The Portfolio Diet
by Jessica Wilcox, RD, LDN, MS

Our patients are often motivated to seek advice on diet, exercise and lifestyle changes that will help them to avoid medication if possible. This recent study provides convincing evidence that for some individuals the benefit of diet changes may provide similar benefits to statins.

The “portfolio diet” is a term coined by David A. Jenkins from the Clinical Nutrition and Risk Factor Modification Center in Toronto, Canada. The portfolio diet focuses on reducing serum cholesterol levels, therefore reducing cardiovascular disease risk, by incorporating specific foods into the diet. The diet combines plant sterols, soy, viscous fiber and almonds with a diet low in saturated fat and cholesterol. There has been an increased interest the potential health benefits of soy protein and nuts, and the National Cholesterol Education Program (NCEP) has recommended the intake of plant sterols (2g/d) and viscous fibers (10-25g/d) be added to the diet for their potential cholesterol lowering effects. Jenkins et al decided to combine all four of these foods with a diet low in saturated fat to determine whether this combination diet was successful in reducing serum cholesterol levels.

The study was conducted to assess whether the portfolio diet could reduce serum cholesterol levels similarly to the reductions seen in statin trials (Jenkins, DA. 2003). Twenty five hyperlipidemic individuals (LDL-C > 4.1 mmol/L), 16 men and 9 postmenopausal women with mean age of 60 years, and a mean body mass index of 26 kg/m², were either patients recruited from the Risk Factor Modification Center at St. Michael’s hospital or answered a newspaper add. None of the subjects had a history of CVD, diabetes, renal or liver disease and none were taking any medications known to effect serum lipids. The initial run-in diet (saturated fat < 7% en, cholesterol < 200mg/d) was followed for one month prior to the start of the study. The subjects were then randomized into either the control very low saturated fat dairy and whole grain cereal diet or the portfolio diet containing soy (16.2g/1,000kcals), viscous fiber (8.3g/1,000kcals), plant sterols (1.2g/1,000kcals) and almonds (16.6g/1,000kcals). The portfolio diet was vegan and the control diet was lacto-ovo vegetarian, both lasted for one month. Significantly, on both the low fat diet and the portfolio diet, LCL-C was reduced by 12.1% and by 35.0% respectively. Weight loss was similar for both diets, and there was no change in blood pressure, serum triglycerides, and HDL-C, lipoprotein (a), or homocysteine concentrations with either diet. The reductions in LDL: HDL-C ratio was significantly lower in the portfolio diet than the control diet. Statins typically reduce LDL-C anywhere from 18-55% in hyperlipidemic individuals. Therefore, the reduction in LDL-C by 35% seen with the portfolio diet is hopeful.

Further research conducted by Jenkins et al compared the effects of the portfolio diet versus Lovastatin on both serum lipids and C-reactive protein (CRP) (Jenkins, DA. 2003). The study was a randomized parallel design, and participants (25 men, 21 postmenopausal women, mean age 59 years, BMI average 27.6) were stratified based on sex and LDL-C levels. Again, they were randomized to a very low saturated fat dairy and whole grain diet, with or without a statin or the portfolio diet (as mentioned above). The results are shown in the following table.

	Control	Statin	Portfolio
LDL-C	↓ 8.0 %	↓ 30.9 %	↓ 28.6
LDL-C : HDL-C	↑ 3.0	↓ 28.4	↓ 23.5
CRP	↓ 10.0	↓ 33.3	↓ 28.2
CHD risk	↓ 3.0	↓ 25.8	↓ 24.9

The reduction in blood lipids in both the statin and portfolio groups were significantly greater that the changes seen in the control group, although there were no significant differences between the statin and portfolio groups. The same results were seen fro CRP. The results of this study indicate that statins are the most effective in lowering all four risk factors, although, the portfolio diet shows remarkably similar results. 

Compliance with the portfolio diet may not be easy for most people. Jenkins et al also studied the ability for individuals to follow the portfolio diet under real world conditions (Jenkins, DA. 2006). His results indicated that 30 % of motivated patients who ate the portfolio diet were able to lower their LDL-C > than 20% under real world conditions. The author stated that these individuals were motivated and that not all participants that began the study were able to complete the study. Sixty six participants began the study and 55 completed the study. Compliance was satisfactory for nut and plant sterol rich margarine, but low with soy and viscous fiber. If individuals can make lifestyle changes to incorporate new foods into their diets then this diet may be effective in lowering cholesterol and therefore CVD risk.

Jessica Wilcox, RD, LDN, MS is a former member of the Live Nutrition team. She is a graduate of Nauset High and Colorado State University. She served part of her internship at Live Nutrition and after graduation she was on the LN staff during 2003-2005. Jessica then returned to graduate school in Montana, where she is now in clinical practice.