JustTheScience

Originally synthesized from kelp by Japanese researchers in 1908, Monosodium Glutamate (MSG) is now a major component of the food industry with 2009 global production levels estimated at 2 million tons (Sano 2009). ¹  The glutamate class of acids including MSG activates taste sensors that are responsible for the savory flavor, also called “umami,” which is considered to be a basic taste along with sweet, sour, salty, and bitter (Rolls 2009) (Kurihara 2009). ^2 3  Americanized Chinese food is widely known for its MSG content, particularly due to the 1960′s MSG related phenomenon dubbed “Chinese Restaurant Syndrome (CRS).”  Afflicted individuals with CRS exhibited symptoms including burning sensations, and facial and chest pain, following eating at Chinese restaurants that used MSG as a food additive (Schaumburg et al 1969). ⁴  Media coverage caused hyper-awareness of the syndrome, as is evident by a 1979 survey by Kerr et al (1979), in which 43% of respondents stated that they had suffered from CRS, despite only 2% of respondents reporting ever having symptoms matching those widely attributed to CRS.⁵

Although public awareness of the symptoms of Chinese Restaurant Syndrome is high, the question remains whether or not there is legitimate scientific evidence for this condition.  A large double blind study by Geha et al (2000) of people who self reported a sensitivity to MSG found that some individuals exhibited reactions to direct ingestion of MSG.  Results were neither consistent upon retesting nor were any of the effects persistent or serious.⁶  Rosenblum et al (1971) found no difference in symptoms between individuals ingesting MSG and a placebo (Sodium Chloride (table salt)) and no symptoms resulting from this study matched those of CRS.⁷  Tarasoff and Kelly (1993) found no difference between a placebo and MSG when the MSG was ingested with food, even at high concentrations. ⁸  Woods et al (1998) and Woessner et al (1999)  found no link between MSG intake and asthma exasperation in asthmatics who self reported a sensitivity to MSG,⁹¹⁰  and Hawkins (2009) found that the blood/brain barrier is impermeable to glutamates.¹¹ Finally, Burrin and Stoll (2009) found that natural and artificial dietary glutamates are metabolized in the same manner and are both a major oxidative fuel for the gut, an important precursor for a key neurotransmitter (glutathione).  ¹²

Key Points

• MSG is a major component of the food industry; 2009 global production levels estimated at 2 million tons.¹³
• MSG activates taste sensors responsible for the savory flavor (called “unami”).^14 15
• MSG was attributed to a phenomenon called “Chinese Restaurant Syndrome.”  Afflicted individuals exhibited symptoms including burning sensations, and facial and chest pain, following eat at Chinese restaurants that used MSG as a food additive.¹⁶
• A 2000 study reported inconsistent results that were neither persistent or serious to direct ingestion of MSG.¹⁷
• 1971 study found no difference in symptoms between individuals ingesting MSG or Sodium Chloride (table salt).¹⁸
• 1993 study found no difference between individuals ingesting a MSG or a placebo with food or drink, even at high concentrations.¹⁹
• 1998 and 1999 studies found no link between MSG intake and asthma exasperation in asthmatics who self-reported a sensitivity to MSG.²⁰²¹
• 2009 study found blood/brain barrier is impermeable by glutamates (including MSG). ²²
• 2009 study found dietary glutamates are both a major oxidative fuel for the gut, and an important precursor for the neurotransmitter glutathione. ²³

1. History of glutamate production [↩]
2. Functional neuroimaging of umami taste: what makes umami pleasant? [↩]
3. Glutamate: from discovery as a food flavor to role as a basic taste (umami) [↩]
4. Monosodium L-Glutamate: Its Pharmacology and Role in the Chinese Restaurant Syndrome [↩]
5. Prevalence of the “Chinese restaurant syndrome” [↩]
6. Multicenter, double-blind, placebo-controlled, multiple-challenge evaluation of reported reactions to monosodium glutamate [↩]
7. Single and double blind studies with oral monosodium glutamate in man [↩]
8. Monosodium L-glutamate: a double-blind study and review [↩]
9. The effects of monosodium glutamate in adults with asthma who perceive themselves to be monosodium glutamate–intolerant [↩]
10. Monosodium glutamate sensitivity in asthma [↩]
11. The blood-brain barrier and glutamate [↩]
12. Metabolic fate and function of dietary glutamate in the gut [↩]
13. History of glutamate production [↩]
14. Functional neuroimaging of umami taste: what makes umami pleasant? [↩]
15. Glutamate: from discovery as a food flavor to role as a basic taste (umami) [↩]
16. Monosodium L-Glutamate: Its Pharmacology and Role in the Chinese Restaurant Syndrome [↩]
17. Multicenter, double-blind, placebo-controlled, multiple-challenge evaluation of reported reactions to monosodium glutamate [↩]
18. Single and double blind studies with oral monosodium glutamate in man [↩]
19. Monosodium L-glutamate: a double-blind study and review [↩]
20. The effects of monosodium glutamate in adults with asthma who perceive themselves to be monosodium glutamate–intolerant [↩]
21. Monosodium glutamate sensitivity in asthma [↩]
22. The blood-brain barrier and glutamate [↩]
23. Metabolic fate and function of dietary glutamate in the gut [↩]

The organic food industry has grown dramatically over the last several years, and it’s a natural assumption that eating organic foods is better for you.  Organic foods are grown in an environment perceived to be free of harmful pesticides and herbicides, and in some instances are deemed to be more nutritional than those grown in a conventional manner.  Are there any significant differences between organic and normally raised agricultural products?

One well known difference between organically and non-organically grown produce are the chemicals, or lack thereof, utilized during the growing process.  Studies have found negative effects resulting from acute exposure to pesticides (Grandjean et al 2006) and herbicides (Kamel et al 2003) on farm workers and their children (if exposed prenatally).¹²  For the consumers of produce from farms that utilize pesticides and herbicides, however, it’s been shown that actual exposure to these chemicals is relatively small.   Leblac et al (2000) determined that an average person’s exposure to pesticides is 4% of an individual’s maximum recommended exposure. ³  Galal-Gorchev H. (1991) found that a person’s exposure to pesticide residue is well below established acceptable daily intake levels in the 21 western countries that supply data on the matter. ⁴   Juhler et al (1999) determined dietary exposure to pesticides does not affect male spermazoa,⁵ and Safe (1995) found an individual’s exposure to estrogenic compounds from organochlorine pesticides is 0.0000025% of the daily intake of estrogenic flavonoids in the diet.⁶  While organic farming has been shown to lower pesticide residues in food by 2/3, much organic produce is not pesticide free due to legacy contamination and drift from other fields (Baker et al 2002). ⁷

As far as differences in nutritional value between organic and conventionally grown produce, much of the current literature is suggesting a need for further research, although some slightly notable differences have been found. A review of 55 articles on the subject found conventionally produced crops had significantly higher nitrogen content, and organically produced crops had significantly higher acidity and phosphorus content.  These differences were attributed to the difference in production methods and none of them had a material impact on the food’s nutritional value (Dangour et al 2009) (Bourne and Prescott 2002). ^8 9  A study by Magkos et al (2003) found higher levels of ascorbic acid in organically grown leafy vegetables and potatoes and lower protein levels in some organic vegetables and cereals, but found this evidence to be inadequate to make a definitive argument.  A study by Caris-Veyrat et al (2004) found that organic tomatoes had higher levels of antioxidants (vitamin C, carotenoids, and polyphenols) than conventionally grown tomatoes, but when both types of tomatoes were fed to people for 3 weeks, no difference was found in antioxidant levels in the bloodstream between those that consumed organic or conventional. ^10 11   Similarly, Tarozzi et al (2005) found that organic red oranges have a greater total antioxidant activity than those grown conventionally, but did not investigate whether or not the organic oranges would alter antioxidant levels in the bloodstream  ¹²

1. Pesticide Exposure and Stunting as Independent Predictors of Neurobehavioral Deficits in Ecuadorian School Children [↩]
2. Neurobehavioral performance and work experience in Florida farmworkers [↩]
3. Estimation of the dietary intake of pesticide residues, lead, cadmium, arsenic and radionuclides in France [↩]
4. Dietary intake of pesticide residues: cadmium, mercury, and lead [↩]
5. Human Semen Quality in Relation to Dietary Pesticide Exposure and Organic Diet [↩]
6. Environmental and Dietary Estrogens and Human Health: Is There a Problem? [↩]
7. Pesticide residues in conventional, IPM-grown and organic foods: Insights from three U.S. data sets [↩]
8. Nutritional quality of organic foods: a systematic review [↩]
9. A Comparison of the Nutritional Value, Sensory Qualities, and Food Safety of Organically and Conventionally Produced Foods [↩]
10. Organic food: nutritious food or food for thought? A review of the evidence [↩]
11. Influence of Organic versus Conventional Agricultural Practice on the Antioxidant Microconstituent Content of Tomatoes and Derived Purees; Consequences on Antioxidant Plasma Status in Humans [↩]
12. Antioxidant effectiveness of organically and non-organically grown red oranges in cell culture systems [↩]

Several methodologies and training tools exist to aid in training dogs.  While several factors incorporate into the overall effectiveness of a training regiment (personality, age, consistency, etc), we will examine and summarize some recent studies that have exemplified both effective and non-effective measures.  Please note that this is not a definitive summary of all available options, nor should this replace the advice of a professional.

A 2001 study by Pongrácz et al found that it is not necessary for the dogs’ owner to be the only individual conducting the training, and that a stranger can be equally effective at training, given equal skill.¹  Furthermore, a bond between dog and trainer (even if the trainer is a stranger) can grow in as little as 3 ten minute sessions (Gàcsi et al 2001). ²  A study on different methods of training showed that there was a strong correlation between both use of rewards in training and resulting positive desired behaviors and use of punishment in training and resulting undesired negative behaviors (Hiby et al 2004). ³  Somewhat tangentially, McKinley and Young (2002) describe the Model-Rival method as a very effective training method, which rewards with positive social interaction instead of treats. ⁴ Increasing the amount of verbal communication between the trainer and the dog has been demonstrated to improve training effectiveness (Pongrácz et al 2004), while communication through physical demonstration is only effective if done in a consistent manner (Kubinyi et al 2003) (Pongrácz et al 2002). ^5 6 7  Kubinyi et al (2003) found that it took over 30 independent repetitions for a dog to learn a task through demonstration and in some cases it took over 180.  However, once it was imprinted it remained as a new behavior in the dog and proved durable. ⁸

The myriad available training tools have also been subjected to several recent studies.  Schilder and van der Borg (2003) found that dogs trained using shock collars showed more signs of “stress signals” and lower ear positions than those trained without. ⁹  However, Schalke et al (2005 and 2006) found that stress resulting from shock collars can be reduced when utilized by those with advanced experience, specifically when the animal is made to understand that it can affect whether or not it is shocked.  This particular association is difficult to cultivate, and therefore the authors suggest shock collar usage should be minimal. ^10 11  Head collars or halters have been shown to be an effective, humane and non-physiologically stressing alternative to traditional and shock collars for training purposes (Ogburn et al 1998). ¹²  Citronella spray collars that are marketed to deter barking behaviors have been shown to work in the short term but only if used intermittently (Wells 2001).¹³  Dogs tend to become accustom to these collars and the deterrent effects will diminish (Wells 2001).  Scentless spray collars have been found to be less effective (Moffat et al 2003).¹⁴¹⁵

1. Social learning in dogs: the effect of a human demonstrator on the performance of dogs in a detour task [↩]
2. Attachment behavior of adult dogs (Canis familiaris) living at rescue centers: Forming new bonds [↩]
3. Dog Training Methods: their use, effectiveness and interaction with behavior and welfare [↩]
4. The efficacy of the model–rival method when compared with operant conditioning for training domestic dogs to perform a retrieval–selection task [↩]
5. Verbal Attention Getting as a Key Factor in Social Learning Between Dog (Canis familiaris) and Human [↩]
6. Dogs (Canis familiaris) learn their owners via observation in a manipulation task [↩]
7. Interaction between individual experience and social learning in dogs [↩]
8. Social mimetic behavior and social anticipation in dogs: preliminary results [↩]
9. Training dogs with help of the shock collar: short and long term behavioural effects [↩]
10. Stress Symptoms Caused by the Use of Electric Training Collars on Dogs (Canis familiaris) in Everyday Life Situations [↩]
11. Clinical signs caused by the use of electric training collars on dogs in everyday life situations [↩]
12. Comparison of behavioral and physiological responses of dogs wearing two different types of collars [↩]
13. The effectiveness of a citronella spray collar in reducing certain forms of barking in dogs [↩]
14. The effectiveness of a citronella spray collar in reducing certain forms of barking in dogs [↩]
15. Effectiveness and Comparison of Citronella and Scentless Spray Bark Collars for the Control of Barking in a Veterinary Hospital Setting [↩]

There have been many different theories regarding when and how often an individual should eat, among them: including vs. skipping breakfast, not eating anything before bedtime, and eating several smaller meals vs. fewer concentrated meals.  In this article, we intend to examine whether or not feeding timing and frequency is relevant to metabolism, and/or satiation.

Including breakfast in one’s day has been shown to have myriad effects.  De Castro (2004) found those that skip breakfast are more likely to overeat later. ¹   Additionally, Schlundt et al (1992) and Stubbs et al (1996) found those that eat breakfast eat less fat throughout the day and are less prone to impulsive eating of familiar foods. ²³ However, multiple studies have found that feeding frequency and timing does not have an effect on metabolic performance (Wilhelmine et al 1998) (Dallosso et al 1982) ( Verboeket van de Venne and Westerterp 1998) (Wolfram et al 1987). ^4 5 6 7 In addition, Goldberg et al (1998) found that one’s metabolic rate while sleeping is roughly concurrent with one’s basal metabolic rate (BMR), which in combination with results from the previously mentioned studies suggests that there are no adverse metabolic effects from eating before sleeping.⁸  However, it is important if you are partaking in late night eating that you eat a prepared portion of food, as it’s been demonstrated that it’s common for individuals to overindulge late (Waller et al 2004). ⁹

Eating more frequent smaller meals has been shown to decrease future hunger more effectively than eating few highly concentrated meals (Speechly and Buffenstein 1999).  Johnstone et al (2000) found similar results in their study, and also determined that the nutritional composition of these smaller meals (i.e. high in protein, fat, or carbohydrates) did not affect later decreased hunger, provided they contained a similar caloric composition^10 11

1. The time of day of food intake influences overall intake in humans [↩]
2. The role of breakfast in the treatment of obesity: a randomized clinical trial [↩]
3. Breakfasts high in protein, fat or carbohydrate: effect on within-day appetite and energy balance [↩]
4. Effect of the pattern of food intake on human energy metabolism [↩]
5. Feeding frequency and energy balance in adult males [↩]
6. Frequency of feeding, weight reduction and energy metabolism [↩]
7. Thermogenesis in humans after varying meal time frequency [↩]
8. Overnight and basal metabolic rates in men and women [↩]
9. Evening Ready-to-Eat Cereal Consumption Contributes to Weight Management [↩]
10. Greater Appetite Control Associated with an Increased Frequency of Eating in Lean Males [↩]
11. Altering the temporal distribution of energy intake with isoenergetically dense foods given as snacks does not affect total daily energy intake in normal-weight men [↩]

Stretching prior to, and following exercise is a commonly recommended practice.  Whether or not there are benefits in including this in one’s routine is a controversial subject.  Studies exist that have found little to no benefit of including stretching as part of an athletic regimen (Thacker et al 2004). ¹  Other studies exist that have found stretching before or after athletic activity slightly reduces muscle, ligament, and tendon injuries as well as soreness (Jamtvedt et al 2009). ² In addition, Herbert and Gabriel (2002) found that stretching before or after exercising does not confer protection from muscle soreness and that stretching before exercising does not practically reduce the risk of injury.³ In this article, we intend to examine in more details whether or not there are benefits associated with incorporating the three major types of stretching (static, dynamic, and ballistic) as part of a regular exercise routine.

Static stretching takes place when an individual’s body is at rest, and one holds each stretch for thirty seconds to one minute.  In individuals who are not yet fully involved in a committed athletic program, evidence exists that static stretching can help them ease into a new program without stressing the body (Kokkonen et al 2007).⁴  Static stretching also increases torque in concentric muscle movements (Cramer et al 2006), flexibility (O’Sullivan et al 2009), and range of motion over the long term (LaRoche and Connolly 2006).  Static stretching has otherwise been found have no or negative effects on athletic performance, including a reduction in muscle power endurance, (Yamaguchi et al 2006) (Yamaguchi and Ishii 2005) (Nelson et al 2005) (Brandenburg 2006), sprinting and endurance running performance (Fletcher and Anness 2007) (Wilson et al 2008) (Heyes and Walker 2007), muscle activation (Cramer et al 2004), and jumping height (Holt and Lambourne 2008) (Bradly et al 2007). ^{5 6 7 89 10 11 12 1314 15 16 17}

Dynamic stretching utilizes momentum from form to propel the body beyond in an extended range of motion.  This has been shown to have the greatest positive effect on a range of metrics, including improved muscular power (Yamaguchi and Ishii 2005), sprinting (Fletcher and Anness 2007), and high speed running performance (Little and Williams 2006).^18 19 20 A long-term dynamic stretching program has been positively correlated with sustained muscle power, strength, muscular endurance, anaerobic capacity, and agility performance enhancements (Herman and Smith 2008).²¹  However, it has not been shown to improve running economy (Heyes and Walker 2007). ²²

Ballistic stretching uses bouncing movements to force limbs into an extended range of motion when the muscle has not relaxed enough to enter it.  Studies have shown the existence of some benefits, including improved vertical jump height (Woolstenhulme et al 2006) and general range of motion as a result of ballistic stretching (LaRoche and Connolly 2006).^23 24  Compared to the other two types, there is a dearth of research on ballistic stretching specifically comparisons between ballistic and dynamic stretching.

In short, due to the different benefits of the three types of stretching it is important to make sure that your stretching program will benefit your athletic regimen and not undermine it.

1. The Impact of Stretching on Sports Injury Risk: A Systematic Review of the Literature [↩]
2. A pragmatic randomised trial of stretching before and after physical activity to prevent injury and soreness [↩]
3. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review [↩]
4. Chronic Static Stretching Improves Exercise Performance [↩]
5. Acute Effects of Static Stretching on Maximal Eccentric Torque Production in Women [↩]
6. Effects of Static Stretching for 30 Seconds and Dynamic Stretching on Leg Extension Power [↩]
7. Acute Effect of Static Stretching on Power Output During Concentric Dynamic Constant External Resistance Leg Extension [↩]
8. Acute Muscle Stretching Inhibits Muscle Strength Endurance Performance [↩]
9. Duration of stretch does not influence the degree of force loss following static stretching [↩]
10. The Acute Effects of Combined Static and Dynamic Stretch Protocols on Fifty-Meter Sprint Performance in Track-and-Field Athletes [↩]
11. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects [↩]
12. Pre-exercise stretching does not impact upon running economy [↩]
13. The acute effects of static stretching on peak torque, mean power output, electromyography, and mechanomyography [↩]
14. The Effects Of Static Stretching On Energy Cost And Endurance Performance During Treadmill Running [↩]
15. The Effect of Static,Ballistic, and Proprioceptive Neuromuscular Facilitation Stretching on Vertical Jump Performance [↩]
16. The Impact of Different Warm-Up Protocols on Vertical Jump Performance in Male Collegiate Athletes [↩]
17. Effects of Stretching on Passive Muscle Tension and Response to Eccentric Exercise [↩]
18. Effects of Static Stretching for 30 Seconds and Dynamic Stretching on Leg Extension Power [↩]
19. The Acute Effects of Combined Static and Dynamic Stretch Protocols on Fifty-Meter Sprint Performance in Track-and-Field Athletes [↩]
20. Effects of Differential Stretching Protocols During Warm-Ups on High-Speed Motor Capacities in Professional Soccer Players [↩]
21. Four-Week Dynamic Stretching Warm-up Intervention Elicits Longer-Term Performance Benefits [↩]
22. Pre-exercise stretching does not impact upon running economy [↩]
23. Ballistic Stretching Increases Flexibility and Acute Vertical Jump Height When Combined With Basketball Activity [↩]
24. Effects of Stretching on Passive Muscle Tension and Response to Eccentric Exercise [↩]