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Blueberry Effects on Dark Vision and Glare Recovery

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ClinicalTrials.gov Identifier: NCT01942746
Recruitment Status : Completed
First Posted : September 16, 2013
Last Update Posted : September 16, 2013
Sponsor:
Collaborators:
Dalhousie University
U.S. Highbush Blueberry Council
Information provided by (Responsible Party):
Wilhelmina Kalt, Atlantic Food and Horticulture Research Center

Brief Summary:
Clinical evidence for effects of plant anthocyanins on vision, and particularly night vision is controversial. Two clinical trials were conducted to investigate whether blueberry juice consumption affected visual dark adaptation, functional night vision, and recovery after photo-bleaching of the retina. One trial (S2) employed a 3 week intervention and washout period, and two doses of blueberries plus a placebo. The other trial (L1) employed a 12 week intervention plus an 8 week washout and tested one blueberry juice dose against a juice placebo.

Condition or disease Intervention/treatment Phase
Blindness and Low Vision Dietary Supplement: Blueberry Juice S2 Dietary Supplement: Blueberry Capsules S2 Dietary Supplement: Placebo Capsule S2 Dietary Supplement: Placebo Juice L1 Dietary Supplement: Blueberry Juice L1 Not Applicable

Detailed Description:
Vision Tests: 1. Dark adaptometry, 2. scotopic visual acuity, 3. scotopic contrast sensitivity, 4. rod/cone conversion, 5. recovery after retinal photobleaching

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 72 participants
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Placebo-controlled Cross-over Studies Examining Blueberries Effects on Dark Vision and Recovery After Photo-bleaching
Study Start Date : July 2005
Actual Primary Completion Date : July 2006
Actual Study Completion Date : July 2006


Arm Intervention/treatment
Active Comparator: Blueberry Juice
Commercially prepared single strength blueberry juice which was composed of a 50:50 blend of two highbush blueberry species (Vaccinium corymbosum L. 'Rubel' and V. ashei Reade 'TifBlue'). Volunteers consumed 300 mls of juice/day (247-271 mg anthocyanins (as C3G) daily) while on this intervention, for either 3 weeks (Blueberry Juice S2) or 12 weeks (Blueberry Juice L1).
Dietary Supplement: Blueberry Juice S2
Blueberry Juice S2 was commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars. Colorimetric analysis showed that S2 juice contained 6.04 (SD=0.20) mg anthocyanins (C3G) eq/g dry mass.
Other Name: Single-strength blueberry juice, commercially prepared

Dietary Supplement: Blueberry Juice L1
Blueberry Juice L1 was commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars. Colorimetric analysis showed that L1 juice contained 6.83 (SD=0.20) mg cyanidin-3-glucoside equivalents (C3GE)/g dry mass at the start of the study, declining to 5.52 (SD=0.09) mg C3GE/g dry mass after 3 months refrigerated storage.
Other Name: single strength blueberry juice, commercially prepared

Active Comparator: Blueberry Capsules
Commercially prepared single strength blueberry juice which was composed of a 50:50 blend of two highbush blueberry species (Vaccinium corymbosum L. 'Rubel' and V. ashei Reade 'TifBlue')was freeze dried to a powder and encapsulated in gelatin capsules (Blueberry Capsules S2). Volunteers consumed 3 capsules/daily (7.11mg anthocyanin (as C3G eq) for 3 weeks.
Dietary Supplement: Blueberry Capsules S2
Commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars was freeze dried then powdered and encapsulated in gelatin capsules. Colorimetric analysis indicated an anthocyanin concentration in the powder of 2.37(SD=0.18) mg C3G eq per capsule.
Other Name: freeze-dried blueberry juice powder

Placebo Comparator: Placebo
Volunteers consumed in S2 three placebo capsules daily for 3 weeks. In L1 volunteers consumed 300ml placebo juice for twelve weeks. Placebo products contained no anthocyanins.
Dietary Supplement: Placebo Capsule S2
Placebo Capsule S2 (containing no anthocyanins) were prepared by freeze drying red beets and grinding them to fine powder before encapsulating in gelatine capsules. Red beets do not contain anthocyanins.
Other Name: Red beet powder

Dietary Supplement: Placebo Juice L1
Placebo juice was prepared from water, sugars, citric acid, sodium citrate, and artificial colors and flavours, then pasteurized. The placebo juice contains no anthocyanins.

No Intervention: Washout (S2 and L1)
Washout periods involved no study products. Washout was 3 weeks in S2 and or 8 weeks (L1) in duration.



Primary Outcome Measures :
  1. Rate of vision adaptation to low light after blueberry juice and placebo ingestion for 3 weeks (S2). [ Time Frame: Pre-intervention, and changes after 3 weeks of intervention, and again after 3 weeks of washout ]
    Effect of blueberry products and placebo on the rate of vision adaptation to low light. The rate of vision adaptation is measured by lowest perceptible light intensity after 30 min of darkness (dark threshold); time to reach dark threshold (min); time to reach rod/cone transition (min) [Time Frame: Pre-intervention, after 3 weeks intervention, again after a 3 week washout.] [Designated as safety issue: No]

  2. Rate of vision adaptation to low light after ingestion of blueberry juice and placebo for 12 weeks (L1). [ Time Frame: Preintervention, and changes after 8 and 12 weeks of intervention and after 4 and 8 weeks of washout ]
    Effect of blueberry products and placebo on the rate of vision adaptation to low light. The rate of vision adaptation is measured by lowest perceptible light intensity after 30 min of darkness (dark threshold); time to reach dark threshold (min); time to reach rod/cone transition (min) [Time Frame: Pre-intervention, after 8 and 12 weeks intervention, and again after 4 and 8 weeks washout] [Designated as safety issue: No]


Secondary Outcome Measures :
  1. Rate of recovery of visual acuity after retinal photostress (S2). [ Time Frame: Pre-intervention testing and testing for changes after 3 weeks of intervention and 3 weeks of washout ]
    After dark adaptation testing (primary outcome) and contrast sensitivity and visual acuity testing (other pre-specified outcome measures), participants are subjected to photostress of the retina using bright light. The time (sec) required to recover pre-stress acuity is measured.

  2. Rate of recovery of visual acquity after retinal photostress (L1). [ Time Frame: Pre-intervention and then testing for changes after 8 and 12 weeks of intervention and 4 and 8 weeks of washout. ]
    After dark adaptation testing (primary outcome) and contrast sensitivity and visual acuity testing (other pre-specified outcome measures) participants are subjected to photostress of the retina using bright light. The time (sec) required to recover pre-stress acuity is measured.


Other Outcome Measures:
  1. Visual acuity and contrast sensitivity testing after dark adaptation (S2). [ Time Frame: Testing preintervention and testing for changes after 3 weeks of intervention and 3 weeks of washout ]
    After dark adaptation testing (primary outcome measure) and before measuring rate of recovery from photo stress (secondary outcome) visual acuity in darkness and contrast sensitivity in darkness was measured using defined optotypes with different degrees of crowding and contrast. Performance was defined as the number of correct answers in 12 tests of acuity and 8 tests of contrast sensitivity.

  2. Visual acuity and contrast sensitivity testing after dark adaptation (L1). [ Time Frame: Testing preintervention and testing for changes after 8 & 12 weeks of intervention and 4 & 8 weeks of washout ]
    After dark adaptation testing (primary outcome measure) and before testing rate of recovery from photo stress (secondary outcome) visual acuity in darkness and contrast sensitivity in darkness was measured using defined optotypes with different degrees of crowding and contrast. Performance was defined as the number of correct answers in 12 tests of acuity and 8 tests of contrast sensitivity.



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Ages Eligible for Study:   35 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • visual acuity better than 6/7.5 on EDTRS acuity chart at 2.5m
  • visual contrast sensitivity within normal range at 2.5m as tested on Visteck 3000
  • stereo acuity better than 80 seconds of arc on Frisby stereoacuity test
  • no ocular history other than refractive glasses
  • no family history of eye disease

Exclusion Criteria:

  • family history of retinal degeneration, glaucoma, diabetes, hypertension, cataract, or amblyopia (dimness in vision).
  • evidence in subject (upon examination) of amblyopia (dimness in vision), manifest strabismus (unable to focus both eyes on one spot), or anisotropia (non-uniform responsiveness between both eyes).
  • intraocular pressure above 21mmHG from an average of three measures using Mentor tonopen-XL

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01942746


Locations
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Canada, Nova Scotia
Atlantic Food and Horicultural Research Center
Kentville, Nova Scotia, Canada, B4N1J5
Sponsors and Collaborators
Atlantic Food and Horticulture Research Center
Dalhousie University
U.S. Highbush Blueberry Council
Investigators
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Principal Investigator: Wilhelmina Kalt, PhD Agriculture and Agri-Food Canada
Principal Investigator: Francois Tremblay, PhD Dalhousie University and IWK Health Center
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Wilhelmina Kalt, Scientist, Atlantic Food and Horticulture Research Center
ClinicalTrials.gov Identifier: NCT01942746    
Other Study ID Numbers: Blueberries and Vision
First Posted: September 16, 2013    Key Record Dates
Last Update Posted: September 16, 2013
Last Verified: September 2013
Keywords provided by Wilhelmina Kalt, Atlantic Food and Horticulture Research Center:
blueberry
anthocyanin
dark vision
photo bleaching
Visual Perception
Photic Stimulation
Additional relevant MeSH terms:
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Blindness
Vision, Low
Vision Disorders
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases
Eye Diseases