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Introduction
With elevated LDL-cholesterol being a causal risk factor for atherosclerotic heart disease, having interventions to lower blood lipids, and in particular LDL-C, are crucial for population health. A number of drugs are now incredibly effective for this, with statins being the most widely used.
However, for those who do not wish to take a medication and/or have only a mild elevation, there may be potential for dietary intervention to lower LDL-C to a point where a statin (or other drug) is not needed.
A number of aspects of healthy dietary patterns have been known to reduce the liklihood of elevated blood lipids. Most notably perhaps, the ratio of polyunsaturated to saturated fat in the diet (P:S ratio). And an absolute low level of saturated fat in the diet (e.g. < 10% of calories).
However, work by Dr. David Jenkins and collegegues put forward the idea of a “portfolio” of specific nutrients/foods that could additionally lower LDL-C. This became known as the Portfolio Diet. The four primary pillars of this portfolio diet are: soy protein, viscous fibers, nuts, and plant sterols.
In this episode, Danny talks to the originator of this work, Dr. Jenkins.
Related resources
- Sigma Statements – 3-part series on lipids, diet and heart disease:
- Podcast Episodes:
- Episode 430: Soy – Yes, No, Maybe?
- Episode 317: Understanding Diet & Heart Disease Risk
- [06.24]The origins of the glycaemic index and the role of dietary fiber
- [13.40]What is the Portfolio diet?
- [15.50]Initial studies – magnitude of effect vs. first generation statins
- [18.40]The portfolio is built on a background of a healthy diet
- [26.50]Where are we now? Current evidence on the portfolio diet
- [29.10]Mechanisms of soy protein lowering lipids
- [36.38]The FDA review of the health claim on soy
- [40.05]What are viscous fibers? How do they lower lipids?
- [44.58]The mechanisms for how different nuts can reduce lipids
- [47.55]Current evidence on plant sterols for lowering lipids
- [53.30]Next big research questions to answer
- [55.40]Practical steps to reduce LDL-cholesterol via the diet
The Hosts
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Dr. Alan Flanagan has a PhD in nutrition from the University of Surrey, where his doctoral research focused on circadian rhythms, feeding, and chrononutrition.
This work was based on human intervention trials. He also has a Masters in Nutritional Medicine from the same institution.
Dr. Flanagan is a regular co-host of Sigma Nutrition Radio. He also produces written content for Sigma Nutrition, as part of his role as Research Communication Officer.
Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.
Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.
Key Ideas
Key Idea: Replacement in Nutrition Science
When talking about addition of a food/nutrient, we need to consider the impact of the overall shift in the diet. There are two elements:
- Don’t just think of “food X” as “nutrient Y”, e.g. dairy is not just calcium
- When we add a food/nutrient, we typically end up replacing something else. Therefore the net result is the consequence of both the addition of the nutrient(s) and the nutrients that are reduced (i.e. have been replaced).
As an example, in this episode we considered the impact of introducing soy foods into the diet for cardiovascular disease risk. So in above to the above couple of points, we need to realise that:
- Introducing soy foods not only increases soy protein intake, but also isoflavones, micronutrients, etc.
- Typically soy foods take the place of animal-based foods that can be high in saturated fat. For example, using tofu instead of red meat or using soy milk instead of cow’s milk. So the impact on lipids will be influenced not only by what soy contains, but what it is replacing. Therefore, the benefit of adding tofu to the diet will be much larger for someone who replaces fatty cuts of meat, than it will be for someone who already consumes a low saturated fat diet, and includes the tofu instead of chickpeas for example.