Grow New Teeth?

Picture from Amazon

Last week I wrote about how consuming too much energy drinks can cause erosion in our teeth. I grind my teeth a lot when I sleep and have been using a night splint for the last 20 years. Also, I used to drink a lot more Coca Cola, sports drinks and consume energy gels back when I was competing. So I am worried about the erosion in my teeth.

If we fall and our bones break, the bones have the ability to heal and grow back. However with our teeth, the same cannot be said. Once you lose a tooth, that's it, unless you put in a dental implant to hold an artificial tooth on top.*

What if I told you now that growing back teeth may be a possibility in less than 5 years. Japanese researchers are now experimenting with an experimental drug that may regrow human teeth.

This is after years of study around Uterine sensitization-associated gene-1 (USAG-1), an antibody shown to inhibit the growth of teeth in ferrets and mice. However, back in 2021, the researchers found a monoclonal antibody (usually used in fighting cancer) that disrupted the interaction between USAG-1 and molecules known as bone morphogenetic protein or BMP. 

Suppressing USAG-1 benefits tooth growth. And believe it or not, ferrets have a similar dental characteristics to humans. Both develop 2 sets of teeth in a lifetime, a temporary set or "baby" teeth followed by a permanent adult set.

The researchers have started trials on humans. It will last 11 months and focus on 30 males between the ages of 30 and 64 with each missing at least one tooth. The drug will be administered intravenously to assess it's effectiveness and safety. Previous animal studies did not show any adverse side effects.

The researchers are hoping that if the trial goes well, they can administer this treatment to patients between the ages of 2 to 7 who are missing at least 4 teeth. The end goal will be to have tooth regrowing medicine by 2030. 

Although the current treatment will be focused on young patients with congenital tooth deficiency, the treatment will eventually be available to anyone who is missing a tooth. Human trials began last September 2024. Let's wait and see.

Reference

Murashima-Suginami A, Kiso H, Tokita Y et al (2021). Anti- USAG-1 Therapy For Tooth Regeneration Through BMP. Sci Advances. 7(7): eabf1798. DOI: 10.1126/sciadv.abf1798

* Thanks to Dr Winston Tan and Dr Dr Frank Liew who have been looking after my implants and teeth all these years.

Too Much Energy Drinks Causes Tooth Erosion

Guess what I'm drinking in my 2 water bottles in 2001?

My patient who is a dentist tells me he is seeing a lot of younger patients having erosion in their teeth.  The features of their particular erosion is non-bacterial acid induced loss of dental hard tissue. A notable contribution is due to increased consumption of acidic drinks, especially energy drinks. 

Fortunately, I never had any Red Bull or Monster in my water bottles when I was still training seriously or racing.

Like I wrote previously, energy drinks are thought to be beneficial for performance. My platoon mates in the army when we were doing national service, would frequently load up with energy drinks such as Red Bull. There was no Monster drink then. They would consume it especially in the morning before physical training and Standard Obstacle Course (SOC) training sessions. Those who were less fit tended to count on those energy drinks. One of them commented that without Red Bull he would definitely fail his fitness tests.

Some of them would also mix Red Bull with alcohol when they book out on Fridays so they can party the night away.

This was similar when I was in university. Some of my classmates did the same when cramming for an exam or writing a paper.

Energy drinks from the study

A paper published last year (Martinez et al, 2024) was investigating the pH of energy (pictured above) and pre workout/ sports drinks (below) and the consumption frequency and habits among amateur athletes. Their study analyzed the pH of 67 commercially available energy drinks and pre workout/ sports drinks. There were 43 energy drinks and 24 pre workout/ sports drinks.

Pre workout/ sports drinks

The authors also did a survey among 113 amateur athletes who completed an anonymous questionnaire to find out about the use of different beverages during various sports activities. The participants participated in strength training, endurance sports and some of them participated in both. They reported consuming energy and/ or pre workout/ sports drinks before, during or after workout.

Ready for the results? The average pH for the beverages studied was 3.3. The pH level at which enamel erosion begins is approximately 5.5, which is known as the critical pH. When the pH in our mouths drop below this level, the enamel starts to dissolve, leading to tooth decay.

51 percent of the participants surveyed said, they consumed at least one of the beverages studied. Most participants aged ≤ 29 consumed them 3-5 times each week while the older participants consumed them 1-2 times per week.

Shocked? The study showed that ALL the  energy drinks and the majority of pre workout beverages evaluated have erosive pH levels that can damage tooth enamel. Please remember this when using energy drinks or pre workout/ sports drinks. 

I always carry water with me during my bike rides instead of energy or sports drinks. Drinking plain water after your sports drinks is a good way to mitigate the erosive nature of the energy drinks. You may also want to brush your teeth when you get home.

Reference

Marthiez Lm, Lietz, LL, Tarin CC et al (2024). Analysis Of The pH Levels In Energy And Pre-Workout Beverages And Frequency Of Consumption: A Cross-Sectional Study. BMC Oral Health. 24,1082. DOI: 10.1186/s12903-024-04843-0.

Take your pick

Nose Strips Help You Race Faster?

Picture by Tim de Waele, Getty images

A patient just asked me about nasal (or nose) strips. She had seen lots of runners using them recently and wonder if they can help her run faster. 

I remember getting a couple of Breathe Right nasal strip samples in my goodie bag in a triathlon race that I took part way back in 1999. I had never used them before and I thought there's no harm in trying them in the race. 

Paula Ratcliffe in her heyday- M Hewitt, Getty images

I actually won that race but felt that the nasal strip did not help much except giving me a funny tan on my nose as race day was blistering hot. I remember seeing Jan Ullrich and Paula Radcliffe wear them when they were racing as well. 

Picture by O Docelin, Getty images

I noticed them again during the Tour De France this year (pictured above). Many cyclists were seen using them, some even using custom decorated ones. 

Bastille Day -Tim de Waele, Getty Images

So are these nose strips worth wearing? Do they help improve your sporting performance? Yes they do help with the "negative pressure" that builds up and blocks your nostrils during heavy breathing. They do improve airflow by enlarging your breathing passageway. 

However, what really matters is the amount of oxygen that gets into your bloodstream and not the amount of air you breathe in. For most people, the normal air you breathe in will mostly saturate your blood's oxygen carrying capacity.

A recent systematic review concluded that nasal strips do not help with VO2 max, rates of perceived exertion or heart rate response (the body's response to exercise).

If you're eating an energy bar on the bike or run, the nasal strip can help increase the ease of eating and trying to breathe at the same time. They can increase the comfort of breathing, especially if you have a deviated septum, some nose congestion or allergies, but they do not offer a performance advantage.

There is no real 'downside' and at best a placebo effect for those using them. I personally think it is more of a fashion statement if you look at the pictures from the 2025 TDF.

Should you try the nose strips? Yes, if you suffer from specific nose structure issues or want to use them as a fashion statement. They are not expensive and a good placebo effect is a legal performance enhancer.

References

Dinardi RR, Ferreira CHS, Silverira GS et al (2021). Does The External Nasal Dilator Strip Help In Sports Activity? A Systematic Review And Meta-Analysis. Eur Arch Otorhino. 278(5): 1307-1320. DOI: 1007/s00405-020-06202-5.

Illidi CR, Romer LM, Johnson MA et al (2023). Distinguishing Science From Pseudoscience In Commercial Respiratory Interventions: An Evidence-based Guide For Health And Exercise Professionals. Eur J Appl Physiol. 123(8): 1599-1625. DOI: 10.1007/s00421-023-05166-8

No Need To Cool Down After Exercise?

Athletes, coaches and physical education teachers have always been told that an active cool down is more effective for promoting post exercise recovery than a passive cool down (no activity). This is assumed to allow for individuals to perform better during subsequent training sessions or competition and perhaps even lower the risk of injury. 

However, there is not much research on whether the above is true. I've written previously how it may be unnecessary to cool down after exercise. What if I say that in some cases an active cool down may even be harmful?

The most widely used post recovery exercise intervention is probably the active cool down. It is commonly referred to as the 'warm down'. This is usually a 5 to 15 minutes of low to moderate intensity exercises after exercise/ competition. Some will do a slow jog, cyclists often ride easy on the bike while it's attached to a stationary trainer.

The following review by Van Hooren and Peake (2018) compares the effects of various types of active cool downs with passive cool downs on sports performance, injuries, long term adaptive responses and markers of post exercise recovery.

Ready for the summary? 

The review shows that an active cool down helps lead to faster removal of lactate in blood. However the practical relevance of this finding is questionable since lactate is not necessarily removed faster from muscles. 

An active cool down can partially prevent the depression of circulating immune cell counts after exercise, although it is unknown if this leads to fewer infections and illnesses.

An active cool down can definitely result in a faster recovery of the cardiovascular and respiratory system after exercise/ competition, but it remains unknown if this reduces post exercise fainting and cardiovascular complications.

Active cool downs does NOT significantly reduce delayed onset of muscle soreness (DOMs) or improve the recovery of indirect markers of muscle damage. It does not significantly alter the recovery of neuromuscular and contractile properties of muscles, it does not improve range of motion of muscles, and does not reduce musculotendinous stiffness following exercise. It may even interfere with glycogen synthesis.

The review also provided evidence that an active cool down generally does not improve and may even negatively affect performance if the time between successive training sessions or competition is > 4 hours.

An active cool down also has no substantial effects on next day(s) sports performance although some beneficial effects have been reported. They do not prevent injuries and preliminary evidence suggests that performing regular cool downs do not reduce the long term adaptive response.

However, most individuals perceive an active cool down as being more beneficial than a passive cool down. The effectiveness of an active cool down may differ depending on each individual's preferences and beliefs. Some athletes may benefit more from an active cool down while others may prefer to perform no cool down at all.

Some general guidelines for those who still wish to perform an active cool down. It should involve aerobic activities performed at low to moderate intensities to increase blood flow, but prevent development of substantial additional fatigue. 

It should involve low to moderate impact to prevent additional muscular damage or DOMs. It should be shorter than 30 minutes to prevent substantial interference with glycogen resynthesis. So make sure you eat/ drink quickly after exercise or competition. 

Some evidence also suggest that an active cool down should involve the same muscles used in the preceding activity. Now you know.

Reference

Van Hooren B, Peake JM (2018). DO We Need A Cool-Down After Exercise? A Narrative Review Of The Psychophysiological Effects And The Effects On Performance, Injuries And The Long-Term Adaptive Response. Sports Med. 48:1575-1595. DOI: 10.1007/s40279-018-0916-2

Cycling Helps Prevent Dementia?

Riding towards the sun

My laptop could not connect to the hotel WIFI network last weekend when I was away, so I'm only posting last week's post now.

Many of you reading this will know that on the Saturdays that I'm not traveling, I do a long bike ride with my usual cycling group. Since I was away, I also missed my Saturday bike ride.

I may have missed my Saturday ride, but I did get to read a very interesting article on cycling. Researchers found that sustained aerobic exercises (like cycling) may reduce the risk of dementia (Hou et al, 2025).

There were 479, 723 participants ( 260,730 females, 54.4 percent) with a mean age of 56.5 years in that study. These data were collected from the UK Biobank with the aim to investigate the long-term association between travel modes and dementia risk and to evaluate whether genetic predisposition can modify the association between travel modes and dementia risk.

To understand the link between brain health and common forms of travel, the participants were asked if they usually used motor vehicles, walking, cycling or public transport.

The researchers found that participants that cycled regularly (not including commuting to work) had a lower risk of developing dementia compared to those who walked, drove or used public transport. They were 19 percent less likely to develop all-cause dementia and 22 percent less likely to develop Alzheimer's disease.

The authors suggest that "this likely stems from cycling's higher aerobic intensity and cognitive engagement (e.g. navigation, coordination), which may enhance neuroplasticity more than walking alone". Other than regular exposure to fresh air from cycling, the physical demands of cycling plus the need to stay alert whilst on the roads or trails may help to maintain brain health.

This is supported by other studies (Erickson et al, 2011) where cycling or other aerobic exercises causes the hippocampus, the part of the brain responsible for memory formation, learning and spatial navigation to grow. Note that typically, the hippocampus reduces in size during late adulthood (from the mid to late 60's).

The authors concluded that the findings "suggest that promoting active travel strategies, particularly cycling, may be associated with lower dementia risk among middle-aged and older adults, which carries substantial public health benefits".

Now, that's a very good reason to keep cycling. Let's make our roads safer for cycling.

References

Erickson KI, Voss MW, Prakash RS et al (2011). Exercise Training Increases Size Of Hippocampus And improves Momory. ProNatl Acad Sci USA. 10897): 3017-3022. DOI: 10.1073/pnas.1015950108

Hou C, Zhang Y, Zhao F et al (2025). Active Travel Mode And Incident Dementia And Brain Structure. JAMA Netw Open. 8(6): e2514316. DOI: jamanetworkopen.2025.14316

Time Of The Day When You Are At Your Best

Picture from Healthyplace.com

I have been out of school for decades and have not sat for any tests or exams in quite a while. But I do see new patients almost every day I am working in our clinics. I do take plenty of "tests" too, since every single patient I see will evaluate my treatment and decide if I made them better.

You must be wondering why I am writing about tests this week, Well, the Singapore primary school leaving exams (PSLE) just ended this past week.  Parents whose children just sat for the exams must heave a collective sigh of relief now that it's all over. 

The typical start times for the PSLE oral exams are at 0800 while written exams generally commence at 0815 hours. That's definitely an early start for those taking exams.

Unlike the students sitting for exams, we usually see new patients in our clinic whenever we can fit them in for an appointment. This may not necessarily be the best according to a group of researchers who analyzed the results of over 100,000 oral exams. They found a clear Gaussian distribution (also know as the Normal distribution or bell curve) in pass rates that peaked at noon. 

Passing rate by hour 

Between 11 am and 1 pm is the best time (pictured above). Any earlier or later the chances of passing significantly decreased. In fact the earlier or later in the day these students took a test, the less likely they were to pass.

The reason being our cognitive (or conscious intellectual ability) performance improves over the course of the morning and then declines in the afternoon. We also may have declining energy levels later in the afternoon. If your exam is scheduled later in the day, you may also stress about it and this usually leads to poorer performance.

According to the author's, the examiner's cognitive performance and fatigue level also matters. Both the examiner and student will be at their peak level of performance during the mid day hours.

This all means that whenever possible if you have to take a test or exam, an important meeting or a job interview, you should schedule it between 11 am and 1 pm. It can be the difference between passing and failing. 

Perhaps we should only see new patients in our clinics between 11 am and 1 pm then. 

Reference

Vicario CM, Nitsche MA, Lucifora C et al (2025). Timing Matters! Academic Assessment Changes Throughout The Day. Frontiers Psychol. 16:1605041. DOI: 10.3389/fpsyg.1605041

Training In Hot Conditions Makes You Eat More?

Just after sunrise

After all the rainy days during the first 2 weeks of September, the temperatures were nice and cool. This past week it seems like "someone turned the tap off" and it's been way hotter. 

I weighed myself yesterday morning before and after my regular Saturday ride before work and found that I had lost 2 kg (mostly water) despite eating and drinking more during the ride. These 3 hour rides, when warmer, make me feel like I'm making my body work double time. I've noticed that when the temperature is higher, I need to eat more (during the ride) or else I cannot keep up with my friends.

On Saturday rides that are cooler, I sometimes don't even eat the banana that I bring with me and can still ride well without tiring.

Turns out that training in Singapore's heat and humidity does not just make one more comfortable in hot conditions, it actually changes how our muscles use energy (Xu et al, 2025).

The authors in the study quoted above show that a month of structured heat acclimation training can help change your metabolism to race stronger when it's hot and probably in cooler temperatures too.

The researchers split 18 trained middle and long distance runners into 2 groups. Both groups completed treadmill tests and metabolic assessments at temperatures of 30-32 °C (or 86-89 °F).

The first group trained in normal temperatures (20-25 °Celsius or 68-77 °F). The other group did 20 sessions of heat acclimation over 4 weeks. They ran in tem[eratures between 30-36 °C that pushed their core temperatures to 39-40 °C (or 102-104 °F).

No prizes for guessing that the heat acclimated group made more notable adaptations compared to the control group. Their core temperature during the subsequent treadmill test was lower by 0.4 °C, a clear sign of improved thermoregulation. They were also more efficient aerobically, as oxygen uptake improved by 4 and 3.7 percent at the *first and second ventilatory thresholds.

Plasma volume improved by 4 percent, haemoglobin by 2 percent and erythropoietin by 13 percent after heat acclimation, showing better oxygen support. All signs of heat adaptation.

At submaximal intensities (75 and 85 percent VO2 max, carbohydrate oxidation dropped by 15-19 percent in the heat acclimated group. The runners used less blood glucose and muscle glycogen, using more of the body fat instead. Exactly like I wrote above when I do not need to eat as much during cooler rides. In the picture above, carbohydrate (CHO) use and energy expenditure (EE) before and after control (black bars) and heat training (red).

Upon finishing the treadmill test, the heat acclimated runners cleared lactate more efficiently demonstrating improved recovery.

However, VO2 max did not change, suggesting that having a higher VO2 max (compared to someone else) may not mean you will race faster. The efficiency gains were more beneficial.

Take home message? Those of us who live in sunny and super humid Singapore can train almost all year round in such conditions. A 4 week block of 5 days a week may give you the metabolic edge of using less carbohydrates at higher intensities. This spares your glycogen stores and delays fatigue. The thermoregulatory and blood adaptations will help you stay cooler and deliver oxygen more effectively, especially if you are going to be racing in a friendlier climate. 

You will need to monitor the above parameters and allow for adequate recovery to get the benefits. This is when your blood, sweat (lots of it) and tears will pay off if you do it correctly.

Reference

Xu Y, Ye C, Ma S et al (2025). Four-Week Heat Acclimation Lowers Carbohydrate Oxidation Of Trained Runners During Submaximal Exercise In The Heat. Frontal Physiol. DOI: 10.3389/fphys.2025.1581594/full

*First ventilatory threshold (VT1) is when your breathing becomes noticeably deeper and lactate starts to accumulate in the blood. This indicates a shift from using mostly fat to carbohydrate during exercise.

VT2 or second ventilatory threshold occurs later, this is often when breathing is rapid, more labored leading to a sharp increase in carbon dioxide production. This is when a significant shift to anaerobic metabolism.

Still not too hot