The first phase of the study involved 13 hyperlipidemic individuals who were instructed to consume the standard Portfolio Eating Plan for four weeks after a brief run-in period. After the four weeks, researchers found that the subjects lowered their LDL cholesterol by about 30 percent compared to baseline measures. Although these findings were statistically significant, the lack of a control group and sample size still left questions about the clinical significance yet to be answered.1
Portfolio Eating Plan Compared to a Statin Drug
The real test for the Portfolio Eating Plan (PEP) came with the addition of two control groups and a larger sample size. In Phase 3 of the study, a negative control, the NCEP Step 2 diet alone, and a positive control, the NCEP Step 2 diet and 20 mg Lovastatin, were tested against the PEP. With a sample size of 46 men and women after four weeks the PEP reduced LDL cholesterol levels by 28.6 percent (p< 0.001) while the Lovastatin treatment lowered LDL cholesterol levels by 30.9 percent (p< 0.001). PEP and Lovastatin treatments performed statistically the same. Similarly, Lovastatin and the PEP reduced c-reactive protein, a marker of inflammation, by 33.3 percent (P =.002), and 28.2 percent (P =.02). These findings were published in the Journal of the American Medical Association (Jul 2003) since this was rare occasion when a dietary approach created such a reduction.2
Although the results were well-received, there were still some skeptics who challenged the University of Toronto team to test this approach over a longer term, such as one year, and in a mixed diet of free-living individuals rather than a strict vegetarian protocol. This would lead to Phase 4.
In Phase 4, 66 hyperlipidemic men and women followed the PEP protocol for 52 weeks and were permitted to follow the protocol as they saw fit. This allowed the participants to live their normal daily lives and apply PEP as they chose for the 52 weeks. A full lipid panel was conducted 10 times throughout the study. At the end of the 52 weeks (one year) LDL cholesterol was reduced on average 13 percent, triglycerides were reduced on average 10 percent, and the total to HDL ratio was reduced about 12 percent. These findings strongly suggested that the PEP protocol could be modified with more animal-based products like meat, poultry and dairy while still producing a significant and meaningful result.3
In addition to lipid measures, the team tracked blood pressure levels throughout the study and found that the reductions from baseline in systolic and diastolic blood pressure at 1 year (n=66 subjects) were -4.2+/-1.3 mm Hg (P=0.002) and -2.3+/-0.7 mm Hg (P=0.001), respectively. Diastolic blood pressure reduction was significantly related to weight change (r=0.30, n=50, P=0.036). Researchers further found that compliance with almond intake advice was related to blood pressure reduction (systolic: r=-0.34, n=50, P=0.017; diastolic: r=-0.29, n=50, P=0.041). The reductions in blood pressure were greater in individuals who also lost weight on the PEP. Note that there was no control group in this study and some of the blood pressure effects may have been due to a placebo effect. But these interesting findings on blood pressure add to the body of evidence supporting dietary approaches that include whole grains, fruits, vegetables and nuts to lower blood pressure such as the Dietary Approaches to Stop Hypertension (DASH) dietary protocol.4
1. David J.A. Jenkins. Cyril W.C. Kendall. Dorothea Faulkner, Edward Vidgen, Elke A. Trautwein, Tina L. Parker, Augustine Marchie, George Kournbridis, Karen G. Lapsley, Robert G. Josse, Lawrence A. Leiter, and Philip W. Connelly A Dietary Portfolio Approach to Cholesterol Reduction: Combined Effects of Plant Sterols, Vegetable Proteins, and Viscous Fibers in Hypercholesterolemia, Metabolism December 2002, V51 N12.
2. Jenkins DJ, Kendall CW, Marchie A, Faulkner DA, Wong JM, de Souza R, Emam A, Parker TL, Vidgen E, Lapsley KG, Trautwein EA, Josse RG, Leiter LA, Connelly PW. Effects of a dietary portfolio of cholesterol-lowering foods vs lovastatin on serum lipids and C-reactive protein. JAMA. 2003 Jul 23;290(4):502-10.
3. Jenkins DJ, Kendall CW, Faulkner DA, Nguyen T, Kemp T, Marchie A, Wong JM, de Souza R, Emam A, Vidgen E, Trautwein EA, Lapsley KG, Holmes C, Josse RG, Leiter LA, Connelly PW, Singer W. Assessment of the longer-term effects of a dietary portfolio of cholesterol-lowering foods in hypercholesterolemia. Am J Clin Nutr. 2006 Mar;83(3):582-91.
4. Jenkins DJ, Kendall CW, Faulkner DA, Kemp T, Marchie A, Nguyen TH, Wong JM, de Souza R, Emam A, Vidgen E, Trautwein EA, Lapsley KG, Josse RG, Leiter LA, Singer W. Long-term effects of a plant-based dietary portfolio of cholesterol-lowering foods on blood pressure. Eur J Clin Nutr. 2008 Jun;62(6):781-8. Epub 2007 Apr 25.
