EAL

DLM: Almonds (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to see whether the plasma cholesterol in a population on a fairly low-fat diet could be lowered by a diet higher in total fat as MUFA than the original diet of the subjects.

Inclusion Criteria:

Total plasma cholesterol (TC) more than 220mg per dL
Triglycerides (TG) less than 350mg per dL
Informed consent was signed by all subjects.

Exclusion Criteria:

Nut or grain allergy.

Description of Study Protocol:

Recruitment

Subjects were recruited at the YMCA Cardiac Rehabilitation Unit in Palo Alto, CA.

Design

Baseline blood sampling for high-density-lipoprotein cholesterol (HDL-C), total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C), triglycerides (TG) and very-low-density-lipoprotein cholesterol (VLDL-C) completed for all subjects during days one, seven and 14 of the two-week baseline period and baseline values are an average of these results
Two-week baseline period:
- Subjects were given a kitchen food scale, written instructions and blank food record forms
- Subjects kept a three-day weighed food record during week one
- Subjects were instructed not to change their typical food pattern and kept weekly food frequency records
- Subjects received no information about the experimental diet until the end of this period
Nine-week intervention diet:
- Group meeting were held with the subjects on the evening before day one of the intervention period
- A detailed list of foods describing the basic diet pattern was given to each subject and explained by the investigators
- Foods classified into four categories: Unlimited, limited, not allowed and unchanged
  - Unlimited foods included:
    - All grains and grain products
    - Fruits
    - Vegetables
    - Legumes
    - Nonfat or 2% fat dairy products
    - Low-fat fish
    - Almond oil distributed to subjects to use in place of all other fats normally used
  - Limited foods, not to exceed two to three servings per week, included:
    - Lean beef
    - Poultry
    - Medium-fat cheeses
    - Eggs (limited to amount consumed before study)
    - Low-fat cookies and cakes.
  - Foods not allowed included:
    - Margarine
    - Butter
    - All vegetable oils
    - Mayonnaise
    - Most meats
    - Shellfish
    - Whole-fat dairy products
    - Any bakery product containing fats or oils
    - Chips
    - Ice cream
    - Avocados
    - All nuts except for the almonds given to the subjects
  - Unchanged foods included:
    - Tea
    - Coffee
    - Alcoholic beverages
- Subjects kept a three-day weighed food records during weeks four and eight of the intervention phase for computerized nutrient analyses
- Subjects kept weekly food frequency records that were discussed with investigators at the end of weeks three, six, eight and nine of the intervention phase
- Blood sampling was performed at weeks three, six, eight and nine of the intervention phase.

Intervention

During the nine-week intervention phase, all subjects were asked to consume:

100 grams per day of almonds [34 grams monounsaturated fatty acids (MUFA), 12 grams of polyunsaturated fatty acids (PUFA), and six grams of saturated fatty acids (SFA)]
- 50 grams as whole unblanched raw almonds
- 50 grams as ground almonds
- All almonds came from the same batch of raw almonds and were the nonpareil variety grown in California
- A three-week supply of almonds was packaged in one box and distributed to the subjects every three weeks.
Subjects used the detailed food lists shown above to direct the remainder of the diet.

Statistical Analysis

A one-way repeated measures analysis of variance (ANOVA) of the lipid levels was performed on the baseline and lipid levels obtained at weeks three, six, eight and nine
Means were compared using Duncan's multiple range test.

Data Collection Summary:

Timing of Measurements

Plasma cholesterol and lipoprotein measurements were taken during the baseline period (days one, seven and 14) and at weeks three, six, eight and nine during the intervention period
Three-day weighed food records were analyzed for weeks one, four and eight of the study
Weekly food frequency records were discussed at the end of weeks three, six, eight and nine of the intervention period
Body weights were measured at baseline and weeks three, six, eight and nine of the study.

Dependent Variables

TC
HDL-C
LDL-C
VLDL-C
TG
TC:HDL-C ratio.

Independent Variables

Nine-week diet containing the following fatty acid profile found in California almonds:
- 34 grams MUFA
- 12 grams PUFA
- Six grams SFA
Elimination or limited intake of most other sources of fat in the diet.

Control Variables

TC, more than 220mg per dL
TG, less than 350mg per dL
No subject taking cholesterol-lowering medication.

Description of Actual Data Sample:

Initial N: 30 male and female subjects
Attrition (final N): 26 (13 male, 13 female).

Age

Mean age±SD: 56±12.5 years
Range: 29 to 81 years.

Other Relevant Demographics

All subjects had total plasma cholesterol above 220mg per dL
Recruited from a cardiac rehabilitation center in California
Population group was already concerned with TC control
Dietary fat intake at baseline approximately consisted of 28% calories from total fat.

Anthropometrics

Mean Body Weight was 74.9kg at baseline; 74.1kg at week three; 74.8kg at week six; 74.1kg at week eight and 74.3kg at week nine. No statistical difference between any of these values.

Location

Palo Alto, California, United States.

Summary of Results:

Time	TC (mg/dL)*	HDL-C (mg/dL)	LDL-C (mg/dL)*	VLDL-C (mg/dL)	TG (mg/dL)	TC:HDL-C ratio (mg/dL)
Baseline	235^a±5	58±4	154^a±4.6	23±2.2	114±11	4.38±0.24
Week Three	215^b±5	59±4	133^b±4.6	23±2.2	116±11	4.03±0.24
Week Six	210^b±+5	58±+4	131^b±4.6	22±2.2	108±11	3.92±0.24
Week Eight	217^b±5	60±4	133^b±4.6	24±2.2	122±11	3.99±0.24
Week Nine	214^b±5	58±4	135^b±4.6	22±2.2	109±11	4.02±0.24

*Means with different superscripts are significantly different: TC, P<0.05; LDL-C, P<0.01.

Other Findings

Mean change in daily diet composition from baseline to week eight of the diet period (from three-day diet records):
- Total kilocalorie intake ↑ 81 kilocalories
- Total fat intake ↑ 23 grams
- MUFA intake ↑ 21 grams
- PUFA intake ↑ 3 grams
- SFA intake ↓ 2 grams
- PUFA:SFA ratio ↑ 0.4
- Carbohydrate intake ↓ 33 grams
- Protein intake ↑ 15 grams
- Dietary fiber ↑ 5 grams
- Cholesterol ↓ 50 mg
- Fat kilocalories (%) ↑ 9%
- Carbohydrate kilocalories (percentage) ↓ 8%
- Protein kilocalories (percentage) ↑ 3%.

Author Conclusion:

A diet higher in total fat than the diet usually recommended for total cholesterol lowering can be effective at reducing elevated total cholesterol when the diet is high in plant foods. The higher fat content of almonds, and possibly other nuts high in monounsaturated fatty acids, should not preclude their use in hypolipidemic diets provided this does not lead to weight gain.

Funding Source:

Industry:

Reviewer Comments:

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	No
	6.6.	Were extra or unplanned treatments described?	No
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	No
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes