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.
It has long been suggested that smoking is directly toxic to bone, but the extent to which smoking increased fracture risk was uncertain. Now, a recent meta-analysis of studies from all over the world has found that smoking is associated with a significantly increased risk of hip and other osteoporotic fractures in both men and women. After adjusting for age and weight, the risk of hip fracture, for example, was 55% higher in smokers than in non-smokers.
Looking at the impact of smoking in another way, researchers Law and Hackshaw reported in 1997 that one hip fracture in eight is attributable to smoking, regardless of other risk factors.
Kanis, J.A., et al. 2005. Smoking and fracture risk: A meta-analysis. Osteoporos Int, 1(2), 155-162.
Law, M.R., Hackshaw, A.K. 1997. A meta-analysis of cigarette smoking, bone mineral density and risk of hip fracture: Recognition of a major effect. BMJ, 315, 841-846.
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.