Claim: The “Living Carnivore” Diet is Good for Weight Loss

Verdict: Broadly true, but misleading

“Within 30 days I lost 20 pounds. JD Vance is also on the diet and you can see how different he looks.”

“The way that you're supposed to eat it is bite for bite. You take a bite of the meat, you take a bite of the sauerkraut”

RFK Jr.

After Vice President JD Vance credited his weight loss to RFK Jr’s recommended “meat and sauerkraut” diet, the “Living Carnivore” diet has been under the spotlight. But does it really work?

The Good News: Weight Loss is Reasonable

For the goal of weight loss – without considering other issues – and despite no direct evidence on the Living Carnivore diet specifically, it doesn't seem too bad. This largely comes down to the benefits of eating fermented foods. Generally speaking, there are multiple benefits to consuming fermented foods, as shown by a study using data from the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018.

The study found that each 100 g of microbe-containing foods was associated with reduced BMI, waist circumference, systolic blood pressure, C-reactive protein, plasma glucose and triglyceride, and increased high density lipoprotein cholesterols. The mechanisms of action get a little complicated, but generally include influencing gene expression, slowing gastric emptying and modulation of the gut microbiome.

The carnivore side of the diet is where the problems come in. Purely for weight loss, there is some evidence that they can lead to weight loss and increased satiety.

The Bad News: Nutrient Deficiencies and Cholesterol

A 2026 scoping review focused on the carnivore diet noted these benefits for weight loss, but stressed the “substantial risks” of nutrient deficiencies. Overall, the carnivore diet can lead to deficiencies in thiamine, vitamin C, vitamin D, magnesium, iodine, potassium, calcium and fibre. The deficiency in fibre is also pretty extreme, at less than 1/25th of the adequate intake. It's debatable whether you could rectify these issues by adding fermented foods.

Perhaps unsurprisingly, low-density lipoprotein cholesterol and total cholesterol generally increase, carrying risks of heart disease, and some versions have high sodium, potentially leading to high blood pressure and more.

And it should go without saying that eating “bite for bite” is probably useless, it takes a long time to digest food, relative to actual eating process. It all hits your stomach basically simultaneously anyway.

Overall, the diet – especially fermented foods – could help weight loss, but it’s terrible as an overall diet.

Claim: Two Recent “Measles-Associated” Deaths May Have Been “Fabricated”

Verdict: Broadly false, but some questions remain open

“The announcement appears to have been premature, and the deaths may even have been altogether fabricated by one of the Governor's hopeful staffers. The Lancaster County Coroner says that it has no record of any measles deaths. State law requires that all measles deaths be reported to the coroner.” – RFK Jr

Governor Shapiro's unseemly rush to Lancaster County to convene a national press conference and his…

Two deaths that the Pennsylvania Department of Health called “measles-associated” have been at the centre of a political firestorm this week. RFK Jr. said these deaths may have been “fabricated,” but more broadly, disputes that measles was the cause of death.

The Two Deaths: What We Know

A great FactCheck.org post runs through the details of the deaths. In short, while few details have been released, we do know that two individuals died, that they had not been vaccinated and that they had confirmed measles infections. While we know next-to-nothing about one case, the other case has since been confirmed to have been an infant whose primary cause of death was a “traumatic laceration of the spleen.”

This child contracted measles before birth and died shortly afterwards. It’s worth noting that this child would not ordinarily have been vaccinated by this point.

One thing to note: It has been clearly confirmed by the coroner and other state health officials that the deaths were not fabricated, as RFK Jr. claimed.

The “Cause of Death” in Measles Cases

RFK Jr. said the coroner had no record of any “measles deaths,” but this is misleading on its own. In fact, most deaths from measles do not list measles as a primary cause of death. Instead, the primary cause of death is usually the specific complication leading to death. One study from the 1970s looked at this and found that only 9.9% of 454 cases actually listed “measles” as the primary cause of death.

Measles and the Spleen

Since details are only available in one case, the focus has been on that child. The coroner claimed that measles didn’t contribute to the death, because the spleen was not enlarged [3]. However, vaccine expert Dr. Paul Offit noted that this is hard to determine after a rupture, and such a rupture should have a clear explanation. This has not been settled yet.

It’s worth noting that an enlarged spleen is a known complication of measles, present in one third of all cases in a recent Polish study and 15.4% of all infant cases.

Overall, these cases were not fabricated. That said, health officials could have avoided a lot of confusion by being clearer in the way the cases were reported.

The “Physical Activity Paradox” in Dementia Risk Revealed in New Study

A new study has revealed a so-called “physical activity paradox” in dementia risk. In a nutshell, even though physical activity is generally considered to be protective, in some cases it can actually increase your risk. Just looking at “physical activity” as a single factor misses a lot of crucial detail.

The Different Types of Physical Activity  

The researchers identify four different types of physical activity: leisure-time, occupational, household and commuting activity. They’re basically pointing out that having a physically-demanding occupation is different from doing chores around the house or cycling to the office.

However, much of the evidence focuses on leisure time physical activity, which only represents 12% of all physical activity around the world.

The Study: Reviewing the Evidence on Different Types of Physical Activity

The researchers basically wanted to update a previous review they published in 2022, adding evidence from the intervening years and performing the analysis for different types of activity separately. The new paper [1] uses the 57 studies included in that review, and adds 17 new cohort and case-control studies published between the start of 2021 and May 2026. This led to a combined sample of over 4.2 million participants.

Studies were excluded if they had a follow-up of less than a year, if diagnoses were based on self-report or cause of death data, if people had dementia or mild cognitive impairment at baseline, or any research focusing specifically on people with a diagnosed disease.

What They Found: Leisure Time Activity Protects, Occupational Activity Doesn’t

The analysis found that leisure time physical activity was associated with a 24% lower chance of all-cause dementia, while occupational activity increased risk by around 20%. These were the two areas with the most research, but less reliable findings also suggest that household activity reduces risk by 15% and commuting activity increases it by 10%.

Limitations to Keep in Mind

As always, there are issues to keep in mind. Firstly, physical activity was based on self-reporting, which is open to bias, and secondly, the type of studies included make it hard to rule out reverse causation. Notably, 93% of studies came from high income countries, so the evidence base is not very representative of the world. The results broadly held for specific types of dementia, but vascular dementia wasn’t as well covered. 

However, the core findings generally seem robust.

Does Socialisation Reduce Cognitive Decline? A New Study Says Yes

For people who don’t already have dementia, but are worried about it, learning about protective factors and risk factors for cognitive decline is one of the only steps you can take. A common piece of advice is to remain socially active, but does it really make a difference?

A new study [1] looked into this and found a very clear correlation between higher levels of social engagement and better cognitive performance.

Why Researching the Impact of Social Engagement is Difficult

Defining social engagement isn’t as easy as you might think. As a paper tackling this issue points out, researchers tend to use many different, overlapping terms. For example, social participation, social connectedness and community engagement are all used, and other studies may focus instead on social isolation. The paper points out that the subtle distinctions between these methods makes it difficult to interpret the evidence as a whole.

What the New Study Adds

The new research [1] used a composite measure called the Social Engagement Index, which covers specific things like whether you live with other people, whether you went out for fun in the past month, whether you visited friends or family, whether you’re married, employed and more. The idea is to cover many metrics of social engagement and use all of them to produce the final score.

They used data from the National Health and Aging Trends Study from 2011 to 2019, which covers Americans aged 65 or older enrolled in Medicare, and discounted anyone likely to have dementia at the start of the study. They found that higher social engagement (at baseline) was associated with a reduced decline in memory, orientation (i.e. what day is it? Who is the vice president?) and executive function. This was also incremental: the more engaged, the better the outcome.

Does Social Engagement Reduce Cognitive Decline?

The overall picture isn’t as clear as we might like. A “systematic review of reviews” covered this issue (section 4.1 for a summary) and despite emphasizing that low social engagement increases your risk, concluded that the data on the presumed protective effect is inconsistent. That said, the difference between a protective effect and avoiding an increase in risk seems more of a philosophical issue than a practical one.

As the new study also suggests, it certainly seems better to be socially engaged than to not be.

Claim: There is No Study Showing that Children Were Protected by the COVID Vaccine

Verdict: False and misleading

“Do you think that the COVID vaccine protected children? [...] Can you show me one study ... that shows that children were protected by the COVID vaccine? [...] that it did more good than harm to children. Can you show me one study that shows that?”

RFK talks vaccines, measles in interview with CNN's Dana Bash – RFK Jr. (from 7:25)

In his recent interview with CNN, RFK Jr. implicitly claimed – via a series of pointed, “gotcha” questions – that there were no studies showing that the COVID-19 vaccine protected children. Explicitly asking about proof “it did more good than harm,” he argued that there is no overall benefit to vaccinating children.

Is he right?

There is Plenty of Evidence that the COVID Vaccine Protects Children

RFK Jr. is absolutely incorrect to imply that no such evidence exists. While most people cannot pull a citation out of their heads on command, that isn’t the same as showing no evidence exists.

A systematic review of such studies was published in JAMA Pediatrics in 2023. It includes data from 15 observational studies and 2 randomized controlled trials focusing on children aged 5 to 11. The total number of participants was almost 11 million vaccinated and over 2.6 million unvaccinated children.

Among other things, this study found a lower risk of any COVID infection (53% reduction), symptomatic COVID infection (47% reduction), hospitalisations due to COVID-related illnesses (68% reduction) and multisystem inflammatory syndrome in children (95% reduction). It also found a 92% increase in the risk of adverse events, but only a non-significant increase in the risk of adverse events that prevent normal daily activities. 

What He Might Have Meant: The Risk of Myocarditis

This study did find the well-known risk of myocarditis following vaccination in younger people. However, this amounted to 1.3 cases per million after a first dose and 1.8 per million after a second dose.

Of course, this is not something to discount because of low incidence: it’s a legitimate concern.

However, this risk has to be compared to the risks following COVID infection, which is less likely in vaccinated children. A study from the UK found that there was an increased risk of myocarditis or pericarditis in the first 6 months after vaccination (in young people aged between 5 and 18), but noted that the risk is even higher after COVID infection.

Even without considering other risks (see images), it’s clear that the COVID vaccine is safer than COVID itself, even for myocarditis in young people.

New Study Suggests Blood Pressure Variability is What Matters for Cognitive Decline

A new study has found a new insight on the relationship between blood pressure and cognitive decline. Since hypertension is a well-established – and controllable – risk factor for cognitive decline, scientists assumed that reducing it is the best strategy. But this seems to be missing a crucial piece of the puzzle.

The Problem: Mixed Results on Lowering Blood Pressure

The new paper points out that different studies disagree about the cognitive benefits of interventions to reduce blood pressure.  

The SPRINT-MIND study recruited people with hypertension but not diabetes. It found a reduced risk of mild cognitive impairment for people on a more intensive blood pressure reduction regimen, but no difference in probable dementia.

Conversely, the ACCORD-MIND trial focused on people with type 2 diabetes and included a similar comparison of a more intensive vs. less intensive blood pressure reduction regimen. In this case, though, there was no difference in cognitive function.

What the New Study Did

The new research [1] pooled data from both of these trials, and analyzed the data again at participant-level. The paper notes that blood pressure variability (BPV) is linked to both cardiovascular events and cognitive decline, and tends to be higher in people with diabetes.

To test whether this is the important factor, researchers looked at BPV between each visit in the original studies. The original researchers used varying cognitive tests, but the authors identified two essentially equivalent measures of psychomotor processing speed among them. They used these to compare results across both studies.

What They Found: Higher Variability, Greater Decline

People with more variability in their blood pressure saw greater cognitive decline over the study period. In particular, those in the highest third of BPV had a faster rate of decline than those in lower thirds. The relationship seemed to be linear: each 10% increment of BPV led to consistently higher levels of decline.

What the Study is Missing

The study only focused on one measure of cognitive decline, rather than a global score. All participants also had a high cardiovascular risk, so the results might not carry over to other populations.

 What Doctors Can Do

One thing the study suggests is optimizing drug selection and timing to reduce BPV where possible. Doctors can also try novel interventions specifically designed to bring down BPV.

Claim: Autism Prevalence Has Exploded, and We’re Not Just “Noticing It More”

Verdict: Largely false and misleading

“In 1970, the biggest epidemiological study at that time in history was performed [...] they were looking for autism, and they knew what autism looked like. And they came back with an incident rate of 0.8 per 10,000. So less than in 1 in 10,000. The rate, according to CDC today in this country, is one in every 31 children. [...] One of the talking points [...] is, oh, we're just noticing it more. But this is an absurdity.”

Trump signs executive order on childhood vaccines(from 7:10)

– RFK Jr

During the signing of an executive order on vaccines, one point made by both RFK Jr. and Trump about autism prevalence is very common: is there something weird going on with the increasing rate of autism?

What the Study RFK Jr. is Referencing Actually Says

RFK Jr. mentions this study specifically. As he said, it was released in 1970 and involved around 900,000 children in Wisconsin.

The study looked at the DSM-II entry for “childhood schizophrenia,” and notes three groups of cases:

• A) What they call “classic” infant autism. This included an early onset, a desire for “sameness,” withdrawal and speech problems.

• B) These children had some of the classic autism symptoms but the onset was later.

• C) Likely psychosis with some complicating factors making diagnosis difficult.

RFK Jr. slightly misquotes the results for group A. Their prevalence was 0.7 cases per 10,000 children. Including group B would raise this to around 2.4 per 10,000. He also incorrectly implies the authors screened all 8-year olds in the state, but this is incorrect. They found cases from existing records from healthcare facilities for kids aged 3 to 12.

 It is true that a recent CDC estimate puts the figure at 1 in 31, based on modern diagnostic criteria (ICD-9 or 10). The modern DSM edition is V.

What’s Really Happening

You may have noticed that group B above would likely be just considered on the autism spectrum today. The differences between the 1970 diagnostic criteria and modern ones are hard to overstate, now encompassing Asperger’s syndrome, Rett’s disorder and others, and clearly differentiated from schizophrenia.

Despite RFK’s assertion, studies suggest that these changes, increased awareness and more effective screening are responsible for (at least) most of the apparent rise in diagnoses. For instance, previously under-represented groups like women and non-white people have a sharper rise in diagnoses.

Claim: The Phrase “Vaccines Do Not Cause Autism” is Not Supported By Science

Verdict: False and misleading

“The phrase ‘Vaccines do not cause autism’ is not supported by science.”

RFK, Jr.  

The CDC quietly updated its page on the link between vaccines and autism this week. Of note, it argues – like RFK, Jr. did in the quote above – that it is not an evidence-based claim to say “vaccines do not cause autism.”

But, is it?

There is No Evidence That Vaccines Cause Autism

Studies consistently show that specific vaccine-related concerns about autism – the Measles-Mumps-Rubella vaccine (MMR), thimerosal and mercury – are not linked to the condition.

Addressing Specific Claims from the CDC: Aluminium and Certain Vaccines

The CDC’s edited page contends that some vaccines (DTaP, Hib, HepB, IPV and others) have not been studied adequately with regards to autism. It also points the finger at aluminium in vaccines.

It is broadly true that these vaccines have not been studied specifically with regards to autism. However, one study looked at 42 neuropsychological outcomes at ages 7 to 10 based on vaccines received in the first year of life, including many mentioned by the CDC. It found no adverse effect from the full, timely vaccine schedule vs. receiving fewer vaccines or less frequently.

For aluminium, the CDC criticises a Danish study on over 1.2 million children which found no link between autism or any of 49 other conditions and cumulative aluminium exposure from vaccines received up to age 2. The CDC’s criticism simply cherry-picks figures from the supplementary material (see attached picture): it does not invalidate the result.

What “No Evidence” Really Means

One of my favourite scientific papers of all time finds that “the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials.”

So, is it reasonable to say the protective effect of parachutes “is not supported by science”?

Of course it is not. The key to understanding why is mechanism. If there is a mechanism – in this case, well-understood physics – we do not need systematic study to make a valid claim.

Conversely, if there is no science-based mechanism – as with vaccines and autism – we do not need specific studies to rule it out. On the contrary, anybody making such a claim would need to present actual evidence, rather than simply point to the absence of specific studies.

Claim: There Are Cyclospora Outbreaks Every Summer

Verdict: True, but highly misleading

“First of all, there are Cyclospora outbreaks every summer. [...] Now that we know the probable culprit, I think it’s going to be much easier for people to make healthy choices.”

RFK Jr., July 17th, 2026 (Relevant question at 7:57)

As the outbreak of cyclosporiasis cases continues across multiple states in the US, RFK Jr. took to the Ryan Gorman Show to promote his push for healthier hospital food. At the end of the interview, in response to a question about the Cyclospora outbreak, he downplayed it, noting that there are outbreaks every summer.

But is this true?

There Are Cyclospora Outbreaks Every Summer...

The core of RFK Jr.’s claim is correct: there are Cyclospora outbreaks in the US every year.

Data from CDC Wonder confirms this simple fact. For instance, in 2022, there were 3,091 cases, largely as a result of contaminated leafy greens. Likewise, the database shows outbreaks of thousands of cases in all recent years.

 ...But This One is Much Bigger

Despite being technically true, RFK’s comment drastically underplays the current outbreak by creating a sense of equivalence with previous outbreaks. This is highly misleading.

The CDC reports that as of July 14th, there are 1,645 lab-confirmed domestic cases, and notes that there are 5,100 further cases that need to be tested for domestic origin. Note that the lab-confirmed domestic cases so far are already over half of the total for the entire year of 2022. The CDC also notes that by this time in 2025 there were only 249 reported cases – less than one-sixth of the current number.

Data going back to 1990 shows how the situation has developed over time. Most years, there were fewer than 100 cases. Notable exceptions include 1996 (1,646 cases), 1997 (1,594 total cases), 2005 (692 total cases) and 2015 (546 cases).

The outbreaks do appear to be getting bigger, generally speaking. Data from CDC Wonder for 2017 to 2023 [2] show between 1,000 and 4,700 cases per year, peaking at 4,703 in 2019, declining in 2020 and 2021, before climbing to 4,463 in 2023.

However, even data for Michigan alone show 5,002 cases so far in 2026.

In summary, it is highly misleading to equate the current outbreak with those experienced previously. The current outbreak is bigger than any in the past 36 years.

Does the MIND Diet Really Prevent Neurodegenerative Disease?

Diet gets a lot of attention when it comes to preventing neurodegenerative disease, because improving it is one of the few simple, preventative actions we can all take.

This is exactly what motivated some researchers to devise what’s called the “MIND” diet, which was specifically designed to protect against cognitive decline and neurodegenerative diseases. But does it really work?

Developing the MIND Diet

The full name of the MIND diet is the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay. Combining elements from the popular Mediterranean diet and the blood pressure focused DASH diet, it also incorporates other foods that evidence suggests help with dementia.

Broadly, it suggests eating:

• Vegetables, especially leafy greens

• Berries

• Whole grains

• Beans and legumes

• Nuts

• Poultry

• Non-fried fish

• Extra virgin olive oil

Initial research scored participants on how well their diet matched the MIND diet, and found a link between MIND diet score and reduced cognitive decline with age.

Testing the MIND Diet

The same research group also tested how the MIND diet impacted Alzheimer’s risk. The methodology and cohort were basically the same – based in Chicago, n = 923, mainly white and non-Hispanic – except they used the participants’ annual Alzheimer’s assessment instead of their global cognitive score. As in the previous study, they compared the MIND diet with the Mediterranean and DASH diets.

The study suggested strong adherence to all of these diets reduced Alzheimer’s risk, but MIND outperformed the others for people who only partially followed the recommendations.  

However, a randomized controlled trial of the MIND diet came to a conflicting conclusion. The test pitted the MIND diet against a control diet (n = 604) with a mild calorie restriction, and found that both diets improved global cognition scores. People following MIND scored a little better, but the difference wasn’t statistically significant.

Does the MIND Diet Really Work?

The best answer to this question comes from a meta-analysis focusing on dementia in general . The authors combined three studies for a cohort analysis (n = 18,136) and 11 studies for the meta-analysis (n = 224,049). Both analyses found that the mind diet is associated with lower dementia risk in older adults.

More evidence is still needed – especially for non-Western populations and specific types of dementia – but overall, it does seem effective.