Our Research – Does vitamin E help bone health?

Aging causes an increase in oxidative stress and inflammation in our bodies. Along with declining estrogen levels, these changes may lead to bone loss in postmenopausal women. The effects of estrogen on bone have been investigated in great detail, but not much is known about the effects of antioxidants and anti-inflammatory substances on bone. Since vitamin E has both antioxidant and anti-inflammatory properties, it may be beneficial to bones. In order to assess whether vitamin E can affect bone loss, our group studied the relationship between vitamin E and bone turnover markers in postmenopausal women. Bone turnover markers are chemicals in the body that can provide information about bone formation and bone resorption (bone loss) and are measured by either a blood test or urine test.  Bone turnover markers can be used in research studies to test the short term effects of diet on bone health. The bone turnover markers that we looked at were :  1) bone alkaline phosphatase (BAP) which is a bone formation marker in the blood and, 2) urinary N-telopeptides/creatinine (uNTx/Cr) which is a bone resorption maker in the urine.

In our study, we looked at relationships between blood levels of two forms of vitamin E and bone turnover markers in a sample of healthy postmenopausal women in the US who participated in a national survey in years 1999-2002. These two forms of vitamin E were alpha-tocopherol and gamma-tocopherol, and are described below in more detail:

Alpha-tocopherol: Has a high antioxidant activity and is the most common form in dietary supplements.

Unfortified food sources: sunflower seeds, almonds, hazelnuts, peanuts; sunflower, safflower and grapeseed oils; avocados; green vegetables

Gamma-tocopherol: Has a high anti-inflammatory property and is the major form of vitamin E in North American diets

Unfortified food sources: Pecans, peanuts; soybean and canola oils

We also looked at the relationship between alpha-tocopherol intake (data was not available for intake of gamma-tocopherol from food sources) from food and supplements and bone turnover markers.  It has been shown that high intakes of alpha-tocopherol from dietary supplements can lower blood levels of gamma-tocopherol. We do not know how this change can affect our health. The results of our study were published in June 2012 in the Journal of American Bone and Mineral Research.  There were no relationships between alpha-tocopherol intake from food sources and bone turnover markers. As expected, we found that women who used vitamin E supplements had high blood levels of alpha-tocopherol and low blood levels of gamma-tocopherol. These women also had lower levels of BAP (a bone formation marker). We found no relationships between blood levels of alpha-tocopherol and gamma-tocopherol and uNTx/Cr (a bone resorption marker). These results suggest that vitamin E supplements may not help bone health. More research is needed in this area to find out if vitamin E intake from food sources can improve bone health or not.

So what is the bottom line?  As long as you have a balanced diet, and do not overeat or completely eliminate one food group, you will not be causing imbalances in your blood levels of various nutrients. Also, unlike supplements, whole and unprocessed foods contain a mixture of different types of vitamin E as well as many other nutrients all of which may play a role in our health.  For example almonds are high in vitamin E but they are also high in calcium and magnesium two other important nutrients in bone health. In conclusion, we believe the best way to get nutrients, including vitamin E, is to get them from food sources.

 

http://www.ncbi.nlm.nih.gov/pubmed/22308007

By Maryam S. Hamidi, PhD and Hajera Khaja, M.Sc

Our director, Dr. Angela M. Cheung, has been awarded the Tier 1 Canada Research Chair in Musculoskeletal and Postmenopausal Health

Congratulations to our director Dr. Angela M. Cheung for being awarded the Tier 1 Canada Research Chair in Musculoskeletal and Postmenopausal Health! The Canada Research Chair program attracts and retains the world’s most accomplished and promising scientists. The focus of Dr. Cheung’s work is to improve the quality of life, health and healthcare of people with musculoskeletal conditions, especially postmenopausal women.

Dr. Cheung is a professor of medicine at the University of Toronto, a staff physician at the University Health Network and the founding director of Osteoporosis Program, Centre of Excellence in Skeletal Health Assessment and Women’s Health Program at the University Health Network and Mount Sinai Hospital.

We are all very proud to be part of her team.

UHN news release

Dr. Angela M. Cheung

 

Where goes research?

10714668_10152658896936355_1525971406_nWhen research is completed, its results don’t just stay in academic hallways – they end up being shared with other researchers, healthcare professionals and you, the public.

In part 1 of this blog, we’ll bare how researchers, including our group, share findings amongst themselves. This is a crucial step in science and without it, we would not be able to receive useful feedback from other researchers and would have much fewer opportunities to form new collaborations. Without this step, the progress in science would be stifled!

The main way to share research findings with other researchers is by publishing a study report in a scientific journal, which is typically read by other researchers and healthcare professionals around the globe. But, let’s back up a bit. Before sending our study report to a journal, we often present it at an international conference attended by other researchers and healthcare professionals.

First, we send a mini study description, called an abstract, to the conference leaders in hopes that it gets selected from thousands of other abstracts for a presentation. The conference leaders put together a group of experts who review all of the abstracts, but select only those studies that were according to the highest scientific standards and provide new information. This selection process is known as a peer-review. After weeks of waiting, we receive an email that lets us know whether or not our abstract got selected, and if the answer is “yes”, we then prepare for a presentation.

The BEST PART about these conference presentations is the passionate discussions that follow them! The conversations first start in the presentation rooms. This is where researchers present their work and the audience members ask questions and provide feedback, tips and ideas. Then, the conversations spill over to the coffee counters in the conference hallways, sidewalks and park benches, and phone calls, emails and in-person exchanges lasting years and even decades.

This is how we grow research collaborations ORGANICALLY. This is also how researchers, especially the young ones who are still in training, get to meet their peers and more established researchers and receive tips that help them write a better report for a scientific journal.

Our Osteoporosis Program at the University Health Network has just returned from one of the biggest conferences in the world that focuses on bone health. It is hosted every fall by the American Society for Bone and Mineral Research. Our group’s researchers, doctors and trainees attend this conference and present our home-grown studies, which are selected year after year from thousands of reviewed studies. This year, we were honoured to present the following topics:

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Dr Maryam Hamidi – oral presentation – Young Investigator Award winner
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Dr Olga Gajic-Veljanoski – oral presentation – Young Investigator Travel Grant winner
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Dr Andy Wong – poster presentation – Young Investigator Travel Grant winner

 

  • Vitamin K supplementation and bone health in older women with low vitamin K levels
  • Body frailty and fractures: roles of muscle and bone
  • Effects of heparin, a blood-clot medication, on women’s skeleton
  • Changes in bone on a high-resolution CT scan in people with arthritis of the spine
  • Bone density testing in kidney disease patients not yet on dialysis
  • A new way to improve the accuracy of bone CT scan
  • Osteoporosis treatment in men living in nursing homes
  • Characteristics of atypical thigh fractures on an x-ray and under the microscope
  • Complications of atypical thigh fractures identified by various tools
  • Similarities between atypical fractures occuring at both thighs
  • Issues with the treatment of atypical thigh fractures
  • Early detection atypical thigh fractures

 

 

Let us know if you have any questions or comments about what we shared with you here. In part 2 of this blog, we will impart how our research findings get shared with other healthcare professionals to help enhance patient care.

By Dr Luba Slatkovska and Kevin Chia
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Help tackle osteoporosis: donate or participate

Osteoporosis Program Report

The Osteoporosis Program was recently profiled in the UHN Arthritis Program Clinical and Research Report. The report highlights our fracture care and prevention study, The Bridge Study, and shows how our outreach through social media is helping to raise awareness of osteoporosis.

Click on the image below to read the full report.

Bridge Study-ACreport

 

To support the work of Dr. Angela Cheung and the Osteoporosis Program, please contact Anette Larsson at: anette.larsson@uhn.ca

Vitamin K and bone health (part 2)

In our last post, we introduced the different types of vitamin K and their dietary sources, and we also noted that vitamin K has some important functions in maintaining our bone health. The question then arises: can taking vitamin K supplements protect us from osteoporosis and fractures?

Our knowledge on whether vitamin K is involved in osteoporosis comes from two types of studies — observational studies and clinical trials.

What do observational studies show?

In observational studies, researchers study the relationships between people’s behaviours and how the behaviour affects certain things. In the case of vitamin K and bone health studies for example, the ‘behaviour’ could be eating a diet that is high or low in vitamin K and seeing if there is a relationship between the diet and bone mineral density (BMD) scores or number of fractures.

To date, the majority of observational studies on vitamin K and bone health have shown that an increased risk of fractures is linked to:

  • low levels of vitamin K in the blood
  • low vitamin K1 and low vitamin K2  from diet
  • high levels of the bone protein osteocalcin in its non-functional form (osteocalcin needs vitamin K to function properly)

It is important to note however that these results may not be fully reliable. Some things to keep in mind when thinking about these results are:

  • Many things can affect a person’s diet and their food choices including their age, level of education, income, taste preferences, health consciousness, and so on. These same things can also affect a person’s bone health.
  • If a person’s diet is low in vitamin K, it is often the case that their diet is low in fruits, vegetables, cheese, and yogurt (all of which are sources of vitamin K).
  • If a person’s vitamin K levels are high, this may be an indication that they are eating an overall healthy diet that is also high in many other nutrients which are good for bone health, such as calcium, magnesium, vitamin C etc. It is also possible that they are more health conscious and do not smoke, do not drink much alcohol, and exercise more, all of which are also good for bone health.

As much as researchers try to think about all of the above scenarios and take them into account when analyzing the data from their research, it is not possible to fully control for everything and isolate only the effects of vitamin K on bone health. It may be a combination of the all of these scenarios and not necessarily the vitamin K alone that is leading to fewer fractures.

What do clinical trials show?

Clinical trials give us stronger evidence to show that one thing affects (or does not affect) another thing. This is because in clinical trials we try to control certain elements before measuring the outcome. In the case of vitamin K trials, the participants are first randomly assigned into groups. Participants in one group get a vitamin K supplement and participants in another group get  a placebo pill with no vitamin K in it. Some studies can also have more than just two groups — for example, there can be 3 groups and the participants in each group may get a different dose of vitamin K. These groups usually take their assigned pills for a number of years and at the end of the study,  the researchers compare the BMD scores and the number of fractures in the various groups. These types of clinical trials can help us single out the effects of vitamin K.

Because many clinical trials have looked at the effects of the K vitamins on bone health in different populations (women with or without osteoporosis; women taking or not taking osteoporosis medications; women of different ethnic backgrounds etc.) and in different vitamin K supplement doses, they have given conflicting results. To  get a better sense of what all the data show, the best option is to do a meta-analysis, which is a type of study which combines the results of several individual studies and provides one overall result.

In the most recent meta-analysis of clinical trials that looked at vitamin K and its effect on BMD, after taking into considerations the differences in the patient populations and differences in the way the studies were conducted, the results showed that taking vitamin K supplements has no beneficial effects on BMD.

In the case of fractures, there are a number of clinical trials that suggest that vitamin K supplements may reduce risk of fractures. However, these studies all have weaknesses, making the results inconclusive. For example, a study with positive results that is often cited by proponents of vitamin K supplementation is ‘The Vitamin K Supplementation in Postmenopausal Women with Osteopenia’ trial. This clinical trial was conducted by our research group and we found that although there were no differences in BMD, there were fewer fractures in the group of women who were taking vitamin K1 supplements compared to the women in the placebo group. But because so few study participants had fractures, the difference between the vitamin K1 group and the placebo group could have been simply by chance and not actually due to the vitamin K1 supplement.

Conclusions

What we do not know at this time is if vitamin K supplements can help reduce the risk of fractures. This is a relatively new area of research and finding real answers can take a long time. More research is definitely needed, especially clinical trials that have a large number of participants.

At present, we do NOT recommend taking vitamin K supplements to prevent osteoporosis and fractures in postmenopausal women. We recommend eating a healthy diet that is high in vegetables and fruits, has about 2-3 servings of protein, and 2 servings of dairy per day. Such diets are high in vitamin K as well as many other nutrients that are important for bone health.


Reference: Hamidi MS, Gajic-Veljanoski O, Cheung AM. Vitamin K and Bone Health. J Clin Densitom 2013;16(4):409-13. doi: 10.1016/j.jocd.2013.08.017.

Vitamin K and bone health (part 1)

The idea of using nutritional supplements to prevent diseases has been gaining currency over the past several years. For osteoporosis, vitamin K has been getting a lot of attention because of its role in bone health. But can vitamin K supplements actually prevent osteoporosis? In a review article published recently in the Journal of Clinical Densitometry, our nutrition expert, Dr. Maryam S. Hamidi along with Dr. Gajic-Veljanoski, our clinical epidemiologist, and Dr. Cheung , a professor of medicine and the director of our program, survey the existing research literature on vitamin K and its effects on bone health. 

Background on vitamin K

vitamin KVitamin K is a fat-soluble vitamin that plays different roles in our bodies but  is mostly known for its role in blood coagulation.*

Vitamin K is not just one substance. It represents a group of compounds that are chemically very similar. There are two main forms of vitamin K — vitamin K1 and vitamin K2. Vitamin K1 is made by plants and is also the form of vitamin K that is most present in our diets. The main sources of vitamin K1 include green leafy vegetables, broccoli, brussel sprouts, avacado, kiwi, green grapes, some herbs, and green and herbal teas. Vitamin K2 further represents many different forms of vitamin K, known as menaquinones (MK-n). MK-4 to MK-10 are  the main forms of vitamin K2 that we get in our diet from foods from animal sources or fermented products.  Dietary sources of MK-4 include fish, eggs, liver, kidney, milk, butter, and fermented cheese or vegetables. Although vitamin K1 is the form we ingest mostly, MK-4 is the form of vitamin K that is most present in our bodies, leading some researchers propose that vitamin K1 is being converted in our bodies to MK-4.

Vitamin K and bone function

Vitamin K is involved in three broad areas of bone health:

  • vitamin K helps calcium get into bone
  • vitamin K is required for osteocalcin, an important bone protein, to function during bone formation
  • vitamin K may also be involved in maintaining bone strength

Research on vitamin K, bone density, and fractures

Our knowledge on how vitamin K affects bone health comes from two types of studies — observational studies and clinical trials. In part 2, we will summarize the latest research on vitamin K and osteoporosis and whether current research supports the idea of taking vitamin K supplements for osteoporosis prevention.


*Contrary to general belief, getting too much vitamin K from diet does not cause blood clots in healthy people who are not taking blood thinning medications. That said, vitamin K reduces the effectiveness of blood thinning medications and people who take such medications should monitor their intakes of vitamin K to avoid blood clotting complications.

Reference: Hamidi MS, Gajic-Veljanoski O, Cheung AM. Vitamin K and Bone Health. J Clin Densitom 2013;16(4):409-13. doi: 10.1016/j.jocd.2013.08.017.

Our Research at ASBMR 2013

Several researchers from our group were in attendance at The American Society of Bone and Mineral Research (ASBMR) Annual Meeting held in Baltimore MD last week (Oct 4-7). We presented the latest findings from our ongoing research studies, including atypical femur fractures, ankylosing spondilytis, vibration therapy, nutrition and body composition and more. We’ll be talking about these findings on this blog in the near future, but in the meanwhile, here are some of our colleagues at work at ASBMR.

(Click on the images to view full size)