1) A study examined whether consuming avocados, a source of lutein, improved cognitive function in older adults. 2) Participants who ate half an avocado per day for 6 months saw greater increases in lutein levels in the brain and improved performance on spatial working memory tasks compared to a control group. 3) Increases in brain lutein levels were correlated with improved spatial working memory and problem-solving efficiency, but serum lutein levels did not correlate with cognitive measures.

1. Avocado Consumption Increases Neural Lutein Concentrations
which Improves Cognitive Function
Elizabeth J. Johnson, Ph.D.
Antioxidants Research Laboratory
Jean Mayer USDA Human Nutrition Research Center on Aging
Tufts University

2. Background

3. Rationale
• There is a need for novel, cost-effective public health strategies that
will delay, slow, or prevent cognitive decline associated with aging.
• Our preliminary studies suggest that lutein may also be important in
cognitive function in the elderly.
• Avocados are likely a highly bioavailable source of lutein.

4. Rationale
• There is a need for novel, cost-effective public health strategies that
will delay, slow, or prevent cognitive decline associated with aging.
• Our preliminary studies suggest that lutein may also be important in
cognitive function in the elderly.
• Avocados are likely a highly bioavailable source of lutein.

5. Rationale
• There is a need for novel, cost-effective public health strategies that
will delay, slow, or prevent cognitive decline associated with aging.
• Our preliminary studies suggest that lutein may also be important in
cognitive function in the elderly.
• Avocados are likely a highly bioavailable source of lutein.

6. Methods

7. Subjects
• Men and women aged >50 y (n=20, treatment group; n=20, control group)
who meet the following criteria:
lutein intake of <3 mg/d
macular pigment density <0.5 OD
MMSE score >24
BMI 19-29 kg/m2
• Exclusions:
carotenoid supplements for >2 mo prior to study start
>2 alcoholic beverages/day
fat absorption/metabolism
anemia, diabetes, bleeding disorders, hyperlipidemia

8. Subjects
• Men and women aged >50 y (n=22, treatment group; n=22, control group)
who meet the following criteria:
lutein intake of <3 mg/d
macular pigment density <0.5 OD
MMSE score >24
BMI 19-29 kg/m2
• Exclusions:
carotenoid supplements for >2 mo prior to study start
>2 alcoholic beverages/day
fat absorption/metabolism
anemia, diabetes, bleeding disorders, hyperlipidemia

9. Study Design
Month/Study Measures 0 1 2 3 4 5 6
Avocado or control meal pick-up/delivery x x x x x x
Height, weight, blood draw x x x
Macular pigment & cognitive measures x x x
Mood & fatigue, FFQ x x x
Telephone calls x x x x
Current medication review x x x
Dietician interview x x x
Compliance calendars x x x x x x

10. Test Assessment
Choice reaction time General alertness and motor speed
Delayed matching to sample Forced choice recognition memory for non-
verbalizable patterns, testing matching and short
term visual memory
Spatial span
Spatial span reverse
Working memory capacity, and is a visuospatial
analogue of the Digit Span test
Paired associates learning Episodic and new learning
Spatial working memory Retention and manipulation of visuospatial
information. This self-ordered test has notable
executive function demands, and measures
strategy use as well as errors.
Rapid visual information processing Sustained attention
Stockings of Cambridge Spatial planning test which gives a measure of
frontal lobe
Cognitive Measures
CANTAB, Cambridge Cognition Ltd

11. www.macularmetrics.com
Heterochromatic flicker photometer
(for measure of macular pigment optical density, MPOD)

12. Section through fovea of rhesus monkey (Macaca mulatta). © Max Snodderly, 2002

13. Biomarker Measures in Plasma
Biomarker Method Reference or Source
Bioavailability: carotenoids Reverse-phase HPLC Johnson, et al., 2000
Oxidative capacity:LDL LDL resistance against
Cu2+-induced oxidation
Chen, et al., 2005
Inflammation: b-amyloid Direct solid-phase
enzyme immunoassay
Innugenetic, Inc.,
Belguim
Inflammation: CRP Chemiluminescent
assay
DPC, Los Angeles, CA

14. Results

15. No change in inflammation of
oxidative stress in either group.

16. No change in inflammation of
oxidative stress in either group.
Measures in normal range.

17. b
c
a
Serum Lutein, nmol/L (mean + SD)
Month
Change from baseline, P value: a0.001, b0.05, c0.0005

18. Macular Pigment Density (mean + SD)
Month
a
b c
Change from baseline, P value: a0.05, b0.005, c0.0005

19. Lutein supplement vs Avocado
Lutein Supplement* Avocado
subjects (n) 11 20
age, yrs 60-80 50-85
lutein, mg/d 12 0.5
study duration, days 120 180
total lutein dose, g/d x day 1.44 0.9
serum lutein (∆ from baseline), nmol/L 315 84
MP density (∆ from baseline), OD 0.041 0.101
*Johnson et al, AJCN 87:1521-9 (2008)

20. Lutein supplement vs Avocado
Lutein Supplement* Avocado
subjects (n) 11 20
age, yrs 60-80 50-85
lutein, mg/d 12 0.5
study duration, days 120 180
total lutein dose, g/d x day 1.44 0.9
serum lutein (∆ from baseline), nmol/L 315 84
MP density (∆ from baseline), OD 0.041 0.101
*Johnson et al, 2008

21. Lutein supplement vs Avocado
Lutein Supplement* Avocado
subjects (n) 11 20
age, yrs 60-80 50-85
lutein, mg/d 12 0.5
study duration, days 120 180
total lutein dose, g/d x day 1.44 0.9
serum lutein (∆ from baseline), nmol/L 315 84
MP density (∆ from baseline), OD 0.041 0.101
*Johnson et al, 2008

22. Lutein supplement vs Avocado
Serum Lutein
(∆ baseline), nmol/L/lutein total dose
Macular Pigment Density
(∆ baseline), OD/ lutein total dose

23. Lutein supplement vs Avocado
Serum Lutein
(∆ baseline), nmol/L/lutein total dose
Macular Pigment Density
(∆ baseline), OD/ lutein total dose
~2x ~4x

24. Why?
HDL
MUFA major transporter of lutein neural tissue

25. Control Group:
No relationships between lutein status and cognitive function
were observed.
Avocado Group:
The change in MP density (6-0 months) was related to the
change in spatial working memory (p<0.009)
• The change in MP density (6-0 months) was related to
improved efficiency of approaching a problem (p<0.036)
• No significant relationships between change in serum lutein
and cognitive function.
Relationship between Lutein Status and Cognitive Function

26. Control Group:
No relationships between lutein status and cognitive function
were observed.
Avocado Group:
The change in MP density (6-0 months) was related to the
change in spatial working memory (p<0.009)
The change in MP density (6-0 months) was related to
improved efficiency of approaching a problem (p<0.036)
No significant relationships between change in serum lutein
and cognitive function.
Relationship between Lutein Status and Cognitive Function

27. Spatial Span forwarda
Paired Associates Learningc
Spatial Working Memoryb
Control, n = 20
Avocado, n = 20
Significant time effect (p <):
a0.05, b0.01, c0.001
No differences between groups
p <0.05
p <0.05

28. Significant time effect:
• Learning effect?
• Bioactives in potatoes/chickpeas?

29. Per 100 g Avocado Chickpea Potato
Lutein, mg 0.5 0.0 0.0
MUFA, g 9.8 0.4 0.0
Vitamin C, mg 8.8 0.1 13.0
Folate, mg 89 25 9

31. Conclusion
A dietary intervention with avocados to increase
neural lutein levels could be an effective dietary
strategy for cognitive health in older adults.

32. Acknowledgments
Antioxidants Research Laboratory:
Rohini Vishwanathan, Ph.D
Emily Mohn, M.S.
Oliver Chen, Ph.D.
Jordan Haddock, B.S.
Metabolic Research Unit
Helen M. Rasmussen, Ph.D, R.D.
Neuroscience and Aging Laboratory
Tammy M. Scott, Ph.D,
Supported by Hass Avocado Board and USDA 58-1950-0-014