Tuesday, April 20, 2010

Vitamin K in Bone Health

Phylloquinone (vitamin K1) is in foods of plant origin, especially leafy greens and soybean, canola, and olive oil. Menaquinone (vitamin K2) includes multiple forms found in cow’s liver, some meats, and products of bacterial fermentation such as cheese, natto, and miso. Little is known about the contribution of menaquinones to vitamin K status and while initially thought that 50 percent of the daily requirement for vitamin K was provided by intestinal flora, there is insufficient evidence to support this (Booth, 2003).

The different vitamin K entities have tissue-specific distribution. Liver, the main storage site, contains longchain menaquinones (MK-7 through MK-13) and a minor amount of phylloquinone. In plasma and bone, the major forms are phylloquinone followed by short-chain menaquinones MK-4 through MK-8.

The only known biochemical role for vitamin K is as a cofactor in carboxylation of specific glutamate residues in certain proteins. Finding vitamin K-dependent proteins in the skeleton lead to the hypothesis that vitamin K has a role in bone (Booth, 2003). Furthermore, α–carboxyglutamyl residues in these proteins provide mineral binding properties. There are at least three vitamin K-dependent proteins in bone and cartilage; osteocalcin, matrix gla protein, and protein S. Osteocalcin, the best understood of the three, is synthesized by osteoblasts during bone matrix formation. Its hydroxyapatite-binding capacity is associated with α-carboxylation of glutamate residues 17, 21 and 24; carboxylation of residue 17 is required for the conformation that allows binding of osteocalcin to hydroxyapatite.

Percent undercarboxylated Osteocalcin (ucOC) is a marker of vitamin K status. However, an inverse relation exists between serum 25(OH)vitamin D and ucOC. Thus, controlling vitamin D status is important when assessing the impact of vitamin K on bone health (Booth, 2003). Until recently, supporting evidence of a role for vitamin K in age-related bone loss was largely based on associations between dietary intakes or biological markers of vitamin K status and bone mineral density (BMD) or hip fracture. Randomized controlled trials (RCT) attempt to determine whether vitamin K1 has a role in the prevention or treatment of osteoporosis.

This article summarizes four key RCTs of vitamin K1 with dose ranging from 200 ug to 5000 ug per day (1-4). Three trials studied postmenopausal women while the fourth studied older women and men; these studies controlled vitamin D and calcium intakes (previous Vitamin K1 trials have not always done so). Furthermore, subjects started with comparable vitamin K status in all studies and vitamin D status in three of the studies. All studies followed BMD; unfortunately only one also monitored fracture incidence.

Giving vitamin K1 at 200 ug and 5000 ug per day appeared to have a positive effect on bone (1,2). Subjects treated with 200 ug showed a continuous significant increase in BMD over 6 months at the ultradistal radius. Fracture incidence was lower with a 5000 ug vitamin K1 treatment despite no effect on bone density. Vitamin K’s effect may have been on bone microarchitecture. However, since very few subjects had fractures, the observed difference in fracture rate may have occurred by chance. In a third study (3) where vitamin D status was not assessed, 1000 ug of vitamin K1 had no effect on BMD. Finally in a fourth study (4), 500 ug vitamin K1 had no effect on BMD. Larger trials including a range of K1 doses. with fracture as an endpoint and side effect monitoring, are needed.

Implications for Counselling Patients:

In my work at the Osteoporosis Program I am seeing an increasing number of patients taking calcium supplements including vitamin K with marketers stressing its importance in bone health. The typical dose of 50 ug/tablet is so paltry that I feel obliged to explain that a serving of leafy green vegetables provides 200 – 300 ug vitamin K along with many other nutrients and health benefits. I clarify how little their supplements provide in relation to the levels being tested in RCTs.

I also see patients taking anticoagulants who have the misconception that they should avoid all leafy greens because their vitamin K content will interfere with anticoagulation. I recommend to them the need for reasonable consistency in intake of leafy greens from day
to day rather than avoidance.


Binkley N, Harke J, Krueger D, Engelke J, Vallarta-Ast N, Gemar D, Checovich M, Chappell R, Suttie J. (2009). Vitamin K treatment reduces undercarboxylated osteocalcin but does not alter bone turnover, density or geometry in healthy postmenopausal North American women. Journal of Bone and Mineral Research. 24:983-991.

Bolton-Smith C, McMurdo M, Paterson C,Mole P, Harvey J, Fenton S, Prynne C, Mishra G, Shearer M. (2007). Two-year randomized controlled trial of vitamin K1(phylloquinone) and vitamin D3 plus calcium on the bone health of older women. Journal of Bone and Mineral Research. 4: 509-19.

Booth S L. (2003). Dietary vitamin K and skeletal health. In: Nutritional aspects of bone health., The Royal Society of Chemistry: Cambridge, UK.

Booth SL, Dallal G, Shea MK, Gundberg C, Peterson JW, Dawson- Hughes B. (2008). Effect of vtamin K supplementation on bone loss in elderly men and women. Journal of Clinical Endocrinology and Metabolism. 93: 1217-1233.

Cheung A, Tile L, Lee Y, Tomlinson G, Hawker G, Scher J, Hu H, Vieth R, Thompson L, Jamal S, Josse R. (2008). Vitamin K supplementation in postmenopausal women with osteopenia (ECKO Trial): A randomized controlled trial. Public Library of Science Medicine. 5(10): 1461-1471.


Debbie Reid, MSc, RD
BC Women's Hospital and Health Centre
Vancouver, BC
E: dreid@cw.bc.ca

Wednesday, April 7, 2010

From Meal Trays to Dining Room…

Sunnybrook Health Sciences Centre houses Canada’s largest veteran population, providing long term and complex continuing care to approximately 500 elderly veterans. In June of 2007, six Nursing Home units, representing 204 beds in the Veterans Centre, were converted from tray meal service to a bulk meal service dining room to align with the Ontario Ministry of Health and Long Term Care Dietary standards. The project presented a unique opportunity, not only because of the size of the population involved, but because most other long term care facilities offering bulk meal service have done so from the time of opening and rarely undergo a change in service model.

As dietitians working in food services our priorities are meeting nutrition standards, menu planning, meeting fiscal responsibilities, and patient/resident satisfaction. To evaluate that we met our objectives fo r this project, we retrospectively collected data pre – and post-implementation looking at nutritional parameters (e .g., weight, nutritional risk level , diet), financials, and food satisfaction. Converting to a bulk meal service did not appear to impact the residents’ nutritional status parameters, we were able to operate within our financial objectives, and our third party food satisfaction survey showed that changing the meal service model had no sustained impact on residents’ satisfaction with food. Despite achieving our food service objectives, the food serv ice team spent the majority of time addressing the unforeseen social outcomes of this change.

Adjusting to anything new takes time. The bulk meal service model had many benefits for residents, however, asking anyone to change their daily routine, especially around meals, inevitably results in some resistance. The new daily social interaction among residents at meal times allowed many relationships to flourish but also opened the door for conflict among others. Who sits with whom in the dining room was not an easy puzzle to put together. Waiting for tables to be served exposed residents to wait times that were previously less obvious when they ate in their rooms. Dietary restrictions were more visible to tablemates, and suddenly, residents started asking for specific food items of which they had not previously been aware. This phenomenon stimulated discussion among the care team about liberalizing the resident menu.

Despite the fact that forecasting, preparation, and production were done separately for each seating, having a ‘second seating’ at meals gave some residents the perception that ‘first seating’ received preferential treatment, and that those seated second were getting leftovers. Education with staff, residents and family members was necessary to dispel this myth.

The bulk meal service was implemented in phases bringing on one nursing unit per week over four weeks so that we could focus on the particular needs of each unit. Unique challenges surfaced when the implementation took place on the Cognitive Unit. Continuity is important for these residents; they may not be able to recall yesterday’s events but adapt well to routines. One resident, when offered a choice of two entrées replied, “I don’t want either, I just want my lunch tray”. Where family members previously made menu selections for residents with the tray service, some residents appeared overwhelmed having to shift to making seemingly simple food choices three times a day. Over time, the bulk meal service became routine and these challenges now seem to be non-issues. All of our experiences during the implementation prompted good discussion between our department and the care team about dining room philosophy and creating a home-like environment. Dining ‘ground rules’ for processes and conduct for both staff and residents continues to be a work in progress to improve the quality of the dining room experience.

Resident satisfaction with the bulk meal service was of high importance for both our department and for the organization in evaluating the success of the project. Despite the fact that there does not appear to be a difference in resident satisfaction over the long term, it is important to note that the satisfaction survey primarily assessed operations and food services para meters (e.g., quality, timeliness, temperature ). The potential impact of a dining environment and mealtimes on other factors related to quality of life cannot be discounted.

Lessons learned from this project:

1. Get to know the population and consider the social impact of the change for the residents and families;

2. Consider a broader survey tool to evaluate the impact of changing the meal service model on residents’ quality of life;

3. Recognize the value of ongoing communication with the residents and families; and,

4. Be patient!


Alexa Edmonstone, RD
Clinical Dietitian
E: alexa.edmonstone@sunnybrook.ca

Ann Robertson, RD
Director, Food Services

Sunnybrook Healthcare Food Services

E: ann.robertson@sunnybrook.ca