Tag Archive for: UK Biobank

Fish Oil: Reserve Judgment

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Let’s put the fish oil study from Tuesday in perspective. The most important thing is that observational studies such as these cannot demonstrate cause and effect. That’s not just a way to weasel out of making definitive statements; it’s because while fish oil supplements are associated in some way with atrial fibrillation in people who have no diagnosed heart disease, it may be something else that people who take fish oil supplements do that’s actually the culprit. Remember the hazard ratio (HR) was only 13%. What were the remaining 87% doing that was different?

The Problems

As I see it, these were the problems with this research paper.

Just as in the multivitamin study, researchers collected a whole host of dietary data and didn’t use much of it; they adjusted for those who ate oily and un-oily fish, but that was it. Fruit intake, vegetable intake, fiber intake, and a whole lot more dietary factors that have been shown to limit the development of cardiovascular disease were not considered. That may have impacted the HR.

The major problem was that they didn’t report the rate of AFib in those who did not take fish oil supplements. How can you not? What happens to those who do not take fish oil supplements could have provided comparison groups, which seems like a better analysis to conduct. No explanation. They just chose not to do it.

The final critique is that this study was conceived and executed by statisticians and epidemiologists. There were no nutrition experts on the team reported in the paper. I don’t know how that’s possible. If you’re considering a nutritional intervention, such as taking a fish oil supplement, there has to be someone who understands nutrition to consider other factors. It can’t be all statistics without thoughtful guidance.

The Big Question

How? How would fish oil supplements cause the development of AFib?

Research has shown that eating oily fish does not appear to cause AFib. Why would fish oil? The researchers cited a couple of possibilities having to do with an impact on channels that control electrical pathways but overall, no one has given any explanation.

This was not the first study that has examined fish oil supplements in large studies and found some relationship with AFib; there are also several that show no relationship at all. In this case, we have to reserve judgment because we can’t prove things either way.

The Bottom Line

What should you do? First, eat the healthiest diet you can and exercise regularly, because lifestyle is more important than supplements. Second, if you have already been diagnosed with CVD as I have—a stent more than 20 years ago—taking fish oil may be beneficial. If you’re under 60, it seems taking fish oil isn’t an issue and there’s no reason to stop. If you’re older than 60, should you begin to take fish oil supplements? It’s a matter of choice. I have to reserve judgment for now.

Next Tuesday is our primary election day in Michigan, and I’m taking the day off—I’m an election worker—but you’ll still get a Memo that goes into questions on this fish oil issue. There’s more to consider and I’ll let you know what those issues are.

What are you prepared to do today?

        Dr. Chet

Reference: BMJMED 2024;3:e000451.doi:10.1136/ bmjmed-2022-000451

Fish Oil and Atrial Fibrillation

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Researchers recently published an observational study on over 415,000 subjects in the UK Biobank database who took a fish oil supplement. During a follow-up period of almost 12 years, they statistically demonstrated a 13% increased hazard ratio (a measure over time of how often a particular event happens in one group compared to another group) in the development of atrial fibrillation in subjects. Atrial fibrillation is a type of arrhythmia, or abnormal heartbeat, that can result in extremely fast and irregular beats from the upper chambers of the heart. In those subjcts, there was a 5% increased risk of stroke.

The resultant impact was an attack on dietary supplements for being too easily available, leading to overconsumption, and questionable because of the lack of purity in dietary supplements. The Medscape Cardiology online section put out a video by a reputable researcher explaining who should take fish oil supplements. But if they’re so bad, why would she recommend them at all?

The other part of the results showed that if someone already had cardiovascular disease (CVD), the hazard ratio of developing major cardiac events was reduced if they took fish oil supplements. That’s why the expert made the video, taking the good and trying to make sense of it. Still, it gave the appearance of being a pitch for a pharmaceutical solution.

That’s the set-up for this week’s Memos. I’ll give you at least one of the questions you might have: Yes, this study tested only supplement use (and dietary intake) upon entrance to the study and nothing the rest of the 11.9 years, just like the multivitamin study from last week. But there’s so much more that I’ll cover on Saturday about the problems with this study. Just so you know, I’m still taking my fish oil supplements.

What are you prepared to do today?

        Dr. Chet

Reference: BMJMED 2024;3:e000451.doi:10.1136/ bmjmed-2022-000451

A Closer Look at Ultra-Processed Food Risk

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I think the results of the UK Biobank ultra-processed food (UPF) study were interesting, as I relayed on Tuesday, but the researchers went further. They estimated how substituting non-UPF plant-sourced foods for any of the other three sources of food resulted in a reduction of cardiovascular disease (CVD) morbidity and mortality. Further, and what got the headlines, substituting UPF plant-sourced foods for any of the other three increased the risk of CVD morbidity and mortality.

That led some experts to speculate about how processing destroyed fiber and phytonutrients and may even increase the amounts of negative chemicals that have been associated with disease in UPF plant-sourced foods. The problem is that there are no randomized-controlled trials to prove that. Here are a few things that stood out to me.

Theoretically…

The most important issue was this: The determination made about UPF increasing or decreasing the risk of CVD was theoretical and based on calculations. They used a 10% substitution for the non-UPF or UPF plant-sourced foods to calculate the expected raising or lowering of risk. What they could have done was divide the subjects into actual groups based on percentage of nutrients they actually ate instead of running theoretical statistical formulae. My impression is that so few people were diagnosed or died from CVD during the nine-year observational period that they wouldn’t have enough subjects for each group.

So few subjects were diagnosed or died? In the entire subject population—over 118,000 subjects followed for nine years—there were only 7,806 people diagnosed with CVD and only 529 deaths from CVD. Only? Most of the subjects were between 40 and 70, prime time for being diagnosed with some form of CVD.

When looking at the percentage of UPF-plant-sourced foods, the highest percentages were from industrialized packaged breads (9.9%),

pastries, buns, and cakes (6.9%) and biscuits (the kind called cookies in the U.S.) at 3.9%. That’s over half the amount of UPF-plant based foods on the list provided in the research paper. While wheat and other grains were certainly stripped of nutrients in the ultra-processing, that’s nothing new—that’s been happening to flour for over 100 years. What was missing were any fruits or vegetables processed in that manner.

The Bottom Line

Should you take the corn chips and vegan burgers out of your cart? Don’t get the impression that I think UPF plant-based foods should be eaten in mass quantities. I don’t. But I don’t think this study provided much direction in a reasonable response to the issue. On top of that, the analysis of the data may be just plain wrong. We’re not done yet, but we’ll get to that after the 4th of July. One more holiday challenge coming up on Tuesday.

What are you prepared to do today?

        Dr. Chet

Reference: DOI:
https://doi.org/10.1016/j.lanepe.2024.100948


Is Ultra-Processed Food Worthless?

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Ultra-processed food (UPF) has been in the news again: researchers have found a relationship between plant-based UPF and cardiovascular disease (CVD) and mortality. Health news writers were brimming with opinions on what the study meant. The comment that got my attention was that UPF manufacturing destroyed good nutrients found in plant foods to the point that there was no benefit to eating them. For example, store-bought cereals and cookies are worthless no matter how much fruit or nuts are added.

Is that true?

Let’s begin by looking at the study. Researchers used data from the UK Biobank database. They selected only the participants who completed at least two 24-hour dietary recalls—118,397 subjects. All participants were part of the healthcare system in the UK, so the researchers were able to collect diagnostic and mortality data from electronic medical records.

Researchers divided the dietary data into four groups:

  • Non-UPF plant-sourced foods (fresh grapes or canned corn)
  • UPF plant-sourced foods (corn chips or vegan burgers)
  • Non-UPF animal-sourced foods (ground beef or canned tuna)
  • UPF animal-sourced foods (chicken nuggets or ice cream)

The two main findings were that the more UPF plant-sourced foods were eaten, the higher the risk of CVD and CVD mortality; second, the increase of non-UPF plant-sourced foods reduced the risk of CVD and mortality. I think those results were to be expected. In Saturday’s Memo, we’ll take a closer look at whether the expert diatribes about negating the benefits of UPF-plant-sourced foods were warranted.

Don’t forget that the Men’s Health Webinar is this Wednesday evening. If you want to participate, respond by tonight to get the login information. The live webinar is free.

What are you prepared to do today?

        Dr. Chet

Reference: DOI:
https://doi.org/10.1016/j.lanepe.2024.100948