Vitamin D Supplementation increases Voluntary Physical Activity Levels in Nursing Home Patients Over the course of a semester does vitamin D3 supplementation, and the resultant increase in muscle strength and bone density, lead to increased physical activity in nursing home residents in the absence of added encouragement?

The elderly often suffer from low serum levels of vitamin D, reduced muscle strength, and decreased bone density (reviewed in: Hamilton, 2010). Muscle biopsies have revealed that the muscle fibers most affected in the elderly are type II, the 'fast twitch' fibers. When a person begins to fall they instinctively attempt to prevent or break their fall and this reaction depends heavily on fast twitch muscle fibers. The elderly therefore suffer from an increased risk of falling down and bone fractures. Although conclusive evidence has yet to be found that low serum levels of vitamin D cause this condition, there is a large body of evidence that diet supplementation with vitamin D and calcium can increase muscle strength and bone density, thereby reducing the number of falls and fractures. Dietary supplementation with vitamin D could therefore substantially improve the quality of life of the elderly.

The sources of vitamin D are diet and skin exposure to ultraviolet-B radiation (sunlight). Natural dietary sources include most fatty fish like cod, mackerel, and salmon, beef liver, and egg yolks. A number of foods are also fortified with vitamin D, like commercial cereals and milk. When exposed to sunlight cholesterol (7-dehidrocholesterol) in our skin is converted to pre-vitamin D3 (reviewed in: Hamilton, 2010). Pre-vitamin D3 is then rapidly converted to vitamin D3. Vitamin D3 is then converted to 25-hydroxy vitamin D in the liver, and then converted to its active form 1, 25 hydroxy vitamin D in the kidney. The active form of vitamin D is then transported in the blood by virtue of binding to vitamin D binding protein, where it can gain access to tissues and organs throughout the body to influence metabolic process.

Unfortunately, the elderly, especially those confined to nursing homes, are rarely exposed to sunlight and their diets typically lack sufficient vitamin D supplementation to make up for the loss of sunlight exposure. A large number of studies have shown supplementing the diets of nursing home residents with vitamin D (> 1000 IU/day) and calcium increases muscle strength and bone density within a relatively short period of time (reviewed in: Hamilton, 2010). Muscle biopsies of nursing home residents, done before and after an extended period of vitamin D diet supplementation, revealed that type II muscle fibers increased in number and size by the end of the study period. These changes occurred in the absence of physical exercise and reduced the number of falls and fractures.

What hasn't been studied is whether the changes in muscle strength and bone density following vitamin D dietary supplementation led to nursing home residents becoming more active voluntarily, as a marker for increased quality of life. The possibility that this may occur is suggested by studies that found mobility has a direct impact on a person's mental and physical health regardless of age (Williamson et al., 2009, and references within) and a strong inverse correlation between serum vitamin D levels and nursing home residence mortality was found (Semba et al., 2010).

Towards the goal of understanding the impact of vitamin D supplementation on voluntary nursing home resident physical activity, we designed a study to examine changes is physical habits during 3 months of vitamin D dietary supplementation. The study design included a double-blind approach, using bread infused with 1000 IU of vitamin D during lunch. Neither the study participants nor the researchers will be aware of which study participant will receive the vitamin D infused bread. Half of the participants received vitamin D bread. The 20 residents chosen for the study were otherwise healthy, with no known physical limitations other than advanced age (median age = 75.2). Serum vitamin D levels will be checked independently on a weekly basis during the study period to ensure dietary supplementation is effective in raising levels above 75 ng/mL (Hamilton, 2010). Questionnaires were administered at the beginning and end of the study period to assess changes in physical habits, mood, and cognition. To control for the subjective aspect of the questionnaires, all study participants wore a wrist band containing a GPS tracking device. Information from these tracking devices was recorded on computers running software designed to quantitate levels of physical activity 24/7 during the study period.

Questionnaire: The following questions were adapted from the European Organization for Research and Treatment of Cancer questionnaire to assess quality of life (2010).

Birth Date:

Do you experience physical difficulties when standing up from a seated position?
3. Do you experience physical difficulties when walking?

4. Do you experience physical difficulties when standing for more than a few seconds?

5. Do you experience physical difficulties when carrying heavy objects?

6. Do you experience physical difficulties when tidying up your room?

7. Do you experience shortness of breath when walking, standing, carrying heavy objects, or tidying up your room?

8. Do you experience rapid fatigue when walking, standing, carrying heavy objects, or tidying up your room?

9. How often during the past week have you felt depressed?

10. How often during the past week have you felt anxious?

11. How often during the past week have you felt irritable?

12. How often during the past week have you had problems with your memory?

13. How often during the past week have you had problems with sleeping?

14. How would you rate your health during the past week?

15. How would you rate your quality of life during the past week?

16. How many activities are you currently involved in that involves physical exertion?

17. Are there any activities that you would like to participate in, but due to physical limitations avoid them. Write down the number of such activities.

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

1 2-3 4

Excellent Very Poor

1 2-3 4-5-6 7

Excellent Very Poor

1 2-3 4-5-6 7

Number of activities:

Number of activities:

Questionnaire Data:

Test Subjects + Controls

Test Subjects Only

Questions (N=20):

Avg. Score at 0 months (N = 20)

Avg. Score at 3 months (N = 10)

1. Standing up

28.2

19.3**

2. Walking

30.8

16.4***

3. Standing

33.1

22.5*

4. Carrying objects

36.4

26.7**

5. Cleaning

29.1

23.2*

6. Shortness of breath

34.6

28.8*

7. Rapid fatigue

35.2

30.2

8. Depressed

35.4

24.5**

9. Anxious

25.3

22.4

10. Irritable

26.3

28.9

11. Memory

33.2

24.7***

12. Sleeping

37.6

19.9***

13. Overall health rating

5.5

3.2**

14. Overall Quality of life

4.5

3.0**

15. Number of physical activities

0.8

1.5*

16. Desired number of physical activities

1.8

1.0**

Total Average Score =

Std. Error =

+/- 27.9

+/- 9.4

Std. Deviation =

87.8

Notes: * p < 0.05, ** p < 0.01, *** p < 0.005; degrees of freedom = 28; Questions 15 and 16 are used only to help validate the results of the questionnaire and the scores are not included in the analysis.

Conclusions:

The overall change in perceived physical activity and mental health improved significantly over the course of the study (p < 0.01, Students T test, one-tailed). This change in perception was further validated by a significant increase in the number of physical activities engaged in and a decrease in the desire to engage in more physical activities (Questions 15 and 16). More objectively, there was also an increase in voluntary physical activity as indicated by the GPS tracking data (p < 0.001, data not shown). These results indicate 1000 IU of vitamin D per day over a three-month period increased both physical activity and quality of life perceptions.

The results of questions 15 and 16 are particularly interesting, because they show a greater inclination to engage in physical activities as the discomfort and pain associated with standing up, walking, standing still, or carrying objects was supposedly diminished by vitamin D-induced increases in muscle strength and bone density. This indicates that persons suffering from age-related physical limitations would be more willing to voluntarily engage in physical activity if the severity of their symptoms could be reduced. Vitamin D supplementation seems to hold great promise…