The Scottish Fruit Study

  • End date
    Mar 21, 2025
  • participants needed
  • sponsor
    University of Aberdeen
Updated on 7 October 2022
Accepts healthy volunteers


The purpose of this study is to determine if new varieties of fruits grown in Scotland which can adapt better to climate change namely, honeyberries and cherries, have the same health benefits as established fruits such as raspberries. To do this we will investigate the effects of consuming honeyberries, cherries, and raspberries on short term changes in blood glucose, and on short term memory.


As humans spend most of their day in a postprandial state, it is imperative that the metabolic effects of diets are well understood if the incidence of chronic disorders such as type 2 diabetes (T2D) is to be controlled. Current estimates place global incidence of diabetes at 537 million, and this number is predicted to rise a further 45% by 2045. T2D is linked to increased risk of developing other chronic health conditions including cardiovascular disease (CVD) and dementia.

Controlling the acute glycaemic response and avoiding hyperglycaemia is essential for reducing diabetic risk. In addition, acute hyperglycaemia may provoke metabolic reactions increasing CVD risk and lower episodic memory even in non-diabetic individuals. Diet has an important role to play, and modern Western diets typically have high glycaemic loads due to excessive refined and total carbohydrate contents. As a result, the average blood glucose concentration of individuals has increased over the past three decades.

Polyphenolic constituents of foods may help to delay starch and disaccharide digestion and glucose absorption following a carbohydrate-containing meal or beverage. In vitro studies suggest that some polyphenols found in fruits are effective inhibitors of digestive enzymes, α-amylases and α-glucosidases and inhibit the action of intestinal glucose transporters. There is only a small amount of information available from human studies however, randomized controlled trials (RCTs) have shown that fruits reduced postprandial glucose concentrations following consumption of either starch, glucose or sucrose loads. Strategies to control chronic postprandial hyperglycaemia through increased consumption of such polyphenol rich foods would strengthen efforts to reduce the risk of developing T2D in the general population.

The aim of this study is to test the health benefits of new climate resistant fruit high in polyphenols grown in Scotland with and an existing crop already established in the fruit market. The hypothesis is that consumption of honeyberries and cherries grown in Scotland is as effective as raspberries in reducing the postprandial glycemic response in normal weight /overweight, healthy men, and post-menopausal women. With a secondary objective looking at the effects of these fruits on cognitive function.

This is a randomized cross over study and will aim to recruit 28 normal to overweight (BMI ≥ 18.5 and < 39.9), men or post-menopausal women (post-menopausal defined as not having had a period for over a year), aged ≥40 and ≤ 70 years who will attend four study sessions. The first study session will be an oral glucose tolerance test (OGTT) and the remaining three will be identical in all respects except for the addition of the fruit. Consecutive blood samples will be collected in all 4 study sessions which will be used to measure glucose, insulin, C-peptide, incretins, and lipids. Cognitive function the secondary outcome will be measured using a series of memory tests.

Condition Postprandial Hypoglycemia, Age-Related Memory Disorders
Treatment Raspberry, Honeyberry, Cherry
Clinical Study IdentifierNCT05513404
SponsorUniversity of Aberdeen
Last Modified on7 October 2022


Yes No Not Sure

Inclusion Criteria

Healthy men or post-menopausal women
Aged ≥40 and ≤ 70 years old
BMI ≥ 18.5 kg/m2
HbA1c <6.5%
Neuropsychological screening tasks will include the Mini-Mental State Examination (MMSE)
the National Adult Reading Test (NART), the Geriatric Depression Scale (GDS), the Trail
Making Test (TMT), the Controlled Oral Word Association Test (COWAT), the Hopkins Verbal
Learning Test (HVLT)
MMSE >= 27
NART, TMT, COWAT and HVLT within acceptable norms

Exclusion Criteria

Exclusion Criteria
Those with any of the following will be excluded from participation
We will ask the volunteers to complete a questionnaire to state current health complaints
and current medication use
Chronic illness, including: thromboembolic or coagulation disease unregulated thyroid
disease kidney disease hepatic disease severe gastrointestinal disorders pulmonary disease
(e.g. chronic bronchitis, COPD, pacemaker implant) Alcohol or any other substance abuse
Eating disorders a history of neurological abnormalities, Women who are lactating or
breastfeeding, pregnant Allergic/intolerant to foods provided in the study (Fruit allergy)
Alcohol and/or other substance abuse Smoking and the use of e-cigarettes Physically active
at a competitive level (exercising strenuously on a daily basis for long periods of time)
Medication exclusion criteria Oral steroids Tricyclic antidepressants, neuroleptics
Anticoagulants Digoxin and anti-arrhythmics Insulin, Sulphonylureas, Thiazolidinediones
(glitazones), metformin. Chronic use of anti-inflammatories (e.g. > 200mgs doses of
aspirin, ibuprofen), current psycho-active medication chlorphenamine
Neuropsychological exclusion criteria
MMSE < 27
GDS > 5
Self-report of prior diagnosis of dementia, probable dementia, or mild cognitive
History of stroke, severe head injury or other neurological condition which may
adversely affect cognition
history of anxiety and depression
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