Macular DegenerationNCT05283941
Pistachios and Neural Macular Pigment
A study testing Pistachio Group in people with Macular Degeneration and Retinal Degeneration, run by Tufts University at 1 site in United States.
Trial summary
Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss as people age. Studies have shown that lutein and zeaxanthin, nutrients found in green leafy vegetables and egg yolks, can help protect against AMD in older adults. Read more about this study
- Who is it for?
- Ages 40 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Macular Degeneration, Retinal Degeneration, Retinal Diseases
- What is being tested?
- Pistachio Group
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 10 Jun 2022to 30 Nov 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 40 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Adult men and women, aged 40 - 70 years
- Body Mass Index (BMI): 20.0 - 36.9 kg/m2
- Low macular pigment density at baseline (<0.5 OD)
- Low lutein and zeaxanthin intake at baseline (<2 mg/d)
Who cannot join
- Inability to perform the heteroflicker photometry procedures with or without corrective lenses (i.e. glasses or contact lenses) during in-house screening.
- History of (self-reported):
- Fat malabsorption
- Use of drugs that interfere with fat absorption or metabolism
- Tree nut allergy
- Eye disease, including macular degeneration and cataracts
Show all 18Show fewer
- Small bowel disease or resection
- Atrophic gastritis
- Hyperlipidemia
- Insulin-requiring diabetes
- > 14 alcoholic drinks per week
- Pancreatic disease
- Bleeding disorders
- Pregnancy (or hoping to become pregnant during participation in the study)
- Carotenoid or fatty acid dietary supplements within 2 months of the study
- Non-English speaker
- Any condition that would make it unlikely that the participant would be able to complete the requirements of the study.
- Individuals on lipid-lowering medication will be considered if they maintain their regimen throughout the study and meet all inclusion/exclusion criteria.
Trial locations and contacts
1 site in 1 country.
United States1 site, 1 recruiting
- Recruiting
Clinical and Translational Research Center (CTRC) - Tufts
Boston, Massachusetts, 02111
Olaniyi Ogunbodede, 617-636-4714, oogunbodede@tuftsmedicalcenter.org
Rupali Ranade, (617) 636-4714, rranade@tuftsmedicalcenter.org
About this study
Official title: Pistachios and Neural Macular Pigment; a Randomized Controlled Trial
Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss as people age. Studies have shown that lutein and zeaxanthin, nutrients found in green leafy vegetables and egg yolks, can help protect against AMD in older adults. These nutrients form a pigment in the retina (macular pigment) that can help protect the retina from light damage. Pistachios are rich sources of both lutein and zeaxanthin; thus, dietary intake of pistachios could serve as a beneficial food source for eye health.
Read the detailed description
Lutein and its isomer zeaxanthin (L/Z) are dietary carotenoids that cross the blood brain barrier and exclusively accumulate in the macular region of the retina, where they are referred to as macular pigment (MP). MP density (MPD) has been reported to be significantly related to decreased risk of age-related macular degeneration as well as cognitive function in both young and older adults. Studies in non-human primates and humans find that MPD is significantly related to lutein brain concentrations. MPD, a non-invasive measure, is thus a biomarker for brain concentrations of L/Z. This may be of interest given the report that L/Z concentrations in the older adult brain are positively related to a variety of pre mortem cognitive measures. Furthermore, L/Z supplementation was found to significantly improve verbal fluency scores in healthy older adults. Pistachios are a bioavailable source of L/Z. L/Z are transported in the circulation primarily on high density lipoproteins (HDL) and HDL levels were found to be significantly related to MPD. Thus, increasing dietary intake of L/Z as well as changing lipoprotein levels may impact MPD. This is of interest given that a pistachio enriched diet has been reported to improve lipid profile in healthy and mild hypercholesterolemic patients. Based on the sum of these findings, the objective of this study was to investigate the effect of a long-term pistachio intervention on MPD.
The overall goal of the proposal is to determine whether the consumption of pistachios is a practical way to increase L/Z status. This will primarily be accomplished by performing a nutritional study to demonstrate that pistachios are a bioavailable source of L/Z to neural tissue (i.e., MP). Cross-sectional and intervention studies report a significant relationship between L/Z levels and ocular and cognitive health. Current L/Z intakes in the U.S. are lower than levels associated with health. This randomized, parallel study will test the efficacy of pistachios on increasing L/Z neural status (i.e., MPD).
- Being tested
- Pistachio Group
- Keywords
- age related macular degeneration, lutein, zeaxanthin, pistachios, macular pigment, AMD
- Medical subject headings
- Macular Degeneration, Retinal Degeneration, Retinal Diseases, Eye Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pistachio GroupDietary supplement
Consumption of 2-ounce packs of pistachio nuts, daily, for 12 weeks.
| Study group | Role | What they receive |
|---|---|---|
| Pistachio Group | Experimental | The pistachio group will receive pistachio nuts in 2-ounce packs. This group will consume one pack every day over the course of the 12-week study. Receives: Dietary Supplement: Pistachio Group |
| Control (Usual Diet) Group | No intervention | The control group will not receive pistachio nuts. They will be asked to make no changes and continue to eat their regular diet. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change from baseline Macular Pigment (MP) Density over 12 weeks
A non-invasive psychophysical technique, known as heterochromatic flicker photometry (HFP), will be used to measure MP density of the retina.
Measured: Measured at baseline, 6 weeks and 12 weeks.
Secondary outcomes (1)
Serum concentrations of lutein and zeaxanthin (dietary carotenoids)
Serum carotenoids will be measured by HPLC.
Measured: Measured at baseline and 12 weeks.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Mar 2022
- Study start10 Jun 2022
- Primary completion30 Nov 2023 (estimated)
- Study completion30 Nov 2023 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Macular DegenerationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Investigator, Outcomes assessor
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tufts University
- Sponsor type
- University, hospital or other
- Collaborators
- American Pistachio Growers
- Responsible party
- Sponsor
- Investigators
- Tammy Scott, Principal investigator, Tufts University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05283941
- Sponsor's protocol ID
- N322001 FSU054
- Status last verified
- Mar 2023
- First submitted
- 22 Feb 2022
- Last updated
- 9 Mar 2023
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Scott TM, Ogunbodede O, McKay DL, Johnson EJ. Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial. J Nutr. 2025 Jan;155(1):168-174. doi: 10.1016/j.tjnut.2024.10.022. Epub 2024 Oct 18.
PubMed 39426460
Study at a glance
From the registry record, last updated by the sponsor on 9 Mar 2023. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pistachios and Neural Macular Pigment; a Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT05283941
- Acronym / sponsor ID
- N322001 FSU054
- Keywords
- age related macular degeneration, lutein, zeaxanthin, pistachios, macular pigment, AMD
- Study type
- Interventional
- Recruitment status
- Unknown status
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Tufts UniversityUniversity, hospital or other
- Collaborators
- American Pistachio Growers
- Study start
- 10 Jun 2022 (actual)
- Primary completion
- 30 Nov 2023 (estimated)
- Study completion
- 30 Nov 2023 (estimated)
- First posted
- 17 Mar 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss as people age. Studies have shown that lutein and zeaxanthin, nutrients found in green leafy vegetables and egg yolks, can help protect against AMD in older adults. These nutrients form a pigment in the retina (macular pigment) that can help protect the retina from light damage. Pistachios are rich sources of both lutein and zeaxanthin; thus, dietary intake of pistachios could serve as a beneficial food source for eye health.
Detailed description
Lutein and its isomer zeaxanthin (L/Z) are dietary carotenoids that cross the blood brain barrier and exclusively accumulate in the macular region of the retina, where they are referred to as macular pigment (MP). MP density (MPD) has been reported to be significantly related to decreased risk of age-related macular degeneration as well as cognitive function in both young and older adults. Studies in non-human primates and humans find that MPD is significantly related to lutein brain concentrations. MPD, a non-invasive measure, is thus a biomarker for brain concentrations of L/Z. This may be of interest given the report that L/Z concentrations in the older adult brain are positively related to a variety of pre mortem cognitive measures. Furthermore, L/Z supplementation was found to significantly improve verbal fluency scores in healthy older adults. Pistachios are a bioavailable source of L/Z. L/Z are transported in the circulation primarily on high density lipoproteins (HDL) and HDL levels were found to be significantly related to MPD. Thus, increasing dietary intake of L/Z as well as changing lipoprotein levels may impact MPD. This is of interest given that a pistachio enriched diet has been reported to improve lipid profile in healthy and mild hypercholesterolemic patients. Based on the sum of these findings, the objective of this study was to investigate the effect of a long-term pistachio intervention on MPD.
The overall goal of the proposal is to determine whether the consumption of pistachios is a practical way to increase L/Z status. This will primarily be accomplished by performing a nutritional study to demonstrate that pistachios are a bioavailable source of L/Z to neural tissue (i.e., MP). Cross-sectional and intervention studies report a significant relationship between L/Z levels and ocular and cognitive health. Current L/Z intakes in the U.S. are lower than levels associated with health. This randomized, parallel study will test the efficacy of pistachios on increasing L/Z neural status (i.e., MPD).
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Pistachio Group | Experimental | Dietary Supplement: Pistachio GroupThe pistachio group will receive pistachio nuts in 2-ounce packs. This group will consume one pack every day over the course of the 12-week study. |
| Control (Usual Diet) Group | No intervention | –The control group will not receive pistachio nuts. They will be asked to make no changes and continue to eat their regular diet. |
Who may qualify
- Ages
- 40 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Adult men and women, aged 40 - 70 years
- Body Mass Index (BMI): 20.0 - 36.9 kg/m2
- Low macular pigment density at baseline (<0.5 OD)
- Low lutein and zeaxanthin intake at baseline (<2 mg/d)
Key exclusion criteria (18 listed)
- Inability to perform the heteroflicker photometry procedures with or without corrective lenses (i.e. glasses or contact lenses) during in-house screening.
- History of (self-reported):
- Individuals on lipid-lowering medication will be considered if they maintain their regimen throughout the study and meet all inclusion/exclusion criteria.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Pistachio GroupConsumption of 2-ounce packs of pistachio nuts, daily, for 12 weeks. | Dietary supplement | Pistachio Group |
Primary outcome
Change from baseline Macular Pigment (MP) Density over 12 weeks
Time frame: Measured at baseline, 6 weeks and 12 weeks.
A non-invasive psychophysical technique, known as heterochromatic flicker photometry (HFP), will be used to measure MP density of the retina.
1 secondary outcome
Serum concentrations of lutein and zeaxanthin (dietary carotenoids)
Time frame: Measured at baseline and 12 weeks.
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Mar 2023.
- Derived from this study: PubMed 39426460Scott TM, Ogunbodede O, McKay DL, Johnson EJ. Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial. J Nutr. 2025 Jan;155(1):168-174. doi: 10.1016/j.tjnut.2024.10.022. Epub 2024 Oct 18.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Tammy Scott principal investigator
Tufts University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Pistachio Group in people with Macular Degeneration and Retinal Degeneration, run by Tufts University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: status not confirmed, as of the sponsor's last update on 9 Mar 2023. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
Contact Tammy Scott, PhD (617-962-1496, tammy.scott@tufts.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change from baseline Macular Pigment (MP) Density over 12 weeks (time frame: Measured at baseline, 6 weeks and 12 weeks.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05283941, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Mar 2023.