How our senses help us decide what we eat

Senses help us select our food.

So, this is a blog post about the importance of sensory criteria for selecting food, which was inspired by a day of cooking up goods for the holidays.

What makes people choose the foods that they do? This question may seem obvious to yourself--after all, you know what you like--but this is a question posed by food industry scientists ask themselves day in and day out.

The science of food selection can get crazy complex when you think of the huge variety of foods that you find at your corner grocery store. Food scientists must continually find new "niches" for products to be placed in the marketplace.

How do they do it? The same question can be asked of musicians who endlessly produce new songs that the radio blares as latest hits, but using the same 12 musical notes. Only, in the case of food, scientists only have five notes, or tastes, the "Five-Taste Stimuli":

-sweet
-sour
-bitter
-salty
-savory (umami - think MSG, mushrooms, tomatoes, broth)

Taste rates high in the evaluation for selection from consumers. As it happens, the sensation is produced when the food comes into contact with cilia (tiny hairs) on gustatory cells, which make up around 10,000 taste buds (depending on age; people lose them as they age).

By itself, taste isn't all that complex, but then food is mixed with other sensory criteria:

-sight
-smell
-touch (texture, mouthfeel)
-hearing (yes, the sound of food)

Sight has to do with the presentation or appearance of the food. When we first look at food, we are in a sense already "eating it" with our eyes: judging for shape and color, ripeness or rottenness, smoothness or crunchiness, well-cooked or burnt.

Visual signals, mixed up with several other stimuli, instantly tell your brain whether or not you're ready to eat that grilled chicken breast or let it brown a little longer, or whether to eat that banana or wait until it turns from green to yellow (but not to black).

Smell is a wholly vital part of what it is to create food -- and I would argue that any good food scientist is also an expert at using volatile molecules from food to reach our olfactory epithelium. Flavor, in fact, is around 75 percent smell.

In the olfactory epithelium, which is inside the nasal cavity, is where volatile molecules will act on between 10 to 20 million olfactory cells. These cells can pick up between 2,000 to 4,000 different odors. A few experts are so well trained, they can distinguish closer to 10,000 -- an extremely keen sense of smell.

Touch is a sense that we use for picking our foods because it allows us to pick up on texture, astringency, consistency and temperature. Generally, with food, we start our touch evaluations with our fingers and then as the food moves toward our lips, next is the mouthfeel.

Mouthfeel of a food can tell us a lot more: a smooth texture may mean more fat content, which is more desirable to our energy-seeking brains. It also tells us whether that steak is tender or chewy, dry or moist, if the soda pop is bubbly or flat, if the vegetables are crispy or rubbery, if citrus fruits or vinegar is astringent.

Of course, touch inside the mouth also determines a food's temperature and spiciness. Heat and cold are picked up by the taste buds. The sensation of spiciness, like the one caused by capsaicin in hot peppers, is caused by irritating nerves.

A sense of hearing might not seem as important in food selection, but most of us evaluate food all the time with sound without even realizing it. We like to hear the snap of a celery stick, the crackle of potato chips, the pop of popcorn.

The sounds give clues about whether a food is fresh or sufficiently cooked. Think also of the sound a watermelon makes when you tap it to make sure it's fresh, or the sound stir-fry makes when it's sizzling.

So, back to how food scientists use all these sensory criteria: With the five-taste stimuli and other sensory signals (as in music with 12 notes, beats and rhythms), food scientists can continue creating thousands of foods that flood our grocery stores annually.

Each and every satisfying food can be appreciated for its particular complexity of visual presentation, flavor aroma, texture and sound -- they are what makes us love to eat.

Source:

Brown, A. 2000. Understanding Food: Principles and Preparation. Wadsworth: Belmont, CA.

What happens on a high omega-6 diet

A while back I wrote a review of Queen of Fats: Why Omega-3s Were Removed from the Western Diet and What We Can Do about Them. Susan Allport's book goes into the history of how omega-3s were discovered and what they'll mean for us in the future.

A controversial topic of the book is how omega-6 (king) and omega-3 (queen) compete for space in eicosanoid pathways. The omega-6s, the king, are the greater competitor and more inflammatory, while the omega-3, the queen, are a lesser competitor and less inflammatory.

She goes on about this relationship between omega-6 and omega-3 and gives examples from nature of how both the oils are found and used -- omega-3s in leaves (leaf fats), omega-6s in seeds (seed fats); omega-3s eaten more often in summer months, omega-6s in winter months by animals. The omega-6s are thought to bring on extra fat for warmth, for storage, for hibernation.

It's all pretty interesting stuff. And again, as I said, a bit controversial.

Now, in a new article, Susan gives a single-person account -- herself -- of results one gets from eating a high omega-6 diet for one month. I mean, we're not talking about a randomized, clinical trial. But nevertheless, her results are particularly interesting:

- reduced RMR
- omega-3 drop in blood (10% to 6%)
- omega-6 rise from 21% to 29%

- brachial artery dilation drop by 22%
- gain of 5 pounds

You can read more about her small experiment here. In the meantime, I'm popping my fish oil pills.

Your mind as an anabolic steroid

The figure below, taken from Wilmore et al. (2007), is based on a classic 1972 study conducted by Ariel and Saville. The study demonstrated the existence of what is referred to in exercise physiology as the “placebo effect on muscular strength gains”. The study had two stages. In the first stage, fifteen male university athletes completed a 7-week strength training program. Gains in strength occurred during this period, but were generally small as these were trained athletes.

In the second stage the same participants completed a 4-week strength training program, very much like the previous one (in the first stage). The difference was that some of them took placebos they believed to be anabolic steroids. Significantly greater gains in strength occurred during this second stage for those individuals, even though this stage was shorter in duration (4 weeks). The participants in this classic study increased their strength gains due to one main reason. They strongly believed it would happen.

Again, these were trained athletes; see the maximum weights lifted on the left, which are not in pounds but kilograms. For trained athletes, gains in strength are usually associated with gains in muscle mass. The gains may not look like much, and seem to be mostly in movements involving big muscle groups. Still, if you look carefully, you will notice that the bench press gain is of around 10-15 kg. This is a gain of 22-33 lbs, in a little less than one month!

This classic study has several implications. One is that if someone tells you that a useless supplement will lead to gains from strength training, and you believe that, maybe the gains will indeed happen. This study also provides indirect evidence that “psyching yourself up” for each strength training session may indeed be very useful, as many serious bodybuilders do. It is also reasonable to infer from this study that if you believe that you will not achieve gains from strength training, that belief may become reality.

As a side note, androgenic-anabolic steroids, better known as “anabolic steroids” or simply “steroids”, are synthetic derivatives of the hormone testosterone. Testosterone is present in males and females, but it is usually referred to as a male hormone because it is found in much higher concentrations in males than females.

Steroids have many negative side effects, particularly when taken in large quantities and for long periods of time. They tend to work only when taken in doses above a certain threshold (Wilmore et al., 2007); results below that threshold may actually be placebo effects. The effective thresholds for steroids tend to be high enough to lead to negative health side effects for most people. Still, they are used by bodybuilders as an effective aid to muscle gain, because they do lead to significant muscle gain in high doses. Adding to the negative side effects, steroids do not usually prevent fat gain.

References

Ariel, G., & Saville, W. (1972). Anabolic steroids: The physiological effects of placebos. Medicine and Science in Sports and Exercise, 4(2), 124-126.

Wilmore, J.H., Costill, D.L., & Kenney, W.L. (2007). Physiology of sport and exercise. Champaign, IL: Human Kinetics.

Resveratrol influences belly fat behavior

Fat can not only be unsightly, but if it’s sitting on your belly, may also contribute to overproduction of signaling hormones called adipokines, which are linked to metabolic changes that can worsen health.

New research from Aarhus University has found that abdominal adipose tissue extracted from overweight adults, and then exposed to resveratrol, exhibited reduced adipokine production. According to these authors, "small interfering molecules such as resveratrol are, in this matter, hypothesized to possess beneficial effects and might improve the metabolic profile in human obesity."

The scientists obtained the abdominal adipose tissue via liposuction from seven women and one man, ages 43-55, who had body mass indexes categorized as overweight. All subjects were Caucasian, healthy and not on any medication that could confound the results.

Because previous studies in rodents have shown that calorie restriction reduces production of adipokines by activating an enzyme called Sirtuin 1, the scientists had hypothesized that resveratrol may act similarly. Resveratrol is well-known as a potent Sirtuin 1 activator.

This most recent in vitro study, published in International Journal of Obesity, suggests that regular dietary intake of resveratrol may guard against the metabolic changes that occur when there is excess fat on the body – as it has with rodents and monkeys.

Resveratrol is a phytoalexin (a plant-produced antimicrobial substance) found in small amounts, most notably, in red wine, as well as in other common foods such as grapes, peanuts, and chocolate. The most concentrated natural source is the Japanese Knotweed (Polyganum cuspidatum).

Resveratrol gained scientific interest after it demonstrated effects similar to calorie restriction in slowing the rate of aging and increasing the lifespan in a number of species including nematode worms, mice, and rhesus monkeys. In addition, resveratrol protects overfed mice from weight gain and lemurs from seasonal weight gain.

Source: Olholm J, Paulsen SK, Cullberg KB, Richelsen B, Pedersen SB. Int J Obes (Lond) 2010;34:1546-53.

Middle-aged Mice fed BCAAs live longer

Scientists are actively seeking aging-intervention strategies to help people maintain their youth in anticipation of a sharp rise in the elderly population – due to the "baby boomer" generation – and an unprecedented number of elderly in North America and throughout the developed world.

Now, a new study in the October issue of Cell Metabolism reports that middle-aged, male mice given a cocktail of branched-chain amino acids (BCAAs) – leucine, isoleucine, valine – in their drinking water lived an average of 12 percent longer (869 days compared to 774 days) than middle-aged, male mice drinking regular water.

The scientists, from Milan University, found that the BCAA-fed mice exhibited similar changes as those seen with calorie restriction or resveratrol supplementation, showing an increase in longevity-gene SIRT1 activity and an increase in cardiac and skeletal muscle mitochondria levels.

The treated mice also showed improved exercise endurance and motor coordination, and had fewer signs of damage from oxidative stress.

In future studies, the researchers plan on performing similar experiments with female mice.

"This is the first demonstration that an amino acid mixture can increase survival in mice," said lead researcher Enzo Nisoli, referring to prior studies that showed that the cocktail of BCAAs extends lifespan in yeast.

Getting BCAAs in the Diet

Nisoli suggests that older people may find similar anti-aging benefits from including BCAAs in their diets by eating protein or taking supplements high in BCAAs as part of a complete “nutritional approach” for aging gracefully.

Supplements of BCAAs are widely used by athletes, including bodybuilders, because they help to trigger protein synthesis and drive muscle growth, especially when taken within 20 minutes after workouts.

However, one of the most convenient ways to obtain greater amounts of BCAAs in the diet is by drinking one or more servings of a whey protein-based shake daily.

BCAA-rich whey protein has been shown consistently in several studies to aid in maintaining muscle as well as speeding up muscle recovery and growth after exercise. Preserving skeletal muscle and strength is a significant factor for maintaining long-term health.

Source: D’Antona G, Ragni M, Cardile A, Tedesco L, Dossena M, Bruttini F, Caliaro F, Corsetti G, Bottinelli R, Carruba MO, Valerio A, Nisoli E. Branched-Chain Amino Acid Supplementation Promotes Survival and Supports Cardiac and Skeletal Muscle Mitochondrial Biogenesis in Middle-Aged Mice. Cell Metabolism, 12(4):362-372, October 2010, doi:10.1016/j.cmet.2010.08.016.

My tour of Yale biotech facilities

I had the good fortune of touring Yale University's biotech facilities today, including the 2007-built Yale Stem Cell Center, with its director as our guide: cell biology professor Haifan Lin, PhD.

Walking through a high-tech stem cell facility with Lin was nothing like I expected. Lin was incredibly personable, and he and his staff took us through their labs and offices with a sense of enjoyment and courtesy if introducing us as friends to their home -- "come on into my lab, here's our million-dollar microscope, there's our genomic analyzer, would you like some tea?"

OK, so Lin didn't actually offer us tea, but he might as well have with his ultra-nice Chinese hospitality. On the tour, there were only three of us, all journalists, so it lended to opportunity of intimate discussion and questions.

Lin generously answered everything we wanted him to and with a genuine excitement about it. He shared that he had an appreciation for what we science writers do, saying, in fact, that he'd thought of joining the ranks so he could spread his own message -- that the science of stem cells is promising us a spectacular future free of certain diseases like neurological diseases and cancer.

The Yale Stem Cell Center is actually a conglomeration of several departments rich in expert faculty in areas of stem cell genetics, translational regulation, transcriptional regulation, stem cell assymetry, clinical transplantation, stem cell programming, cancer stem cells, and stem cell for tissue repair.

They all interact and the way the center is built -- with open labs and offices -- allows for plenty of collaboration. All their objectives are centered around a specific goal. "The key is personalized medicine through stem cells," Lin says.










For example, faculty member Dr. Eugene Redmond showed that Parkinson's Disease could be improved in mice and monkeys by injecting neural stem cells. With more trials underway, stem cell injections will likely become the future of treatment for humans.

Also, faculty members Drs. Christopher Breur and Toshihanau Shinoka have built blood vessels to treat congenital heart disease with stem cells. This is important to help the many "blue babies" born each year. In pigs, they had 100 percent success with treatment. The babies that have received the stem cells grow beautifully.

They actually "create living, growing blood vessels from scratch," which means we could eventually replace temporary treatments of today (that have autoimmune rejection problems) with tissue engineering treatments of tomorrow. In Breur and Shinoka's work, the vessels made were indistinguishable from any other vessels in the body.

Lin will soon be presenting a "big talk" at the next world stem cell meeting and he's hoping that the public will begin to become more thrilled about the possibilities that stem cells will bring to medicine.

Several other examples exist of how stem cells will help solve serious medical puzzles, but each all starts with basic research. This basic research is what Yale Stem Cell Center is all about.

Lin illustrates an example of basic research: he gave us a brief overview of DNA, mRNA, rRNA, and tRNA transcription of proteins, then reminded us that only 1 percent of DNA is involved in transcription. The rest, commonly called "junk DNA," is terra incognita. Lin's lab has been able to show that it's not junk, but produce piRNA, important in regulation of the other "big" genes. They sequenced 60,000 plus piRNA!

New technologies at Yale are allowing these developments to happen. "It is like discovering a new world of genes," Lin says, comparing the development in scope to Columbus discovering America. It will lead to new genetic mechanisms, drugs and therapies.

We toured core labs, Lin's own lab, saw high-powered microscopes, a genomic analyzer that could sequence an entire human genome in a week, and lots and lots of miscellaneous science stuff.

New Paradigms and the Future of Medicine

What is the future of medicine and how will we get there? On Monday morning, as part of New Horizons of Science at Yale, Director of Institutes of Systems Biology Lee Hood discussed the advent of 21st-century medicine: p4 medicine.

What are paradigm changes in biology leading to p4, or proactive medicine? There are several changes needed and all overlap and interconnect, but the main drivers in the process are:

- bringing engineering to biology through high throughput biology
- the human genome project
- cross-disciplinary biology
- systems biology

"What's fascinating is that these four paradigm changes are creating a new foundation in medicine," says Dr. Hood. "And they were each met with skepticism."

What does p4 medicine represent? predictive, preventive, personalized, participatory (p4). In other words, it's the taking of genomics and systems biology to finally unravel the complexity of pathology and seeking out preventive and personalized strategies of healthcare.

When Hood was at Caltech, he realized that he would be working on new bioinformatics technologies. At the time, they had known about DNA, RNA, proteins -- but with technology, he realized, they could transform how to understand biology.

His team created five instruments that changed biology. The instruments were automated (in collecting data), integrated information, and served to produce new ways of understanding biology.

The first instrument he produced was a protein sequencer, two hundred times more sensitive than other instruments. With it, they found the first "cancer gene," a platelet-derived growth factor. It sequenced prions related to Mad Cow Disease. It sequenced the first billion-dollar biotechnology product, epo. Also, it discovered the first blood development factor.

Why not commercialize the instruments? Hood pitched this to the University, but was told, "It's not the role of Academia". So, he went out to sell it himself. There have now been 14 companies founded by Hood Labs.

He discussed the human genome projecg and how, in Spring 1985, his bioinformatics technologies helped shape the feasibility of the challenge in the face of opponents who were "vehemently against" the project -- because it would take a way from "legitimate science" (including the National Institutes of Health).

Why has the genome project transformed biology? It provides complete parts of gene lists, transforms biology by providing access to genomics of species, and increases understanding of evolution, understanding of nutrition, and understanding of medicine.

Another instrument, the DNA sequencer, helped bring forth a cross-disciplinary approach of meeting current medical challenges -- merging chemistry, biology, mathematics, molecular biotechnology. The first cross-disciplinary department, at University of Washington, pioneered the new field of proteomics.

The problem with biology and systems biology is that it's "way too complex," but moving into the 21st century, scientists now have the computational and mathematical tools to turn biology into an informational science. Then, taking a systems approach, p4 medicine can attack vexing challenges of healthcare.

"If you think of yourself as a living creature, there are two types of information" that make you -- digital information about your genome, and environmental imprints -- the genotype and phenotype.

"It's a combination of these two types of information that leads to most diseases," Hood says. We need to think about the relationships between the two sets of information to effectively solve disease.

How you think about systems biology is critical: you need to be able to integrate data types, delineate biological networks, acquire global data, and formulate models for "discovery science."

The agenda: Use biology to drive technology and computation needed to create a cross-disciplinary approach to biology.

The Institutes for Systems Biology has just had its 10th anniversary. Back in 2000 when Hood first started the institute there was a lot of skepticism, but now there are 70 more institutes worldwide.

In short, the impact made by systems biology and a computational and systems approach to disease is grand -- it's the approach of seeing etiology of disease as altered biological networks.

He shows how his technologies compute the dynamics of a brain network in prion disease in mice. They found four networks involved in the disease. There about 300 genes in a mouse, two thirds mapped into the networks.

Going on, Hood explains that blood is a window into health and disease with systems diagnosis to identify key network nodal points for early detection, prevention, treatment. In the future, we should have complete genome sequencing of families, the human proteome project, the second human genome project.

Family genome sequencing has itself demonstrated that scientists can use principles of Mendellian genetics to identify 70 percent of sequencing errors, discover variants, and more rapidly find genetic encoding that leads to disease.

What about the future? "One of the most revolutionary biology fields is single-cell analysis," Hood says. This is along with stem cells and computational, systems, integrative biology.

Concluding, he says, there needs to be a transition in healthcare to p4 medicine, so ISB has set up partnerships for "inventing the future." They will be creating 21st century biomedicine involving systems analysis of biology and medicine, technology development, and preventive strategies.

"P4 medicine is about 1) wellness and 2) demystifying disease," Hood says, noting that the ultimate solution is prevention by using systems biology and bioinformatics technologies.

In the Q&A part after this talk, it was asked "when will we reach the p4 zone?" and Hood replied that there are several examples of companies that are reaching this point (and he names 23andme as a pioneer).

Some day, with Hood's leadership and technologies, our own complex biologies will be hacked, reduced to information, for the development of healthcare strategies built around personalized medicine.

If interested in following p4 medicine as it grows in acceptance, check out ISB's newsroom

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