To Fry or Not to Fry: The Acrylamide Question

MariyaK1 Comment

Are you one of the many people that enjoy a crispy toast, some roasted potatoes,Screen Shot 2013-12-02 at 9.52.42 PM or really anything with that delicious crunch?  What’s not to love- such food has pleasant texture, is often tasty, carcinogenic… Wait, what?

Well-cooked foods indeed contain a compound that is known to cause cancer in animals and, likely, in humans. Before we all panic even more than we already do about healthy eating, let’s start from the beginning. What is this compound and why does it lurk in some of our most favorite dishes?

Some Background

Actually, I will start even further: Cooking itself is a crucial human skill. Not only has it allowed us to cooktransform our environment by making inedible and toxic wild foods edible and safe, but it might have made us uniquely human. One of the major theories of why we have such large sophisticated brains is actually based on diet- learning to tame fire provided a lot more calories for the expansion of the brain in our evolutionary past (check up “Catching Fire: How Cooking Made us Human” by anthropologist Dr. Wrangham for more). Dating back to 400,000 years ago at least (with some suggestive evidence dating to about 1.6 million years ago), cooking is an activity to which we seem to be well-adapted, as suggested by our shorter digestive system and smaller jaws. Yet, this important human innovation is not without issues.

 

Back to that potentially cancer-causing compound found in some cooked foods. The name is acrylamide and it is a product of an amino acid (found in many vegetables) that forms at high temperatures. Acrylamide would thus breadbe found in many starchy foods cooked via frying and baking (the magic number seems to be over 120 degrees C or 248 F). The process that creates acrylamides is called the “Maillard Reaction” and is a chemical reaction responsible for the browning of foods when cooked. So if you look on the sliced bread photo on the right, you might guess that the darkest charred piece is highest in this compound. And you would be right.

The health concern with acrylamides did not actually start with diet, as this chemical has been used in toastconstruction, cosmetics, and water treatment for the last 60 years. In 1994, it was classified as “probably carcinogenic” to humans based on animal studies (establishing safety guidelines for it in drinking water, food packaging, and occupational exposure). In 2002, however, the scientific community was alarmed to find out that high acrylamide levels can be found in common popular foods- coffee, fried potatoes, breakfast cereals, and baked products.

That’s troubling news is you are a graduate student relying on a constant supply of coffee and cereal, I must say. Or if you are just about anyone in this fast-paced world, really. 

Acrylamide (AA) does not form in dairy, meat or fish products.  Other than diet and occupational exposure, a huge source of acrylamides is tobacco. Smokers have 3-4 times more AA adducts (when they measure AA levels in blood) than those that don’t smoke. How does it cause cancer? AA is readily absorbed and metabolized in the body to glycidamine, a known animal carcinogen shown to have mutagenic effects and cause damage to chromosomes.

Should we worry & how much?

So how dangerous is this compound to our health anyway? Should we throw away our baking cookbooks? Avoid coffee shops like the plague?

I have picked three published studies on the topic: a large critical review of multiple studies on dietary acrylamide (AA) and various cancer risks (2011), a case-control study in Sweden (2011), and a cohort study in Europe (2013). While I provided a short summary of each at the end of this post, their results can be summarized in the following sentence: epidemiological studies consistently suggest a lack of increased risk of most types of cancer from dietary acrylamides. Sounds like good news. The Food & Drug administration, however, is still concerned and provides tips on reducing this “chemical contaminant” levels in one’s diet HERE. The major points are:

  • Fry less & avoid overcooking (burning, heavy crisping). Least acrylamide-forming cooking methods are boiling, steaming, and microwaving .
  • Eat a healthy balanced diet: one that contains a variety of fresh plant foods (fruits and vegetables).

Take a look at these tips again- these isn’t anything shocking or new here and you probably already know that these are great strategies to feel well and maintain a healthy weight. While using less AA-forming cooking methods allows you to have less acrylamides in your diet in the first place, eating a plant-rich diet might reduce the effect of these compounds already in your food. Surely you’ve heard of antioxidants in fruits and vegetables and that they are somehow good for you. Antioxidants can prevent or delay cell damage and may lower your risk of certain diseases- such as cancer (see this short MedLine Plus article). Also, there is research showing that they can significantly influence acrylamide formation (Xu et al, 2014).

Take-home message

The “common sense” healthy eating advice you probably already heard has a new exciting twist: not only is a diet rich in fresh fruits and vegetables and low in many fried convenience snacks or fast foods is good for a healthy weight and overall health, but it also decreases the amount of potentially cancer-causing compounds that can be found in so many modern foods!

Many of us have hectic lives, so quick and convenient foods will remain a part of them.. yet easy changes to your meal preparation can be still made for a healthier diet. And no need to stress over that morning coffee!

I want to learn more!
Additional Information

Summaries of studies examined

1. CRITICAL REVIEW & META ANALYSIS*

These folks looked at studies that measured dietary intake of AA, intake of AA-rich foods (french fries, fried potatoes), and measured actual biomarkers of AA in the body (took blood samples), which is nice since asking people about what they eat is a mess (people forget, people lie, etc.).

The researchers found a lack of increased risk of most types of cancer from dietary and occupational exposure to AA. One of the studies they looked at showed significant increase in risk of kidney and ovarian cancer from high AA in diet (59% increase and 78% increase), but others showed no increase in risk at all.

2. SWEDISH CASE-CONTROL**

This was a nationwide study that looked at >600 people with esophageal cancer vs. 800 healthy individuals. They assessed their diet with a food frequency quesionnaire (this long thing you fill out asking whether you eat different foods and how often… they asked you to estimate your food intake over the last 20 years!!).

These guys concluded that AA dietary intake in the Swedish population might result in increased risk of the cancer. There was a 23% increase among those consuming the highest amount of AA in diet, and this association was even stronger (88% increase!) in obese individuals.

3. EUROPEAN COHORT***

These guys followed > 470,000 people for about 11 years and had 865 folks with pancreatic cancer. They asked people about their diet (that long questionnaire again) + asked about details of cooking (temperature and methods of cooking) which is very important for AA estimation since it can vary with cooking methods. Researchers found NO ASSOCIATION between high AA intake and risk of pancreatic cancer.

(P.S. interesting fact- Denmark&Netherlands had the HIGHEST intake of AA from food (esp. among men) while Italy had the lowest. It’s all that coffee in the North, perhaps?)

Word of caution in interpreting epidemiological research

I want to raise a couple of warnings when looking at epidemiology work related to nutrition. Indeed, nutrition research seems to drive people crazy: one day coffee or eggs are bad for us, another- they provide positive health effects. How do you make sense of it all? It is important to understand the hardships that nutrition research must constantly deal with. Like with many specific nutrients and compounds, measuring acrylamides in foods is actually extremely hard. You first have to assess someone’s diet correctly (people don’t only forget what they eat, but they even lie in surveys to appear healthier), then estimate AA content through food questionnaires (because they are cheap and easy to collect, that’s what most large scale studies use) which can vary drastically between brands and cooking methods. Lastly, even the database for AA content of various foods are limited- if you can not physically measure AA levels in what people eat (which you wouldn’t-such research would be tremendously expensive!!), you can reference existing databases that have AA contents of various foods. Such databases, however, might not have the exact food items you’re looking for and you’re stuck with estimating again. Lots of opportunities for mistakes here- a database might be based on a European region and you are studying diets in the US.. Or the AA amounts they have are from foods measured in 2002 and you’re trying to calculate AA in diets from the last 20 years.

This is an enormous problem as you are simply measuring AA intake incorrectly (misclassifying AA intake) and the lack of association between dietary intake and cancer risk is really due to the measurement errors.  In plain terms- we don’t see association between cancer and AA levels in diet not because AA doesn’t increase cancer risk, but because the methodology issues of studies do not allow us to detect this true risk. You might have heard that randomized controlled trials, as the gold standard of epidemiology, give the highest level of scientific evidence, so why not just do a bunch of those on acrylamides? Well, it would be quite unethical to randomize people to the high-AA group and feed them la diet of french fries and burnt toast with the expectation that it will cause cancer.

*Pelucchi, C., La Vecchia, C., Bosetti, C., Boyle, P., & Boffetta, P. (2011). Exposure to acrylamide and human cancer—a review and meta-analysis of epidemiologic studies. Annals of oncology, 22(7), 1487-1499.

**Lin, Y., Lagergren, J., & Lu, Y. (2011). Dietary acrylamide intake and risk of esophageal cancer in a population-based case-control study in Sweden. International Journal of Cancer, 128(3), 676-681.

***Obón-Santacana, M., Slimani, N., Lujan-Barroso, L., Travier, N., Hallmans, G., Freisling, H., … & Duell, E. J. (2013). Dietary intake of acrylamide and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Annals of oncology, 24(10), 2645-2651.

Other citations: 

Xu, Y., Cui, B., Ran, R., Liu, Y., Chen, H., Kai, G., & Shi, J. (2014). Risk assessment, formation, and mitigation of dietary acrylamide: Current status and future prospects. Food and Chemical Toxicology, 69, 1-12.

Freshman “-5”

MariyaKLeave a comment

I never heard of “Freshman 15” until my first year in graduate school studying public health… since I never had been a freshman in the United States. It seemed like a rather obvious fact- I knew very well the food environment on campus and how one can gain weight quite easily in it. Yet when I told my friends and family back in Ukraine, they were quite amused and surprised- how can you gain weight in college!?

When I moved to Kiev, the capital of Ukraine, for my freshman year in 2003, I heard references to the “poor student” from all directions. Apparently, a new university student was poor, hungry, and rather slim. This idea is mostly based on the student image of the previous generation, however. The students in 2003 were not as pale and hungry as my parents remembered it- but they were definitely poor and slowly losing weight due to not having home-cooked meals made by moms as before. In 2003 students had more choices to eat out, but the prices prevented us from doing it often- you ended up cooking at home, snacking, or eating at the cafeteria. Indeed, many ended up losing weight, thus the freshman “-5” (about 2.5 kilograms; my term, arbitrarily chosen just like the “15”).

The following picture is of a cafeteria “full/wholesome lunch” at one of the biggest universities in Kiev taken several days ago. It costs $2.50 and includes: fresh broth-based warm soup, small cabbage salad, main course of a meat patty and mashed potatoes, piece of dark rye bread, and “kompot” (freshly boiled fruit drink) as well as a small pastry (dessert, I suppose). Approximately, a meal like this is roughly 700 calories. It would probably be the main meal for a student, who grabbed a quick breakfast and will attempt to make some food at home at the end of the day.

Image

The main feature of this wholesome/full lunch is- while one might not necessarily consider the addition of pastry, potatoes and a piece of fried meat healthy- the portions are very conservative. The opportunities to overeat are indeed limited.

It would be unfair to compare this to an “American” lunch since a standard American lunch does not exist- the dining halls are using the buffet style so a student is free to choose as healthy or unhealthy as they want. Of course, based on the numerous freshmen focus groups last semester, the common sentiment is that choosing “healthy” is quite hard and annoying: the salads are tasteless, the fried and burgers are omnipresent and a dessert lurks around each food station corner. Plus there’s constant social snacking and eating out- taco bell at 2am, burger king for a cheap dinner… Gaining a freshmen 15 is no problem at all.

On the other side, a Ukrainian student increases his/her physical activity by simply going to and from the university (often a trip of about an hour each way), lack of pocket money for fast food, and rather appropriate (and I would argue “healthy”) home meals at the cafeteria.

It is simply the difference in environments– Ukrainian students do not possess a superior understanding of healthy eating necessarily or boast superhuman will-power capabilities.. they are constrained by resources and are exposed to the environment where overindulging opportunities are lower than, for example, at an American university.

P.S. I also believe more eating norms exist in Ukrainian culture that might prevent overeating and junk food consumption in general..but that’s hard to argue at this point.

Why Nutrition Science Doesn’t Suck.

MariyaK1 Comment

Last semester I couldn’t help but complain to friends that nutrition science simply “sucks”: never-ending conflicting information, inability to prove even “common sense” knowledge (e.g. refined sugar is bad!- nutrition science can not definitely prove that it is…is it because people overeat sugar? is it because they overeat in general? is it because they lack key other nutrients?]. Uh, I have read scientific papers showing that adding refined sugar to diet does NOT lead to weight gain, others that showed it definitely does, etc etc etc.

Now that I sit in my nutritional epidemiology class… i finally “feel” for nutrition and understand why it tends to be so messy. Continue reading →

A bit more on Obesity

MariyaKLeave a comment

Since i pondered on the varying rates of overweight and obesity in my previous post, I thought it’d be good to share some epidemiology [social statistics of obesity] on the subject!

So while in the US 1/3 of Americans have obesity (BMI of 30 or higher), it is definitely not an American problem. All over the world there are 1.5 billion people that are obese. In the US particularly , the societal factors most linked to obesity are: education years, socio-economic status, food habits, socio-cultural environment, and poverty.

Some folks argue that the most important factor in causing obesity is the change in culture- global modernization, urbanization, computer lifestyle, access to fast food, driving a car vs. walking. In China and India, for example, modernization goes along with the development of obesity (obesity rates accelerate there way faster than ever seen in the US!).

These cultural changes are not really “changes” to us any more- they are pretty much natural. For example: eating at a fast food place on the run once every other day or your job consisting of sitting on the chair 90% of the time.

The concept being talked about is the “toxic environment”– having increased access to unhealthy food choices that are convenient and inexpensive, sedentary-promoting environment.

This of course is a nice potential explanation. Even as I think of Ukraine and a lower rate of extra body weight: for the most part people cook meals at home vs. eat out. Why? It is simply cheaper. As a bonus- it is also seen as much healthier (depends if you want it to be). But would people spend time on making a healthy dinner at home if McDonald’s became 5 times cheaper? No, I think we would have the same situation in the US where 44% of people eat fast food once a week at least.

That is the official information shared by Dr. Levine from Mayo (who also works at my university with the Obesity Solutions initiative). I have heard many other explanations for why the world’s population is getting heavier. The ones related to food range from  toxic food (GMOs, high fructose corn syrup), artificial sweeteners and other ingredients, MSG, gluten, pasteurized foods (e.g. dairy) and so on.

My thought is… Living your life in this new world is definitely a struggle if you want to have a normal weight and feel your best- it is almost a fight against nature (nature now being replaced by the iron jungle of the city).  Suddenly you have to pay attention to every ingredient, find the time to sign up for a gym and squeeze in some physical activity in your schedule, spend energy on finding not-so-toxic products that probably cost more, etc. But of course it is all about trade-offs… people all over the world are looking for convenience, for a break from hard work. They seek ways to improve their live by modernizing, having transportation, not needing to spend half a day cooking meals and then cleaning after. Yet this comes at a price of poor health eventually. :/

 

 

 

Ukraine and US- Food&Health

MariyaKLeave a comment
Image
Tea time at home 🙂

As my yearly trip to Ukraine came to an end, I sit on the porch drinking my green tea with saponins at 6am (still jet-lagged) and reflect. Something happened during this particular trip- probably due to the fact that I traveled with an “anthropologist” mindset this time around as I had an assignment.

What happened is that I lost my idealistic view of the Ukrainian diet- some morally superior way to eat and take care of one’s health. I realized this as I read yet another “alternative health” article on how Bolivians kicked out McDonald’s out of their country supposedly due to their preference for Real foods. That is very untrue- they simply could not afford to go to the place enough. They didn’t despise fast food in their fantastic and intuitive understanding of nutrition- they just didn’t have enough money to eat it frequently.

Image
Sugary water machine

The same fact struck me in Ukraine. But first- our obesity rates are much lower than in the United States [2010: 48.5% females & 41.2% males- overweight or obese. For US: 76.7% females & 80.5% males*]; slimness is valued higher (especially among young girls) as being overweight is almost unacceptable and publicly so. And yet, you see plenty of people with excess weight- only they tend to be on the older side. As in the United States, being healthy, fit, and in charge of your health is also a fashionable thing, so folks try to read up on nutrition and go to the gym, etc…

In terms of lower obesity rates- I also suspect the USSR legacy is at work here, where overindulgence of any kind was not OK. In USSR era variety was low, portions were small, and getting much than someone else was quire unpopular. This is just a tiny theory though. My other theory is that eating norms are different than those in the US- smaller portions and less snacking is more the norm (can not prove this yet), a normal lunch/dinner is thought to include a warm soup, combining heavy foods (e.g. meat, potatoes, bread) is seen as less ideal, eating out is much less normal than cooking at home..

Is our overall lower weight due to the fact that we choose to eat healthier than Americans?

Well, let me tell you- Ukraine has plenty of “fast food” spots around the cities. Most often they’re some deep fried combinations of bread and either sausages or cabbage.

Image
Street fast food

Of course we also have McDonald’s and you will never see it without a huge line. It is necessary to admit that vegetables are a much more natural addition to our diet in comparison to North Americans- many dishes feature vegetables (they are also the cheapest thing you can buy in a store) and many people know how to cook them in a tasty way. I believe there is less skill among US folks and that’s partially the reason they can’t get enough plants in their diet. Also, my observation has been that, even though Americans call really bad foods “junk food” they still eat plenty of it. The idea of snacking on junk in Ukraine seems to be less popular and a bit more unacceptable (not like I didn’t see folks on the streets with Coke or people buying chips at the store though..).

To summarize my thoughts in 1 sentence: I think Ukrainians are less heavy not because they eat healthier, but simply because they eat less for a number of reasons.

So.. what makes US obesity rates so much higher? Are people there simply more weak and ignorant about what and how much to eat!?  I don’t think so. I think the human animal is born with strong survival instincts- i think we are programmed to consume food, even in excess, since throughout the majority of our time on earth tomorrow was unpredictable in terms of nourishment. I believe it is natural to eat more than we need for this reason. United States simply created an environment that becomes unhealthy- opportunities to eat strong-tasting calorie-rich foods are too abundant, too varied, and too affordable.

Image
Slimness&fashion-  crucial tool for social mobility in Ukr.

Lastly, my thoughts and theories do not even begin to cover the potential reasons Ukrainians are not as heavy as Americans. Moreover, they could be simply wrong.  But no despair! My trip home was also a research trip- I collected 42 surveys on food and health.

Once I collect enough responses from Americans, I hope the analysis will give me a glimpse at the differences in the two cultures. Hopefully it will add to my understanding of our lower obesity rates. Would be good to make my opinions slightly more scientific 😉

* http://www.guardian.co.uk/news/datablog/interactive/2013/feb/19/obesity-map-of-world-weight

MORE PICTURES:

Buckwheat- a staple. Considered a superfood in US
Buckwheat- a staple. Considered a superfood in US
Sushi is a terribly popular lunch item
Sushi & Japanese food is a terribly popular lunch item. (this lunch is $3)
Weight loss teas, coffees, and so on 🙂
Lots of pastry items… Considered very fattening yet sell well.

PROTEIN

Link MariyaKLeave a comment

Finally I get to post about something not too many people are questioning..Protein overconsumption! 😀

Whether I talk to a body-builder or a dietician, health effects of eating too much protein do not seem to be on anyone’s radar (unless a kidney disease is suspected).

Beef it up!
In developed countries people are eating approximately 30% more protein than the RDA recommended intake (1.2g of protein/kg of body weight/day vs. 0.83g RDA). Yet this is considered harmless or even beneficial (for satiety, obesity prevention). In general, we can think of all kinds of anti-fat or anti-sugar arguments, yet protein seems to be the nutrient we don’t need to worry about. There are many protein-enriched snacks and drinks that seem to have a health halo effect. I think people are not even sure why the label claim “x grams of protein!” seems exciting or promising some sort of a benefit (unless one is a gym enthusiast). Perhaps it is the fact that we don’t know any “bad” health effects of this nutrient.

Longevity & health studies
In terms of living longer, calorie restriction(CR) is the only non-genetic intervention that can lead to life extension in different organisms (from yeast to rodents to monkeys and supposedly humans). Calorie restriction means reduced energy intake (moderate CR is about 30% less calories than recommended) without malnutrition. Studies on the famous Okinawa centenarians suggest it is their moderate eating that contributes to health and longevity.
So CR should not be confused with starving or extreme undereating- many people and cultures might do so without much thought- eating about 1700 calories/day for a person with 2000 being a goal is already calorie restriction.

In mice CR studies, general CR increases longevity and induces a reduction in the level of IGF-1 (insulin-like growth factor 1). IGF-1 is an important growth factor that mediates the growth of cells and inhibits apoptosis (cell death); it is IMPORTANT because there is considerable evidence that a reduction in IGF-1 signaling plays a key role in modulating cancer and aging in humans and rodents. HOWEVER, for us humans CR does not reduce IGF-1 concentration unless protein intake is also reduced. This suggests that protein intake is more important than calorie intake in terms of IGF-1 levels in humans.

Median protein requirement for a healthy adult, by the way, is 0.65 g/kg/day. Decreased protein intake discussed with CR does not go below this number.

image

mTOR
I first came across the idea of not going crazy on the protein while reading about mTOR. The mammalian target of rapamycin (mTOR) signaling system seems  to be connected with aging and cancer
development (also cardiovascular and neurodegenerative diseases). The insulin/IGF-1/mTOR pathway is downregulated by calorie restriction, and in turn activates other anti-aging pathways in mammalian cells.

Conclusion
It is necessary to see more human studies with caloric and protein restriction and the effect on health and longevity. We all know overeating is not great- it does lead to weight gain and associated health issues. But it also might be speeding up our aging, wear&tear, and increasing chances of various chronic diseases. This could be crucial for a culture that believes protein to be a healthy macronutrient which needs no limitation 😉

Some LINKS:

Why Protein is the new “It” Ingredient

http://online.wsj.com/article/SB10001424127887324789504578384351639102798.html

Macronutrient Balance and Lifespan

http://www.impactaging.com/papers/v1/n10/full/100098.html

Shall we Snack?

MariyaKLeave a comment

How we think about the food we eat matters. Really matters. The way you categorize your food- whether it qualifies as a meal or a snack- can influence whether & how much you will eat later that day.

Today we talked about snacks in the psychology of eating class. My personal cross-cultural observation of snacking between Ukraine and US is that Americans tend to snack more often.. they snack in various situations (at work, in class, on the run) and some believe snacking throughout the day is beneficial for weight maintenance. This perception comes from the idea that eating more small meals throughout the day (snacking) will keep your metabolism up or keep your hunger down. While it does elevate your metabolism somewhat, the problem is that most people can’t seem to eat “small” meals throughout the day… instead they end up simply eating all day long. In terms of hunger management.. it is quite individualistic- perhaps having a snack truly makes you less hungry throughout the day…or it makes you even hungrier (now, that depends on the snack too; carb-rich snacks tend to make us hungrier after consumption…and we can argue that processed foods have an addictive quality where you just have to finish the whole bag).

SNACK vs. MEAL

What’s a snack? Usually something small or in pieces.. it is eaten between meals. If you’re surprised by how someone might confuse a meal with a snack- people do think differently about which is which…some foods can be seen as both by different people- e.g. pizza or bagels (hey, some eat cereal for dinner!). Generally, though, “snack food” is perceived as food  not consumed to satiation (versus a meal); it also involves eating alone and for a short period of time.

A study by the ASU provost/my psychology professor Capaldi* showed that the cognitive feature of food (whether you perceive it as being part of a meal or a snack) moderates food intake regardless of hunger and satiety following a load. In simpler terms- if people ate the same amount of calories, but perceived the food as a SNACK, they ate more afterwards (even though their satiety level was the same as for those consuming the same food only seen as a MEAL). It has to do with norms- we feel it is much more appropriate to eat a full meal after some snacking then after a meal.

PROBLEMATIC DEFINITION
So your categorization of food might be important for how much you eat…This might be a problem with the way eating has evolved lately. Meals are generally seen as a sit-down occasion with utensil use…but in the hectic modern life your lunches and dinners might not involve a plate, fork, or even sitting down to eat. As a result, you might not register your lunch as a satiating meal and feel the need to eat later. Indeed, taking the time to eat in a calm atmosphere might make you feel more satisfied with your meal (has anyone else ever felt like they didn’t really eat if they grabbed something on the fly? I definitely do).

Shall we snack!? Currently,  evidence does not support many theories that encourage increasing frequency of eating for weight management**. Some suggest that snacking is one of the main causes of overconsumption and obesity***. In the end, you can’t recommend the whole population to either snack frequently or avoid it altogether. Some might find snacking to keep their appetite down.. while for others it may be difficult to control food quantities once they commence eating.  I suppose you should go with your gut and be mindful of whatever you are eating 😉

* Capaldi, E. D., Owens, J. Q., & Privitera, G. J. (2006). Isocaloric meal and snack foods differentially affect eating behavior. Appetite, 46(2), 117-123.

**Palmer, M. A., Capra, S., & Baines, S. K. (2011). To Snack or Not to Snack: What should we advise for weight management?. Nutrition & Dietetics, 68(1), 60-64.

***Buchholz, T. G. (2003). Burger, fries and lawyers: the beef behind obesity lawsuits. US Chamber of Commerce, US Chamber Institute for Legal Reform.

Monotony makes you..slimmer?

MariyaKLeave a comment

This week we were discussing SENSORY SPECIFIC SATIETY in our psychology class and.. I find it fascinating!

Why do we stop eating? Because we got enough calories/feel full/got the right nutrients? Looks like we stop food intake cognitively– by knowing that we ate enough and knowing when it is appropriate to stop [studies on folks with short-term memory loss, it was found that they would eat the meal several times despite having a large meal already, when most of us would report being full at that point]

SSS within a meal

Sensory specific satiety (SSS) basically means you get tired of the taste&texture of food (studies show it happens even if you don’t swallow the food; thus it is not about getting full on calories). To be a bit more scientific in my definition: “as food is consumed, its pleasantness declines while that of other foods remains relatively unchanged”; this phenomenon of SSS leads to the termination of eating a particular food, while promoting the selection of other foods. So after being destructively full after a large meal..many would suddenly find “space” for a dessert.Image

The studies done with SSS show that if you sit down people for lunch and give them several small sandwiches with different flavors of cream cheeses, people will eat considerably more than if all those sandwiches had only one flavor (even if that flavor is a favorite of the individual). Other example is that people eat more of pasta if their bowl had more types/shapes of it. SSS does not mean that you stop wanting food- it means you don’t want more of the same food. For example, after a meal of x, y, z you are given more y… the person would say “thank you I am full”… vs. being given h– something you have not developed sensory satiety for and will still eat (therefore, all you can eat buffets are not such a wonderful idea;)

So truly, this is a great adaptation, because it motivates us to eat a variety of things. It also means that, if our meals has a large variety (in its texture & flavor) we tend to eat more. This is not particularly useful, though, in an environment where delicious food is available 24/7 and one looks to maintain a healthy weight. Think about many sauces or salad dressings that combine both strong sweet and salty tastes (thus, making sure we don’t get satiated as soon..and probably eat more).

SSS seems to work well with fats and proteins, but not so much with basic starches. What this means is that people don’t get sick of eating bread, pasta, and other starchy carbs over time. 

SSS over time…

So far I talked about short-term SSS, or satiety with one meal; however the same is true when the same food is eaten over time (i’m sure you’ve experienced this- if you keep eating the same thing daily you might get tired of it), even though long-term SSS is more complicated. The study I read*, for example, looked at eating high energy-dense snack foods for 12 weeks (hazelnuts, chocolate, potato chips). While people’s sensory-specific satiety decreased (they liked them less) over time, the desire to eat these foods didn’t…and intake increased. So habitually eating high calorie snacks could lead to higher energy intake of the snack and weight gain. You don’t really want to have a low threshold for SSS- that means you don’t get sick of foods and may overeat them more.

Image

Why I find this interesting? It makes me think of dieting…most dieting restricts something– carbs, fats, certain ingredients (gluten; dairy). When people see weight loss, perhaps it is because the more narrow range of foods leads them to quicker sensory satiety and then overall they just eat less? Many diet plans emphasize calculating calories is not important, as if you can eat way over your limit and not gain weight..but perhaps you naturally are lead to consume less because of the monotony of the diet? 

Another thought I had- mono-eating= eating one food at a time until you are food. The idea is- it is better for digestion, but also- looks like you would limit your food intake much more naturally (with less effort) when not having a variety in one meal. 

Overall, I think this is quite interesting. While we want a healthy variety in our diet, we probably want to concentrate it on the vegetables and other healthy foods we don’t get enough of. Variety in ice-cream and chip flavors is probably not essential at this time and age.

*Tey, S. L., Brown, R. C., Gray, A. R., Chisholm, A. W., & Delahunty, C. M. (2012). Long-term consumption of high energy-dense snack foods on sensory-specific satiety and intake. The American journal of clinical nutrition, 95(5), 1038-1047.

*** for more info on SSS, search for papers by Barbara Rolls.

U[mmm]ami.

MariyaKLeave a comment

Some people claim they “crave” protein in their food to feel satisfied… others say it is really the fat that they are after. Do we really crave protein? Can we even “taste” protein in itself?

I used to think that we do not.. until we got on the topic of UMAMI in class. In 1908 Kikunae Ikeda identified the unique taste component of kelp (seaweed) as the salt of glutamic acid (most abundant amino acid in the diet). He used umami(=”savoury deliciousness”)  to describe it, which to a Westerner translates to meaty, broth-like, savoury. Other umami substances are0 inosinate and guanylate

pic_umami_01Umami- the 5th Taste

Glutamate is found in both animal and plant foods; in almost all protein-containing foods (fish, meat, poultry, eggs, cheese), many vegetables (ripe tomatoes, cabbage, maize, green asparagus) and for humans & chimps, in mother’s milk. In addition, glutamate is produced by our bodies and binds with other amino acids to form structural proteins.

The taste of glutamate (on its own + in combination with IMP5 ribonucleotide) is thought to represent the taste of protein (evidence is still scarce). Glutamate has a special quality of enhancing certain flavor characteristics of food (sugar, salt, fat). * Umami, by the way, is tasted by humans and dogs (rats can’t seem to taste it as much). Currently, umami is recognized as the 5th basic taste (others: salt, sour, bitter, sweet)

Wait a second…Glutamate!?

If you’re at all into health, the word “glutamate” has probably evoked some negative connotations. Or- monosodium glutamate- the evil MSG. While umami exists naturally, MSG is a additive (extracted glutamate mixed with salt) which has become quite unpopular in the 90s due to health concerns (for health issues, please google MSG; that’s a whole other topic). If you use MSG, you taste umami, but umami does not contain MSG (MSG on its own does not taste good but enhances flavor of other foods). I suppose the original idea was to add umami-tasting MSG to healthy but often disliked foods such as bitter vegetables to increase their intake…of course  now you find MSG in many processed nutritionally poor products (it’s probably not too great to increase our liking of those foods).

UnknownIn conclusion….can we crave protein specifically? Indeed it seems so. The study I reference at the bottom argues that the taste of MSG maybe one of the compounds that represents the taste of dietary protein…this “meaty” umami taste appears to predict the liking and preference for high protein foods.

In fact, I now realize why seaweed, especially dulce flakes were quite popular with my raw vegan friends. We just loved seaweed– it seemed to fill us up when added to raw vegetable dishes. I suppose the umami taste, which is associated with meatiness and richness, might impose the feeling of satisfaction with one’s meal. Note: This website has a fantastic post about umami & being vegan!: http://www.theveganrd.com/2012/04/is-umami-a-secret-ingredient-of-vegan-activism.html

Opinion: While clinical studies do not support the negative health claims of MSG, we could always be weary of natural compounds being extracted and concentrated in unnatural amounts.  So far, it seems that any time a human tries to improve on nature in a lab, the results tend to be disappointing. Want to experience more umami- add sun-dried tomatoes/miso/organic soy sauce to your dish instead (mmm) ;D

*Luscombe-Marsh, N. D., Smeets, A. J. P. G., & Westerterp-Plantenga, M. S. (2008). Taste sensitivity for monosodium glutamate and an increased liking of dietary protein. The British journal of nutrition, 99(4), 904–8. doi:10.1017/S000711450788295X

“New Perspectives on Vegetarian Diets” (Health Conference)

MariyaKLeave a comment

Today was the second day of the healthy lifestyles conference organized by Arizona State University and I was very much impressed by the vegetarian speaker! Actually, I know the professor, Carol Johnston, since I am involved with her vegetarian study..but this is the first time I heard her talk on the subject.Image

I was particularly impressed with the way she discussed limitations of vegetarian studies that many people do not consider (and many vegetarian researchers do not necessarily point out)-

  • The studies usually have many confounders (generally vegetarians studied tend to be more lean, educated, physically active, supplementation, no smoking/drinking, etc).. So a lot of their characteristics have nothing to do with meat avoidance but an overall healthy lifestyle
  • Studies showing fantastically superior health of vegetarians do so due to comparing vegetarians to national averages (which are not so great).  When vegetarians are compared to meat-eating groups who also follow healthy lifestyles, the difference in health is not as prominent.

Some important things to consider with vegetarian and vegan diets is B12 and Vitamin D (also zinc, calcium), since these populations do tend to be low in these vitamins. Dr. Johnston herself raised her two kids omnivorous, since she has concerned with a number of studies showing dangers of low B12 in small children. Indeed, during pregnancy one’s B12 decreases as well.

Some of the well-accepted benefits of vegetarian lifestyle are lower risk for colon and breast cancer.

Of course, Dr. J discussed the ecological piece and the importance of diminishing one’s intake of animal calories for those reasons.Image

Vegetarian for all??

I found it fascinating that once an audience member asked a question about recommending vegetarian diets to lower SES communities, Dr. J answered that she understands we have evolved on meat and we were meant to eat it, but in this day and age with disease, environmental issues, and low animal product quality (+ horrible animal treatment) vegetarian diets in her view are a better solution (but one might need to be a grown person to adopt it). She would not recommend going vegetarian in the 3rd world countries.

I loved the last comment, because my observation has been that people try very hard to prove our ancestral diet was vegan. It seems to be not so, but I don’t believe this fact is a reason against vegetarianism. I think Dr. Johnston’s view is very rational- you do not have to sell the vegetarian diet as the most original and natural for our species (it is not as evidenced by deficiencies due to animal product avoidance), you simply need to concentrate on the fact that this diet might be much better for you personal health, for the environment, and the animals.

P.S. Dr. Johnston also has fascinating research on vinegar and it’s beneficial effect on type 2 diabetes management and weight loss (just google Carol Johnston vinegar diabetes)