[CASE STUDY] Saturated Fat Confusion? How to Make Sense of Clashing Headlines


by Alejandra "Alex" Ruani — Get free science updates here.

“Here we go again”, I thought, rolling my eyes. Why, you may wonder…

In the past days, I noticed major media outlets flooded with 2 incendiary headlines.

Each headline boasted opposite results about saturated fat intake. How come?

Poles apart… So, which one is it?

Consumer confusion

Imagine the confusion this causes in consumers’ minds.

saturated-fat-debate_contradictory-news_the-health-sciences-academy-jpg

Contradictory news stories about saturated fat

One headline says “good for you”. Whereas the other one hints “bad for you, cut it to reduce health risk”. All within days!

So I went in, and inspected both rival scientific studies. I’ll walk you through my validation process. The same process we scientists use at The Health Sciences Academy.

Hopefully this exercise will help you discern fact from fiction when it comes to this heated debate.

New to the ‘sat fat’ debate? In short, there’s ongoing controversy about how much of a ‘threat’ saturated fat poses to your health. Saturated fat is abundant in animal food products such as butter, cheese, and meat, as well as some plant-based foods such as coconut oil, nuts, and avocados. Example below:

brazil-nuts
Saturated Fat in Brazil Nut

Inspecting Study No. 1

I’ll begin with the study behind the “good for you” headline. What does it tell us?

Saturated Fat Study 1

Sat fat study 1 (Veum et al., 2016)

The first thing I discovered when analysing it is that the shock headline misreported the study findings and its context.

The study is okay, but the reporting is bad.

And that’s how junk science often spreads around the web. When the research isn’t properly interpreted by media and bloggers.

Let’s look at some of the key inconsistencies, so you can spot bits like these the next time you see conflicting news stories!

1. Objective

Effects of Low VS High Saturated Fat Diets on Fat Loss

Effects of high vs low saturated fat diets on fat loss (Veum et al., 2016)

As I was reading the first study, I could tell that the researchers mainly looked at fat loss and insulin levels, but not “overall good health” per se.

Question to ask yourself: Is there a mismatch between the news headline and the study objective? Yes, here we have a mismatch. Bad sign.

2. Variables and context

I was curious to see what the participants ate. The researchers assigned them to two different diets:

Comparison of Low Vs High Fat Diets in Saft Fat Study 1

Comparison between the LFHC (low-fat, high-carb) and the VHFLC (very high-fat, low-carb) diets (Veum et al., 2016)

  • a higher-fat, lower-carb diet (73% of calories from fat, 10% from carbs) or
  • a higher-carb, lower-fat diet (30% of calories from fat, 53% from carbs).

Both diets emphasised low-glycaemic carbohydrates and minimally processed foods.

No hydrogenated or trans fats, no added sugars, no highly processed foods. All excluded.

Question to ask yourself: What’s the context (or diet) in which the findings emerged? Here, saturated fat was consumed during carbohydrate restriction. Meaning we cannot say “good for you” if the high-fat intake is simultaneous to high-sugar intake, for instance. So no, sugary shortbread cakes haven’t been ‘okayed’!

3. Results

Both diets resulted in similar fat loss and similar reductions in body weight. One wasn’t “better” than the other.

Question to ask yourself: What are the actual study results? In this case, similar results from both diets. No “winner”.

4. Length and participants

The study was very short (12 weeks) and only involved 38 middle-aged Nordic men with abdominal obesity. This doesn’t represent “everyone” or “you” – as the headline wrongly suggests. We can’t extrapolate these outcomes to everybody else.

Questions to ask yourself: Was it a short- or a long-term study? Who were the study subjects? Was it a small or a large group? When the study is short and the group is small, there’s also a higher risk of a “false positive” (translation: a one-hit-wonder that cannot be reproduced in an identical experiment). Replicability is the secret sauce of good science (see number 6 here).

5. Ethnic and geographical differences

Unlike other humans, cold-climate Arctic and Nordic populations are known to be genetically well-adapted to tolerate huge amounts of fat (example here).

Question to ask yourself: What’s the ethnicity of the study subjects? The subjects were Norwegian. This means we cannot conclude the same for other populations (e.g. Asians) who evolved on different climates, different foods, and experienced different nutrient adaptations.

6. Nutritional genetics

Genetic testing was not included in the research. I’m not sure someone with the “high-carb gene” would have done as well eating 73% in fat calories! The high-carb gene was discovered recently and, if you’ve been paying attention, I introduced it to you in my previous Science Catch-up.

Summary of intervention Sat Fat Study 1

Summary of interventions used in the sat fat study 1. Genotypes weren’t investigated (Veum et al., 2016)

Conversely, there are several genes associated with inefficient fat metabolism. So if you cannot metabolise saturated fat or ketone bodies properly, a high fat diet can do more harm than good. We investigate those and other 21 nutrient-related genes in this Science Report (optional resource).

Question to ask yourself: Did the study investigate the participants’ genetic variants? Some of the best-quality studies I’ve seen take into account inter-individual variability, and looking at the participants’ key genetic variants helps narrow this down. This is the direction of new science. Quite honestly, the rest is getting outdated given how fast personalised nutrition research is moving.

7. Limitations

Limitations are like the “small print” – disclaimers for dubious components in a study which need to be taken with a pinch of salt.

Subjects in Both Diets Experienced Similar Fat and Weight Loss Results Sat Fat Study 1

Subjects in both the low-fat and the high-fat diets experienced similar fat loss results. No control used (Veum et al., 2016)

We already discussed some limitations earlier on, like a small number of participants, no long-term assessment, and a higher risk of false positives.

Question to ask yourself: What are the study limitations? In this one, there wasn’t a “control group” either – such as people consuming their regular diet. A control would have allowed us to rule out alternative explanations of the results. For all we know, the low-glycaemic eating or the removal of trans fats could have also caused the fat loss and insulin sensitivity improvement.

With headline number 1 debunked, shall we dive into headline number 2?

Inspecting Study No. 2

The debate about the risks of saturated fat continues.

The current UK guidelines on saturated fat indicate:

  • no more than 30 grams a day for men and
  • no more than 20 grams a day for women.

But many criticise these guidelines, arguing that there isn’t a proven link between sat fat consumption and heart risk, and that there’s no point in limiting its intake.

Saturated Fat Study 1

Sat fat study 2 (Zong et al., 2016)

This new observational study from Harvard and Unilever suggests the opposite: that there is a link between saturated fat intake and heart disease risk. Well, is there?

Key ‘filter’ questions

Intake of Saturated Fatty Acids in Study 2

Intake (as caloric %) of saturated fatty acids over time (24-28 years). 4:0=butyric acid; 6:0=caproic acid; 8:0=caprylic acid; 10:0=capric acid; 12:0=lauric acid; 14:0=myristic acid; 16:0=palmitic acid; 18:0=stearic acid (Veum et al., 2016)

Let’s use the same questions we asked in the first study to dissect this news story:

1. Objective.

Is there a mismatch between the news headline and the study objective? No, we have a match. Remember, a match is what we want.

2. Context.

What’s the context (or diet) in which the findings emerged? Varied diets, at free will. Participants reported what they ate for about 24-28 years.

3. Results.

What are the actual study results? Replacing just 1% of calories from saturated fat by polyunsaturated fats (e.g. Omega 3), monounsaturated fats (e.g. Omega 9), wholegrains (e.g. oats, brown rice) or plant proteins (e.g. pulses), led to a 5% to 12% lower risk of heart disease.

4. Length and participants.

Risk Education When Saturated Fat Was Replaced Study 2

Heart risk reduction when saturated fat was replaced by other foods (Veum et al., 2016)

Was it a short- or a long-term study? Who were the study subjects? Was it a small or a large group? A long-term study, with a large group of 73,147 female nurses and 42,635 male nurses. All of them were healthy at the start of the study. They completed lengthy food and health questionnaires every 2 or 4 years for 24-28 years.

5. Ethnic differences.

What’s the ethnicity of the study subjects? Very mixed. White, African American, Asian, and others. But the analysis doesn’t include the relative intake risk per ethnic group.

6. Nutritional genetics.

Did the study investigate the participants’ genetic variants? No, this technology didn’t exist when they started. So it makes it very difficult to understand inter-individual variability, and general findings may not apply to “everyone”.

7. Limitations.

What are the study limitations? Because it’s an observational study, the self-reporting by the nurses could introduce inaccuracies. Also, those who ate more sat fat were more likely to engage in less physical activity, less likely to take multivitamins, and had a higher caloric intake. Meaning that these factors (called “confounders”) could have increased heart disease risk too, and not just the sat fat.

Conclusion

While some people keep fighting about saturated fat being good or bad, I suggest that you don’t. There are no winners in that argument. The argument in itself is flawed, because we’re asking the wrong question.

We cannot say that saturated fat is unhealthy for most people. Or that saturated fat is healthy for most people.

Each of us is intrinsically different, metabolise nutrients differently, and respond differently to identical protocols and conditions.

In times of conflicting dietary advice, sharpening your “junk science radar” is critical. Use the list of questions I’ve given you above as smart filters when reading health news!

And if you’d like to polish up your research skills and get better at making sense of the science, we’re developing our Become a Research Pro course. You’re welcome to sign up to be notified when it goes live here.

Besides that, make it a habit to set aside 30 minutes for your Science Catch-ups every other Thursday, where I make sense of news stories by looking at the underlying research for you.

With these tools, you’ll be far ahead everyone else :-)

Your turn

On a scale of 1 to 10, how do you rate your “junk science radar”? Is it polished, or does it need work?

What’s your take on conflicting nutritional advice? Which of the ‘filter questions’ we explored you want to get better at answering?

Tell us in the comments below! What you share can be very helpful to other readers, or even inspire them.

And if you know someone who remains confused in the sat-fat saga, send them this. It’ll do them good!

 

Take the next step

Become a Research Pro. To be notified when this new course goes live, sign up here!

 

The-Health-Sciences-Academy-Alejandra-Ruani-small1-right
Alex Ruani leads the research division at The Health Sciences Academy, where she and her team make sense of complex scientific literature and translate it into easy-to-understand practical concepts for students. She is a Harvard-trained scientific researcher who specialises in cravings and appetite neurobiology, nutrition biochemistry, and nutrigenomics. Besides investigating and teaching the latest advances in health and nutrition science, Alex makes it easier to be smarter with her free Science Catch-ups every other Thursday.
Connect with Alex via email.


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18 Comments

  • Tom Watson

    Reply Reply December 8, 2016

    Hi Alex

    Great science report on saturated fats & Junk science.

    I have recently had a lot of conflicting arguments, on social media.
    All covering the issue of pseudoscience. I find it frustrating that some research is bias and other credible research is wrongly accused.
    I’m not a scientist or professor so I have to keep researching until I’m convinced of the truth.

    I follow T Colin Campbell, Micheal Gregor MD and their peers. I have for years. I have recently come up against accusations of ‘bad science’ regarding The China Study, I’m sure you’ve read it.
    What I have found with some of the research discrediting T Colin Campbell’s work is bias. If you dig a little deeper, you can find connections with certain industries, i.e. Animal agriculture & livestock.

    I would be very grateful if you could shred some light on this for me.
    What do you think of studies or research on both sides of the argument.
    Would you risk reporting on such issues, regarding animal fat & protein, and what are your thoughts on the whole debat?

    Many Thanks Tom

    • cis

      Reply Reply December 8, 2016

      I am interested in this too.

      There is a lot of junk science, but also a lot of “intentionally biased” science. This is where it is useful to be able to debug scientific arguments.
      I only wish our politicians could do this. It seems this is mostly NOT the case!!!

    • You’re welcome, Tom! I like the way you articulated your questions; it shows high learnability and an open mind, very advantageous in times when science is advancing this fast :-)

      The China Study was done nearly half a century ago, in the 1970’s. I think it was an extraordinary piece of research at its time, though it’s become a tad outdated now and only applicable to Chinese populations in the last century, who are known to be dairy intolerant and carry genes that predispose them to metabolise fats, carbs, animal proteins, and other food compounds differently. Meaning we cannot extrapolate the findings to other ethnic groups.

      T Campbell’s other studies were interesting in the old days, but with a few false positives in there which we couldn’t replicate again. Big Science is advancing a lot faster than that and today we know a lot more. Thousands of variables come into play and we need to look at all of them. Cancer is not one but over 200 different diseases, each disease/cancer type with its own risk factors. For example, while dairy may increase cancer risk in some cancer types (e.g. liver), it may actually be protective in others (e.g. colorectal).

      It’s wise to consider your own familial risk and genotypes to narrow down what’s risky for you and what’s actually beneficial. We dive a lot deeper on this in our Nutrition for Cancer Prevention and Longevity course for those who are interested.

      Personalised nutrition is the current direction of new science. Your genome, your microbiome, your metabolome, your connectome… they all count! :-)

  • Yvette

    Reply Reply December 8, 2016

    Alex, this breakdown is extremely useful, helps me a lot…. No one else explains these details…. I love the filter questions that I can use and how everything is structured, made it very easy for me to understand. My junk science radar was inexistant before I found you, your stuff is top notch. Thank you, thank you, thank you!!!

  • cis

    Reply Reply December 8, 2016

    Frankly,
    this can be simplified further…
    *** always disregard the headline and read the actual study by yourself ***

    Of course, the lack of control group in study 1 is worrying… even at design stage, that should have prompted a re-evaluation of the study design. One wonders what kind of planning and approval procedures these studies go through before they are actually run. If I were to sponsor a study, I would want to see a better design that has the power to give me some answers first. Or I’d invest in something else.

    As to study 2, in spite of acknowledging some “confounding factors” e.g. those who ate more saturated fats also exercised less and were less likely to take vitamins and be heavier, the authors still draw firm conclusions and recommendations as if their words were definitive.
    “Lauric acid, myristic acid, palmitic acid, and stearic acid are associated with an increased risk of coronary heart disease, after multivariate adjustment of covariates” and then recommend replacing these, particularly palmitic acid, with “polyunsaturated fats” (as if they were all the same) and whole grain carbohydrates.

    This second article is also published in the bmj. Can we actually call this science?

  • Elizabeth Onyema

    Reply Reply December 8, 2016

    This is my take on saturated fat. Saturated fat cannot be called bad. Just like everything in life, moderation is key. Saturated fat can be found in all good quality fats and oil..so, we cannot totally rid ourselves off it. Everything God has created is good. But like I said earlier ..moderation is key. Saturated fat gotten from grain fed cattle..that doesn’t sound good. But that gotten from grass fed animals is not bad either. I do not agree with the hflc diet because of its limitations on a major macro nutrient. Especially for one who is reasonably very very active..for a 600lb woman …sounds good. Looking this matter through from the African perspective, our fore fathers did have a fair amount of saturated fat from their meals, but naturally sourced and were fond of roasting meats…even fish. The act of roasting did melt a good amount of saturated fat. Coupled with a high physical activity and a good intake of vegetables/complex carbs/ fruits…they obviously did better than our generation health wise as they lived longer in good health and rarely obese . So…..in conclusion….taking in all macro nutrients in its best natural form and in reasonable quantity is what we should look out for. Well done Alex!

    • My pleasure, Elizabeth!

      • malcolm

        Reply Reply March 13, 2017

        Hi
        An interesting comparision of two rather un-representative studies. However the overwhelming message from randomised controlled trials studying the effects of high-fat vs high-carb diets is that high-fat is better for weight loss, which is directly associated with most chronic diseases.
        Then you just need to get over the crazy notion that cholesterol is responsible for heart disease and you have a clear winner.
        Regards,
        Malcolm

  • craig kelly

    Reply Reply December 8, 2016

    Great read thank you.

    The difficulty with all the information available for the “Joe and Betty Bag of donuts’ or layman is this, they are sold on headlines, and live such busy lives that they dont have the time nor the skill set (in most cases) to sieve through all the information that is present today. So when there is a big, bright headline with a catchy hashtag from a high profile media celebrity they may take the information as gospel. This becomes our challenge daily, to battle to tide of BS!

    Nutrition and diet is a very simple science really, its not really rocket science, but its true the day to day implementation of fueling, repairing and energizing the greatest machines ever built (us) is were the challenge arises and all the conflicting information makes it that much harder for the weekend warrior to manage, so they just chase what sounds easiest or sexiest.

    Thank you for the information and quality resources.

    Craig Kelly

    • Craig – you’re so welcome! Yes, the implementation aspect is so important too. “Knowledge without practice is just philosophy that makes good dinner conversation”, right? :-)

  • Sarah B

    Reply Reply December 9, 2016

    Fascinating, Alex, thank you! This was excellent and easy to follow, will definitely use your quality filters. Great lesson!! Very interested in the research pro course.
    Xx
    Sarah

  • Morgan

    Reply Reply December 9, 2016

    Brilliant and simple. Great for the layman caught up in this debate.

  • Daniella

    Reply Reply December 9, 2016

    WOW great stuff Alex!!!!!!!!!!

    This gives me the clarity I needed.

    Tks for sharing the know how..!!!!!

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