Nutrition – The Agora

How Often Should You Eat For Fat Loss and Hypertrophy?

You’ve probably heard from your local gym bro that you need to eat at least 5 meals a day to optimize fat-burning and muscle gains; but is that actually true? Is there any truth to the old-school thinking of eating 5-6 times a day to “stoke the metabolic fire”? This is what we are going to be discussing today! I’d love to hear your guys’s thoughts on this as well!

The Proposed Mechanism

Let’s first talk about why some people think that eating more times throughout the day leads to greater muscle gains and improved body composition through more fat-burning.

For muscle gains, people feel that more meals is better because you are getting more “protein-feedings” throughout the day which should in theory increase the time in which you’re in an anabolic state, leading to greater gains than less meals.

For fat-burning, the claim is that eating more frequently keeps your body in a more frequent state of heightened metabolism than less meals. This is known as postprandial (after eating) thermogenesis (heat production). The body’s metabolic pathways require energy to work which comes from calories and food. So you should be burning more fat, right?

Not exactly.

I’ll be honest. I followed these tenets myself when I was younger for a few years because they felt intuitive and I thought they made sense. However, as I learned more and looked at the research, I discovered that it doesn’t make much of a difference. Let me explain!

The Research

In 2015, there was an excellent meta-analysis published by Dr. Brad Schoenfeld, James Krieger, and others addressing the questions around meal frequency and its effects on body composition (almost literally the title). What they found may shock you! Kidding, I’m not a click-baiting prick. I hope you know that by now, dear reader.

They defined body composition as the culmination of body mass, fat mass, and lean mass which they measured through each of those criterion with the addition of body fat percent.

To keep this section short and sweet, they basically found that none of these factors are significantly influenced by feeding frequency when calories are equated between experimental and control groups¹, which is the proper way to evaluate whether or not there is an effect.

There was one study out of the 15 that were pooled together that did influence the data to show a favorable outcome for 5+ meals compared to 1-2 meals on fat mass and fat-free mass; however, when this study was taken out of the evaluation for further accuracy purposes (this is known as a sensitivity analysis), there showed no differences as with the other metrics¹.

From this meta-analysis, we can conclude pretty well that meal frequency doesn’t really affect your body composition much with all other variables in check. We’ll talk about the practical application of this in a moment. Let’s finish this section talking about the protein issue.

Onto protein!

Since we already determined that frequency doesn’t really matter, that also lumps in protein feedings as not necessarily significant:

“The findings from nitrogen-balance studies have been inconsistent on the topic, with some showing a positive correlation between meal frequency and nitrogen retention and others showing no such relationship”.¹

Nitrogen balance studies reveal the rate of protein metabolism with a positive balance meaning that input of N is greater than losses of N through metabolism and other bodily processes. A positive Nitrogen balance is typically associated with growth because amino acids contain a Nitrogen (amine) group which is part of what classifies it as an amino acid and thus protein; however, as mentioned above, the research is not concise on whether this matters. As of now, we can’t say which is better, so don’t stress yourself out about spacing out your protein to maximize anabolism.

What is going to matter more is total daily protein intake based on your personal needs. So long as you have that in check, you should be okay. The consensus is not yet in on whether or not you should distribute your daily protein evenly across your meals¹. Some studies show greater body composition outcomes with similar-protein meals while others do not¹. We don’t know yet.

Practical Application

Why does any of this matter? I basically just told you that none of this stuff is as important as you may have once thought. Did I shatter your dreams? I’m sorry. But, there is some good news out of this: You can customize these things to whatever fits your lifestyle!

You should revel in the fact that meal frequency isn’t very important! If you’re a 9-5 worker or have other more odd hours for work, it may be hard to get the mystical 5-6 meals/day. Maybe you can only have 2-3 meals each day. Guess what? That’s great! That means they can be bigger than the 5-6 small meals! Sometimes it’s just nice to have a big pile of food (but not go overboard with it).

I know for myself it’s much easier to have 2 full meals and then snacks. It makes my life easier and if I have to pivot or make changes because I’ll be especially busy that day, the snacks give me the flexibility to do so.

It’s important to always consider your personal lifestyle and how the decisions you make regarding training or nutrition are going to impact your life. The goal should be to augment and improve your life, not take away from it. How often you eat really should not be a decision that stresses you out. Choose what’s easy and convenient for you and be on your way!

Regarding protein, since we don’t really know the best way to space it out (if there is a best way), don’t worry about it. Just focus on getting the necessary amount of protein for yourself and your needs; however I do have some advice on how to do it to make your life easier:

Spacing out protein for me has been effective because it allows me to control my appetite. Protein is the most satiating (helps you feel satisfied) macronutrient, so take advantage of that with each meal or as often as you can!
If you’re struggling with eating a lot of protein in food, don’t hesitate to have a shake. Having a shake with each meal may help to curb hunger.
Explore different protein options! While I love meat and eat a lot of chicken, I’m always excited to try a new recipe with just eggs or using legumes or even a different type of meat I’ve never had. Lean sources are great because they provide a lot of protein with little fat that can add up quickly.

I hope you found this useful and understand further to not sweat the small stuff. Meal frequency is certainly one of the more over-hyped things that actually doesn’t matter a lot. What frequency works for you and what do you do for your protein? Thanks for reading!

References

¹Brad Jon Schoenfeld, Alan Albert Aragon, James W. Krieger; Effects of meal frequency on weight loss and body composition: a meta-analysis, Nutrition Reviews, Volume 73, Issue 2, 1 February 2015, Pages 69–82, https://doi.org/10.1093/nutrit/nuu017

There’s No Such Thing As Good and Bad Food

Hi everyone! My latest two podcasts have proven very fruitful for myself and the Bodkast as a whole because, not only has it opened the doors for a new audience courtesy of Andres Vargas at https://www.thestrengthcave.com, it has also allowed me to collaborate with Andres.

I am now writing a monthly article on his site, but no worries, I will also be sharing it here so you can read it. I will share the link here and you can check out Andres’s site because he also has some really great content that’s more training-related that I think you would enjoy.

For now, here’s my first article about the concept of “good” and “bad” food. Enjoy!

You can also check out the two podcasts that we made with Andres here.

Correlations: How The Media Ruin Science

We’ve all seen those headlines and articles claiming something along the lines of “Scientists prove that [food or beverage] causes [adverse medical condition].” For example, meat and cancer (which I debunked here).

The problem with a lot of these claims are that most of these things are not “proven” and there is usually not enough evidence to establish causality (one thing or action causes a certain effect to occur every time you have that thing or do that action). Many of these headlines pull their “facts” from a type of research known as observational study.

These studies essentially follow people and record a certain behavior or pattern and look to find any common trends between the people being observed to develop an association or possible link between “behavior X” and “outcome Y”. These are your meat and cancer studies or red wine and heart health studies (you’ve probably seen basic moms post about that one to justify their alcoholism, I know I have!).

Why does this matter you might ask? Well science gets reported often in the news and state and local representatives, in an ideal world, want to protect their constituents, so they will do what they can to service their community. If a study gets misreported by media claiming that meat causes cancer or dihydrogen monoxide is harmful to our health, then misinformation may be spread by the representative who is simply trying to help their community by banning water or meat because the public who watches the news demands they do something about this travesty!

Here’s another example of why we can’t rely on solely observational studies to make our decisions. Ice cream and drowning. Maybe you’ve heard this before. Ice cream sales are highly correlated with drowning deaths. This means that as ice cream sales increase, so do deaths from drowning. Does ice cream lead to drowning? Or do drownings lead to buying ice cream? Probably not for either. There’s something else at work here known as a “confounding variable” that is clouding the conclusion. Ice cream sales increase likely during the Summer and more people are also likely in the pool during the Summer, also leading to increased potential for drownings.

We have to be careful with news stories that reference research studies because observational research is popular among journalists because they can make bold claims like the ones mentioned before; however, as we’ve seen, those claims don’t actually hold up/are not what the study is actually saying.

On a related note: Be very careful of the word “proven”. Rarely is something proven in science by research and when it is, it has been studied over and over and over and over and over and over and…you get the point. It takes a long time, potentially decades, to establish causality or proof that one thing causes another. We can make associations about things, but causality is a completely different concept because it has to happen 100% of the time. If meat really did “cause” cancer, then there would be an actually be an outright ban on meat to protect the public; however, it’s only an association and it’s weak at that. Not everyone who eats meat will get cancer.

To demonstrate how hard it is to prove something, consider this: Gravity is still a theory. Our explanation of why we observe the effects of gravity is only a theory, meaning we’re pretty sure but not 100% sure. So when someone says that science has proven that processed foods are cancerous or that this causes that, put on your skeptic hat because that person is probably speaking in hyperbole to argue their point rather than present fact.

You may have also heard that insulin causes obesity or “this one thing” causes obesity. Put your skeptic hat on for a minute: There are so many aspects to our lives that could contribute to weight and fat gain, how is it possible that we can pin all the weight gain for the billions of people that gain weight and fat every year? I’m willing to say that it’s impossible. While this may start to sound like a rant, I think it’s appropriate to say because many people will blame one issue when there’s a plethora of other potential things going on.

If you approach someone’s weight problem thinking that there’s only one underlying issue and you try to treat just that one thing, you’re probably going to fail because they could have other factors or behaviors in their life that could be adding onto the complexity of obesity. It’s also belittling to the person to say they just need to stop doing “x” and when they do it, they’re still obese. Don’t be a dick. Be an empathetic non-dick and realize obesity is a complex issue that has many potential causes and it’s up to the trainer or care provider to find those causes and help the person get through them instead of blaming insulin, processed foods, or their lack of motivation. That’s being a dick.

All of this leads to the famous phrase said by many people in the sciences: Correlation does not equal causation. I hope I’ve burned into your mind why this is. I also hope that, if you’ve stuck around for this long to read this (thank you by the way), then you understand to be more skeptical when you see a sweeping headline claiming causality or that science proved something.

Because if we can’t even be 100% sure about gravity, how the hell are we going to be sure about a food causing cancer?

Thanks for reading! What questionable shit have you seen online or on the news?

The Exaggerated Link Between Meat and Cancer

I know I’m not the first one to touch on this, but I see this still being an issue with the rise of vegetarian and vegan diets. Not to say I have a beef (ha) with people who eat this way, but the claim that red or processed meat causes cancer is one rooted in poor reporting of data.

Here’s the story: In 2015, the World Health Organization (WHO) published a report on meat and its links to causing cancer. They categorized red meat as “probably carcinogenic to humans” and processed meat as “definitely carcinogenic to humans”¹. Sounds scary, right? Here’s the issue with this: the WHO doesn’t measure how dangerous something is or the level of risk the item in question has; it measures the strength of the evidence to indicate that it’s carcinogenic (cancer-causing). While that sounds like the same thing, it’s not. If the studies aren’t well-conducted or not measuring what you’re looking for, then the evidence may be strong, but it’s not accurate.

Before we go further, I want to clarify the difference between “red meat” and “processed meat”. The WHO defines red meat as “all mammalian muscle meat, including, beef, veal, pork, lamb, mutton, horse, and goat”¹. Basically, any meat you see in clear packages that looks fresh from the animal. Processed meat is “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation”¹. Think of hot dogs or turkey and pastrami slices.

Study Designs and Confounding Variables

The issue with the body of evidence about meat and cancer is that a lot of it is from what are known as epidemiological studies. This study design attempts to find the source of a disease by following a specific population over a long period of time (years, decades, lifetime, etc.) and see what happens to them. Through this, they attempt to find trends or common habits and behaviors that a lot of the population does as a potential explanation for a disease or condition.

For example, epidemiological studies have found a strong correlation between smoking and lung cancer formation. Through a different type of study called mechanistic studies, they have discovered the chemicals in tobacco that lead to the lung cancer over time from consistent inhalation of cigarettes. Of course, not everyone who smokes will develop cancer though, so we cannot say with 100% certainty that smoking causes cancer. Epidemiological studies cannot prove anything, just find associations.

Back to meat, the problem with these types of studies and meat consumption is that there are so many other areas and functions of a person’s life that could contribute to cancer formation that these external factors could be driving the cancer formation instead of the meat itself. For example, wealthier countries typically consume more meat than poorer countries. Wealthier countries and individuals can also afford more cigarettes; what if someone was smoking and eating meat but the study only was measuring for meat consumption. Was it the cigarettes or the red meat? This is known as a confounding variable. It’s something that cannot be accounted for in a study that may influence the result.

My personal opinion is that there are many confounding variables that are likely contributing to cancer formation in people who eat meat than the actual consumption of meat itself (meat eaters may be more stressed, unhealthier, sedentary, etc.). So while there is a correlation between processed meat and cancer, there are still so many things that could contribute to it, it probably would serve you better to move around more and eat better than to cut out your occasional deli sandwich or sausage.

Relative Risk

On the other hand, there have been some chemicals found in cooked meat that are carcinogenic, should we be concerned? Probably not and here’s why.

While the risk of red or processed meat and cancer risk has been quantified, the number is very misleading. On the Q&A page of the WHO website and in news outlets, you will see that you have an 18% risk of developing cancer if you eat processed (not red) meat daily. The nuance here is that 18% is a relative risk, not an absolute risk. What this means is that if your current risk of cancer without eating red or processed meat is 3%, then your risk of getting cancer moves up to 3.5% if you choose to eat red or processed meat daily. Why 3.5? Relative risk factors in the risk you already have and then multiplies that by the percentage of the new risk factor (18%). Here’s the actual math:

3% (expressed as a decimal is 0.03) x 18% (1.18 as a decimal because you’re adding the risk of 18% from the 3%, hence the 1 in front of the decimal)=3.5%. Try putting in your calculator 0.03 x 1.18.

So in theory, the risk of developing cancer from red or processed meat is very, very small. Almost insignificant. For that individual, the absolute risk of developing cancer from processed or red meat is 0.5% because their total risk of cancer increased by 0.5% after including the relative risk of 18%.

To clarify, the body of evidence for processed (not red meat) shows a strong link between daily consumption of processed meat and cancer risk, meaning that cancer-causing chemicals are most likely in these processed meat, but the risk of actually getting cancer from these chemicals is so small that there are many other things to worry about than the meat you’re eating. As for red meat, the evidence is not as clear as it is for processed meat. They think there could be a link, but confounding variables are still clouding the final decision. The following is a short concise list of a few more points I want to really hammer home quickly.

Quick Takeaways

People say processed meat is in the same category as smoking, so it should be just as bad. Again, this list only measures the strength of the evidence, not the magnitude of risk for the specific item. Smoking is very much more likely to lead to cancer than a hot dog is.
The 18% risk that is so popular to throw around is accounting for processed meat consumption on a daily basis. Chances are you’re probably not eating processed meat every single day.
There are may things in our lives that come with some sort of risk. And many things can cause cancer. What’s life without the things you enjoy? If you enjoy eating red or processed meat every now and then, freaking have it. If you’re afraid of getting cancer because you ate a slice of deli meat, your priorities are out of whack. My point here is there are many things that will kill you, cause cancer, etc. If you spend your whole life trying to avoid them, what kind of life are you living?

Final Points

Should you cut out red and processed meat? Probably not, as you read, the risk of getting cancer from these foods is very slim (even more slim from unprocessed red meat). Conversely, could you benefit from reducing your intake? Yeah, most likely! There are plenty of sources of animal protein that are not red meats which are still tasty and nutritious along with plant-based protein sources that can be often even more nutrient-dense. Many people could probably live healthier lives if they lowered their meat consumption (but not completely eliminated it).

It just simply does not make sense to completely cut out red or processed meat from your diet if you’re worried about cancer; because chances are, you’re probably doing something else in your life that is contributing more to your cancer risk than some meat. Just enjoy your damn food and don’t eat too much of any one thing. Drop a line in the comments about your thoughts or favorite meat-based recipes! Below you can find some other resources if you want to do more reading for yourself.

References

¹Q&A on the carcinogenicity of the consumption of red meat and processed meat

Additional Resources

WHO report says eating processed meat is carcinogenic: Understanding the findings

How to interpret IARC findings on red and processed meat as cancer risk factors

5 Ways To Fight Hunger Cravings

Why the hell can we not stay full during the day? I talk to and overhear a lot of conversations that involve being hungry from busy students or professionals who are at work many hours of the day. What can they do to ensure they stay away from the vending machines at work or on campus or the shitty dining hall/cafeteria food? There’s a few things you can start doing to stave off those hunger cravings.

1: Plan Your Food, Foo

I can’t stress enough how valuable it is to plan your meals ahead of time. Bodybuilders and gym bros/bras have it right with bringing tupperwares of food with them. Now, it isn’t necessary to bring 50 meals with you for an afternoon of work. One large meal should be fine. Take some time either the night before or a few days before to prepare food for the next day or upcoming week.

When you’re prepping, make sure you’re aware of the shelf-life of the food you’re preparing. Chicken is only good for a few days (I never personally go past 3 days) after cooking. Rice and beans last a bit longer, so those are good options. This link shows a great chart for a wide assortment of foods in terms of their storage life fresh, frozen, cooked, etc. Refer to that link if you’re unsure!

2: A Balanced Meal is King

Having a good mix of protein, carbs, and fat in your meal(s) will provide the best bang for your buck. You get a whole mix of nutrients and can fight off cravings by planning smart! For example, having a carb source that is high in fiber (vegetables, legumes, whole grain bread, etc.) with plant protein or lean meat topped off with a quality fat like avocado (which also has fiber) or canola/olive oil will put you in a great position in terms of feeling full for a long time and getting a lot of nutrients in a short time.

Having a balanced meal also just looks better and tastes better from an aesthetics and palatability standpoint. Having different colors, textures, and tastes in the meal elevates the taste, which is so important. Try it for yourself, and you’ll see even just preparing the food gets you excited to eat it.

3: Fiber, dammit!

I will talk about fiber until the day I die. This is such an important nutrient not only for general health (it helps to lower the risk for heart disease, diabetes, and cancer¹), but it also helps to keep you full and satisfied! If you want to learn more about the intricacies of fiber and why it helps you stay full, read my original post about fiber here.

Fiber is a pretty simply nutrient you can start including in your diet right now. If you’re prepping your food already, you can often exchange the carb sources in the meal for a whole grain or higher fiber option. For example, if you made a sandwich, shoot for the 100% whole grain bread. There’s a difference between 100% whole grain and 12-grain products. 12-grain products are often a hybrid between white bread and whole grain. If whole grain, wheat, etc. is available, go for that for fullness. If not, 12-grain isn’t a bad option.

Fiber is also found in fruits and veggies (why do you think we’re always encouraging you to eat them??). In the position stand by the Academy of Nutrition and Dietetics, they have a great chart outlining a whole bunch of common foods that contain fiber. It’s too long for me to embed here, otherwise I would. Check it out for yourself.

If you’re going out with friends or colleagues, look for options with whole grain bread, fruit, or a side of veggies to increase the fiber and satiety you get from that meal. You can also typically find fiber in protein bars like Quest bars or Complete Cookies. It’s very easy now to get fiber in your diet!

4: Protein!!!!

Protein isn’t just for people who go to the gym or the bro who downs a gallon of protein shake. Protein is known as the most satiating macronutrient compared with carbs and fat². Having high protein meals will absolutely help with feelings of fullness and feeling and staying full between meals. You can even double dip and eat foods that are high in protein AND fiber! Then you’re really winning! For example, legumes (beans, lentils, peas, soybeans, etc.) are high in fiber and contain a good amount of protein as well.

Adding protein to your meals (while minimizing the amount of fat that comes from the protein) will keep cravings at bay all day (See what I did there?).

5: Don’t Be Afraid of a Big Meal

Just because a meal is large and may contain a lot of calories (yes, “healthy” food can have a lot of calories) does not mean in any way, shape or form, that is going to make you fat or that it’s “unhealthy”. As a species, we require calories to survive and thrive. Unfortunately, we can’t always eat whenever we freely want to. This should not deter you from eating a bird’s portion when you do get the chance to eat because you’r afraid of gaining weight. If you haven’t eaten all day, chances are you can have a hefty meal and be fine.

Plus, if you’re following these guidelines when having that one meal (balanced, has fiber and protein, etc.), then you may not even eat it all because it will fill you up before you’re finished! My own meals fill up a medium-sized tupperware up to the lid, but I’m okay with it because I know to reach my goals that I need to eat! Food is your friend, let it help you!

What have you done to fight cravings throughout the day? Share below and help someone else! Thanks for reading!

References:

¹Dahl, W., & Stewart, M. (2015). Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fiber. 115(11), 1861.

²Gerstein, Woodward-Lopez, Evans, Kelsey, & Drewnowski. (2004). Clarifying concepts about macronutrients’ effects on satiation and satiety. Journal of the American Dietetic Association, 104(7), 1151-1153.

Low Fat, Low Carb-Either Still Works: Media Misses The Mark Again

Hey everyone, Michael here. This is the first article on the blog from my friend Dr. Chris Berger. He’s an exercise physiologist and university professor, so he has a lot of good information to share. I hope you enjoy!

Admit it – You’ve had it with the latest studies telling you what to do. I know I have. As a doctor of my profession, high-quality data are the lifeblood of what I do. I carefully structure my research and the classes that I teach on the basis of the best science out there. But even us PhDs have to roll our eyes occasionally at what gets published and, more importantly, how the media run with it.

Consider, for example, the attention a new study got from the New York Times. On Tuesday the 20th of February, the Times published a piece titled, “The Key to Weight Loss Is Diet Quality, Not Quantity, a New Study Finds”. Alright. Let’s break this down shall we? First, “weight loss” has no key. Weight is the product of mass times gravity so, I suppose, you could go into orbit and be happy with your weight absent gravity but… I have some bad news for you – you’d still be FAT! Next, the notion that something as complicated as body composition (and our very personal concepts of what is ideal) does not have a “key”. Why do we keep thinking that celebrities have a “secret” or that there is some trick to having a healthy body composition? Any rational expert in the health sciences will tell you that body composition is dynamic and that obesity is multifactorial. We owe our percent body fat to a lot of things. Have we engineered physical activity out of our lives? (Yes) Are we readily exposed to high-calorie palatable foods? (Yes) Have we cut the hell out of PE in schools? (Ask your kid about that one or…do you not want to interrupt his video game?) My point is that when you see news of a study that concludes that it’s this – this one thing here everybody – that is making us fat, you need to be critical of the work.

Not surprisingly, this study cited by the Times was praised by an MD – a cardiologist to be exact. Now don’t get me wrong, I respect physicians. I just wish that they would respect me. I have something they don’t have – a thorough understanding of how physical activity impacts body structure and function and the research skills to find out more. And without them, one draws bone-headed conclusions. Don’t believe me? Repeating: The Times published a piece titled, “The Key to Weight Loss Is Diet Quality, Not Quantity, a New Study Finds”. Yet what the study ACTUALLY concluded was the following (and I’m copying this verbatim):

In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom.

But do you even need a PhD or an MD to translate this for you? THEY FOUND NO DIFFERENCE.

Americans are fat for a lot of reasons but I’d like it to be the case that when we make personal efforts to improve our health, we do so with good information. We rely on the news media to so inform us. Instead, what we often have is a rush to headlines and an “endorsement” by somebody who seems credible. Clickbait. Bear this in mind for the next time you hear the “breaking news” on something in the health sciences. Educate yourself on how to read and be critical of studies using the attached guide from the International Food Information Council Foundation and be careful not to jump to conclusions. There is a lot to know in the health sciences and it’s not likely that one research paper will tell you it all.

Christopher Berger, PhD, ACSM EP-C, CSCS

References:

Gardner CD et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018 Feb 20;319(7):667-679.

Fresh vs. Frozen (vs. Canned) Produce, Who Wins? Part 3: Canned

WE ARE BACK

To finish up this monster of a blog post all about The Produce Wars. Which is better, and which is worse?? (SPOILER ALERT) Well, hopefully, by now you’ve seen that each type has its pros and cons, and that not one is better than the other, because each has its own way of processing, storage, cooking method, etc. that will help it retain nutrients or lose some in these processes. With that being said, let’s finish up by discussing canned produce and its trade-offs. We’ll wrap up with some application of where and how you can use this information.

Let’s go

Canned Produce

Processing

Here’s where canned produce can fall short pretty dramatically in terms of nutrient availability. For many canned products, they undergo “Thermal Processing” which simply means heating something to kill bacteria and other microorganisms. As we learned earlier, water-soluble vitamins such as C & B are very sensitive to heat, and are lost in this process.

For example, carrots and broccoli saw losses greater than 80% just from the canning process alone¹. Interestingly, however, corn and beets saw very small changes when canned¹, perhaps because they’re tougher on the exterior?

The B-vitamins appear to be all over the board in terms of how much of the nutrients are lost. Thiamin (B1) saw 25%-66% losses in spinach, while the same study saw no changes in the Thiamin content of tomatoes². Honestly, the story seems pretty similar across the other B-vitamins. There was so much variability, that I’m not going to waste your time going into the details behind it all. You can read the review itself if you’re curious¹. My takeaway for the B-vitmins since they’re so variable is to try to derive them from non-canned sources if you can since the losses appeared to be higher than the retention for most of the studies¹. There’s a helpful chart that you can refer to that pretty much spells it out for you!

When turning to the fat-soluble vitamins, there is a different story. Vitamin A actually saw some increases in its concentration after the canning process! One study found increases ranging from 7%-50% in green beans, sweet potatoes, spinach, and collard greens³. But the picture isn’t perfect. In that same study, peaches showed a 50% drop along with a 13% decrease for vitamin A in tomatoes. Upon further reading of this review, one can see that the research about canning and vitamin A content is actually pretty fuzzy, consisting of studies on both sides⁴. My opinion on this would be to acquire your vitamin A from a variety of canned products if they’re your only option.

Not much research has been conducted on vitamin E and canned foods because the foods with the highest concentration of the vitamin are not typically canned or fruits/veggies; however, some studies have shown large increases after processing in tomatoes⁵. It appears as though heat, similar with vitamin A, activates the vitamin within the food and allows it to be extracted/consumed in a greater amount than in the raw form. This only occurs up to a certain extent. After being converted to tomato paste, some losses of vitamin E occurred⁵. Interestingly, the USDA reports that canned products, when compared with their fresh or frozen alternative, have higher amounts of vitamin E⁴.

Here is where things get kinda interesting. The amount of minerals in canned products can actually get increased during the canning process⁵. When canning, water is often added to preserve the food longer or create a syrup base to the food. Depending on the geographical processing location, the water may actually add minerals such as potassium and calcium⁵. With this, however, comes the enormous increase in sodium. That is my one caveat if you’re going to get canned, search for low sodium or salt-free options when available and financially feasible.

For fiber, the rule stays the same: physical preparation/removal is going to lower the fiber content. In foods such as tomatoes and asparagus, the researchers saw a 27% drop in fiber content; however, other foods, even after physical prep, did not see changes, largely due to the outer or thicker layers remaining intact².

Storage

Moving on to storage of canned products, we start again with ascorbic acid (vitamin C). Pretty simple here, and, as you can imagine, not much losses are incurred after storing canned foods for a long time (18 months in these studies). Losses for vitamin C were no more than 15% for a variety of veggies¹.

For the B-vitamins, there actually appears to be variety in losses depending on the food. Thiamin, riboflavin, and niacin, which are all B-vitamins, saw significant losses after 8 months in canned tomatoes⁶, but saw no changes in fiddlehead greens⁷. I had to google what fiddlehead greens are. I’m not sure we have those in the US or Arizona at least lol.

There were not a whole lot of studies that observed the effect of canned storage on vitamin A, but the few that did showed little to no change in the amount of the vitamin over time when in storage⁴.

One funny thing that happens with canned foods is that, depending on the material of the can, the food will experience increases or decreases in the amount of iron or copper. Steel-plated tin cans have been shown to increase the amount of iron in a food⁸. Other than that, other minerals are not really affected during storage⁸.

There wasn’t much to be said about fiber in canned foods, but the summary is that some foods like fiddlehead greens may experience a decrease as much as 25% if canned and stored for 10 months⁴.

Cooking

Since canned products are often already cooked, there are few additional losses from cooking for vitamin C, assuming that little if any water is added and the food is cooked only to get heated¹.

Many of the studies that considered B-vitamin retention consistently showed that, while frozen and canned products may contain the same amounts of B-vitamins (even though they were low), both forms still have lower amounts than fresh counterparts¹.

Vitamin A studies showed that cooked fresh carrots and other veggies had higher amounts than frozen and canned options, but all forms were still good sources of vitamin A¹.

Unfortunately, there was not much to report about vitamin E except data from the USDA which showed that canned products compared to fresh and frozen had significantly lower amounts of the vitamin¹.

The effects on mineral losses in canned goods was focused primarily on sodium losses. A 1975 study showed that if you rinse the canned food in water before cooking, you can reduce a significant amount of the sodium content by 23-45%⁹.

There were no mentions of fiber losses from canned products, but I imagine that it would be similar to cooking fresh or frozen foods since the main thing that affects fiber content is physical processing.

Takeaways

This is going to be a bit longer than my normal takeaway, as I’m going to wrap up this entire series, but I hope you have learned something from this small series of posts. The primary idea I wanted to communicate to you was that fruits, veggies, and other produce goods come in different shapes, sizes, and forms. Each form has its own pros and cons, and each contains more or less of certain nutrients than the other. Mainly, this set of posts was to relieve stress that some people feel when getting hung up about buying the fresh or frozen option. Either one is fine. The fact that you’re eating veggies is great, and be happy about that. With that, a quick summary of each option’s yays and nays:

Fresh produce often showed higher amounts of the nutrients, but would degrade significantly faster. Unless you’re going through your produce drawer every three days, I’d advise mixing it up a bit. Fresh produce can also cost more than the frozen or canned, which can be a barrier for many people. No one shouldn’t feel bad about buying cost-appropriate options, as they can contain similar or even more of certain nutrients.

Frozen and canned goods possess a lot of benefits just like fresh foods do. Obviously, they last longer and retain their nutrients for a longer period of time. Also, many food companies are now making strides in nutrient-dense frozen meals that taste freaking awesome! If you’re busy and on-the-go, frozen meals can be an awesome option for you.

Canned goods are great in that they are often enhanced with delicious flavors that would be a pain in the ass to make your own. Or, they are already cooked, and all you have to do is heat them up and you have food! My advice with canned foods is drain the sodium before cooking by rinsing it for a few seconds.

I also think it’s important to note that there were some limitations in the review and research I used, so these data are not going to 100% accurate and correct all the time 24/7. The studies varied greatly on how they measured losses and retention-mostly on a dry weight vs. wet weight basis-and the years that they were published. As time goes on, research methods improve and may even invalidate some older studies, so these papers are not without their faults, but they still provide some valuable information about how you can make smarter decisions about what you eat!

In conclusion, fresh, frozen, and canned foods are all great and can be part of a healthy diet. Learn to experiment with all the options an variety you’re given, and you’ll come across some pretty cool stuff! Let me know some canned or frozen recipes or foods you found that changed your life! Thanks for reading!

References

¹Rickman, J., Barrett, D., & Bruhn, C. (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. Journal of the Science of Food and Agriculture, 87(6), 930-944.

²2Martin-Belloso O and Llanos-Barriobero E, Proximate composition, minerals and vitamins in selected canned vegetables. Eur Food Res Technol 212: 182–187(2001).

³3Lessin WJ, Catigani GL and Schwartz SJ, Quantification of cis–trans isomers of provitamin A carotenoids in fresh and processed fruits and vegetables. J Agric Food Chem 45: 3728–3732 (1997).

⁴Rickman, J., Bruhn, C., & Barrett, D. (2007). Nutritional comparison of fresh, frozen, and canned fruits and vegetables II. Vitamin A and carotenoids, vitamin E, minerals and fiber. Journal of the Science of Food and Agriculture, 87(7), 1185-1196.

⁵Abushita AA, Daood HGand Biacs PA, Change in carotenoids and antioxidant vitamins in tomato as a function of varietal and technological factors. J Agric Food Chem48: 2075–2081 (2000).

⁶Saccani G, Trifiró A, Cortesi A, Gherardi S, Zanotti Aand Montanari A, Effects of production technology and storage conditions on the content of water-soluble vitamins in tomato purees. Ind Conserve 76: 107–118 (2001).

⁷Bushway AA, Serreze DV, McGann DF, True RH, Work TM and Bushway RJ, Effect of processing method and storage time on the nutrient composition of fiddlehead greens. J Food Sci 50: 1491–1492, 1516 (1985).

⁸Elkins ER, Nutrient content of raw and canned green beans, peaches, and sweet potatoes. Food Technol 33: 66–70 (1979).

⁹Sinar LJ and Mason M, Sodium in four canned vegetables. J Am Diet Assoc66: 155–157 (1975).