Finding the healthiest foods for you as an individual is an important component of building long-lasting, longevity-inducing health. We are all different, from our genes to our microbiome to our daily lifestyle patterns. As a result, we all thrive on different diets.
For example, some people have genetic polymorphisms in fat metabolism pathways that make a ketogenic diet inappropriate. Additionally, some people may have genes or a microbiome that make a higher carbohydrate diet suitable.
A new project known as the Personalized Responses to Dietary Composition Trial(PREDICT) seeks to identify what drives our unique responses to diet. There are multiple ongoing trials looking at how each one of us responds differently to meals, and how other factors such as the microbiome and meal timing alter our response. This has the potential to be very useful in finding the healthiest foods for each and every one of us.
They’ve already published some data on the project, and more is on the way. You can check out the White Paper of the project by signing up at https://joinzoe.com/our-science. Note: Zoe is a company that is collaborating with various other entities. Their goal is to develop a platform using AI to help people identify their ideal diet.
We have no affiliation with ZOE and receive no compensation from them. We’re simply reporting their data.
Metabolic responses to meals
During the PREDICT I trial, researchers feed individuals muffins of varying macronutrient composition and measure their metabolic response to these foods. They chose muffins because they could standardize them.
The researchers theorize that the normally used fasting measures of metabolism are flawed because we rarely spend time in the fasting state during the day. Instead, our postprandial(After meal) responses are a more valid measure to look at for cardiometabolic health as they will drive inflammation, which impairs cardiometabolic health.
This is a depiction of their working model:
Essentially, their model posits that the healthiest foods for an individual will generally create less inflammation. Additionally, they looked at the most important factors that drive this relationship so they can use it to predict your healthiest foods.
Last year they published phase I of PREDICT I with some interesting findings. They looked at fasting and postprandial measures of insulin, glucose, lipids, and the inflammatory markers IL-6 and GlycA. The main findings are:
- Variation between individuals was greater for postprandial measures than fasting for triglycerides and glucose
- Insulin variation between individuals was greater during fasting
- Even between twins, the postprandial response to the same meal varied greatly
- Blood glucose dips after a meal drove increased food intake
- Postprandial triglycerides correlated much more strongly to PP inflammation(GlycA) than glucose (.83 vs .24)
- Greater microbiome diversity and lower visceral fat blocked the inflammatory response
- People tended to respond in the same way to fixed macronutrient ratios
While there were general trends in the population, the average of the population was not ideal for everyone. For example, while most people had a better glycemic response to carbs during meals earlier in the day, 1 in 4 actually saw the opposite.
This underscores the importance of individualization for diet.
Triglycerides more predictive of inflammation than glucose
People often pay close attention to their postprandial glucose response and make adjustments to lower it. As a result, the use of continuous glucose monitoring has become very common. This is done despite a lack of strong evidence for their use in healthy people. This is an artifact of the unfortunate focus on glycemia in Type 2 diabetics.
While it’s true that people with Type 2 diabetes have impaired glucose tolerance, they also have an impaired ability to clear triglycerides from the blood. Since research has essentially focused on reducing the glycemic response to meals, tools to measure the glycemic response have become common. This doesn’t mean that the glycemic response is more important, it’s just easier to measure.
The mechanism via which triglycerides play a role in postmeal inflammation has been previously characterized. There is a normal increase in triglyceride-rich lipoproteins after meals. If this response is exaggerated or prolonged, there is an increase in small, dense LDL and HDL particles. These particles are more susceptible to oxidation, increase inflammation and promote atherosclerosis.
We handle triglycerides and glucose differently after meals. Glucose rises and drops in between meals, while there is a progressive increase in triglycerides after successive meals. Essentially, after each meal, enterocytes store some triglyceride and release it during subsequent meals.
Meal and activity patterns play a significant role in regulating this response. We covered how meal frequency factors in to increased TGs and endotoxin in this blog. And a recent paper found that people who are sedentary throughout the day have elevated postmeal triglyceride response, even after exercise.
Glucose or fat?
Based on the data from the PREDICT I trial, addressing post-meal glucose excursions at the expense of increasing post-meal triglyceride excursion would increase inflammation rather than decrease it. Replacing carbohydrates with fat will increase post-meal triglycerides, holding all other factors constant.
But at the same time, a low carbohydrate diet increases whole body fat oxidation. Exercise does as well. This is why energy balance matters. In this sense, calories do matter because they are a measure of energy, you could use joules if you prefer.
If you swap out carbohydrates for fat, and this decreases energy intake, post-meal triglycerides will drop. But if you do the same and increase energy intake, this will cause an elevation in postprandial triglycerides and potentially increase the inflammatory response. Even if you increase post-meal fat oxidation, there’s only so much you can metabolize at one time.
Adiposity also matters. If you are lean and healthy, you’ll efficiently move blood triglyceride into fat stores when you consume fat in excess. If you are obese and closer to your fat storage capacity, triglycerides will remain elevated and increase inflammation.
Finally, low level physical activity such as walking utilizes triglycerides as the predominant fuel source. So taking walks between meals and throughout the day is also an effective strategy to lower post-meal triglycerides.
Research is moving in a direction that will allow us to determine the healthiest foods for us as individuals. Continuous glucose monitoring is becoming more popular as people look to find foods that work best for them, but that’s only part of the story.
Based on the evidence from the PREDICT I trial presented above, focus on postprandial glycemia to the detriment of triglycerides may actually worsen cardiometabolic health. Furthermore, recent data from PREDICT I shows the microbiome is a powerful driver of postprandial glycemia, indicating we can change it via long term dietary trends.
They identified microbes associated with better and worse PP glycemia as well as foods associated with these microbes. Bad news for the animal- and plant-based folk: There were bad foods in both camps. We’ll cover this data in detail when the full text version of the paper becomes available.