Nutrition psychology. Meat and health. The case for Continued Influence bias.

In two recent articles, two professors, Christel Larsson and Elizabeth Rothenberg are interviewed, warning that an extreme meat diet can be directly dangerous to health. Their claim resonates with a previous claim by Dr Fogelholm, a Finnish nutrition researcher. Nutrition is a complex topic. Some say it's more complex than rocket science. It's also very political. And for some reason, most countries have a Food agency Sweden) or authority (Finland), which provides the taxpayers with dietary advice. But should university professors really cite these agencies/authorities, or is their job to critically analyze the advice? The claim made by Drs. Larsson and Rothenberg, which is very similar to Dr Fogelholm claim from 2021, are consistent with Dietary guidelines but not with nutrition science. This paradox is interesting from a health perspective and likely explained by a psychological phenomenon called Continued Influence bias. 7 pages.

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In two recent articles, two professors who specialize in nutrition, Christel Larsson and Elisabeth Rothenberg are interviewed, warning that an extreme meat diet, a carnivore diet, can be directly dangerous to health. The first article was published on September 30, 2024 in Göteborgsposten (see below).

The second was published 16 days later (see below).

This is Said to be a screenshot from Hallands nyheter, but the article is yet to be found. 

Dr. Rothenberg is quoted:

“- To put it mildly, it's completely crazy. We are created to eat a versatile diet where meat is included, but where the greater part of the diet should be vegetables”.

Christel Larsson, also a professor of nutrition science, but at the University of Gothenburg, is quoted:

“- The combined scientific evidence shows that excessive meat consumption has no benefits - and this applies to both children and adults. Rather, it is the opposite. An all-round diet in which vegetable foods take a larger place is recommended and a limited amount of meat can be included”.

In the midst of the article, they have a box: Food and diseases. The fifth row reads:

“Red and processed meat increases the risk of cancer”.

Three years ago, Mikael Fogelholm, a Finnish professor in nutrition was interviewed by Finnish state media, and was quoted:

“- The link between colon cancer and red meat is clear”.

Link to source.

The article in Göteborgsposten also interviewed Eva Birath, she is into her seventh year on a carnivore diet. She is quoted:

“- Once I started eating only meat, I felt better than ever, and I continue to do so to this day. My health problems have disappeared.

- I used to eat broccoli and all the greens you are told to eat, but in the end I got serious problems with colon cancer and received treatment for it. Today I am declared healthy, but I am convinced that it is based on my diet, she says”.

Birath's testimony basically points in the opposite direction to Drs. Fogelholm's, Larsson's, and Rothneberg's claims. How is that possible?

Nutrition is a complex topic. Some say it's more complex than rocket science. It's also very political. And for some reason, most countries have a Food agency (Sweden) or authority (Finland), which provides the taxpayers with dietary advice. But should university professors really cite these agencies/authorities, or is their job to critically analyze the advice?

One huge challenge in nutrition is the method. That's because we seldom consume certain macronutrients or micronutrients, but a matrix of food - A meal that contains various nutrients. Some nutrition researchers use Food frequency questionnaires, others use randomized control trials, and a third approach is Paleo Nutrition/Nutrition Anthropology.

Food frequency questionnaires (FFQ) means that the respondents are asked to remember what they have been eating. That means they have to consult their episodic memory. Here's the catch. Episodic memory is constructive in a social fashion (Schacter and Addis, 2007). The implication: the respondent provides an answer which fits the situation. Therefore, FFQs as a method has been criticized (Archer et al. 2018; Aschwarden, 2016; Ioannidis, 2005, 2013, 2018; Peace et al. 2018; Schoenfeld and Ioannidis, 2013).

Randomized control trials (RCT) are more reliable. That's because it's possible to control what people eat.

Paleo Nutrition/Nutrition Anthropology means trying to figure out what our ancestors ate. Paleo anthropologists have made discoveries about our ancestors diet:

• 7.6 Million years ago. That's how long back in time the human lineage goes. One theory suggests the Tugen hills between lake Victoria in Uganda and Lake Turkana in Kenya. They are a vegetarian diet (Pickford och Senut, 2001; Pickford, 2006).
  
  
• 3.5 million years ago they started to eat bone marrow - animal fats rich in micronutrients (Mann, 2018; McPherron et al. 2010; Thompson et al. 2019).
  
  
• 2.6 million years before the present they ate meat (Pobiner, 2013, 2016).

This new diet caused a reduction of their guts and an expansion of their brains - from the occipital lobe and forward (Aiello och Wheeler, 1995; Hublin et al. 2014; Ponzter et al 2016).

A larger brain and in particular prefrontal cortex gave room to new mental function - a proto-language and the executive functions (Adornetti, 2016;Aiello och Dunbar, 1993; Ardila, 2008, Ardila et al. 2018; Barkley, 2001; Coolidge and Wynn, 2018).

One conclusion from paleo nutrition/Nutrition Anthropology is that our species have adapted to an animal source diet.

What does modern nutrition studies say about Drs. Fogelholm's, Larsson's, and Rothenberg's viewpoint - that consumption of meat can be hazardous to health, and even cause cancer?

Two years prior to Dr Fogelholm's claim that the link between colon cancer and red meat is clear, the NutriRecs group published three papers in which they tested if animal source is harmful to health. The group used a new method - GRADE - which downplays FFQs and up-plays RCTs. The result rejected the hypothesis that meat will harm your health, including the claim about meat and cancer (Han et al. 2019; Johnston et al. 2019; Zeraatkar et al. 2019).

One interesting thing is that Dr. Fogelholm knew about NutriRecs conclusion, because he commented on them on October 1, 2019, referring to an article on Linkedin!?

Are there any other studies which can sort out these issues?

A plethora of studies show that animal source food is crucial for children's physical and mental development (Adesogan et al. 2020; Allen, 2003; Balehegn et al. 2019, 2023), as well as to sustain adults physical and mental health (Dobersek et al. 2023; Ede, 2019, 2022, 2024; Itkonen et al. 2020; Margara-Escudero et al. 2022; Pan et al. 2024; Tong et al. 2020; Ylilauri et al. 2019).

Why do nutrition researchers reiterate information which has been rejected? One answer is Continued Influence bias - misinformation continues to influence memory and reasoning about an event, despite the misinformation having been corrected (Cacciatore, 2021).

Conclusion. The claim made by Drs. Larsson and Rothenberg, which is very similar to Dr Fogelholm claim from 2021, are consistent with Dietary guidelines but not with nutrition science. This paradox is interesting from a health perspective and likely explained by a psychological phenomenon called Continued Influence bias.

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