Abstract

Adults who are insulin resistant may improve their blood sugar control without elevating blood lipids if they consume a high protein diet, such as lean pork. To address this hypothesis, we examined cross-sectional data from the Third National Health and Nutrition Examination Survey (1988-1994). A total of 13,794 adults met at least one of the following criteria that places them at increased risk for insulin resistance: overweight (BMI ≥ 27); abdominal obesity (waist circumference >97 cm for women or 102 cm for men); family history of type 2 diabetes; elevated fasting blood sugar (>110 mg/dL); or moderately elevated serum triglyceride (150-499 mg/dL). Subjects were divided into quartiles of total and animal protein intake.

Differences in blood sugar and lipid concentrations by protein quartiles were analyzed using SUDAAN after adjusting for sex, age, BMI, waist circumference, fat, carbohydrate, and alcohol intake, physical activity, and number of risk factors. Adults who ate the most total and animal protein intake had the lowest serum total and high density lipoprotein (HDL) cholesterol. Adults who were in the second lowest quartiles of total and animal protein intake had the lowest insulin concentrations (P < 0.05). Serum low density lipoprotein (LDL) cholesterol, triglycerides, glucose, and glycated hemoglobin were not significantly related to protein intake after adjusting for the confounding variables. Therefore, total and animal protein intakes were not consistently associated with blood sugar control or indicators of cardiovascular risk.

Objective

To examine the relations between protein intake and blood lipid and blood sugar profiles in adults in the Third National Health and Nutrition Examination Survey (1988- 1994) who are potentially insulin resistant. Following questions were identified:

  1. What is the relation between protein intake and blood sugar profiles (fasting and
    postprandial glucose and insulin, C-peptide and hemoglobin A1c) in potentially
    insulin resistant adults?
  2. What is the relation between protein intake and blood lipid profiles (total cholesterol,

Results

The study did not demonstrate a consistent relation between total and animal protein intakes and blood sugar control or blood lipid concentrations. Serum insulin, an indication of insulin resistance, was lowest in adults who were in the second quartile (25th to 50th percentile) of protein intake. However, other indicators of blood sugar control did not differ by quartiles of protein intake. Lower protein intakes were associated with slightly higher total cholesterol concentrations (indicating increased cardiovascular risk) but also slightly higher HDL cholesterol concentrations (indicating decreased cardiovascular risk).

Key Conclusions

The study did not demonstrate a consistent relation between total and animal protein intakes and blood sugar control or blood lipid concentrations.