Plastic or Metal: Which Water Bottle is Best?

 

In ancient times, the philosophers would gather and walk around the marketplace, the agora, and contemplate the weighty matters of the world such as the nature of justice, the ideal city, distinguishing the good from opinion, and seeking truth and knowledge.  All of that walking, talking and thinking in the hot sun can make a scholar dehydrated. So, naturally, the first question these great minds would tackle is: plastic or metal? Which water bottle is best for walking and thinking?

 

Plastics are everywhere. The worldwide production of plastic has exploded from less than 2 million tons in 1950 to about 400 million tons in 2020. Once a plastic item has been used, it tends to stick around for a while. Plastic takes a long time to break down. For example, a plastic water bottle may take 450 years to decompose! Due to this phenomenon, plastic waste is everywhere. Only 10-15% of plastic is recycled. The rest ends up in a landfill or the ocean or is burned off. As the plastic in landfills or in the ocean breaks down, smaller particles called microplastics are produced. When plastic is burned, microplastics are released into the air. Microplastics have been found everywhere including on remote islands, in Antarctica, deep in the ocean and, increasingly, in human tissue and organs. Microplastics enter the body by two routes. Microplastics in the air are inhaled. They also enter by ingestion, for example by eating microplastic laden sea fish or drinking from plastic water bottles (even reusable water bottles). Microplastics have been found throughout the human body. They are present in high concentrations in the liver and kidneys and to lesser degrees in the hair, saliva, blood, colon and lung. Aside from just being present, do microplastics cause human disease? An important study found microplastics in atherosclerotic plaque. In the study, 58% of patients undergoing surgery for blockage in their carotid (neck) arteries had microplastics in their arteries. These patients were 4 times more likely to die, have a heart attack or stroke over the next three years compared to patients without microplastics. Another study found that coastline counties in the United States (where there is a higher exposure to ocean microplastics) had higher risks for diabetes, heart artery disease and stroke. We now know that the brain is full of microplastics as well. It was found that the level of microplastics in the brain increased by 50% from 2016 to 2024. In addition, people with higher levels of brain microplastics had more dementia and Alzheimer’s disease. 

 

Like plastics, metals are everywhere. However, unlike plastics, our bodies require small amounts of certain metals, called essential metals, for normal metabolism. Essential metals include copper, manganese, cobalt and zinc. Small amounts of these metals are needed, but larger quantities can be toxic as are nonessential metals, such as cadmium, arsenic, lead, tungsten, uranium and mercury. Cadmium is present in tobacco smoke, meats, shellfish, and vegetables. Cadmium, tungsten, uranium, cobalt, copper and zinc come from industrial emissions, electric batteries, oil production, welding, and mining. Arsenic is found in the water and some foods. What are the health effects of metals? It has been shown that with high urinary concentrations of cadmium, tungsten, uranium and the essential metal zinc, there is an increased risk for dementia. There is no association of high urinary lead levels and dementia. In addition, there is an association between high urinary levels of cadmium, tungsten, uranium, and the essential metal cobalt and coronary calcification, a measure of plaque in the heart arteries. It is felt that these metals promote atherosclerosis through inflammation. A recent study proved the concept by showing that lead and cadmium exposure leads to increased blood levels of troponin (a measure of heart damage), proBNP (a measure of heart strain) and C reactive protein (a measure of inflammation). Lastly, a study from China showed that long-term exposure to high levels of copper, manganese, aluminum, zinc and cadmium in the drinking water increased the risk for major cardiac events (heart attacks, cardiac deaths). 

 

What should our philosophers choose, a plastic or metal water bottle?  Which one is the healthier choice? Reusable plastic water bottles add to the microplastic load. Wear and tear, repeated washing and exposure to heat damages the inner surface of the bottle, releasing microplastics into the water that is drunk. The concentration of microplastics in reusable bottles is higher than single use water bottles. Most bottles are made of polyethelene terephthalate (PET). Bisphenol A (BPA) is another chemical used to make plastic bottles. BPA has multiple adverse health effects including endocrine problems, diabetes, high blood pressure.  It is best avoided. Most metal water bottles are made of stainless-steel. Stainless-steel does not wear down and release metal into the water. In addition, there are no known adverse health effects of stainless steel. When choosing a stainless-steel water bottle, make sure there is no aluminum and no lead-based solder used to seal the bottle. Lastly, make sure the plastic cap does not contain BPA.

 

So, don your toga, grab your stainless-steel water bottle and head to the agora to think those heavy thoughts.

 

The Inflamed Heart

 

The Chinese New Year was celebrated on February 17 2026, marking the Year of the Fire Horse. This is a rare event as the last Fire Horse year was 1966. In honor of the Fire Horse, this month's column will discuss inflammation. The term inflammation comes from the Latin word "inflammare", meaning "to set on fire". Inflammation is the body’s defense system. The term conveys the idea that a fire is being lit to protect the body. When the body is faced with a stressor, such as an infection, a trauma, or a toxin, the inflammatory response is activated, isolating the insult, removing it and starting the healing process. The five symptoms of inflammation are: redness (rubor) in the area of injury, heat (calor), swelling (tumor), pain (dolor) and loss of function. Acute, short term (few days) inflammation is vital for protection and healing. However, chronic inflammation (lasting months to years) is harmful and attacks healthy tissue. How is the heart affected by inflammation? How can heart inflammation be detected and treated?

 

The heart is not immune to inflammation. Chronic inflammation leads to several types of heart disease. Coronary artery disease is felt to be an inflammatory process. If the wall of a heart artery is damaged (due to high blood pressure, diabetes or smoking) the immune system is activated and the inflammatory process is initiated to heal the arterial wall. Inflammatory cells and cholesterol come to the area to repair the damage. If the process continues over months to years (chronic inflammation) plaque is built up in the artery wall. If allowed to continue, this can lead to blockage in the blood flow to the heart muscle, causing chest pain. Alternatively, inflammation can cause acute rupture of a plaque leading to a heart attack. It is now well established that long-term, low-grade inflammation is the key to heart artery plaque formation, progression and rupture. In addition, congestive heart failure is driven by chronic inflammation. Inflammation promotes damage to the lining of the heart muscle (the endothelium) and scarring of the heart. This leads to destruction and weakening of the heart muscle. Inflammation is promoted by smoking, obesity, high cholesterol, elevated blood pressure, diabetes, and other chronic inflammatory conditions (such as periodontitis, chronic kidney disease, rheumatoid arthritis, COPD).

 

How can inflammation be detected and followed? The blood test C reactive protein (CRP) is a nonspecific marker of inflammation. CRP levels will rise due to multiple conditions such as an infection, a traumatic event, acute arthritis and chronic inflammation. The latter scenario makes it useful for detecting low level, chronic inflammation in heart disease. CRP levels less than 1 mg/L is low risk for chronic inflammation. CRP levels over 3 mg/L denote higher risk for cardiac inflammation. Levels over 10 mg/L usually are present with an active condition, such as an infection. It is felt that CRP is at least as strong a risk marker for heart disease as blood pressure and low-density lipoprotein (LDL). 

 

How can chronic inflammation be treated? First and foremost are lifestyle changes to reduce the risk factors for chronic inflammation. This includes stopping smoking, losing weight and treating blood pressure, cholesterol and diabetes. Physical activity lowers CRP levels. Diet is vitally important as well. There are proinflammatory diets that increase the risk for inflammation and heart disease. On the other hand, the Mediterranean diet with olive oil, nuts and fatty fish intake lowers CRP and the risk for chronic heart disease. Proinflammatory foods include red meat, processed meat, refined carbohydrates and sweetened beverages. Anti-inflammatory items include green leafy vegetables, whole grains, fruits, tea, coffee. Many medications have been trialed to see if they reduce inflammation and cardiac risk. Statins lower both LDL and CRP and are the first line agents used to combat high cholesterol and chronic inflammation. Another cholesterol lowering agent, bempedoic acid, also reduces CRP by 20-30%. Colchicine has been used for many years as an anti-inflammatory agent in gout. Low dose colchicine has also been shown to reduce cardiac events in patients with known heart artery disease by 25%. 

 

What else can be done to lower chronic inflammation? Aside from protecting against a nasty disease, and much like statins, the shingles vaccine has multiple secondary benefits. The shingles vaccine has been shown, in many studies across the world, to reduce the risk for dementia by about 20%. Now a new study showed that those with the vaccine had lower inflammation scores and that the vaccine actually slowed the aging process. 

 

The Fire Horse symbolizes an intense, high-energy year dedicated to rapid change. So, make this the year you tackle your risk for chronic inflammation. Using the tools described here will keep you on track and in the horse race. 

 

 

The Exercise Sweet Spot

 

The eyes of the world are on Milan-Cortina in Italy (pictured above, the Duomo, symbol of the city of Milan). The world’s best athletes are competing in some of the toughest sports in the Winter Olympics. As we watch the events, we know there is a difference in the energy a speed skater expends racing around a track compared to the average person walking on a treadmill. What is that difference and how can it be quantified?  Is there an optimal amount of time spent in our favorite exercises to maximize the benefit? Is there an exercise sweet spot?

 

Exercise is quantified using the metabolic equivalent (MET). The MET is the energy cost of doing any activity such as walking, running, playing a sport or doing household chores. One MET is the energy used just sitting and doing nothing. An activity that costs 4 METS is four times as strenuous as sitting still. Light activity is considered less than 3 METs, moderate activity is 3 to 6 METs and vigorous activity is greater than 6 METs. The higher the METs, the more exercise energy is required and the more calories burned. The table below displays the METs of some common activities and sports: 

Activity/Sport	METs
General bicycling	7.0
Bicycling 14-16 MPH	10.0
Jogging 2.6-3.7 MPH	3.3
Running 4 MPH	6.5
Marathon Running	13.0
Walking the dog	3.0
Walking 2.8-3.4 MPH	3.8
Swimming laps	5.8
Tennis- singles	8.0
Tennis- doubles	4.5
Free weights	6.0
Squats/Pushups	3.0
Exercise classes	5.5
Yoga	2.3
Zumba	6.0
Pilates	2.8
Snow blower	2.5
Snow shoveling	5.0-7.5
Mowing lawn, power mower	5.0
Mowing lawn, hand mower	6.0

 

How does this compare to the energy required for some Olympic sports?

 

Winter Olympic Sports	METs
Ice dancing	14.0
Speed skating	13.8
Cross country skiing	15.0
Biathlon	12.8
Downhill skiing	8.0
Slalom skiing	9.3

 

As we can see, winter sports are very high energy. Also keep in mind that these METs are for the average exerciser. Olympic competitors are working at an even higher rate. The website https://pacompendium.com/adult-compendiun/ has a list of many more activities and sports.

 

What is the optimal number of METs per week? What is a good amount of exercise? It is well known that the largest benefit of exercise occurs when going from doing nothing to doing a moderate amount of physical activity. People doing 150 minutes of moderate exercise per week lower their risk for heart disease and death by 14% compared to people who are sedentary. It is also well known that increasing the exercise volume doesn’t give much more benefit; the mortality benefit plateaus. In other words, exercising more and more doesn’t mean that you will live longer and longer. Mortality isn’t the only thing that reaches a plateau, heart disease, respiratory disease and cancer all hit a limit. Does this relationship hold for various types of exercise? A new study examined this question. The study followed 111,000 participants for 30 years. The study found a similar relationship for multiple different types of activities including walking, jogging, running, bicycling, swimming, tennis, rowing and weight training. All of these exercises lowered the risk of dying and all plateaued as the volume went up. The study used MET hours per week to quantify exercise volume. MET hours per week is derived by multiplying the MET associated with an activity by the hours per week engaged in doing the activity. For example, walking 3 MPH (3.8 MET) for 2 hours each week yields 7.6 MET hours per week. With some exercises (jogging, swimming), mortality actually went up as the volume of exercise per week increased. Is there an exercise “sweet spot”? It turns out that exercising about 5 MET hours per week for any activity in the study gives the maximum mortality benefit. The 5 MET hours per week is not hard to achieve. The time needed to reach the sweet spot for each activity is:

Walking                      90 minutes/week

Jogging                       45 minutes/week

Running                      30 minutes/week

Bicycling                    50 minutes/week

Swimming                  45 minutes/week

Tennis                         45 minutes/week

Rowing                       60 minutes/week

Weight training           90 minutes/week

 

Of course, there may be other reasons to exercise above this rate (for example, to lose weight, to keep in shape, to train for a competition, to control blood pressure, to improve diabetes, to reduce the risk for rhythm problems, etc), but the additional work load won’t reduce the risk of dying further. In addition, engaging in different types of exercises gives additional health benefits. 

 

Why is there an exercise plateau? Why doesn’t mortality continue to decline with more activity? Most studies have shown that elite athletes live longer than the general population. On the other hand, studies have shown that high volume exercisers do experience cardiac abnormalities. Men who do high volume training (50 MET hours/week) have a higher burden of heart artery calcium than nonathletes. Higher coronary calcium levels are consistently found in avid exercisers. Calcium is associated with heart artery blockage and this could certainly limit life span. Similarly, high blood levels of troponin are found in athletes after exercise. Troponin is a measure of damage to the heart muscle and elevations are diagnostic of acute heart attacks. More than 80% of marathoners have troponin concentrations that are above normal cut offs. Troponin in athletes could be a normal physiologic finding or it could be due to transient damage of the heart from over exercising. Lastly, fibrosis or scarring of the heart muscle has been found in endurance athletes. Fibrosis is associated with malignant arrhythmias. No one really knows why these phenomena happen in high volume exercisers or its significance, but it could explain why there is a plateau. 

 

Next, we’ll make use of our MET knowledge and tackle a favorite winter sport, snow shoveling. Shoveling snow exerts a significant workload on the heart. This begs the question, at what age should you stop shoveling snow?  One expert says to stop at age 65. Another expert, citing a study showing that 85% of adults over 50 years of age already have atherosclerosis, says to stop at age 45! Clearly the recommendation must be individualized. If you have known heart disease or do not regularly do an equivalent amount of exercise (for example running at 4 MPH, 6.5 METs; snow shoveling 5.0-7.5 METs) then put down the shovel. If you regularly run on a treadmill at 4 MPH without difficulty at home or in the gym, then go for it. The same thought process should occur during the summer with lawn mowing (power mower 5 METs, hand mower 6 METs).

 

Once you are done with snow shoveling, put on fire, sit back and enjoy the Winter Olympics. Now you can appreciate the difference in energy expenditure between competing in an Olympic speed skating event (13.8 METs plus) versus walking on a treadmill (3.8 METs). However, if your goal is to live longer and not winning an Olympic medal, you can still hit your exercise sweet spot by walking only 13 minutes per day.

 

How to Do CPR in Space (and How to Prevent Sudden Cardiac Arrest on Earth)

                                                    Photo courtesy of Nick Nikolaides
 

Becoming an astronaut is a highly selective process. Only the best, the fittest, are chosen to be astronauts and to go on missions. In 2024, 8,00 people applied to become an astronaut, only 10 were chosen. To be selected, the candidates have to be in perfect physical health. There are vision and height requirements, they need to have excellent heart health and no high blood pressure. Once chosen, the process continues. Astronauts go through one of year of intensive physical training including wilderness survival, underwater training and learning to cope with low gravity. Despite being in tip top shape and low risk, it is still possible that an astronaut could suffer sudden cardiac arrest (SCA) while in space. If that happens, could they be resuscitated? How would cardiopulmonary resuscitation (CPR) be performed in zero gravity? How can astronauts (and those of us on Earth) lower our risk for SCA?

 

Sudden cardiac arrest is a common problem and is often the first manifestation of heart disease. It is an abnormal heart rhythm most often caused by ventricular fibrillation (an irregular heart rhythm from the lower chambers of the heart).  When the heart’s ventricles are fibrillating, they cannot pump blood to the brain and vital organs. If not treated promptly, this leads to death.  Sudden cardiac arrest affects more than 300,000 people in the US each year with a death rate of about 90%. Treatment of SCA involves prompt initiation of CPR and performing defibrillation. Defibrillation is an electric shock to the heart that restores the heart to normal rhythm. The shock is usually provided by an Automatic External Defibrillator (AED). Cardiologists can determine which patients are at high risk for SCA including those with prior heart attack, previous SCA, congestive heart failure and low ejection fraction (below 30%). However, these high-risk patients only account for a small proportion of the SCA total (about 10% of the total number of arrests). In contrast, the majority of SCA occurs in asymptomatic, low-risk people in the general population (more than 50% of the total). It is very hard to predict, or prevent, these events in the general population. 

 

By any measure, astronauts would fall into a low-risk category. Still, the risk is not zero and SCA could occur while on a mission. If SCA happened in space, how would CPR be performed? Traditional CPR relies on gravity to be effective and weightlessness poses a problem. NASA recommends that a rescuer stand behind a victim, wrap their arms around the person (in a bear hug) and squeeze (almost like the Heimlich maneuver, but applying continuous compressions to the chest not the abdomen).  The rescuer and the victim can be moved to a room with medical equipment and the victim strapped down. The rescuer then does compressions in a handstand position, with hands on the patient’s chest and legs braced against a wall. This method can’t provide the compression depth that is recommended, so it would not be as effective as CPR on Earth. One way around this would be to use a LUCAS automated chest compression system, a machine used in emergency medicine with a plunger that automatically does chest compressions to the right depth and at the right rate. Current space vehicles do not have this device (due to size and weight considerations) but do have AEDs.

 

If you are an astronaut or a low-risk citizen of Earth, what can you do to lower the risk for SCA? Over the past twenty years, the incidence of SCA has gone down, but there is room for improvement in preventing it. The CARES (Cardiac Arrest Registry to Enhance Survival) network is a national registry tracking SCA. It currently covers about 40 states. CARES showed that from 2021 to 2024, overall survival improved from 9% to 11%, public AED use increased from 10% to 13%, but bystander CPR remained steady at 41%. However, we can do better. A large study of SCA was published this year covering 500,000 participants, average age 56 and 50% were women. The study showed that the American Heart Association’s Life’s Essential Eight were strongly related to risk for SCA. The eight risk factors are:

Diet- high in fat, low in fruit and vegetable intake

Activity- sedentary lifestyle

Smoking

Sleep- less than seven hours per night

Obesity- high body mass index (BMI), high waist circumference

High Cholesterol

Diabetes

High Blood Pressure

In addition, the study found several novel risk factors for SCA. These are depression, social isolation, low educational level, increased arm fat, reduced grip strength (a marker of frailty) and air pollution. The study concluded that SCA could be reduced by 40% to 60% if these risk factors were controlled or eliminated.

 

With this information, we can now respond to SCA anywhere in the universe and begin to prevent its occurrence. So, if you are planning on being a space tourist (or if you want to reduce your risk for SCA here on Earth), work on controlling these risk factors. And maybe bring your own LUCAS device on board, just in case.