Tag Archives: cardiovascular disease

Women Reduce Risk of Cardiovascular Disease and Diabetes With Strength Training

That's a dumbbell in her right hand. I work-out with those myself.

That’s a dumbbell in her right hand. I work-out with those myself.

I don’t have access to the full scientific report, but I’ve posted part of the abstract below.

The biggest problem with the study at hand is that physical activity apparently was surveyed only at the start of this 14-year study. Results would be much more robust if activity was surveyed every year or two. My overall activity level seems to change every two or three years. How about you?

Moving on.

“Compared to women who reported no strength training, women engaging in any strength training experienced a reduced rate of type 2 diabetes of 30% when controlling for time spent in other activities and other confounders. A risk reduction of 17% was observed for cardiovascular disease among women engaging in strength training. Participation in both strength training and aerobic activity was associated with additional risk reductions for both type 2 diabetes and cardiovascular disease compared to participation in aerobic activity only.

CONCLUSIONS: These data support the inclusion of muscle-strengthening exercises in physical activity regimens for reduced risk of type 2 diabetes and cardiovascular disease, independent of aerobic exercise. Further research is needed to determine the optimum dose and intensity of muscle-strengthening exercises.”

PMID 27580152

Source: Strength Training and the Risk of Type 2 Diabetes and Cardiovascular Disease. – PubMed – NCBI

Steve Parker, M.D.

PS: Cardiovascular disease includes heart attack, cardiac death, stroke, coronary angioplasty, and coronary artery bypass grafting.

Do Potatoes Make You Fat or Diabetic?

Researchers in Denmark say “no.” French fries, maybe.

“The identified studies do not provide convincing evidence to suggest an association between intake of potatoes and risks of obesity, T2D, or CVD. French fries may be associated with increased risks of obesity and T2D although confounding may be present. In this systematic review, only observational studies were identified. These findings underline the need for long-term randomized controlled trials.”

Source: Potatoes and risk of obesity, type 2 diabetes, and cardiovascular disease in apparently healthy adults: a systematic review of clinical intervention and observational studies

Fish Oil Supplements Are a Waste for Many

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

Many of us are eating fish or taking fish oil supplements, hoping that they will prevent heart attacks and the associated premature death. As it turns out, they may do neither.

I’ve been sitting on this research report a few years, waiting until I had time to dig into it. That time never came. The full report is free online (thanks, British Medical Journal!). I scanned the full paper to learn that nearly all the studies in this meta-analysis used fish oil supplements, not the cold-water fatty fish the I recommend my patients eat twice a week.

Here’s the abstract:

Objective: To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer.

Data sources: Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies.

Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate.

Results: Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded.

Conclusion: Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

If you’re taking fish oil supplements on your doctor’s advice, don’t stop without consulting her. The study at hand doesn’t address whether eating cold-water fatty fish twice a week prevents heart attacks and premature death. 

Steve Parker, M.D.

Reference: Hooper, Lee et al. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ  2006;332:752-760 (1 April), doi:10.1136/bmj.38755.366331.2F (published 24 March 2006).

Evolutionary Aspects of Obesity, Insulin Resistance, and Cardiovascular Risk

paleo diet, Paleolithic diet, hunter-gatherer diet

Huaorani hunter in Ecuador

Spreadbury and Samis have a review-type article in Current Cardiovascular Risk Reports. Here’s the abstract:

Cardiovascular disease (CVD) is still virtually absent in those rare populations with minimal Western dietary influence. To date, exercise, altered fats, fibre, anti-oxidants or Mediterranean diet do not appear to overcome the discrepancy in CVD between hunter-gatherer and Western populations. The CVD risk factors of obesity and diabetes are driven by increased caloric intake, with carbohydrates potentially implicated. Paradoxically, non-Westernized diets vary widely in macronutrients, glycemic and insulinemic indices, yet apparently produce no obesity or CVD regardless, even with abundant food. ‘Ancestral’ grain-free whole-food diet may represent the best lifestyle intervention for obesity and CVD. Such diets are composed of the cells of living organisms, while Western grains, flour and sugar are dense, acellular powders. Bacterial inflammation of the small intestine and vagal afferents appears a crucial step in leptin-resistance and obesity. Therefore it may be important that the Western diet resembles a bacterial growth medium.

You may remember Spreadbury’s name from his theory about acellular carbohydrates causing obesity via alterations in gut microorganisms. Spreadbury is with the Gastrointestinal Diseases Research Unit, Queen’s University, Kingston, Ontario, Canada.

You can read the articles for yourself. The following are a few of the authors points I found interesting or want to remember.

Does physical activity explain differences in CVD between Westernized and non-Westernized Peoples? They say “maybe.”

Throughout the article are references to aboriginals like the Hadza, Kitavans, Ache, Shuar, Australian aborigines, and Inuits. I always take comparisons of them to modern Europeans with a grain of salt, because of potential genetic differences between the populations. Moreover, diet and activity levels are only two of myriad cultural differences.

Australian Aborigine in Swamp Darwin

Australian Aborigine in Swamp Darwin

Can dietary changes reduce the incidence of CVD? They say it’s unclear.

Regarding modern paleo diet trials, “All the studies with ad libitum eating [eat all you want] have reported a spontaneous reduction in caloric intake in the order of 15-30%.” (Three references.) “The reduced food intake appeared driven by a satiety increase that was apparently not explicable by energy density, fiber or macronutrient content.” (One reference.)

“In those eating a Westernized diet, carbohydrates are increasingly recognized as being associated with poor metabolic health.” Evidence? Only one reference cited: Zienczuk’s 2012 article on high arctic Inuits.

“…non-Westernized populations with excellent metabolic and cardiovascular health almost invariably have negligible dietary contribution from grains, as well as refined sugar.” No citations.

“For ‘western-style’ diets and most obesogenic diets tested, gut microbiota appear to play a crucial role in obesity.” That’s a bold statement. References? Only one, a mouse study.

The rest of the article is about Spreadbury’s acellular carb/obesity theory. He suggests that small intestine bacteria play a more prominent role than colonic germs. Bacterial-driven inflammation….

The authors provide an example of a grain-free whole-food diet. It’s unrestricted in fruit, leafy or root vegetables, unprocessed meats, eggs, fish, nuts (except peanuts), mushrooms, herbs and spices. Occasional foods to be eaten in moderation are legumes, rice, yogurt, milk, cheeses, sweet corn, palm oil/lard/olive oil, and salt. Avoid almost all processed foods, breads, cereals, cakes/cookies/donuts etc., refined sugars, dried or processed fruits, vegetable/seed oils, and processed meats. They advise a vitamin D supplement. I’m not sure if they came up with this diet on their own, or it’s S. Lindeberg’s outline.

A final quote:

The macronutrient independence of the health from ancestral diet suggests whole foods are more important to health than their macronutrient or other chemical components, and that good health is associated with unprocessed cellular foods. Flour, sugar and processed foods appear to be important drivers of Western metabolic dysfunction, overweight and inflammation, and may prove to have a profound impact on, or even be the initiators of cardiovascular disease.

I’m sure Spreadbury and Samis would agree we need more basic science and clinical research into these issues, involving human test subjects. Maybe I’m prejudiced, but I’m more interested in Asians, Africans, and Europeans than Shuar people.

Steve Parker, M.D.

Reference: Spreadbury, Ian and Samis, Andrew J.S. Evolutionary aspects of obesity, insulin resistance, and cardiovascular risk. Current Cardiovascular Risk Reports, April 2013, vol. 7, issue 2, pp. 136-146.

Don’t Kid Yourself: Obesity Still Shortens Life Even If “Metabolically Healthy”

I'll eat my hat if this dude doesn't have metabolic syndrome

I’ll eat my hat if this dude doesn’t have metabolic syndrome

See details at MedPageToday.

Some folks can get away with smoking or drinking too much, but others can’t. They have hell to pay. There’s one sure-fire way to eliminate smoking-related disease risk.

Some studies suggest you can be healthy and long-lived while obese as long as you’re “metabolically healthy.” That is, if you have normal blood pressure, LDL cholesterol, triglycerides, blood sugar, and waist circumference. (You can be obese with a “normal” waist circumference, but it’s not easy.) A new meta-analysis finds the “metabolically healthy” label is a misnomer: you’re still at higher risk for death or cardiovascular events if you’re obese and free of metabolic syndrome features.

“Our results do not support this concept of ‘benign obesity’ and demonstrate that there is no ‘healthy’ pattern of obesity,” Kramer and colleagues wrote. “Even within the same category of metabolic status (healthy or unhealthy) we show that certain cardiovascular risk factors (blood pressure, waist circumference, low high-density lipoprotein cholesterol level, insulin resistance) progressively increase from normal weight to overweight to obese.”

Click for the scientific journal abstract.

This report does not directly address the “fat but fit” concept, whereby you can counteract some of the adverse health effects of obesity by being fit. By fit, I mean regularly exercising and achieving a decent level of capacity and tolerance for physical activity. Fat but fit still holds.

Steve Parker, M.D.

PS: For an opposing view of the study at hand, see comments by psychologist Deb Burgard. (h/t Beth Mazur)

Do Vegetables and Fruits Prevent Disease?

Switching to the paleo diet often leads to increased vegetable and fruit consumption

Switching to the paleo diet often leads to increased vegetable and fruit consumption

Potential answers are in the American Journal of Clinical Nutrition (2012).  I quote:

For hypertension, coronary heart disease, and stroke, there is convincing evidence that increasing the consumption of vegetables and fruit reduces the risk of disease. There is probable evidence that the risk of cancer in general is inversely associated with the consumption of vegetables and fruit. In addition, there is possible evidence that an increased consumption of vegetables and fruit may prevent body weight gain. As overweight is the most important risk factor for type 2 diabetes mellitus, an increased consumption of vegetables and fruit therefore might indirectly reduces the incidence of type 2 diabetes mellitus. Independent of overweight, there is probable evidence that there is no influence of increased consumption on the risk of type 2 diabetes mellitus. There is possible evidence that increasing the consumption of vegetables and fruit lowers the risk of certain eye diseases, dementia and the risk of osteoporosis. Likewise, current data on asthma, chronic obstructive pulmonary disease, and rheumatoid arthritis indicate that an increase in vegetable and fruit consumption may contribute to the prevention of these diseases. For inflammatory bowel disease, glaucoma, and diabetic retinopathy, there was insufficient evidence regarding an association with the consumption of vegetables and fruit.

It bothers me that vegetables and fruits are lumped together: they’re not the same.

The paleo diet is unfairly characterized as meat-centric. It can certainly provide beaucoup vegetables and fruits. Diabetics should be careful which ones they choose, to avoid spikes in blood sugar.

Steve Parker, M.D.

Too Much Calcium May Be Worse Than Too Little

I’ve been fretting that the paleo diet may not provide enough calcium to keep aging bones strong. On the other hand, the writer(s) at the Joslin Diabetes Blog point out that too much calcium may promote cardiovascular disease.

The February, 2013, issue of British Medical Journal has a pertinent research report. The Joslin blogger writes:

Participants were women from a mammography cohort who were asked about their calcium consumption, using a food frequency questionnaire, at baseline and seven-to-ten years later. The 61, 433 women were followed for a period of 19 years. During that time, 6894 participants died of cardiovascular disease or stroke. The researchers found that the women taking over 1400mg of calcium per day had a higher incidence of cardiovascular disease. Participants whose calcium consumption remained within suggested bounds, between 600mg and 1000mg per day, did not appear to have a greater vulnerability to cardiac disease.

Read the rest.

I confess I haven’t read the BMJ article.

I always wonder about overall death rates when I see results like this. A group may have higher or lower rates of cardiovascular disease, and yet live longer than the comparison group. An intervention could prevent cardiovascular disease and cardiovascular death, yet increase the incidence of death from infection, cancer, accidents, or suicide, etc.

I bet a lot of adults eating a paleo-style diet approach or exceed 600 mg a day of calcium. I’m feeling better about the calcium in paleo diets. But I don’t want to have to depend on feelings.

The Joslin blogger notes that, “Perhaps it is time to have a conversation with your health care provider to determine what the best dose of calcium is for you.” Problem is, I’m not sure any healthcare provider really knows the best “dose” of calcium for the average person, whether supplemental or dietary calcium.

Sorry, men. These findings may or may not apply to you. At least you don’t have to worry about osteoporosis nearly as much as women.

Steve Parker, M.D.

PS: In case you hadn’t run across it elsewhere, note that taking a calcium supplement without a concomitant vitamin D supplement may be more harmful than taking calcium with vitamin D.


Paleo Diet Advocates Fear Modernity

…according to David Gorski at Science-Based Medicine.

Gee, I hadn’t noticed that fear.  Maybe it’s subconscious.

Dr. Gorski makes some good points along with others I disagree with.  I expect the commentators at SBM will address many of the controversial points.  They’re a smart readership.

One uncommon observation of his is that the “complementary and alternative medicine” believers tend to embrace the paleo diet and lifestyle.  I’ve noticed that also.  To the extent that the CAM folks are often unscientific or anti-scientific, those of us examining the paleo diet from a scientific viewpoint have to be wary of “guilt by association.”

A major point that Dr. Gorski didn’t address is that living hunter-gatherers studied over the last century or two don’t have nearly as much cardiovascular disease and death as modern Western societies.  That’s a common meme in the paleosphere, started by the prominent paleo book authors.  (I’ve not reviewed the original sources.)  I’m talking about lower rates of heart attacks, strokes, hypertension, peripheral arterial disease, and premature death.  Note that the mere presence of atherosclerosis may not correlate with these hard clinical endpoints.

Are We Eating Too Much Salt?

Unfairly demonized?

Most paleo diets are quite a bit lower in salt and sodium than standard American diets.  At the same time, they should be quite a bit higher in potassium, which may be very healthy.

Every 10 years or so, “the powers that be” make a push for population-wide salt restriction thinking that it will prevent cardiovascular disease and associated premature death.  The American Council on  Science and Health has a brief review of the latest research on salt restriction, and it’s not supportive of population-wide sodium restriction.

Remember, table salt molecules contain one sodium atom and one chloride atom.  Salt-restricted and low-sodium diets are usually designated by the amount of sodium, not salt.

That being said, I do believe some individuals have elevated blood pressure related to relatively high sodium intake.  This may apply to one of every five adults with high blood pressure.  To find out if you’re one of the five, you could go on a low-sodium diet—1.5 to 3 grams a day—for one or two months and see what it does to your blood pressure.  Get your personal physician’s blessing first.

Steve Parker, M.D.

Heart Disease Deaths in Diabetics Falling Fast

MedPage Today a few months ago reported a dramatic drop in cardiovascular death rates for folks with diabetes:

The death rate from cardiovascular disease in U.S. adults with diabetes fell 40% from 1997 to 2004, CDC and NIH researchers said.

And that’s not all:

Additionally, all-cause mortality in diabetic participants dropped by 23% (95% CI 10% to 35%), Gregg and colleagues reported, from 20.3 to 15.1 per 1,000 person-years after adjusting for age.

The researchers identified several factors that likely account for the improved life expectancy for diabetic Americans.

Among them was the “steady improvements in quality and organization of care, self-management behaviors, and medical treatments, including pharmacological treatment of hyperlipidemia and hypertension,” Gregg and colleagues suggested.

The MedPage Today article didn’t define cardiovascular disease.  It typically includes heart attacks, heart failure, strokes, aortic aneurysms, among a few others.

Hope that cheers you up!

Steve Parker, M.D.