Science Advocacy
Science Advocacy
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
One of my friends swears by the Paleo diet. Does this diet work? Should I try it? – JL, San Diego, CA
Thanks for the question. Let’s get right to it!
The so-called paleo diet is a modern fad diet in which people eat foods that were (supposedly) only available to cavemen during the paleolithic period of human evolution. The idea here is that cave man & cave women were in great shape and didn’t suffer from modern diseases like diabetes and heart disease. Adherents hold that humans evolved to eat this way and the rapid change to a diet high in cereals and dairy, fueled by modern agriculture, has led to all the obesity and many of the health problems we have today. Most modern paleo diets are high in fruits, vegetables, meat, seafood, nuts and seeds, while being low (or containing no) cereals, grains, dairy, legumes (including peanuts), salt and potatoes.
So before we get to whether the diet “works”, let’s talk about the theory around it. Did humans evolve to eat like the hunter-gatherers of the paleolithic age? Was this diet preventing diabetes and heart disease while keeping them in great shape? Do we even know what people form the paleolithic age ate? The answer to all of these questions, I’m afraid, is a resounding no.
Let’s start with the paleolithic age itself. It was very different from our time, and things really weren’t as simple as a bunch of folks living in caves gathering food. The paleolithic age lasted about 2.5 million years, and only ended 12,000 years ago. It ended with the invention of modern agricultural practices (farming and raising livestock). During most of the paleolithic, there were no humans – at least no homo sapiens. Instead there were homo habilis, who were quickly replaced by homo errectus, who were in turn pushed aside by homo neanderthalensis (Neanderthals), who were then usurped by our crafty homo sapien (modern human) ancestors. Homo sapiens have only been around for 300,000 years, and the Neanderthals went extinct only about 40,000 years ago. These humanoids were well into the paleolithic age before they figured out how to cook anything with fire, and fishing using anything other than spears was only invented about 20,000 years ago. The modern continents were generally similar to today (give or take 50 miles), but they were alternatively covered in huge glaciers during successive ice ages. There weren’t many of these humanoids around (at most 1 per square mile), and they also didn’t live very long. Infant and child mortality was very high, such that the average person only lived to about 30 years old. However, if you made it to 15, you could expect to live about 50 years.
We don’t know much about what the humanoids ate back then, but you can be pretty sure there wasn’t much variety in most places. Remember there is no agriculture yet, and no trading or significant food storage. People ate what was around them. In some places that might have been mainly fish, in some places (particularly northern latitudes), it was mainly meat, while in others is was mainly fruits and berries. Many foods we take for granted now and some might consider “paleo” were very different from those of today (many wild nuts and tubers were poisonous), restricted to very small areas (squash and pumpkins were only in Mesoamerica, carrots only in the Middle East, watermelons in southern Africa), just weren’t eaten yet (most beans), or simply didn’t exist (broccoli, cabbage, and cauliflower). The same is true for the meat people ate – for almost all people of the paleolithic period, big game hunting was out of the question – it was simply too dangerous using only spears. Pork and beef were almost never eaten. Instead, meat probably came form small animals. To make things more complicated, there is evidence that some human paleolithic populations did in fact eat some legumes, and even dairy (definitely from reindeer, maybe other animals).
If you add it all up, there is no way a modern paleo diet is representative of an actual paleo diet – there is too much variety, and it includes too many things that true “caveman” would never have seen in his or her life, much less eaten. This effectively debunks the argument that humans evolved to eat this diet so it must be healthier, since the two diets have little in common. Plus, this assumes that humans haven’t evolved in the last 12,000 years (almost 500 generations), which is silly – that’s plenty of time for significant changes in the function of the human digestive tract to adapt to our new diets.
So is it true that this diet will prevent modern “diseases of affluence”? This is also almost certainly untrue. There are a host of reasons people didn’t get diabetes and heart disease back in the paleolithic age – mainly because they didn’t live long enough, but also because people were very active (hunting and gathering) and exercise is extremely beneficial in the prevention of these diseases. Also, who’s to say that some of the older paleo humans didn’t get diabetes and heart disease? Without modern medicine, they would have quickly died, and their death would have been indistinguishable from any other ailment of the time.
Will it help you lose weight? That all depends. As UYBFS often depressingly reminds you, there is one, and only one way to lose weight, and that is to eat fewer calories than you burn. If you cut your calories and/or increase your amount of exercise, you’ll lose weight on this diet and almost any other. If you eat 3,000 calories of meat and berries a day while sitting on your couch, you will gain weight just as fast as you would eating the same calories from McDonald’s.
Fear not, JL, it’s not all bad news! For the most part, the paleo diet is a healthy one. A diet high in fruits and vegetables with little to no processed food is a great idea, so as diets go, it’s not a bad one to try. Just keep in mind that you still have to watch your calories if you want to lose weight. As with all diets, you’ll do better if you add regular exercise. The only caution is that the strict paleo diets tend to be very low in calcium, which can be dangerous, particularly for women. This is easily remedied with by taking a calcium supplement. I know, I know, cavemen didn’t have calcium supplements, but there is a reason you don’t see a lot of cavemen around these days – we know a lot more about health an nutrition than they ever did.
So what’s the bottom line? The paleo diet can be a healthy alternative to diets high in processed foods and simple sugars, which are risk factors for metabolic disorders like obesity and diabetes. Add in some exercise and calcium supplements and it could help you lose weight and feel healthier. However, don’t buy into the “eat like a caveman” thing, and don’t let anyone tell you people evolved to eat a chicken stir fry with kale, zucchini, olive oil and lemon. This sounds healthy – and it is – but it would have been impossible for a paleolithic age human to eat. The modern chicken didn’t exist yet (if you lived in southeast Asia, you could have eaten it’s progenitor, the red junglefowl), kale didn’t exist yet, nor did zucchini (and it’s ancestors could be found only in Mesoamerica), and nowhere on earth could you have found both lemon and olives in the same place. You get the point.
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
I see adds for a supplement called Elysium all over FB, and they seem to have real science behind their product. If it safe? Should I be taking it? – M.B. Boston, MA
Great question. First, some background. Many people know Elysium as a mediocre (58% audience score on Rotten Tomatoes) Matt Damon movie from 2013. Classics scholars will remember Elysium from Greek mythology as a heaven-like place where righteous people go after they die. It is likely that the supplement company (the product is actually called Basis) and the movie where both named after the Greek myth.
The Elysium Basis supplement contains Nicotinamide riboside, which is a precursor for a common and essential enzyme cofactor called nicotinamide adenine dinucleotide (NAD+), and pterostilbene, which is a chemical similar to resveratrol. You may have heard of resveratrol as the “active” antioxidant molecule in red wine. You can buy resveratrol supplements in any health food store. Elysium (the company, not the Matt Damon vehicle) has indeed been all over Facebook lately, and their website is impressive. They list 7 (!!) Nobel Price winners as members of their advisory board, plus a number of other accomplished scientists. Their website is really nice, and they highlight research and discovery efforts much like a biotech or pharmaceutical company would. They have even run a clinical trial with the Basis supplement! Honestly, they have done a great job of providing the appearance of scientific gravitas to their product. However, it’s important to note that their Basis product is really not unique. Many other companies sell nicotinamide riboside supplements, and resveratrol supplements have been available for years.
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
Are “blood boys” like the one on Silicon Valley a real thing, and if so do they work? – D.L. Madison, WI
Yes! They totally are! Well, sort of – here’s the skinny:
The idea of using the blood of younger people to heal or slow the aging process has been around for a while. There has been a recent resurgence in interest for two reasons. First, some intriguing new data has been generated and widely publicized, and second, some folks in Silicon Valley (the place, not the show) may actually be trying it.
The data has come from “heterochronic parabiosis” experiments in mice. Heterochronic parabiosis is the surgical pairing of the circulatory systems of two animals of different ages. Importantly, these experiments are performed in an attempt to understand the role of blood (and the factors it contains) versus the cells in the aging process – not in an attempt to develop a treatment for aging. Studies have shown that the cells in older mice benefit from being exposed to the blood of younger animals. That sounds great! However, there are some caveats. First, these mice are usually surgically connected for weeks to months of time – these effects have never been shown with a single or even multiple infusions – only continuous parabiosis. Second, the younger animals experience negative effects (their cells act like they are older), so it’s not something anyone is likely to sign up for.
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
Is pink slime dangerous and how can I avoid it? – K.B. Chico, CA
Great question! Here’s the skinny:
“Pink slime” is a pejorative term for “lean finely textured beef” (LFTB), “finely textured beef” (FTB), or boneless lean beef trimmings (BLBT). It’s added into ground beef as a filler and to reduce the fat content of the final product. To make pink slime, boneless beef trimmings (small leftover pieces of beef) are heated, centrifuged (spun around really fast to remove the fat), frozen and crushed into a paste. To disinfect it, ammonia or citric acid treatment is often used.
The term was coined by a USDA scientist by the name of Gerald Zirnstein. He didn’t like the look of the pink slime (to be fair, almost no one does), and he objected to it being classified as meat (he was overruled by his USDA superiors). Zirnstein may have had a point – this is probably stretching the definition of meat that most of us would accept. Basically, they took some fatty pieces of meat, removed most of the fat and turned what was left into a paste in the process – I guess that’s sorta meat? More like a meat puree? Whatever you call it, there is little doubt that it is made from meat, so we’ll just call it meat and move on.
Using ammonia to disinfect the LFTB has received much of the media attention, partly because it is specifically banned from use in Canada and the European Union (EU). However, Canada and the EU allow similar products which could be described as pink slime. The citric-acid treated LFTB is used in Canada and the EU allows something called “de-sinewed meat” or “red meat paste.” These all sound gross.
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
Chemtrails aren’t real, right? – A.S. Riverhead, NY.
No, they are not.
Ok, now that this is out of the way, let’s have some fun and learn a bit more about what may be the most wildly preposterous modern conspiracy theory.
Q) What are chemtrails?
A) The word “chemtrail” is used to describe the cloudy trails of condensation (actually called “contrails”) that high altitude planes leave behind them in the sky that conspiracy theorists believe are actually chemicals being sprayed by planes into the atmosphere in an attempt to poison the human race.
Q) Wait, what?
A) That’s right – just read that last sentence again. Give it some time to sink in.Continue reading…
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us an line.
It seems like a lot of celebrities are promoting detox diets. Do they work? Which ones are the safest and most effective? – M.H. Queens, NY.
Great question! These are all over the internet. Before we get into the diets and supplements themselves, let’s talk about “toxins” and how your body gets rid of them. Click here for a basic explanation of what a toxin is.
What toxins are these diets and supplements targeting? Many health blogs will classify toxins as “endotoxins”, which they say are waste products made in your body, and “exotoxins”, which they define as toxins that make their way into your body in your food you eat, the water you drink, or the air you breathe. In the parlance of science, both of these definitions are wrong – an endotoxin is a very specific and dangerous toxin produced by gram-negative bacteria, and an exotoxin is a toxin released by bacteria, often as a defense mechanism. The proper terms for each are metabolic waste products and xenobiotics, respectively. A xenobiotic is something that is foreign to the body, though it may or not be toxic.
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
My friend sent me a link to an article that claims that many children are “addicted to milk”, and that this is the cause of many behavioral, social, and hyperactivity behaviors, maybe even autism. The site looks legit, is any of this true? – RH, Burlingame, CA
Thanks for the question, RH! For our readers, here’s a summary of the article: The author claims that in many children with a “weak digestion” or an “overly permissive gut wall” that partially-digested milk protein peptides (peptides are small bits of proteins) get directly into your blood stream and bind to the same receptors in your brains as opioids (morphine, heroin, codeine). This then causes constipation, hyperactivity, aggressive or disruptive behavior, learning difficulties, and poor social behavior. The author spends a fair amount of time citing very specific behavior examples, including specific references to autism, among them speech delays, misunderstanding social context or failure to make eye contact. The treatment the author suggests is to remove all gluten from the diet (???), then remove all dairy and your child’s behavior will be just fine.
OK, let’s start with the more glaring problems with this “theory”:
If the milk-related peptides are what is causing this “addiction” why would you also remove gluten (a protein not found in milk) from your diet? Apparently these proteins can also be digested to opiate-like peptides! That got me wondering – what other proteins might contain this sequence? The most basic milk-derived opiate is only 4 amino acids long. There are only 20 amino acids used in most proteins, so if you think about it, having a run of 4 amino acids in a row in this specific order could actually be quite common. But how common? To answer this, I used the National Institute of Health (NIH)’s National Center of Biotechnology Information (NCBI) database, which is free to the public and allows people to search for and align sequences of peptides against all the characterized protein sequences known. The results? That same 4 amino acid sequence is present in greater than 100 proteins from cows – I can’t say how many because the database output is limited to the top 100 “hits”. However, I can say that besides casein (the milk protein that this article identifies as the culprit producing these opioids), many of these proteins are guaranteed to be present in any beef you eat. There are over 50 chicken proteins with this sequence, and over 100 from soy… You get the point. The reason we don’t worry about proteins being carved up into small peptides that can cause unwanted effects is because they don’t make it into your blood stream. Your gut wall keeps them out while they are being broken down completely, and even if they somehow did get in, there are enzymes in your blood that can degrade them, and a barrier between the blood and the brain to keep out and stragglers. From a scientific perspective, this whole theory is extremely improbable.
Now let’s get into some of the more complicated issues raised by the author. She uses the term “permissive gut”, which is likely a reference to “leaky gut syndrome”. In the (reputable) medical community, this refers to conditions in which significant inflammation of the GI tract allows for molecules to pass through the intestinal walls that normally would be unable to pass because of their large size or charge. This very clearly occurs in patients with celiac disease and irritable bowel syndrome. However, leaky or permissive gut syndrome not associated with these diseases is not a recognized medical condition. There is also no evidence to support the claim that “leaky gut” could cause the behavioral symptoms claimed in this article. People with irritable bowel disease or celiac disease do not have autism-like behavior issues. I promise useyourbrainforscience.com will tackle “leaky gut” in the future, and we’ll link to it here.
There is no data confirming that opioid peptides derived form milk or wheat protein are actually produced in any significant amounts in humans. If they were could they actually affect behavior? While there is (again) no data on this, it seems unlikely. These molecules are more than 1000-times weaker than morphine, plus the article fails to mention that some milk peptides can also act as antagonists as well, blocking the effects of the opioid receptor.
The author includes a very nice looking figure showing how these peptides could get into the blood stream and activate receptors in the brain. The diagram comes from a University of Florida website that describes the potential link between autism and celiac disease. This site in general is a relatively objective assessment of several potential treatments for autism. The author is quick to call this a “theory” and the website does not provide any data supporting the link between leaky gut, opiate-like milk peptides, and autism. Despite this, I can’t help but wish the author had been a bit more clear about the lack of data supporting this theory.
This brings me to the original article our reader referenced above. The author includes a lot of references, but I can’t help but wonder if she actually read them all. Several of them go out of their way to state that there is no evidence to support a link between these milk peptides and behavior. Most disturbing is that the author lists her credentials as a Masters degree in public health, a registered nurse, and a licensed dietitian. It is troubling to me that a person with these qualifications would so eagerly promote a theory with almost zero data to support it the way she does. She should know how to do this type of scientific research and interpret basic scientific data. What could explain her over-interpretation of the data?
Money – she is trying to attract new patients for her “nutrition care” business, and she is also selling some books. One book is about diets for special needs kids, which probably contains the disproven milk-addiction theory. One is about how to get your child off pharmaceutical medications (she even mentions asthma and seizure meds!) by changing their diet. Please don’t try to manage serious medical conditions like asthma and seizures with diet – that is extremely dangerous – and possibly deadly. The last is about how her son got autism from the hepititis B vaccine. Vaccines do not cause autism. Please don’t buy this woman’s books.
So, to get back to RH’s original question – “is any of this true?” The answer is no – these peptides don’t get into the blood streams of the vast majority of people, if they are even made in the gut at all, and they wouldn’t affect behavior if they did. If you want to experiment with removing gluten or diary from your child’s diet to improve behavior – give it a shot, it can’t hurt, but this will never cure autism, and any effect on behavior would be unrelated to these so-call “opioid peptides.”
Welcome to Ask a Scientist, where we answer questions from our readers on a wide range of scientific topics. Got a scientific question? Drop us a line.
Why does sugar make kids hyper? Is it really a “sugar high”? – KT, Stratford, CT
The belief that sugar makes kids “hyper” has been around for many, many years. Everyone knows this is true, right? It’s been a staple of family sitcoms for generations, after all. Except it’s completely false.
Not only is the idea “sugar makes kids hyper” not true, we’ve known that it isn’t true for a long time. This was the research focus of Dr. Mark Wolraich in the early 1990s and he clearly demonstrated that eating sugar does not lead to hyperactivity in children – neither right after eating a high-sugar treat nor when eating a high-sugar diet over time. Dr. Wolraich and his group even took their investigation a step further, asking why parents always associated high sugar intake with hyperactivity. The answer: observation bias.Continue reading…
