[New Scientific Study] Not All Plant-Based Diets Created Equal?


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

Today, let’s review a new scientific study hot off the press… about plant-based diets!

We see plant-based studies in the news quite often. But what’s a “plant-based diet” anyway?

The definition of a plant-based diet is highly debated these days…

Some say it’s a vegan diet.

Others include vegetarian eating.

While many argue it’s a diet where you eat mostly whole foods coming from plants (70-90% of calories), PLUS a relatively small amount of food from animal sources (typically yogurt, eggs, fish or poultry).

What are plant foods specifically?

As the name indicates, plant foods are edible food substances derived from plants.

Plant foods include:

  • wholegrains (such as quinoa, oats and rye)
  • fruits
  • vegetables
  • nuts
  • seeds
  • legumes
  • oils
  • tea
  • coffee
  • herbs
  • spices
  • fruit juices
  • sweetened beverages
  • refined (white) grains
  • fries
  • sweets

Now, let’s take a look at this list again…

Are all these really “healthful” just because of their plant origin? Or could eating some of them regularly increase our health risks?

The devil is in the detail

When the team and I review plant-based diet studies, we often notice that they are inconsistent, because different researchers use different definitions of a “plant-based diet”…

This makes it very difficult to compare studies “like for like”, since the findings are about different ways of eating!

That’s why a group of researchers are steering a new direction to fix these inconsistencies… and I personally like that.

So, to overcome the problem, they created 3 versions of a plant-based diet:

  • An overall plant-based diet which emphasizes the consumption of all plant food, and reduces (but doesn’t eliminate) animal food intake
  • A healthful plant-based diet that emphasizes the intake of “healthful” plant foods such as wholegrains, fruits and vegetables, and without animal food intake
  • An unhealthful plant-based diet which emphasizes the consumption of “less healthy” plant foods such as fries, but without animal food intake
1_Not all plant-based diets are created equal_The Health Sciences Academy_Alejandra Alex Ruani

Comparison between different types of plant-based diets (Satija et al., 2017)

I think these variations initially make sense. Also, including different dietary choices feels more “democratic” and inclusive.

But the researchers took things a step further…

 

Introducing the Plant-Based Diet Index

After close analysis, the same researchers developed a “Plant-Based Diet Index” to score the diets of 209,298 participants:

  • Healthier plant foods (wholegrains like quinoa, fruits, vegetables, nuts/legumes, oils, tea/coffee) received positive scores
  • Less-healthy plant foods (juices/sweetened beverages, refined grains, fries, sweets) and animal foods received reverse scores

Then based on that, they grouped plant foods into 2 groups:

  • The Healthful Plant-Based Diet Index (which they call called “hPDI”)
  • The Unhealthful Plant-Based Diet Index (called “uPDI”)

After that, the researchers measured the amount of either hDPI or uPDI foods eaten by the participants over 2 years, while performing medical check-ups on their health.

All 209,298 participants were healthy men and women at the start of the study.

How did their plant-based eating affect their health?

Well, the answer is in the type of foods they ate… and the amounts!

(In science, everything is “dose or amount dependant”).

Participants with higher hPDI scores had lower disease risk, in particular heart risk. A high hPDI score is based on eating more of the foods listed in the Healthful Plant-Based Diet Index.

Conversely, those with higher uPDI scores showed higher heart disease risk. A high uPDI score is based on eating more of the foods listed in the Unhealthful Plant-Based Diet Index.

2_Not all plant-based diets are created equal_The Health Sciences Academy_Alejandra Alex Ruani

Researchers measured food types/amounts eaten and heart risk (Satija et al., 2017)

Overall, higher amounts of “healthier” plant foods were associated with lower risk.

Whereas higher amounts of either “less healthy” plant foods were associated with higher risk.

How is this study making us smarter?

Saying that someone eats a plant-based diet doesn’t always mean they are “healthier” or that they have a lower health risk…

Because if a person’s plant-based diet consists PRIMARILY of chips, crisps, fried foods, sweets, brioche buns and juices, the person’s health risks may be higher.

The nutritional quality of plant foods can vary significantly. So it’s crucial that we take into consideration the quality of foods in someone’s plant-based eating practices.

For that reason, when assessing, planning or personalising a client’s diet, it’s important to be specific.

Your key takeaways

We’ve seen that not all plant foods are created equal…

And when we look for diet quality, the devil is in the detail.

Sugar is a plant food. Fructose is a plant food. Fries are a plant food.

Sometimes, smaller yet SMARTER dietary tweaks (rather than massive changes) can also be encouraging and go a long way!

What about you?

Are you a plant-based eater? If so, which of the 3 definitions of plant-based eating are you closer to? Mostly plants with some animal foods? Or all vegan?

Tell us in the comments below, and share this with someone who enjoys plant-based eating!

P.S. Okay, I’ll go first! In case you’re wondering, in our team of scientists we have 1 vegan, 2 vegetarians, a plant-based eater “with benefits” (yours truly!), a couple of (very healthy) meat and cheese eaters, a sporadic low-carber/keto, some meal-skippers… and the list continues… because guess what?

Everyone’s biochemistry is different. We all metabolise nutrients differently. And each of us operate optimally through different nutritional strategies…

As you’ll often hear me say: “If it’s not personalised, it’s not effective!

 

Take the next step

Want to become a Plant-Based Nutritional Advisor?
To be notified when this new certification goes live, raise your hand by clicking 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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20 Comments

  • Amin Gibson Alison

    Reply Reply July 27, 2017

    The overall topic and explanation has been so nice and its modal for good health habit.

    I real look forward to get to know more.

    Amin Gibson

  • Amin Gibson Alison

    Reply Reply July 27, 2017

    The overall topic is very interested and its way forward for health grow modal once followed it will make everyone to their body status.

    Therefore, I am much in this learning new ways plant base diet

  • Roderick Baulk

    Reply Reply July 27, 2017

    I go more for a healthful plant & fungi-based diet.

  • Nyc Gapp

    Reply Reply July 27, 2017

    I’m an ethical vegan following a very hPDI! You include oils in your list of Healthier plant foods. All vegetable oils are highly processed, and should be used sparingly as consumption; even smaller amaounts can result in significant health risk.

  • Dominic

    Reply Reply July 27, 2017

    Thank you so much for providing us with the latest science based research!
    I really appreciate it.

  • Rae

    Reply Reply July 27, 2017

    I am a hPDI vegan and I feel amazing. I have recently had a nutritional analysis done (blood work) and am deficient in nothing! I am also a professionally trained plant-based chef, so preparing healthy foods is easy for me and is something I try to share with clients and friends.

  • Silvia-AR

    Reply Reply July 27, 2017

    Hi
    I try to eat more healthy vegetables and less amount of animal food, but I do not always get it for my work.Sometime I´m stay out , so ussually eat a sandwich, but at home my diet is all healthy.

  • Wildly Intrepid

    Reply Reply July 27, 2017

    Great article. There are so many different documentaries about plant-based diet that this information is crucial. Not everyone understands that there are some healthy and unhealthy ways of eating within it. Thank you.

  • Tony

    Reply Reply July 27, 2017

    when you say “fries” what does that mean exactly?? Fries cooked in oil? if so what kind of oil? baked fries? mcdonalds fries? organic fresh cut fries??? Theres a big difference between all of these.

  • Michelle

    Reply Reply July 28, 2017

    It´s so great to see this study come out. I know of vegans that practically live off of processed “mock meats” and I know vegans that only eat fresh fruits and vegetables, grains, and beans. And yet they are both considered vegan. I would assume their blood profiles differ!
    I am the hDPI vegan on the team. Though I will admit, that on occasion, I do like to have a little bit of something unhealthy.
    I also just wanted to remind everyone that a healthy plant-based diet is not the cure for everything! There is so much false information out there with news like “a raw vegan diet (or insert other lifestyle/diet) cured my cancer”. Can it help? Sure. Should you switch your diet and avoid all other treatments or therapies? Probably not. Instead, a healthy diet (and lifestyle) can work WITH a physician´s plan of action instead of replacing it.
    What do you guys think?

  • Bruce

    Reply Reply July 28, 2017

    Too many variables. The researchers seem to have a bias against animal products. Just as some plant based foods are healthier than others so are animal based foods. The best diet for bumans should include “healthy” animal products. We are omnivores. B12 is one indicator of this.

  • Nicki Kelly

    Reply Reply July 28, 2017

    Due to genetic differences [as Maria pointed out] and ethical preferences, many of us are drawn to plant based diets. I’ve been helping people successfully reduce or eliminate their type 2 diabetes medications, normalise their bad cholesterol levels, lose weight and improve many niggly health issues. I do that by guiding them through the often confusing maze of vegan eating plans and write mouthwatering recipes for them.

    The frustrating issue in my niche is that some members of the public either misinterpret the free online plans that are ‘kindly’ given out like lollies to children; or that their system is not well suited to the dubious recommendation that a one-size-fits-all diet is for them.

    I undo client’s health damages who for months followed a high fat vegan regime such as eating coconut oil by several spoonful each day and glugging olive oil onto each meal, just to find out that lo and behold, it actually did not reduce their weight as they were led to believe, nor reduce their cholesterol :(

    Others follow a very high starch, zero fat plant based eating plan, happily devouring delicious “all you can eat” bowls of muesli, rice, pasta, potato, sweet potato and quinoa, beans etc. with minute flecks of vegetable matter and then wonder why they end up with unwanted weight gain.

    The explosion of interest in plant based eating is partially due to various laser focused documentaries that have been released in recent times. They are pointing to either the eye opening health benefits that can occur for a section of the population by omitting animal based foods or the gross mistreatment of farm animals in our care.

    Either way, after viewing any of these documentaries, people get carried away on a wave of emotion and decide plant based is the way to eat from now on. But many start off by simply leaving away animal based foods and end up unwell.

    Once they realise that maybe some consideration should be given to nutritional needs, another problem can start….

    Namely the lure of the loudest voices online can romance them into thinking the recommendations by their chosen ‘guru’ is written in stone and will guide them towards everlasting health.

    I often point out that specific plant based eating styles are not to be followed like a religious sect, but also need to be adjusted to suit the individual’s needs. Just like an omnivore’s diet: vive le difference!

    • Bruce

      Reply Reply July 29, 2017

      Good job of putting science into dieting. We all have different genetics.

  • chrispo vutungah

    Reply Reply July 30, 2017

    plant based diet does not include any animal products

    • Chrispo – It depends on the person. But we can say that VEGAN diets don’t include any animal products (honey is considered an animal product, for example). When you read this article, you’ll notice that there are many definitions of plant-based diets. While everyone else out there is fighting and getting emotional based on their own dietary ideologies, we need to be more inclusive and respectful of people’s food choices. Also, science is moving fast so it’s important to keep an open mind and be more willing to continue learning.

      • Liz

        Reply Reply July 30, 2017

        I’m open minded and I enjoyed reading this article and the comments.

        I base my diet on plants mostly, with some animal products too. I like honey, eggs, yogurt, etc.

        I feel discriminated when people tell me I’m not plant based because I feel I am since most of my food comes from plants.

        When people talk about ethics, plants are also living things we’re eating and in many cases exterminating… but we have to eat to survive… we’re still at the top of the chain as predators.

  • craig

    Reply Reply August 1, 2017

    I believe in enjoying an eating regime that is full of diversity and variety that allows us to all perform optimally, live with effervescence and vigor, and provide the environment that allows us to massage our DNA and genome which then optimises our physiology to be working for us and not against us!
    Myself personally i enjoy eating a huge array of plant based foods full of fibre, antioxidants, phytochemicals (mother natures pharmacy) and then add to this plenty of legumes, pulses, high fat fish, quality essential fatty acids, and dairy as close to nature as possible. I guess by trying to pigeonhole myself with a label i would fall into the category of the Pescetarianism!

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