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Neurology: High- and Low-Fat Dairy Consumption and Long-Term Risk of Dementia Evidence From a 25-Year Prospective Cohort Study · This Week In Medicine

• 0:00
  [SPEAKER_01]: Welcome back to the DeepDive, where we cut through the noise, get past the clickbait, and really just deliver the hard data you need.
• 0:07
  [SPEAKER_01]: And today, we're talking about something.
• 0:09
  [SPEAKER_01]: Well, for what feels like generations, we've been hearing this persistent, confusing debate about dairy.
• 0:15
  [SPEAKER_01]: the full fat versus low fat battle exactly should we be reaching for full fat or is low fat the only way to go and you know this confusion just gets 10 times worse when we start talking about brain health and aging the information overload is just immense.
• 0:32
  [SPEAKER_01]: it is.
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  [SPEAKER_01]: So today we are going to tackle this giant question using a massive and I mean a really definitive data set.
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  [SPEAKER_01]: We're not talking about some three-month trial.
• 0:40
  [SPEAKER_00]: No.
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  [SPEAKER_01]: We're talking about a quarter century of rigorous observation.
• 0:44
  [SPEAKER_01]: Okay, let's unpack this.
• 0:45
  [SPEAKER_01]: Do it.
• 0:46
  [SPEAKER_01]: So the course source material for our deep dive today.
• 0:49
  [SPEAKER_01]: is a comprehensive 25-year perspective cohorts study.
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  [SPEAKER_01]: It was published in the journal Neurology.
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  [SPEAKER_01]: And researchers tracked the specific consumption patterns of all kinds of dairy products, high fat low fat, and then they correlated those habits with the long-term risk of developing dementia.
• 1:05
  [SPEAKER_00]: And that's really our mission today to distill those two and a half decades of data for you.
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  [SPEAKER_00]: The medical community knew the link was uncertain, but no one had really drilled down into the differences between specific products.
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  [SPEAKER_01]: Especially the fat content.
• 1:19
  [SPEAKER_00]: Especially the fat content.
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  [SPEAKER_00]: The goal was to bring some real clarity.
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  [SPEAKER_00]: Does the fat, or maybe something else about the product, actually change long-term dementia risk?
• 1:28
  [SPEAKER_01]: Okay, so to really appreciate the power of these results, we need to understand where they came from, the foundation of the study.
• 1:35
  [SPEAKER_00]: Absolutely.
• 1:35
  [SPEAKER_00]: This isn't a sample size of a few hundred people.
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  [SPEAKER_00]: The research used data from it's called the mammal diet and cancer cohort based in Sweden.
• 1:43
  [SPEAKER_01]: and the scale is just what makes this so compelling.
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  [SPEAKER_01]: They included 27,670 participants in the final analysis.
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  [SPEAKER_00]: A huge number.
• 1:51
  [SPEAKER_01]: It's huge.
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  [SPEAKER_01]: And crucially, they weren't starting with a young population.
• 1:54
  [SPEAKER_01]: The mean baseline age was 58.1 years.
• 1:57
  [SPEAKER_01]: So positions them right at that age were long-term cognitive trends really start to matter.
• 2:02
  [SPEAKER_00]: And that baseline data was collected way back in the early to mid-1990s.
• 2:06
  [SPEAKER_01]: All right, between 91 and 96.
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  [SPEAKER_01]: And that length of observation, that's the gold standard here, isn't it?
• 2:12
  [SPEAKER_00]: It absolutely is.
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  [SPEAKER_00]: The follow-up period was a median of 25 years.
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  [SPEAKER_00]: I mean, just think about the logistics required to track over 27,000 people for that long.
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  [SPEAKER_01]: It's incredible.
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  [SPEAKER_00]: And over that time, they meticulously recorded 3,200 and eight incident cases of dementia.
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  [SPEAKER_00]: That kind of longevity gives you incredibly robust data, minimizes the chance that short-term changes
• 2:36
  [SPEAKER_01]: Okay, and speaking of rigor, how did they even document what people were eating 25 years ago?
• 2:41
  [SPEAKER_01]: I can barely remember what I yesterday.
• 2:43
  [SPEAKER_01]: You know, poor dietary recall has to be the biggest weakness in these long-term studies.
• 2:47
  [SPEAKER_00]: It is, and they used a technique designed specifically to counteract that.
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  [SPEAKER_00]: It wasn't just a simple questionnaire.
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  [SPEAKER_00]: It was a comprehensive three-part system at the start of the study.
• 2:56
  [SPEAKER_01]: Great parts.
• 2:57
  [SPEAKER_00]: Yeah, first to seven-day food diary, second a very detailed food frequency question, Aaron F. F.Q.
• 3:02
  [SPEAKER_00]: And third, they did a structured dietary interview to clarify anything that was ambiguous.
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  [SPEAKER_01]: So that combination really nails down a reliable baseline.
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  [SPEAKER_00]: It's critical for a study this long, yes.
• 3:12
  [SPEAKER_01]: Okay, so they knew exactly what these thousands of people were eating in the early 90s then they tracked them for a quarter of a century.
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  [SPEAKER_01]: What were the specific outcomes they measured?
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  [SPEAKER_00]: The primary outcome was all caused dementia.
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  [SPEAKER_00]: But they also broke it down for a more granular look.
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  [SPEAKER_01]: Right.
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  [SPEAKER_00]: So the secondary outcomes were Alzheimer's disease, or AD, and vascular dementia, or VAD, which is more about blood flow to the brain.
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  [SPEAKER_01]: Okay, got it.
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  [SPEAKER_01]: So they have this massive long-term rigorous data set.
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  [SPEAKER_01]: Let's get to the results because this is where the popular narrative about dairy is dairy really starts to fall apart.
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  [SPEAKER_00]: It really does and we have to start with what I think is the biggest finding.
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  [SPEAKER_00]: The null findings.
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  [SPEAKER_01]: Meaning didn't have an effect.
• 3:54
  [SPEAKER_00]: Exactly.
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  [SPEAKER_00]: When the researchers looked at the vast majority of dairy products, they found absolutely no significant association with all cause dementia risk.
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  [SPEAKER_00]: This is the crucial context.
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  [SPEAKER_01]: So which products fell into that no association group?
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  [SPEAKER_00]: There's a pretty long list, low fat cheese and low fat cream no association.
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  [SPEAKER_00]: Both high fat milk and low fat milk.
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  [SPEAKER_00]: Also, no association.
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  [SPEAKER_00]: Even fermented milk, so things like yogurt and kefir, whether high fat or low fat, didn't show a clear link and butter, no association with all caused dementia risk.
• 4:27
  [SPEAKER_01]: Wait a minute, that's a major surprise.
• 4:31
  [SPEAKER_01]: If the whole debate has been full fat versus low fat, you expect high fat milk or butter to show something.
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  [SPEAKER_00]: You would, but they didn't.
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  [SPEAKER_00]: And that suggests the story isn't just about the presence of fat.
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  [SPEAKER_00]: It's about something in the specific structure of the food.
• 4:44
  [SPEAKER_01]: The food matrix.
• 4:45
  [SPEAKER_00]: You've hit on the key takeaway before we even get to the significant results.
• 4:49
  [SPEAKER_00]: If it were just about saturated fat, you'd think high fat milk and butter would follow the same pattern as the other high fat products.
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  [SPEAKER_01]: But they did it?
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  [SPEAKER_00]: They didn't, which pivots the whole conversation away from a simple nutrition label and more into how fats, proteins, vitamins are all arranged within a specific food.
• 5:06
  [SPEAKER_01]: And that's where it's really interesting, because this deep dive revealed two specific high fat products that did show a statistically significant inverse association.
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  [SPEAKER_01]: Let's start with high fat cheese.
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  [SPEAKER_00]: Right, high fat cheese gave some of the most compelling risk reduction numbers, and the findings centered on people with the consistently, you know, relatively high level of intake.
• 5:26
  [SPEAKER_01]: Oh, how are we talking?
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  [SPEAKER_00]: We're talking about consuming 50 grams per day or more.
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  [SPEAKER_00]: And the cheese had to be greater than 20 percent fat.
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  [SPEAKER_01]: Okay, let's ground that number.
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  [SPEAKER_01]: What does 50 grams of high fat cheese actually look like in a daily diet?
• 5:39
  [SPEAKER_00]: It's surprisingly little, which just shows how much consistency matters over two decades.
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  [SPEAKER_00]: It's roughly two to three standard slices of cheese or maybe a small handful of cheese cubes.
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  [SPEAKER_01]: So it's not like you have to make some massive dietary change.
• 5:56
  [SPEAKER_00]: That is all.
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  [SPEAKER_00]: It just means incorporating it into your daily rhythm.
• 5:59
  [SPEAKER_01]: And when they compared this high intake against a much lower intake, say, less than 15 grams a day, what was the risk profile for all caused dementia?
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  [SPEAKER_00]: The high-fat cheese consumers saw an associated reduced risk of all caused to mention with the hazard ratio of 0.87.
• 6:13
  [SPEAKER_00]: Should we go to that translates to about a 13% lower risk over that 25-year period?
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  [SPEAKER_01]: A 13% reduction is significant.
• 6:21
  [SPEAKER_01]: But you mentioned the results were even stronger for some of the specific dementia types.
• 6:25
  [SPEAKER_00]: Absolutely.
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  [SPEAKER_00]: The association got remarkably stronger when they looked at vascular dementia, VD.
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  [SPEAKER_00]: For that specifically, the high-fat cheese group
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  [SPEAKER_01]: Wow, a 29% lower risk for vascular dementia.
• 6:40
  [SPEAKER_01]: That's a massive percentage drop.
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  [SPEAKER_01]: It suggests some kind of vascular protective mechanism.
• 6:45
  [SPEAKER_00]: It does.
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  [SPEAKER_00]: And we can't gloss over the genetic findings here because this is where diet and personalized medicine start to intersect.
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  [SPEAKER_01]: Right, the APOE for allial.
• 6:53
  [SPEAKER_00]: Exactly.
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  [SPEAKER_00]: That's the major known genetic risk factor for late onset Alzheimer's.
• 6:57
  [SPEAKER_01]: So how did diet interact with genetics in this study?
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  [SPEAKER_00]: They found that the protective association, that reduction in Alzheimer's risk, was specifically and significantly found only among the APOE4 non-carriers.
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  [SPEAKER_01]: OK, so for the population who don't carry that highest genetic risk factor, adding high fat cheese seemed to offer a layer of protection.
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  [SPEAKER_00]: Precisely, for that group, the HR was 0.87, just like for all caused dementia.
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  [SPEAKER_01]: But for those who do carry the gene, the effect was muted, or absent.
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  [SPEAKER_00]: it was muted or absent.
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  [SPEAKER_00]: And this highlights a crucial complexity, you know, a dietary factor that might be protective for one huge segment of the population may not be for another.
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  [SPEAKER_01]: It makes simple public health messaging really difficult.
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  [SPEAKER_00]: Very difficult.
• 7:39
  [SPEAKER_00]: Yeah.
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  [SPEAKER_00]: But it does offer a path toward more personalized nutritional guidance.
• 7:43
  [SPEAKER_01]: Fascinating.
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  [SPEAKER_01]: Okay, let's move to the second key finding.
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  [SPEAKER_01]: High-fat cream.
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  [SPEAKER_01]: Did the same pattern hold true there?
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  [SPEAKER_00]: It did.
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  [SPEAKER_00]: It maintained that same theme of specificity.
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  [SPEAKER_00]: The key metric for high fat cream was consuming 20 grams per day or more.
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  [SPEAKER_01]: And what kind of cream?
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  [SPEAKER_00]: Cream that was greater than 30 percent fat.
• 8:02
  [SPEAKER_00]: So think heavy cream or whipping cream used regularly.
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  [SPEAKER_01]: And the results for that group?
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  [SPEAKER_00]: Individuals consuming that amount of high fat cream had a 16 percent lower risk of all cause dementia in HR of 0.84.
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  [SPEAKER_01]: And was that across the board for the other dimension types as well?
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  [SPEAKER_00]: It was.
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  [SPEAKER_00]: The study reported that high-fat cream consumption was inversely associated with the risk of both AD and VD.
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  [SPEAKER_01]: So the central finding is just starkly specific.
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  [SPEAKER_01]: Only higher intake of these two distinct high-fat products, cheese and cream showed a lower risk.
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  [SPEAKER_01]: And all the other high-fat dairy, like milk and butter, showed nothing.
• 8:37
  [SPEAKER_00]: Exactly.
• 8:38
  [SPEAKER_01]: So what does this all mean?
• 8:39
  [SPEAKER_01]: We have these two incredibly specific products that jump out while everything else, including chemically similar things, like butter, showed no effect.
• 8:47
  [SPEAKER_00]: Well, the first, and I mean, this is the most important message, is the limitation the author's themselves point out.
• 8:53
  [SPEAKER_00]: This was a purely observational design.
• 8:55
  [SPEAKER_01]: Right.
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  [SPEAKER_01]: So that's vital context.
• 8:57
  [SPEAKER_01]: Correlation, not causation.
• 8:58
  [SPEAKER_00]: We can't say this enough.
• 9:00
  [SPEAKER_00]: You cannot tell people that eating cheese causes this risk reduction.
• 9:03
  [SPEAKER_01]: Right, it's like the umbrella analogy seeing umbrellas when it rains doesn't mean umbrellas caused rain.
• 9:08
  [SPEAKER_00]: It's the perfect analogy.
• 9:10
  [SPEAKER_00]: The people who eat 50 grams of high fat cheese every day might share other habits, maybe they're more affluent or the fewer processed foods.
• 9:17
  [SPEAKER_00]: Even with statistical controls, you can't eliminate every other possibility.
• 9:22
  [SPEAKER_01]: But the findings are specific enough to suggest that the protective factor, if there is one, is tied to the unique composition of cheese and cream.
• 9:31
  [SPEAKER_00]: precisely.
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  [SPEAKER_00]: It wasn't just general dairy fat.
• 9:33
  [SPEAKER_00]: High fat cheese is a fermented product.
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  [SPEAKER_00]: It's often rich in things like vitamin K2, which plays a role in cardiovascular health and cream.
• 9:42
  [SPEAKER_00]: cream, though it's high in fat, has unique phospholipid structures that are highly concentrated compared to just plain hole milk.
• 9:50
  [SPEAKER_00]: Those are the compounds researchers are now looking at rather than just focusing on total fat.
• 9:54
  [SPEAKER_01]: So the application for you, listening to this, is not to take it as a license to just consume unlimited full fat product.
• 10:00
  [SPEAKER_01]: I'm on it all.
• 10:01
  [SPEAKER_01]: It's an instruction to appreciate the nuance.
• 10:04
  [SPEAKER_01]: The finding here is about the specificity of certain foods, not a blanket endorsement of the whole dairy aisle.
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  [SPEAKER_00]: and the real takeaways that contrast with high-fat milk and butter.
• 10:13
  [SPEAKER_00]: The scientific focus has to shift now to why the matrix of cheese and cream is unique.
• 10:19
  [SPEAKER_00]: Is the fermentation, the concentration process, those are the next frontiers.
• 10:23
  [SPEAKER_01]: Okay, so to summarize the core takeaways from this 25-year deep dive, specific high-fat dairy products.
• 10:30
  [SPEAKER_01]: We're talking 50 grams or more a day of high-fat cheese, and 20 grams or more of high-fat cream,
• 10:39
  [SPEAKER_00]: particularly vast yield advantage right over 25 year follow up in this massive Swedish cohort meanwhile low fat versions high fat milk but are they all showed no such association which leaves us with a final provocative thought for you to explore the data really suggests that when we talk about nutrition and brain health we might be focusing too much on simple macros fat protein carbs and not enough on the microscopic interactions so given the specificity here the most important
• 11:09
  [SPEAKER_00]: is the secret to dairy's potential protective effect, less about the fat itself, and more about the bacterial and enzymatic action that creates the unique structural and micronutrient composition found only in concentrated, often fermented foods like high fat cheese and cream.
• 11:25
  [SPEAKER_01]: Food for thought indeed.
• 11:26
  [SPEAKER_01]: Thank you for joining us for the deep dive, we'll see you next time!