydroxyvitamin D status in relation to BMD among U.S. adults. J of Bone Miner Res, 24(5):935-942.

Weak bones in vegetarians?

You might have seen the recent news headlines proclaiming that “Vegetarian Diet Weakens Bones.” This headline, which was published by news sources all around the world, stemmed from an overview analysis (known as a “meta-analysis”) of nine published studies which compared the bone density of vegetarians and omnivores. From the way the news headline was written, you would think that the researchers had found compelling evidence that vegetarians had weaker bones, lower bone density, and increased risk of fracture. The research findings, however, found that vegetarians as a group had only a slightly lower bone density than omnivores and that this difference was neither clinically significant nor likely to result in increased fracture risk. Once again, the wise consumer is advised to look beyond the headlines and sort research facts from journalistic fiction.


The story for vegans (vegetarians who eat no flesh foods nor consume any animal products such as eggs or dairy) is a different issue. This new meta-analysis, as in previous individual studies, found that vegans exhibit significantly lower bone density than either vegetarians or omnivores. Vegans have also been noted to have lower body weight and reduced intakes of protein and calcium.


And what about the fracture risk of vegetarians and vegans? At the Center for Better Bones, our focus is on fracture risk, not bone density, and while this new study did not address fracture risk, other studies have done so. For example, in 2007, the large European EPIC–Oxford study reported the risk of fracture to be similar for meat eaters, fish eaters, and vegetarians, whereas vegans as a group had a 30% increased risk of fracture. I suspect that low body weight combined with sub-optimal intakes of protein, calcium, and bone-building minerals place vegans at higher risk of fracture, even though they, as other vegetarians, likely have a reduced acid load. This line of thinking is supported by the additional EPIC-Oxford finding that vegans who consumed more calories and at least 525 mg of calcium per day had a fracture rate nearly similar to egg- and milk-eating vegetarians and omnivores.



Ho-Pham, LT, Nguyen, ND, Nguyen, TV. 2009. Effect of vegetarian diets on bone mineral density: A Bayesian meta-analysis. Am J Clin Nutr 90:1-8.

Appleby, P, Roddam, A, Allen, N and Key, T. 2007. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr 61:1400-06.


Prunes and osteoporosis: Your questions answered

My recent blog on the bone-building action of prunes drew a lot of attention and generated several interesting follow-up questions. Let me answer your questions as best I can.

Q. Wouldn’t eating 9-10 prunes a day cause diarrhea and/or gas?

A. As we well know, prunes have a laxative effect. The studies using 9-10 prunes a day, however, found that if people introduce the prunes slowly, taking a few to start and adding more over time, they do not experience excessively loose stools. Also, at the Center for Better Bones we find that soaking or lightly cooking the prunes also helps improve their digestibility, as does eating them warmed a bit, if necessary. Another tip is to spread your prunes out over at least 2 meals. Incidentally, prunes make a tasty dessert or sweet addition to hot cereal.

Q. Will eating all these prunes each day cause me to gain weight?

A. As it appears, consuming prunes did not cause weight gain and, in fact, prune researcher, Dr. Bahram Arjmandi specifically addresses this question, suggesting that prunes are so satisfying that they can actually aid in weight control. Also, recent work at the San Diego State University found snacking on prunes twice a day curbed the appetite while improving blood lipids, which actually aids weight management.

Q. I try to keep my blood sugar under control. Wouldn’t eating these prunes harm my blood sugar?

A. As Dr. Arjmandi reports, “Because prunes are low on the glycemic scale, they should not be a problem for people with diabetes.”

Q. Does drinking prune juice have the same effect as eating prunes?

A. All of the research I have found uses whole prunes, so I have to say that we simply do not know if prune juice would have the same bone-building impact.

Q. You list prunes as being an “acid-forming food.” So how can they help bones?

A. We have to remember that foods have many qualities, and not all acid-forming foods are bad for bones. In fact, protein is acid forming and yet adequate protein is essential for optimum bone health. Although prunes are slightly acid-forming, they contain phenolic and flavonoid plant compounds, which increase bone growth factors, so overall their impact on bone is very positive.


Can prunes reverse bone loss?

My friend and fellow osteoporosis researcher Dr. Bahram Arjmandi says yes, the humble prune can reverse bone loss, and his research data is looking strong. For more than a decade Dr. Arjmandi of Florida State University in Tallahassee has tested a wide variety of “functional foods” for their potential impact on bone health. He has studied soy, blueberries, strawberries, raisins, dates, and finally prunes. No other natural substance, he reports, comes near to having the bone-building effect of prunes. Further, when I saw him at the ASBMR international bone meeting last fall, he reported he had never seen any natural substance produce such consistent beneficial bone-building results.

prunes-5b1-5dDr. Arjmandi’s several successful animal and human studies document that special phenolic compounds in dried plums up-regulate growth factors linked to bone formation (such as IGF-1) and counter the activity of factors that inhibit bone formation (such as TNF-alpha). It probably also helps that prunes are one of the foods highest in antioxidants and also contain generous amounts of various key bone nutrients including potassium, boron, and copper. While Dr. Arjmandi has found other natural substances capable of halting bone loss, prunes were the only food found to actually restore lost bone.

This summer Dr. Arjmandi and colleagues will complete a landmark, controlled human clinical trial on prunes and bone health. For this study, 120 post-menopausal women have been taking either 100 grams of prunes (9-10 a day) or an equivalent portion of dried apples for one year. While it will be a few more months before all the research data is in, thus far 30 women in the prune group have had at least a 6% increase in hip bone, and one woman had an exceptional 11% increase consuming prunes over the year. Preliminary data from a segment of research subjects found that all prune-eaters showed at least some improvement in bone mass by six months into the study. [update on this study can be found here]

For several years I have heard Dr. Arjmandi speak of his prune research and read many of his research articles. It makes sense: if you could limit factors that hinder bone formation, such as inflammation and oxidative stress, and at the same time up-regulate new bone formation growth factors, and provide key bone nutrients, you could well accomplish the unthinkable and stimulate new bone formation with a simple, wholesome food substance.

At the Center for Better Bones, a group of us (including myself) are doing our own “prune experiment.” If you are inclined to join us, take Dr. Arjmandi’s advice and start slowly with a few prunes a day, working up to the full 9-10 over time. I have found soaked or stewed prunes are easier to digest, and Dr. Arjmandi has found that prunes do not lead to either weight gain or increased blood sugar levels. Also they should help build new bone in men as well as women.



Arjmandi, BH et al. 2002. Dried plums improve indices of bone formation in postmenopausal women. Journal of Women’s Health & Gender-Based Medicine, 11:61-68.

Hooshmand, S and Arjmandi, BH. 2009. Viewpoint: Dried plum, an emerging functional food that may effectively improve bone health. Ageing Res Rev, Apr 8:122-7.


Declining nutrient content of US foods

When we eat a carrot or apple today are we getting all the nutrients we have been told the food contains?  The answer is no.  According to the data collected by the USDA (U.S. Dept. of Agriculture), today we would need to eat five apples to get all the same nutrients that one apple contained in 1965. The same USDA data reported significant loss of minerals in both vegetables and fruits between 1940 and 1991. Some of the mineral reductions in vegetables and fruits were reported as below.

(Mineral Reductions from 1940 to 1991)


  • Potassium: -16%
  • Magnesium; -24%
  • Calcium; -46%
  • Zinc: -59%
  • Copper -76%
  • Iron: -27%
  • Sodium: -49


  • Potassium: -19%
  • Magnesium; -16%
  • Calcium; -16%
  • Zinc: -27%
  • Copper -20%
  • Iron: -20%
  • Sodium: -29

Many factors contribute to this loss of nutrient content. These factors include modern farm methods, soil depletion, the use of pesticides and herbicides, and imbalanced fertilizers.


Potassium: The great unknown bone protector

Potassium is a “hidden,” yet great, bone builder due to its role in protecting bone from the ravages of metabolic acidosis. As it occurs, the typical Western diet leads to an accumulation of excess acids in the body. These acids must be buffered (i.e., neutralized) for the body system to maintain its all important acid-alkaline, pH balance.

Without a precise, slightly alkaline blood pH, the body cannot survive. To maintain this essential minute-to-minute pH balance the body first looks to the blood, tissues, and extracellular fluids for buffering compounds. When these are exhausted, the body readily draws alkaline mineral compound reserves from bone to buffer these life-threatening metabolic acids. Potassium in the form of potassium citrate from vegetables and fruits, beans, nuts, and seeds is the major dietary source of acid neutralizing alkaline compounds.

It is interesting to note that the RDA for potassium is 4,700 mg, nearly six times that of calcium. The average adult intake, however, is only 2,300 mg for women and 3,250 mg for men. Several studies have documented that bone loss in menopausal women can be halted by neutralizing low-grade chronic metabolic acids with potassium. If you are interested in these studies, see the research articles cited below.

Potassium plays an essential role in neutralizing metabolic acids. In this capacity, it protects bone. With adequate dietary potassium intake, the skeleton does not need to sacrifice itself in order for the body to maintain systemic pH balance. Given this important fact, it is likely that dietary potassium is as important as dietary calcium for long-term bone strength.



Brown, S.E. and Jaffe, R. 2000. Acid-alkaline balance and its effect on bone health. International Journal of Integrative Medicine, 2(6), 7-15.

Frassetto, L. et al. 2005. Long-term persistence of the urine calcium-lowering effect of potassium bicarbonate in post-menopausal women. Journal of Clinical Endocrinology and Metabolism, 90(2), 831-834.


High-dose vitamin K: New-found protection from bone fracture and cancer?

In September of 2008, I attended the large American Society for Bone Mineral Research Meeting held in Montreal, Canada. Generally these meetings are dominated by pharmacological approaches to bone health, but, looking at the big book schedule of lectures, I was delighted to find an entire session on vitamin K.

In this session, several of the top vitamin K researchers reported with disappointment their findings that vitamin K did not seem to improve bone density. I was not too upset by this finding, and really did not expect vitamin K to increase bone density much. Previously, French researchers and others had already noted that higher vitamin K status was inversely correlated with fracture incidence independent of bone density. What I did not expect, however, were the astonishing findings regarding dramatic reductions in both fracture and cancer in postmenopausal women given daily 5 mg of vitamin K1 over 2 to 4 years. The placebo-controlled study, known as the ECKO trial, was conducted by researchers from the University of Toronto, and involved 440 postmenopausal women with osteopenia.

The primary goal, or endpoint, of the study was to see if high dose vitamin K1 (5 mg/day) would increase bone density. The secondary endpoint included changes in bone turnover markers, height, fractures, adverse effects, and health related quality of life. While the study showed no significant changes in bone density over the 2-4 year period, fewer women in the vitamin K group had clinical fractures (9 as compared to 20, a 55% reduction in fractures) and fewer had cancers (3 as compared to 12, a 75% reduction in cancers). Although the study was not designed to test the ability of high dose vitamin K to reduce fractures and cancer, the findings certainly suggest this is a strong possibility.

Years ago at the Center for Better Bones, we identified vitamin D and vitamin K as the two most promising, yet most understudied, bone-building nutrients. The vitamin D story has exploded, as you probably know, and I am sure this remarkable vitamin K1 study and the growing documentation on vitamin K2 in the form of MK-7 are now fueling a vitamin K revolution.



Cheung, Angela, et al. 2008. Vitamin K supplementation in postmenopausal women with osteopenia (ECKO Trial): A randomized controlled trial, PLoS Medicine, 5(10):1461-1472.

What is the difference between vitamin D2 and vitamin D3?

Vitamin D3, also known as cholecalciferol, is the natural form of vitamin D for humans. Vitamin D3 is produced in the skin with sunlight exposure. Vitamin D2, known as ergocalciferol, is a compound produced by irradiating yeast with ultraviolet light.

A substantial body of research documents that vitamin D3 is the preferable form and researchers clearly recommend its use. Vitamin D3 has been found to be at least three times as potent as vitamin D2, and is more stable, safe, and useful in the body.

The less desirable vitamin D2 has been generally used in prescription vitamin preparations and in food fortification, while the nutritional and health food industries generally use the superior, natural vitamin D form, D3. Dr. John Cannell, vitamin D advocate and founder of the nonprofit Vitamin D Council, speaks of vitamin D3 in the following manner:

“If you take ergocalciferol, or “vegetarian” vitamin D, be warned. Ergocalciferol is not vitamin D, but a vitamin D-like patent drug whose patent has expired. It does not normally occur in the human body and is probably a weak agonist at the receptor site, meaning it may actually partially block vitamin D actions. Ergocalciferol is the villain in most of the reported cases of toxicity in the world’s literature. All bets are off in terms of measuring blood levels if you take ergocalciferol. Some of the labs can pick it up, and some can’t. Don’t take ergocalciferol; it is not vitamin D.” For more details, see Dr. Alan Gaby’s summary of the research comparing vitamin D2 and D3.



Interview with Dr. Cannell in the Townsend Letter for Doctors and Patients, November 2006, page 96.

Gaby AR. Vitamin D3 more potent than vitamin D2. Townsend Letter for Doctors and Patients, October 2005.