Welcome to this months “Science Review” which is all about Cholesterol and whether the Portfolio Diet could be a future consideration when it comes to reducing LDL (Low Density Lipoprotein)…the bad cholesterol!

High cholesterol is recognised as a main risk factor for cardiovascular disease (CVD), which in turn causes 9 million annual deaths globally (1). General practice treatment includes recommendations to follow a low fat diet and prescription of statin. (2) This reviews aims to outline the latest research surrounding the portfolio diet as an alternative means to lowering cholesterol and whether GP’s could use the motivational interviewing (MI) technique for greater patient uptake, adherence and results.

If you understand what cholesterol is and ‘the numbers’ to watch out for then skip straight to evidence relating to the portfolio diet here. If you don’t know your numbers, you can order an ‘at-home-test’ kit here

Disclaimer: As always, this science review is based on an assignment I completed for my MSc in Nutritional Medicine (which I haven’t finished qualifying in yet. Therefore (disclaimer) I am not a registered nutritionist yet). My result for this assignment was 77% considered “Excellent and a Distinction” by the University of Surrey, but as always… could do better.

Let’s start by knowing our numbers

Before we get stuck into the Portfolio diet as a potential practice for lowering cholesterol, it’s important to first understand two key points: 1) What is the role of Cholesterol and 2) What is considered ‘high’ cholesterol and problematic for health.

1 – The Role of Cholesterol

Cholesterol is both synthesised within the body and consumed as part of our diet. Although it gets a bad rep, cholesterol plays an important role in our body. It’s main function is to maintain the integrity and fluidity of cell membranes and without it our cells may rupture. It also acts as an important precursor for the synthesis of substances that are vital such as steroid hormones (Testosterone & progesterone), bile acids and vitamin D. However, you can have too much of a good thing and elevated levels of Cholesterol in the blood stream can lead to heart attacks and strokes (1)

2 – Knowing your Numbers

Cholesterol is made up of a number of different ‘types’ and you’re probably aware of LDL’s, which are considered “bad cholesterol”. Depending on where you get tested you may get results for different combinations. According to the NHS England (32), the numbers you should be aware of when you get your results are:

Result	Healthy level (mmol/L)
Total cholesterol	5 or below
HDL (good cholesterol)	1 or above
Non-HDL (bad cholesterol)	4 or below
Fasting triglycerides (when you’re asked not to eat for several hours before the test)	1.7 or below
Non-fasting triglycerides (when you eat as normal before the test)	2.3 or below
Total cholesterol to HDL cholesterol ratio	6 or below

I’ll add a caveat to that and say, it’s always good to look at your LDL cholesterol also and speak with your GP about anything above 3.4

If you’re over 40 and never had your Cholesterol checked, then I’d suggest you book an appointment with a GP. However, if you don’t have time you can easily do an at home blood test now to check your cholesterol. I do mine every 6 months. Click this link At home Cholesterol Check to and get a simple test for £39.00. Full transparency, I’ll get a small commission if you click this link.

Now Let’s get stuck in to the Science

Evidence relating to The Portfolio Diet (PD) for decreasing Low-Density-Lipoprotein Cholesterol (LDL)

The predominant dietary recommendation for lowering cholesterol remains one of consuming less than 7% saturated fat and 200mg of cholesterol per day (1). However, more recent guidance has emphasised inclusion of: plant sterols and viscous fibre (3) or soy and nuts (4) with studies (5-9) showing a reduced serum cholesterol of between 5-10% when including one of these dietary elements.

Professor David Jenkins has led the way in researching the combined effect of (8.2g-10g) viscous fibre, (16.2g-22.7g) soy protein, (2.9g-23g) raw almonds and (1g-1.2g) plant sterol/100kcal – aptly named the portfolio diet (PD). The first preliminary study (8) commenced in 2000 with 13 participants who were already being treated for high cholesterol. Initial results demonstrated a 22% decrease in total cholesterol (TC), a 29% reduction in LDL-C and a reduction of 30% in calculated CHD risk. However, this study lacked a control group, randomisation or a long-term aspect in relation to ‘real world’ adherence. 

A repeat study in 2003 (10) with 25 participants and a control group who followed a very low saturated fat (VLSF) diet also showed promising results. LDL-C was decreased by 35% in the PD group versus 12% in the VLFD group along with decreases in LDL:HDL (high-density lipoprotein) ratios of 30% and 5.1% respectively. However, whilst both of these studies showed promising results, they lacked comparative results against the consistent success of statins (11). This was approached in 2003 when Jenkins et al (12) conducted a study on 46 participants comparing the effects of Lovastatin vs the PD on serum lipids and c-reactive protein. Results were significant showing a decrease in LDL-C by 30.9% for the statin group and 28.6% for the PD group along with reduced LDL:HDL ratios of 28.4% and 23.5% and reduced C-reactive proteins 33.3% and 28.2% respectively. Whilst all three studies (8,10,12) progressed upon the former, they were all conducted with patients who had previously taken part in trials and all had the majority of food provided for the duration of the trial.

In 2006, Jenkins et al (13) commenced carrying out a randomised control trial (RCT) with 66 patients to assess ‘real world effects’ on adherence and subsequently the results that could be achieved with the PD when patients are in control of their own dietary purchase and intake. Results showed less adherence for viscous fibre and soy and after 12 months only 2 participants were following a vegan diet. However, despite the decline in adherence, the results showed a mean reduction of LDL-C of 13% with approximately a third of participants achieving reductions greater than 20%, which is associated with first degree treatment in statins (25-30%) (13). From all studies it is important to note the most favoured results came with 8.3g viscous fibre, 1.2g plant sterol, 16.6g almonds and 16.6g soy. However, the results from the last study (13) with higher amounts may have been impacted by the lower adherence as opposed to the dosage.

Since 2008, Jenkins et al has carried out further studies showing significant reductions to confirm the PD as a means of reducing LDL-C (14-16) along with focussing on enhancement of the portfolio of foods to include monounsaturated fatty acids (MUFA’s) (17), Strawberries (18) and the potential of this diet to also lower c-reactive protein (19) and blood pressure (20). A search of of clinicaltrials.gov in relation to the condition ‘Hyperlipidemias’ against the term ‘portfolio’ found a total of 11 trials whereas when we used the term ‘statin’ we found 686. The consistency and success of lowering LDL-C via statin has unfortunately made diet less of a focus for control and/or treatment and this is perhaps because it relies heavily on intrinsic motivation by the individual to change. Research regarding motivational interviewing (MI) as a technique for change in health care has been positive. However, the research is unclear for whom it is most beneficial and limited in relation to lipid management (21).

Could motivational interviewing help improve patient outcomes?

MI has been defined as “…a collaborative, goal-orientated style of communication with particular attention to the language of change. It is designed to strengthen personal motivation for, and commitment to, a specific goal by eliciting and exploring the persons own reason for change within an atmosphere of acceptance and compassion” (22).In layman’s terms, a GP would have a collaborative conversation during patient visits with the aim of strengthening the patients own motivation and commitment to adopt dietary changes. But is it practical and is there any evidence it works for the introduction of the PD specifically to lower LDL-C in patients? 

In a study by Mhurchú et al (23), 121 patients with hyperlipidemia had improved dietary habits and body mass index (BMI) after a 3 month intervention that was either: standard GP script or motivational, but there were no significant differences between the groups nor resultant lipid levels (23).

Although there have been other studies specifically looking at the effects of MI in the health care practice, there are only a few that have included TC and LDL-C (21, 23-26).

One particular study (25) recruited 38 GP’s across 25 primarily care centres in Spain to work with 227 patients with uncontrolled dyslipidemia. The control group received practice standard care regarding: exercise, diet, lifestyle and statin use whereas the experimental groups intervention was based on MI techniques. The results showed a decrease in TC and LDL-C across both groups, but with no significant difference between groups. The same was found for adherence to diet, levels of exercise/activity and weight-loss (25)

Another study (26) focused on MI techniques with overweight or obese adolescents who had dyslipidemia . After 6 months, there were decreases in LDL-C, TC and Tricylglycerol (TGA). However, they did not find any significant changes between the groups that underwent MI alone or with their parents. This suggests, MI can have a positive effect in treating patients, but do GP’s have the capacity to provide such an intervention? The above study provided 4 x one-on-one MI sessions plus 4 follow up phone calls per patient in a 6 month period.

A search of the various databases could not find any RCT that specifically looked at the effects of a PD intervention on lowering LDL-C with a) general practice care and b) MI; to fully ascertain whether MI has a significant role to play in decreasing LDL-C with the PD. The closest study we could find brought us back to Jenkins et all, (14) who in 2011 conducted a RCT with 351 participants with hyperlipidemia. Participants were randomised to: Control – LSFD, Test 1 – PD + 2 clinic visits (routine) or Test 2 – PD + 7 clinic visits (intensive) over a period of 6 months. The results were clear. Clinic visits proved significantly effective in supporting the lowering of LDL-C. 3% control, 13.1% for routine and 13.8% for intensive. However, the results did not show significant difference between the routine and intensive groups demonstrating a little amount of support may go a long way and that counselling for consumption of these cholesterol lowering foods in real world conditions could be beneficial. However, this study did not indicate MI as a specific technique. Therefore, a repeat of this study specifically using MI techniques could be beneficial.

Let’s Conclude

To conclude, evidence shows implementation of the PD may have positive effects on decreasing TC & LDL-C thus contributing towards lowering CVD risk (8, 14, 16-20, 27-30). However, adherence to the diet decreases from trial to real-world living (13) and the field would benefit from further RCT by more than one research lead (Jenkins). Although there is some evidence to suggest ‘counselling’ may have positive outcomes for lowering LDL-C (25, 26) and MI may have positive effects in primary care settings (21, 31), there is no clear evidence yet to demonstrate specifically that MI would significantly improve adherence to the PD in a real world environment and we recommend a repeat of Jenkins 2011 study (14) to include MI techniques.

Take Homes for You

1. If you haven’t had your Cholesterol checked, then book an appointment with your GP or go for an at-home-test-kit from our friends at Medichecks. Click this link: medichecks.sjv.io/mgQXoZ
2. If you have high cholesterol you should always follow the GP’s advice regarding any prescription for Statin, but you could also discuss whether the Portfolio diet is an option for you
3. If you know you have high cholesterol and want to add the portfolio diet to your daily diet go for: 45-50g of Soy Protein, 20g of viscous fibre from oats, barley, Psyllium, apples & oranges; 2g of plant sterol from margarines; and 42g of almonds (do not follow if you have allergies to any of these ingredient)

References

1. The British Heart Foundation. Global Heart and Circulatory Diseases Factsheet 2021 [updated July 2021. Available from: https://www.bhf.org.uk/-/media/files/research/heart-statistics/bhf-cvd-statistics-global-factsheet.pdf?la=en&rev=9dcb0101dae8492ba5731e16d195c029&hash=A5B0E9FCCF85BA40CCFCFFFEC377A91833DF0B7B
2. NHS England. Lipid Management Pathway Guidance. In: subgroup Ac, editor. 2020.
3. The National Heart Lung and BIood Institute. National Cholesterol Education Programme ATP III guidelines ‘at a glance; quick desk reference 2021 [Available from: https://www.nhlbi.nih.gov/files/docs/guidelines/atglance.pdf.
4. The American Heart Association. Prevention and Treatment of High Cholesterol (Hyperlipidemia) 2021 [Available from: https://www.heart.org/en/health-topics/cholesterol/prevention-and-treatment-of-high-cholesterol-hyperlipidemia.
5. Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of the effects of soy protein intake on serum lipids. The New England journal of medicine. 1995; 333 (5):276-82.
6. Brown L, Rosner B, Willett WW, Sacks FM. Cholesterol-lowering effects of dietary fiber : a meta-analysis. The American journal of clinical nutrition. 1999; 69 (1):30-42.
7. Anderson JW, Allgood LD, Lawrence A, Altringer LA, Jerdack GR, Hengehold DA, et al. Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia : meta-analysis of 8 controlled trials. The American journal of clinical nutrition. 2000; 71(2):472-9.
8. Jenkins DJA, Kendall CWC, Faulkner D, Vidgen E, Trautwein EA, Parker TL, et al. A dietary portfolio approach to cholesterol reduction: Combined effects of plant sterols, vegetable proteins, and viscous fibers in hypercholesterolemia. Metabolism, clinical and experimental. 2002; 51(12):1596-604.
9. Phung OJP, Makanji SS, White CMP, Coleman CIP. Almonds Have a Neutral Effect on Serum Lipid Profiles: A Meta-Analysis of Randomized Trials. Journal of the American Dietetic Association. 2009; 109(5):865-73.
10. Jenkins DJA, Kendall CWC, Marchie A, Faulkner D, Vidgen E, Lapsley KG, et al. The effect of combining plant sterols, soy protein, viscous fibers, and almonds in treating hypercholesterolemia. Metabolism, clinical and experimental. 2003; 52(11):1478-83.
11. Chiavaroli L, Nishi SK, Khan TA, Braunstein CR, Glenn AJ, Mejia SB, et al. Portfolio Dietary Pattern and Cardiovascular Disease: A Systematic Review and Meta-analysis of Controlled Trials. Progress in cardiovascular diseases. 2018; 61(1):43-53.
12. Jenkins DJA, Kendall CWC, Marchie A, Faulkner DA, Wong JMW, de Souza R, et al. Effects of a Dietary Portfolio of Cholesterol-Lowering Foods vs Lovastatin on Serum Lipids and C-Reactive Protein. JAMA : the journal of the American Medical Association. 2003; 290(4):502-10.
13. Jenkins DJA, Kendall CWC, Trautwein EA, Lapsley KG, Holmes C, Josse RG, et al. Assessment of the longer-term effects of a dietary portfolio of cholesterol-lowering foods in hypercholesterolemia. The American journal of clinical nutrition. 2006; 83(3):582-91.
14. Jenkins DJA, Jones PJH, Lamarche B, Kendall CWC, Faulkner D, Cermakova L, et al. Effect of a Dietary Portfolio of Cholesterol-Lowering Foods Given at 2 Levels of Intensity of Dietary Advice on Serum Lipids in Hyperlipidemia: A Randomized Controlled Trial. JAMA : the journal of the American Medical Association. 2011; 306(8):831-9.
15. Jenkins DJA, Wong JMW, Kendall CWC, Esfahani A, Ng VWY, Leong TCK, et al. Effect of a 6-month vegan low-carbohydrate (‘Eco-Atkins’) diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial. BMJ open. 2014; 4(2):e003505-e.
16. Jenkins W, Jenkins A, Jenkins A, Brydson C. The Portfolio Diet for Cardiovascular Disease Risk Reduction: An Evidence Based Approach to Lower Cholesterol Through Plant Food Consumption. Saint Louis: Elsevier Science & Technology; 2019.
17. Jenkins DJA, Chiavaroli L, Wong JMW, Kendall C, Lewis GF, Vidgen E, et al. Adding monounsaturated fatty acids to a dietary portfolio of cholesterol-lowering foods in hypercholesterolemia. Canadian Medical Association journal (CMAJ). 2010; 182(18):1961-7.
18. Jenkins DJA, Nguyen TH, Kendall CWC, Faulkner DA, Bashyam B, Kim IJ, et al. The effect of strawberries in a cholesterol-lowering dietary portfolio. Metabolism, clinical and experimental. 2008; 57(12):1636-44.
19. Jenkins DJA, Kendall CWC, Josse RG, Leiter LA, Singer W, Connelly PW, et al. Direct comparison of dietary portfolio vs statin on C-reactive protein. European journal of clinical nutrition. 2005; 59(7):851-60.
20. Jenkins DJA, Kendall CWC, Faulkner DA, Kemp T, Marchie A, Nguyen TH, et al. Long-term effects of a plant-based dietary portfolio of cholesterol-lowering foods on blood pressure. European journal of clinical nutrition. 2008; 62(6):781-8.
21. Frost H, Campbell P, Maxwell M, O’Carroll RE, Dombrowski SU, Williams B, et al. Effectiveness of Motivational Interviewing on adult behaviour change in health and social care settings: A systematic review of reviews. PloS one. 2018; 13(10):e0204890-e.
22. Miller WR, Rollnick S. Motivational interviewing : helping people change. 3rd ed. New York ;: Guilford; 2013.
23. Mhurchú CN, Margetts BM, Speller V. Randomized clinical trial comparing the effectiveness of two dietary interventions for patients with hyperlipidaemia. Clinical science (1979). 1998; 95(4):479.
24. Pérula LA, Bosch JM, Bóveda J, Campiñez M, Barragán N, Arboniés JC, et al. Effectiveness of Motivational Interviewing in improving lipid level in patients with dyslipidemia assisted by general practitioners: Dislip-EM study protocol. BMC family practice. 2011; 12(1):125-.
25. Bóveda-Fontán J, Barragán-Brun N, Campiñez-Navarro M, Pérula-de Torres LÁ, Bosch-Fontcuberta JM, Martín-Álvarez R, et al. Effectiveness of motivational interviewing in patients with dyslipidemia: a randomized cluster trial. BMC family practice. 2015; 16(1):151-.
26. Chahal N, Rush J, Manlhiot C, Boydell KM, Jelen A, McCrindle BW. Dyslipidemia management in overweight or obese adolescents: A mixed-methods clinical trial of motivational interviewing. SAGE open medicine. 2017; 5:2050312117707152-.
27. Kendall CWC, Jenkins DJA. A Dietary portfolio: Maximal reduction of low-density lipoprotein cholesterol with diet. Current atherosclerosis reports. 2004; 6(6):492-8.
28. Ramprasath VR, Jenkins DJA, Lamarche B, Kendall CWC, Faulkner D, Cermakova L, et al. Consumption of a dietary portfolio of cholesterol lowering foods improves blood lipids without affecting concentrations of fat soluble compounds. Nutrition journal. 2014; 13(1):101-.
29. Jenkins A. The portfolio diet of foods to lower cholesterol and reduce cardiovascular disease : an evidence based approach for plant food consumption. London, England: Academic Press; 2020.
30. Vázquez-Manjarrez N, Guevara-Cruz M, Flores-López A, Pichardo-Ontiveros E, Tovar AR, Torres N. Effect of a dietary intervention with functional foods on LDL-C concentrations and lipoprotein subclasses in overweight subjects with hypercholesterolemia: Results of a controlled trial. Clinical nutrition (Edinburgh, Scotland). 2021; 40(5):2527-34.
31. Rubak S, Sandbaek A, Lauritzen T, Christensen B. Motivational interviewing: a systematic review and meta-analysis. British Journal of General Practice. 2005; 55(513):305-12
32. 32. https://www.nhs.uk/conditions/high-cholesterol/cholesterol-levels/