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The Portfolio Diet

Submitted by on September 12, 2011 – 8:56 am2 Comments
 

If you’ve ever been diagnosed with high cholesterol, your doctor has probably given you the standard chat about all the foods you should avoid.  The general list of no-no’s includes anything high in cholesterol (eggs, shellfish, butter, red meat, cheese), as well as foods high in saturated fat (whole milk dairy/cheese, red/processed meats).  If statistics are a reliable indicator, though, you probably ended up taking a statin drug anyway.  That’s because restrictive diets are hard to stick to, and you probably didn’t get that high cholesterol because you love eating avocado and sprout sandwiches.

But for the past decade or so, a team of researchers has been publishing papers about the effects of an experimental diet called the “Portfolio Diet” on blood lipid levels of people with high cholesterol.  Unlike prevailing dietary approaches that emphasize what foods to avoid, the Portfolio Diet focuses on ADDING a handful of beneficial foods to the daily diet. The portfolio of foods and nutrients  included: nuts, soy protein, plant sterol-enriched margarine, and “viscous” (soluble) fiber specifically found in foods like oats, barley, eggplant, okra and psyllium husk supplements.

Each of these foods was selected based on previous research which suggested a different and complementary cholesterol-lowering mechanism; the hypothesis was that if a portfolio of all these foods was eaten daily as part of a low saturated fat diet, it could help lower cholesterol by launching a multi-pronged attack on all the ways that cholesterol is manufactured, transported and/or recycled in the body.  The researchers wanted to compare the benefits of this Portfolio Diet compared to (1) a typical low-saturated fat diet, and (2) a typical low-saturated fat diet plus a statin drug.

Their initial findings, published in 2003, were interesting but largely impractical.  While their experimental Portfolio diet did lower cholesterol as much as people on a standard low-saturated fat diet who took a statin (as compared to the control group that just followed a typical low-saturated fat diet), there were several limitations.  First of all, the study groups were each less than 20 people, making it difficult to draw any widespread conclusions.  Secondly, the researchers provided the participants with virtually all the food for their meals to ensure compliance– a circumstance that would not be replicated in real-life settings.  Thirdly, the amount of fiber in the Portfolio Diet was so colon-blowingly-large (78g per 1,000 calories… or 140g/day on an 1,800 calorie/day diet) that most Americans (whose average fiber intake is reportedly only ~14g/day) attempting to follow it would probably spend half their day on the toilet or warming the planet irreparably through the  toxic cloud of methane gas they produced as a result.

Last month, however, the researchers published a study in JAMA with much more promising–and practicable–results.  They took a scaled-back version of their Portfolio Diet to test against the original, intensive version, to determine whether it would still provide the same cholesterol-lowering results as compared to the standard, low-saturated fat “control” diet.  Furthermore, they tested these 3 diets in a larger test group than the original study (between 80-90 people in each group), and allowed the participants to prepare their own food rather than having it provided to them–thus simulating real-life conditions much more closely.  The participants included both men and women, and the average participant was overweight (average BMI=27).  The experiment lasted 6 months.

The results?  Not only did the scaled-back version of the Portfolio Diet result in the same degree of cholesterol lowering as the intensified version… but the participants’ food records indicated that the average intake of Portfolio foods among the scaled-back group was LESS THAN HALF (41%) of the target amount!  In other words, the dieters reaped a significant benefit (LDL reductions of ~13%) from adding a relatively modest amount of Portfolio foods to their low-saturated fat diets.  In real terms, this translated into an average decrease of LDL levels from 171 mg/dL to 147 mg/dL.  Though the more closely participants adhered to the diet, the greater their reduction in LDL was.

The Nuts and Bolts of the Experimental Portfolio Diet

So what, exactly, did the participants eat, and how much?

  • For starters, all groups followed a low-saturated fat diet.  In this study, it was a vegetarian diet that included eggwhites and low-fat dairy products, but no meat.  Because only animal products have cholesterol, the vegetarian diet resulted in a significant reduction of dietary cholesterol intake to below 200mg/day among ALL study groups, even the controls.
  • Secondly, all groups were counseled to restrict their calories to an amount designed to maintain their current weight, such that weight gain or weight loss would not muddy the results.  In reality, this translated into intakes of about 1,800-1,900 calories per day, including the portfolio foods.  (This is an important point, since adding a minimum of ~600-700 calories worth of Portfolio foods per day to achieve target nutrient levels could result in weight gain unless something else was taken away to compensate for it!)  After 6 months, no group had lost a significant amount of weight.
  • Third, the scaled-back Portfolio Dieters had nutritional counseling twice during the 6-month study period to help them adhere to the diet.  (Consider this a thinly-veiled plug to make an appointment with a registered dietitian!)
  • The ACTUAL average intake of portfolio foods/nutrients per day, assuming an 1,800 calorie/day diet, was as follows:
    • 11g of “viscous” fiber per day (mainly from psyllium husk fiber supplements, oats, oat bran and/or barley)
    • 21g of soy protein per day
    • 1.1g of plant sterols per day from an enriched margarine product
    • 47g of nuts (including peanuts) per day

How do these nutrients translate into actual foods and portions?  And how many calories are associated with these portions?  Read on:

“Viscous fiber”:

    • 1 cup cooked plain oatmeal has 4g fiber and 160 calories
    • 1/2 cup of cooked pearled barley has 3g of fiber and 95 calories
    • 1 slice oat bran bread has ~1.4g fiber and ~80 calories (varies by brand; read labels for precise info)
    • Psyllium husk powder (dietary supplement): 2 TBSPs have 9-10g fiber and ~35-45 calories, depending on the brand
    • Note: other good sources of “viscous” fiber include okra, eggplant, strawberries, beans.
    • For gluten-free readers: pearled barley is off limits, but certified Gluten-free oats are marketed by Bob’s Red Mill and Arrowhead Mills.  Psyllium husk is naturally gluten-free, but check your product’s label to ensure it was not processed in a facility/on equipment that also processes gluten-containing ingredients.

Soy protein:

    • 1/2 cup of raw, firm tofu (~4.5 oz) has 20g of protein and 180 calories
    • 1 cup plain soymilk has 6g protein and 80-120 calories
    • 1/2 cup shelled edamame (boiled soybeans) has ~10g protein and ~100 calories
    • 1 oz of dry roasted “soy nuts” (1/4 to 1/3 cup depending on brand) has 10-11g protein and 120-140 calories
    • Note: study participants also ate more processed soy products, such as meatless soy “deli slices”

Plant Sterols (from enriched margarine products):

Nuts:

    • 47g of nuts is about 1.7 ounces, or 1/3 cup of most nut varieties (270-340 calories for dry-roasted, depending on the variety.  Read the label of your favorite nut for more precise info or check out this chart for a comparison by nut type.)

The bottom line?  While much more research is needed to validate these results and refine exact quantities of foods and nutrients needed to achieve optimal benefits from a cholesterol-lowering persepctive, the fact remains that swapping in nutritious, high-fiber, plant-based foods such as those in the Portfolio Diet for animal protein foods and refined grains in your current diet is very likely to benefit your health in many ways.   If you can’t go all the way, the study’s results nonetheless suggest that swapping in a smaller amount of these foods is still likely to produce some benefit, so give it a try!

 

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2 Comments »

  • Carrie Ann Miller says:

    This post is excellent! Thank you for providing such a great summary of the diet and the foods that are included. Do you know of any sites or books that provide more guidance, or recipes/menus?

  • Tamara says:

    Hi Carrie Ann,
    I am not aware of any other resources related to the portfolio diet, though I haven’t looked into it with any great depth. As far as I can tell, at this point it remains an experimental diet that lives only in the research world, though I’m sure some entrepreneurial person will author a book to popularize it at some point and make a killing. I’d think about making sure to include a portfolio food at each meal, plus include a serving of psyllium husk fiber supplement daily. So for example, oatmeal with some nuts sprinkled on for breakfast, lentils/beans at lunch, tofu or edamame at dinner, etc.. That will probably get you pretty close…

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