Why do Nutrition Recommendations Seem to Constantly Change and Conflict? (Part 1 of 2)

Nutrition recommendations seem to change with the weather. Protein will ruin your kidneys one day, and the next day you’re supposed to eat at least 150 grams daily to be healthy. What makes the issue more dizzying is that even nutrition professionals disagree on the “right” approach to diet and nutrition. Are dietary recommendations actually changing or is there so much noise in the nutrition and diet media that it’s hard to keep track of who’s saying what and what’s legitimate?

Here are a few reasons that some nutrition recommendations seem to constantly change and why others seem stuck in the Stone Age. I also offer tips for how you can navigate the seeming madness.

• Nutrition research and application can be messy (hard to control): When researchers study pharmaceutical drugs, they are often searching to understand single mechanisms of action (a biochemical target for a given medication). With nutrition, we can study nutrients in a similar way in supplement form, but outside of studies on single nutrients (e.g. vitamin D, chromium, phosphatidylcholine, etc.) many nutrition research questions require studying individuals, groups of people, or populations. People eat a wide variety of foods that contain hundreds of different nutrients. Thus, it’s hard to parse out which nutrient might have an impact on a specific disease process or biochemical pathway, or whether the synergy between two or more nutrients is the “X factor” that yields a measurable biological impact. Similarly, clinical nutrition research (i.e. human research) is faced with the challenges of studying human beings. Humans are hard to control, erratic, and don’t follow diets for long. It would be much easier if we could study robots that we could program and control. Tip: One of the hardest lessons in my life has been learning how to embrace that multiple “truths” can coexist. For example, a low FODMAP diet might have significant, compelling evidence to alleviate symptoms of irritable bowel syndrome (IBS), this diet is extremely hard to follow. The evidence may conflict with the day-to-day reality of following a challenging dietary protocol.

• Nutrition is a young science: While nutrition and food have been studied for hundreds of years, the first vitamin was only isolated in 1926 (vitamin B1, aka Thiamin). (1) What we know of as nutrition science is new and with that, there is a lot yet to discover about the impact of food and nutrients on human health. Tip: Consider that some of the recommendations that seem “certain” now may change in the future. As more research is published, we’ll have a clearer picture of which recommendations should continue and which need to adjust with the growing body of evidence.

• Nutrition specialization: As with any health field (e.g. medicine, physical therapy, nursing), nutrition has areas of specialization. Some nutrition professionals study infant nutrition while others spend their careers looking into the impact of protein on muscle development, athletic performance or wound healing. Certain nutritionists are experts in fatty acids like DHA (an omega 3 fatty acid in fish), and others work as clinical dietitians in oncology departments or doing intravenous nutrition calculations for ICU patients. These varied areas of nutrition expertise often limit the accuracy and nuance of the information conveyed by any single nutrition professional. Tip: Keep in mind who is providing the nutrition advice or guidance. Influencers aren’t a great source for nutrition information. They might do a great job of connecting with you and sharing their personal life, but that doesn’t mean you should follow their diet-of-the-week or buy the probiotic they’re linking to. Another example is during the pandemic people would ask my thoughts on the vaccine. I would have to remind them that I’m a dietitian, not an immunologist or public health professional.

• Bias: As much as I would love to say that we scientists can become completely aware of and control our biases, it’s impossible. Some nutrition professionals may or may not have received training in how to identify and address bias, but unless a social media diet influencer has done specific training then you can be certain they are showing up on your social media feed with a significant amount of bias. Example A: You’ll notice on your social media feed or at your family gathering that when someone has “success” on a diet, they may preach to their community that everyone should follow their diet. Example B: If someone already believes that a certain diet is “best” then they might seek out information that confirms what they already believe (ignoring information that might contradict what they hold true). This is called confirmation bias. Example C: Research funding can come with inherent bias. While funding organizations (e.g. the National Dairy Council or a supplement company) and researchers (e.g. nutrition faculty at a given university) have methods and strategies to minimize bias, it’s nearly impossible to completely avoid it. One way to identify someone who is aware of bias is to take notice if they provide caveats and exceptions to a stated nutrition information or recommendation. While we can’t caveat everything, we can try to acknowledge that there might be individuals or groups for whom specific information might not apply. Tip: Try to consider the angle or motivation of a person you’re hearing nutrition advice from: their life experiences, their values, their training (or lack of), who pays their bills. All of these things can influence someone’s bias.

• New evidence is published frequently: It’s no secret that scientific publication rates have skyrocketed over the last several decades. (2) With so much data to sift through, read, analyze and interpret, it’s difficult to keep up with the rate of information being published every week. Tip: Stay patient. Interpretation of large amounts of data takes time.

• Public health messaging versus personalized advice: We learned a lot about the challenges of public health messaging from the pandemic. Recommendations for quarantining, masking, prevention, and even vaccinations were ever changing. These changes were due to consideration by public health professionals of the building data from the pandemic that informed their recommendations. Public health professionals are speaking to populations of people, while your doctor or dietitian are providing personalized recommendations based on what they know about your health history, family history, risk factors, lifestyle, allergies, dietary intake, medications, supplements, and countless other factors that influence their recommendations for you. Tip: If you’re seeking personalized advice, work with a nutrition clinician. If you’re wanting an overview of what we know about nutrition as it relates to the majority of a population, then a public health professional is the best person to learn from.

• Media benefits from confusion: Media outlets know that many of us are trying to figure out the “best” diet, and they get a lot of play from diet and nutrition controversy and changes. Thus, a media outlet might publish an article claiming some dramatic change in diet recommendations when it might be based on a single published study. We also have to account for bias in reporting and media. Like scientists, reporters and journalists have varying levels of understanding and acknowledgement of bias in their reporting and writing. When a study published on Monday says “keto will protect you from X disease” and Friday another study says “a vegan diet will save you from Y disease,” media outlets can get double the ad revenue from all those clicks and attention to the conflicting information. Tip: Media makes money on ads based on number of clicks and views, so they want your attention for the latest fad. Don’t change your diet from a single article on Mind Body Green or Business Insider.

• Reporters may have limited foundational nutrition knowledge: Health reporters who publish about a nutrition study likely don’t have as nuanced a perspective on nutrition as might be necessarily to fully convey the interpretation of the data within the context of the nutrition landscape. Tip: You can read about many reporters’ backgrounds at the bottom of their articles or at their publication website. Find out how much training they have in their given area or how long they’ve been writing about nutrition-specific topics.

• Nutrition research isn’t well funded: This seems like a point that has little to do with why research recommendations seem to constantly change or conflict, but it needs to be on the list because when we don’t have enough nutrition research, then we are left with a lot of nutrition research questions hanging, left unanswered until there are researchers and funders to help facilitate the projects getting done. With fewer answers than we have questions, we our natural inclination is to try to make sense of the limited information we have. Some people will try to fill in the blanks with theories while others will lean on only the existing evidence. This can make for a lot of confusion for people who are just trying to make a decision about how to eat day-to-day. Tip: There may not be a lot you can do about the challenges of nutrition research funding other than being patient, but if you do have influence in this realm, please support nutrition research funding!

• Social media influencers often lack training and have conflicts of interest: While some large accounts on social media are run by trained scientists and nutrition professionals, many influencers touting the benefits of certain diets aren’t nutrition professionals. They may share their personal experience or they may promote a certain diet or product because they’re getting paid to do so. While I don’t think this is all bad, as I understand the value of someone sharing their lived experience as a powerful way to connect with people, I do think it’s important that influencers acknowledge when they’re earning money when they sell something related to their post(s). Legally, they’re supposed to do this, but it doesn’t always happen. Tip: It’s fine to follow influencers, just know that they may not have your best interest or your safety in mind. Consume their content with caution.

• Changing recommendations based on the greater research landscape, not single studies: We are trained in healthcare sciences to consider the larger body of evidence and not depend on a single study to base our recommendations (if more than one study exists). This creates frustration for many involved parties as sometimes larger organizations like the government’s Dietary Guidelines for Americans (DGAs) or the American Heart Association can seem to move at a snail’s pace to make seemingly obvious changes to their guidelines. In my view, it took entirely too long for the DGAs to finally admit that cholesterol is not a nutrient of concern when it comes to health. This type of issue can make nutrition recommendations seem slow and out of touch with the constantly changing nutrition research terrain. Tip: Try finding researchers in a given area of study (e.g. ketogenic diet or a certain nutrient). Some of them have started showing up on social media, too. Often career researchers will share the latest overview on their field even when institutions or the government haven’t formally updated their guidelines.

I’m sure there are more reasons that nutrition recommendations seem to be constantly changing, and if you can think of any please share. I hope this gives some perspective on why the conversation around diet and nutrition is frustrating and ever-changing. Please know that even nutrition professionals feel frustrated and overwhelmed by the firehose of both nutrition data and social media diet messages. It’s hard to keep up with it all and have time to do anything else!

References

1. Mozaffarian D, Rosenberg I, Uauy R. History of modern nutrition science—implications for current research, dietary guidelines, and food policy. Bmj. 2018 Jun 13;361.

2. Bornmann L, Mutz R. Growth rates of modern science: A bibliometric analysis based on the number of publications and cited references. Journal of the association for information science and technology. 2015 Nov;66(11):2215-22.