Dyslipidemia, Obesity, Abdominal
Conditions
Keywords
Almond, Carbohydrate, Diet, Cholesterol
Brief summary
Increased abdominal adiposity is a key feature of metabolic syndrome, which describes a cluster of cardiovascular disease (CVD) risk factors that also includes insulin resistance, high blood pressure and an atherogenic lipoprotein phenotype characterized by increased plasma triglycerides, low HDL-C, and increased levels of small LDL particles. While lifestyle intervention remains the cornerstone for managing obesity and metabolic syndrome, the optimal dietary macronutrient distribution for improving blood lipids and CVD risk remains a topic of controversy. While both low carbohydrate diets and weight reduction are effective for managing atherogenic dyslipidemia, long-term compliance is low, and it becomes imperative to identify alternative dietary approaches. Increased consumption of almonds has been shown to lower LDL-C, an effect that exceeds that predicted from changes in fatty acid intake. However, although LDL-C lowering by almonds has been demonstrated in patients with diabetes, there have been no trials in non-diabetic patients with abdominal obesity. Moreover, there is limited information of the effects of almond intake on LDL particle subclasses. The overall objective of the present study is to determine whether lipoprotein measures of CVD risk in individuals with increased abdominal adiposity are reduced by almond supplementation in a diet with overall macronutrient content that conforms to current guidelines. Our main hypothesis is that in these individuals, almond consumption can reduce levels of small and medium LDL particles without the need to restrict dietary carbohydrates to levels below those currently recommended. This hypothesis will be tested by comparing the lipoprotein effects of an almond-supplemented diet (20%E) with those of two reference diets that do not contain almond products: one with similar content of carbohydrate, protein, and fat (standard reference), and the other in which carbohydrate content is reduced by substitution of protein and monounsaturated fat (low-carbohydrate reference). We will provide the diets for 3 weeks each in a randomized 3-period crossover design to 40 individuals with increased abdominal adiposity. We will test whether the almond supplemented diet will result in lower levels of lipoprotein measures of CVD risk, specifically LDL-C and small and medium LDL particles, compared to either the standard or low-carbohydrate reference diets.
Interventions
OTHERStandard reference diet
50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat
OTHERAlmond supplemented diet
50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat, 20% energy from almonds
OTHERLow carbohydrate reference diet
26% energy from carbohydrate, 29% energy from protein, 45% energy from total fat
Sponsors
Almond Board of California
UCSF Benioff Children's Hospital Oakland
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Investigator)
Eligibility
Sex/Gender
ALL
Age
20 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Age 20 or older * Increased abdominal adiposity as defined by waist circumference ≥102 for men or ≥88 for women. * Fasting blood sugar (FBS) \< 126 mg/dl * Weight stable for \> 3 months.
Exclusion criteria
* History of coronary heart disease, cerebrovascular disease, peripheral vascular disease, bleeding disorder, liver or renal disease, diabetes, lung disease, HIV, or cancer (other than skin cancer) in the last 5 years. * Taking hormones or drugs known to affect lipid metabolism or blood pressure. * Systolic blood pressure \> 160 mm Hg and diastolic blood pressure \> 95 mm Hg. * Body mass index (BMI) \> 38 kg/m2 * User of nicotine products or recreational drugs * Refusal to abstain from alcohol or dietary supplements during the study. * Total- and LDL-C \> 95th percentile for sex and age. * Fasting triglycerides \> 50mg/dl and \> 500 mg/dl * Abnormal thyroid stimulating hormone (TSH) levels. * Pregnant or breast-feeding
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Total and LDL cholesterol | 3 weeks, 8 weeks, 13 weeks | Change in total and LDL cholesterol between each of the 3 test diets |
| Change in small and medium LDL particles | 3 weeks, 8 weeks, and 13 weeks | Change in small and medium LDL particles between each of the 3 test diets |
| Change in apolipoprotein B | 3 weeks, 8 week, 13 weeks | Change in apolipoprotein B between each of the 3 test diets |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in HDL-cholesterol | 3 weeks, 8 weeks, 13 weeks | Change in HDL-cholesterol between each of the 3 test diets |
| Change in large HDL particles | 3 weeks, 8 weeks, 13 weeks | Change in large HDL particles between each of the 3 test diets |
| Change in total/HDL-cholesterol ratio | 3 weeks, 8 weeks, 13 weeks | Change in total/HDL-cholesterol ratio between each of the 3 test diets |
| Change in HOMA-IR | 3 weeks, 8 weeks, 13 weeks | Change in homeostatic model assessment insulin resistance (HOMA-IR) after each of the 3 test diets |
| Change in apolipoprotein AI | 3 weeks, 8 weeks, 13 weeks | Change in apolipoprotein AI between each of the 3 test diets |
| Change in LDL peak particle diameter | 3 weeks, 8 week, 13 weeks | Change in LDL peak particle diameter between each of the 3 test diets |
| Change in plasma triglycerides | 3 weeks, 8 weeks, 13 weeks | Change in plasma triglycerides between each of the 3 test diets |
Countries
United States
Outcome results
None listed