Crossover study of diets enriched with virgin olive oil, walnuts or almonds. Effects on lipids and other cardiovascular risk markers

ISRCTN	ISRCTN68210440
DOI	https://doi.org/10.1186/ISRCTN68210440
Protocol serial number	INC0706
Sponsor	International Nut and Dried Fruit Foundation (Spain)
Funders	International Nut and Dried Fruit Foundation (Spain), Spanish Ministry of Science and Innovation (Spain) - Instituto de Salud Carlos III (CIBER Fisiopatología de la Obesidad y Nutrición [CIBERobn])

Submission date: 08/11/2010
Registration date: 14/12/2010
Last edited: 14/12/2010

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Nutritional, Metabolic, Endocrine

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Emilio Ros
Scientific

Hospital Clínic de Barcelona
C/ Villarroel 170
Barcelona
08036
Spain

Phone	+34 (0)93 2279383
Email	eros@clinic.ub.es

Study information

Primary study design	Interventional
Study design	Randomised crossover nutrional intervention study
Secondary study design	Randomised controlled trial
Study type	Participant information sheet
Scientific title	Effects of diets enriched with virgin olive oil, walnuts or almonds on lipids and other cardiovascular risk markers: a randomised crossover study
Study acronym	ONA
Study objectives	Virgin olive oil and nuts are basic components of the Mediterranean diet, a heart-healthy dietary pattern. Nuts have well known cholesterol lowering effects, while evidence is unclear for virgin olive oil. We designed a study in hypercholesterolemic patients to assess the effects on serum lipids and other intermediate markers of cardiovascular risk of replacing 40% of the fat in the background diet with virgin olive oil, walnuts or almonds. Our hypothesis is that daily intake of virgin olive oil will be associated with low density lipoprotein (LDL) cholesterol lowering to a similar extent than walnuts and almonds consumed at similar doses as percent of total energy.
Ethics approval(s)	The Institutional Review Board of the Hospital Clínic of Barcelona approved on the 21st March 2006 (ref: CEIC 3110-2006)
Health condition(s) or problem(s) studied	Nutrition
Intervention	In participants following a background Mediterranean-type isocaloric diet with similar energy, total fat and saturated fat content will be allocated to 3 random sequential periods lasting 4 weeks each in which 40% of energy (25% of fat) is replaced by virgin olive oil, walnuts or almonds. 1. Virgin olive oil is provided in 0.5 litre units sufficient to cover daily allowances of 35 to 50 g, depending on total energy requirements 2. Raw, shelled Spanish almonds (Marcona variety) provided in pre-packaged daily allowances from 50 to 75 g (almonds) 3. Spanish-grown walnuts (Serr/Chandler variety) from 40 to 65 g No washout necessary between arms because after a dietary intervention is terminated serum lipid changes stabilise in less than 3 weeks. Duration of the study for all participants is 16 weeks.
Intervention type	Other
Primary outcome measure(s)	Effects of the three diets on the serum lipid profile, with LDL cholesterol changes from baseline
Key secondary outcome measure(s)	1. Medical records, including anthropometric measurements (height, weight and waist circumference) and blood pressure at baseline and end of each diet period 2. Food, energy and nutrient intake assessed by 7-day food records at the end of each diet period 3. Plasma fatty acid proportions (as objective measure of compliance); concentrations of noncholesterol sterols, high-sensitivity C-reactive protein, homocysteine, oxidized LDL, ICAM-1, and VCAM-1; and in vitro LDL oxidizability assay to determine lag time of conjugated diene formation at baseline and end of each diet period
Completion date	15/12/2007

Eligibility

Participant type(s)	Patient
Age group	Adult
Sex	All
Target sample size at registration	20
Key inclusion criteria	1. Asymptomatic men and women with moderate hypercholesterolemia, age 25 to 75 years (after menopause in women) 2. Serum LDL cholesterol more than 3.36 mmol/L 3. Triglycerides less than 2.82 mmol/L 4. Absence of chronic illnesses or secondary hypercholesterolemia 5. No known allergy to nuts 6. Participants can be under stable lipid-lowering drug treatment (statins or fibrates, statins at doses of no more than simvastatin 40 mg/day or equivalent) 7. Written informed consent
Key exclusion criteria	1. Subjects on a weight-losing diet 2. Familial hypercholesterolemia 3. Established type 2 diabetes 4. Fatty food intolerance 5. Consumption of products that can influence cholesterol metabolism (other than statins and fibrates), such as resins, ezetimibe, psyllium, fish oil concentrates, soy lecithin, or phytoestrogens
Date of first enrolment	10/01/2007
Date of final enrolment	15/12/2007

Locations

Countries of recruitment

Spain

Study participating centre

Hospital Clínic de Barcelona

Barcelona
08036
Spain

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not provided at time of registration
IPD sharing plan

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes