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Racial Differences in Physical Activity and Acquisition of Coronary Artery Calcification

1200 words

Last week a study was published stating that white men who exercised 3 times the recommendation of 1.5 hours (450 minutes, 7.5 hours) had a higher chance of getting coronary artery calcification (CAC), which is the accumulation of plaque and calcium in the arteries of the heart. You, of course see news headlines such as: “Physically active white men at high risk for plaque buildup in arteries“; “White Men Who Exercise Every Day Have 86 Per Cent Higher Risk of Heart Disease Than Black Men, Study Claims“; “Excessive Exercise May Harm The Heart, Study Suggests “; “Excessive exercise increases risk of arterial plaque buildup in white men“; (and my personal favorite headline about this study): “You can exercise yourself to death, says new study“. People just passing by and reading the title (like most do) may then conclude that “they’re saying not to exercise because of CAC.” No, this is not what they are saying at all.

The Coronary Artery Risk Development in Young Adults (CARDIA) study is one of the most important studies in the study of coronary heart disease that have been undertaken. It is a sample of men and women, about equal numbers of each race, from Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California. The study began in 1985-86 and there were follow-up examinations at “1987-1988 (Year 2), 1990-1991 (Year 5), 1992-1993 (Year 7), 1995-1996 (Year 10), 2000-2001 (Year 15), 2005-2006 (Year 20), 2010-2011 (Year 25), and 2015-2016 (Year 30).” The CARDIA website writes:

Data have also been collected on physical measurements such as weight and body composition as well as lifestyle factors such as dietary and exercise patterns, substance use (tobacco and alcohol), behavioral and psychological variables, medical and family history, and other chemistries (e.g., insulin).

So there is a goldmine of information to be gleaned from this data. The study that is getting press in the news uses data from this cohort.

The study

The study is titled 25-Year Physical Activity Trajectories and Development of Subclinical Coronary Artery Disease as Measured by Coronary Artery Calcium by Laddu et al (2017). They studied three cohorts by the amount of time they exercised per week: below requirement, at requirements, or above requirements. It is recommended to exercise at least 150 minutes per week.

There were 3,175 men and women who participated in the CARDIA study between 1985 and 2011 who had CAC data available for 25 years. About 47.4 percent of the sample was black, with 56.6 being women. The cohort “consisted of 18.9% black men, 24.6% white men, 28.6% black women, and 28.0% white women” (Laddu et al, 2017).

Of the three activity levels they studies (below 150 minutes, 150 minutes, and over 150 minutes), they observed that white men who exercised 3 times the weekly recommendation (150 minutes(3)= 450 minutes=7.5 hours) had a higher chance of developing CAC. It’s worth noting that exercise time was self-reported (which is the only way I can see how something like this would work, are you supposed to follow people with a camera every day to see how long they engage in physical activity?).

In regards to the physical activity measurement, Laddu et al (2017) write:

At each of the 8 examinations, self-reported leisure-time PA was ascertained by the interviewer-administered CARDIA Physical Activity History Questionnaire.17 Participants were asked about the frequency of participation in 13 specific categories (8 vigorous intensity and 5 moderate intensity) of recreational sports, exercise, home maintenance, and occupational activities during the previous 12 months. Intensity for each activity was expressed as metabolic equivalents (METs), in which 1 MET is defined as the energy expended at rest, which is approximately equivalent to an oxygen consumption of 3.5 mL per 1 kg of body weight per minute.18Vigorous activities (≥6 METs) included running or jogging; racquet sports; biking; swimming; exercise or dance class; job lifting, carrying, or digging; shoveling or lifting during leisure; and strenuous sports. Moderate-intensity activities (3-5 METs) included nonstrenuous sports, walking and hiking, golfing and bowling, home exercises or calisthenics, and home maintenance or gardening.19 Each activity was scored according to whether it was performed for 1 hour or longer during any 1 month during the past year, the number of months it was performed at that level, and the number of months the activity was performed frequently. Each activity was then assigned an intensity score, ranging from 3 to 8 METs, and a duration threshold (ranging from 2-5 hours per week), above which participation was considered to be frequent.20

This is a good metric; though I would like to see a study that looks at just gym-going activity and death, time spent in the gym strength training/moderate to intense cardio. Nevertheless, white men who reported more physical activity had a higher chance of acquiring CAC. Though I can see people’s recall being hazy, people over/under reporting, etc etc.

White men who exercised 7.5 hours per week were 27 percent more likely to get CAC, whereas blacks who exercised that much were at no greater risk to acquire CAC when compared to whites (7.5 hours of exercise compared to less than 2.5 hours per week). Black women who exercised less than the recommendations had a higher chance of acquiring CAC. The researchers couldn’t ascertain why white men who exercised three times the recommendations had such a higher chance of acquiring CAC by the time they reached middle age, but Dr. Jamal Rana says “however this plaque buildup may well be of the more stable kind, and thus less likely to rupture and causes heart attack, which was not evaluated in this study.” The head author, Dr. Deepika Laddu also reiterated: “it does not suggest that anyone should stop exercising.” So people who just read these click bait headlines who say “They’re telling whites not to exercise!”, you’re wrong and you should read papers and not news articles.

This is the perfect example of people reading click baity, fear-mongering headlines and running with it. I saw some people saying “They’re telling us not to exercise!” No. If you were to read the paper and any serious news articles on the matter, you’d see that they do not recommend that people do not exercise. Now the question is, why do whites who exercise more than 7.5 hours per week have a higher chance of acquiring heart disease? I can think of a few explanations (though they are not satisfactory): 1) genes: which genes? Why? How do they interact with the body over time to lead to arterial calcification?; 2) dietary habits: I’d like to know what their diet was like and see their macro composition, carbohydrates, not saturated fat, causes heart disease (Siri-Tirino et al, 2010; de Souza et al, 2015) so that may be a huge contributing factor.

Nevertheless, this is yet another physiological race difference. Oddly enough, black men are more likely than white men to have hypertension (Hicken et al, 2013).

Even though black men, on average, have higher rates of hypertension than white men, white men who are physically active for 7.5 had a higher chance of acquiring CAC than those who exercised less than 2.5 hours per week. This effect wasn’t seen in black men who had physical activity at that level, which, of course, implies that differences in genes and SES underlie this difference. I await more papers into this matter into the mechanisms of how and why this occurs and will ruminate on this myself in the future. No, this study does not tell white men not to exercise.

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Diet and Exercise: Don’t Do It?

1800 words

On Twitter, JayMan linked to a video about a time traveling dietician who travels back to the 70s to give nutritional advice to a couple. He kept going back on what he said, re eggs and cholesterol, Paleo diet, etc. Then at the end of the video, the ‘time traveling dietician’ says “It turns out it’s genetic. It doesn’t matter whether you exercise or what you eat.”

I then asked JayMan if he was advising people to not diet or exercise—and if he was doing so—what credentials does he have to give such advice? “Appeal to authority!” So if some random guy gave me legal advice and I asked his credentials, is that an appeal to authority? Similarly, if someone is trying to give me medical advice, is asking where he got his medical license an appeal to authority? The thing is, people have specialties for a reason. I wouldn’t take diet and exercise advice from some anon blogger with no credentials, just like I wouldn’t take legal advice from a biologist. Anyway, I’ll review some studies on exercise, dieting, and sitting in regards to all-cause mortality.

Sitting and all-cause mortality

Listening to such advice—like not dieting or exercising—will lower your quality of life and life expectancy. The longer you sit, the more likely you are to have rolled shoulders among other postural imbalances. One of the biggest reasons that sitting is related to all-cause mortality (Chau et al, 2013Biddle et al, 2016). So listening to this shitty advice to ‘not exercise’ will lead an individual to having a lower QoL and lower life expectancy.

Sitting is associated with all-cause mortality because if, say, one is sitting at a desk for 8 hours per day then goes home and sits for the rest of the day, circulation will not get not get to the lower extremities. Furthermore, even mild-to-moderate exercise attenuates the situation (Chau et al, 2013). Further, reducing sedentary behavior (and of course, watching less TV) can possibly raise life expectancy in the US (Katzmarzyk and Lee, 2012). They found that cutting daily sitting time to less than three hours can increase life expectancy by two years (and, of course, quality of life). There is a large body of research on sitting and all-cause mortality (Stamatakis et al, 2013). It’s also worth noting that too much sitting decreases life expectancy—even with exercise. So JayMan’s (unprofessional) advice will lead to someone having a shitty life quality and lower life expectancy.

Dieting, and all-cause mortality

This is a bit trickier. I know that dieting for weight loss doesn’t work (Aamodt, 2016; Fung, 2016)—that is, traditional dieting (high-carb diets). The traditional advice is to eat high-carb, low-fat and moderate protein—this is due to what occurred in the 70s—the demonization of fat and the championing of carbs. This, clearly, is wrong. This has led to the obesity epidemic and the cause is our evolutionary novel environments. The main reason is that we have constructed environments for ourselves that are novel, and thus we’ve not had enough time to adapt to what we eat/how we live our new lives in our modernized world.

Indeed, even hunter-gathers don’t have our disease rates that we have—having low to no cases of our diseases of civilization (see Taubes, 2007 for a review). Why is this? It’s because they are physically active and they do not eat the same processed carbohydrates that we in first-world societies do.

In regards to exercise and all-cause mortality, people who exercise more often have a lower chance of dying from all causes than more sedentary people (Oja et al, 2016O’Donovan et al, 2017). So it’s becoming clear that JayMan is just talking out out his ass here. I’d love to hear any MD say to a patient “Don’t diet, don’t exercise. Don’t eat well. It doesn’t work.” Because that MD will be a shill for Big Food.

Further, when I say ‘diet’, I don’t mean eating below the BMR. Your ‘diet’ is what you eat, and by changing your diet, you’re changing to healthier habits and eating higher-quality foods. People like JayMan make it seem like you should eat whatever you want and not to exercise. Following this advice, however, will lead to deleterious consequences.

It DOES matter what you put into your body; it DOES matter if you exercise or not. If you do not, you will have a lower life expectancy than who does exercise and eats well.

On a side note, I know that dieting does not work for weight loss. Traditional dieting, that is. Dr. Jason Fung, world-renowned obesity, diabetes and intermittent fasting expert, has people lose and keep their weight off. He actually understands what causes obesity—insulin. Higher insulin levels are also tied to the obesity pathway through lack of glucagon receptors (Lee et al, 2014). Why is this important? First, we have to understand what insulin does in the body. Once you understand what insulin does in the body then you will see why JayMan is wrong.

Insulin inhibits the breakdown of fat in the adipose tissue by inhibiting the lipase that hydrolyzes (the chemical breakdown of a compound due to a reaction with water) the fat out of the cell. Since insulin facilitates the entry of glucose into the cell, when this occurs, the glucose is synthesized into glycerol. Along with the fatty acids in the liver, they both are synthesized into triglycerides in the liver. Due to these mechanisms, insulin is directly involved with the shuttling of more fat into the adipocyte. Since insulin has this effect on fat metabolism in the body, it has a fat-sparing effect. Insulin drives most cells to prefer carbohydrates for energy. Putting this all together, insulin indirectly stimulates the accumulation of fat into the adipose tissue.

Does this physiologic process sound that you can ‘eat whatever you want’? Or does it tell you that you should lower your carb intake as to not induce blood glucose spikes which lead to an increase in insulin? Over time, these constant blood glucose/insulin spikes lead to insulin resistance which has the body produce more insulin due to the insulin resistance resulting in a vicious cycle.

So, it seems that in order to have a higher QoL and life expectancy, one must consume processed carbs very sparingly.

These behaviors of over consuming processed carbohydrates come down to the environments we have constructed for ourselves—obesogenic environments. An obesogenic environment “refers to an environment that helps, or contributes to,
obesity” (Powell, Spears, and Rebori, 2010).

Our current obesogenic environment also contributes to dementia and cognitive impairment. What makes environments ‘obesogenic’ “is the increased presence of food cues and the increased consumption of a diet which compromises our ability to resist those cues” (Martin and Davidson, 2015). So if our obesogenic environments change, then we should see a reduction in the number of overweight/obese people.

Diet is very important for Type II diabetics. For instance, TII diabetics can manage, and even reverse, their disease with a low-carb ketogenic diet (LCKD) lowering their hBA1c, having a better lipid profile, cardiac benefits, weight loss etc (Westman et al, 2008; Azar, Beydoun, and Albadri, 2016; Noakes and Windt, 2016; Saslow et al, 2017). I wonder if JayMan would tell TII diabetics not to diet or exercise…. That’d be a recipe for disaster. TII diabetics need to keep their insulin down and eating an LCKD will do that; taking JayMan’s ‘advice’ not to diet or exercise will quickly lead to more weight gain, an exacerbation of problems and, eventually, death due to complications from not correctly managing the disease. JayMan needs to learn the literature and understand these papers to truly understand why he is wrong.

Exercise and all-cause mortality

The relationship between vigorous exercise and all-cause mortality is well studied. Gebel et al (2015) conclude that “Independent of the total amount of physical activity, engaging in some vigorous activity was protective against all-cause mortality. This finding applied to both sexes, all age categories, people with different weight status, and people with or without cardiometabolic disease.” Reduced exercise capacity also causes higher all-cause mortality rates (McAuley et al, 2016).

Unfit thin people had two times higher mortality rate than normal weight fit people. Further, overweight and obese fit people had similar mortality rates when compared to normal weight fit people (Barry et al, 2013). Clearly, physical activity needs to be heightened if one wants to live a longer, higher quality life. This runs completely opposite of what JayMan is implying.

Exercise into old age is also related to higher cognition and lower mortality rate in when compared to individuals who do not exercise. Exercise also protects against cognitive degeneration in the elderly (Bherer, Erikson and Lie-Ambrose, 2013; Carvalho et al, 2014; Paillard, 2015). If you want to keep your cognition into old age and live longer, it seems like your best bet is to exercise at a young age in order to stave off cognitive degeneration.

Strength and mortality

Finally, one last thing I need to touch on is strength and mortality. Strength is, obviously, increased through exercise. Stronger men live longer—and are protected from more disease such as cancer—than weaker men, even when controlling for cardiorespiratory fitness and other confounds (Ruiz et al, 2008).

As I have covered in the past, differences in grip strength account for differences in mortality in men—which also has a racial component (Araujo et al, 2010; Volkalis, Halle, and Meisinger, 2015). The stronger you are, the less chance you have of acquiring cancer and other maladies. Does the advice of ‘don’t exercise’ sound good now? It doesn’t, and I don’t know why anyone would seriously imply that dieting and exercise doesn’t work.

Conclusion

Dieting (meaning eating a higher quality diet, not attempting to lose weight) and exercise do work to increase life expectancy. The advice of “don’t do anything, it’s genetic” makes no sense at all after one sees the amount of literature there is on eating mindfully and exercising. I know that exercise does not induce weight loss, but it does contribute to living longer and staving off disease.

People should stay in their lane and leave things to the professionals—the people who are actually working with individuals every day and know and understand what they are going through. The canard of ‘eat whatever, don’t exercise, it’s genetic’ is very dangerous, especially today when obesity rates are skyrocketing. JayMan needs to learn the literature and how and why exercise and eating right leads to a higher quality of life and life expectancy. Thankfully, people like JayMan who say not to diet or exercise have no pull in the real world.

Clearly, to live longer, eat right, don’t sit for too long (because even if you exercise, sitting too long will lower your life expectancy) and exercise into old age and your chance of acquiring a whole slew of deleterious diseases will be lessened.