Macro nutrients balance and heart disease

[jim mcnamara]

From meeting of cardiologists in Spain:
Study on +135000 people worldwide, researchers interpretation:

High carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.

Note that the study included many residents of third world countries where macronutrient (fats and carbohydrates) over consumption is not common.
For biology types:
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32252-3/fulltext?elsca1=tlpr
For normal humans:
https://www.medpagetoday.com/meetingcoverage/esc/67566

 

[Ygggdrasil]

A few notes to keep in mind with the interpretation of the results:
1. The macronutrient consumption data are based on food frequency questionaires, a somewhat unreliable means to measuring food consumption. How accurate do you think you'd be if asked about how much of each type of food you ate over the past few months? For more disucssion of problems with food frequency questionaires and other general issues with studies on nutrition see: http://fivethirtyeight.com/features/you-cant-trust-what-you-read-about-nutrition/

2. The study is an observational study that can only assess correlation, not causation. People who reported eating more carbohydrates had higher mortality. Was eating more carbohydrates the cause of the higher mortality, or were there other differences between people who ate more carbohydrates and those who ate less? A common problem with these studies is that people who follow dietary guidelines are more likely to follow other guidelines for healthy living, so one could just be picking up a signal from decreased mortality of those who pay attention to their health, in general. Socioeconomic factors are another potential confounding factor in the results. In many of the third world countries studied, a diet higher in animal protein would likely be more expensive than a diet higher in carbohydrates. These confounding variables make inferring causation difficult. Randomized controlled trials would provide a gold standard for assessing whether there is a causal relationship between carbohydrate intake and mortality, though these are notoriously difficult to perform (how do you get a large cohort of people to change their diets for long periods of time?).

3. Even if the differences in diet are causally related to the changes in mortality and CV events, the exact mechanism is unclear. For example, in a commentary published in the Lancet along side the research paper (I would recommend reading the commentary if you are interested in the subject), the authors note:

Micronutrient malnutrition is an important problem in many of the countries included in PURE. Animal products are rich sources of zinc, bioavailable iron, vitamin K2, and vitamin B12, which might be suboptimal in populations consuming high carbohydrate diets. Therefore, one potential explanation for the PURE results is that nutrient-dense meats corrected one or more nutrient deficiencies

If the results are partly due to consumption of animal products alleviating micronutrient malnutrition, it is unclear whether the results would be as applicable in populations where micronutrient malnutrition is not an issue.

Overall, the study is a very important piece of evidence in determining the best amount of carbohydrates, proteins and fats to include in one's diet. However, it is not a definitive study, so one needs to consider the entire body of evidence including observational studies (such as this one) done in a number of different populations, randomized clinical trials, and laboratory experiments that get at the mechanisms involved.

 

[Ygggdrasil]

Saw a good piece in The Atlantic about the study:

This week, the world learned the results of an enormous study of food and health. The study included 135,335 people from 18 different countries across five continents who were followed for seven years. It’s known as the Prospective Urban Rural Epidemiology study, or PURE, and the results were presented at the European Society of Cardiology meeting in Barcelona and published in The Lancet.

The practically important findings were that the healthiest people in the world had diets that are full of fruits, beans, seeds, vegetables, and whole grains, and low in refined carbohydrates and sugar.

As a writer and a reader, though, this is very boring. If I pitched that to my editor, he would laugh at me. What is new here? Why is this interesting? You know what would be novel? You getting fired! Now get out there and find me a story, dammit!

Let’s look at the internet. The coverage of the study was mostly fine, but the headlines alone promise novelty. Stat ran “Huge New Study Casts Doubt on Conventional Wisdom About Fat and Carbs.” Reuters ran “Study Challenges Conventional Wisdom on Fats, Fruits, and Vegetables.” Medscape ran “PURE Shakes Up Nutritional Field: Finds High Fat Intake Beneficial.” Even the editors at The Lancet used the headline “PURE Study Challenges the Definition of a Healthy Diet.”

Does it?

https://www.theatlantic.com/health/...ate-intake-of-things-linked-to-health/538428/

Worth a read if you are interested in the subject.

 

[Laroxe]

Saw a good piece in The Atlantic about the study:

https://www.theatlantic.com/health/...ate-intake-of-things-linked-to-health/538428/

Worth a read if you are interested in the subject.

I have to say, I wasn't keen on the Atlantic article, this research and other papers are essentially discrediting the last 20 years of dietary advice, and it has very real implications for the way in which poor quality epidemiology is used to support current medical opinion. In many ways public health advice hasn't moved on much from the seven deadly sins. In fact its only in very recent times that a good diet has been defined as the one with the least nutritional value in an attempt to "treat" obesity, the recognition that reducing fats isn't necessarily good for people has shifted the focus to carbohydrates, principally simple sugars. This continues despite the predicted health tsunami of increasing heart disease and shorter life expectancy failing to appear, in fact the incidence of heart disease has been falling, in a way that cannot be explained by better interventions and life expectancy continues to rise though this has slowed.
I'm not sure why the author thinks that this is the diet of the healthiest populations, the last time I looked this would be the Swiss, depending on what measure you use and this is not a country associated with rampant vegetarianism.
I suspect that there are a great many biases involved in the industry of public health and the promotion of specific healthy foods which influence many of the findings and there have been a fairly continuous stream of papers, challenging the role of fats in heart disease which have simply been dismissed or attacked. This one is very difficult to dismiss and if you look around any supermarket, just note how many products are labeled low fat and the economic effects of this study, we have yet to see how it will effect the drug companies as statins come under increasing scruitiny.
I think this is far more important than the author of the Atlantic article suggests and he makes a number of sweeping statements that don't represent what the study actually suggests.

 

[bohm2]

These are some other studies that question the link between saturated fat and heart disease and/or mortality:

The following is a list of review papers and meta-analyses on saturated fats.

In recent years, there have been a total of at least 17 meta-analyses and systematic reviews, plus 5 non-systematic reviews that have have failed to find a clear link between saturated fats and heart disease/cardiovascular death:

–3 meta-analyses (2, 4, 11), 3 systematic reviews (2, 4, 12)) and 2 non-systematic reviews (3, 13) examined epidemiological data (the kind of evidence that can show association but not causation) and found that saturated fats are not associated with heart disease (in one review, polys but not carbs were found to pose less cardiovascular risk).

–6 meta-analyses (1, 4, 5, 9, 15, 16), 5 systematic reviews (1, 4, 5, 12, 15) and 3 non-systematic reviews (3, 10, 13) examined clinical trials (the more rigorous kind of data that can demonstrate cause and effect), and found no effect of saturated fats on either cardiovascular mortality or total mortality. Some reviews also found no effect on cardiovascular events. The effect on the “soft” endpoint of heart disease is more varied, because measures of heart disease (LDL-C vs. HDL-C , etc) are debated. In some analyses, replacing saturated fats with polyunsaturated vegetable oils reduce cardiovascular events (but not deaths). In one analysis looking only at cardiovascular events (14), a benefit was seen in replacing saturated fats with polyunsaturated vegetable oils.

There have also been commentaries and other non-systematic reviews (6, 7, 8)...

http://www.nutrition-coalition.org/saturated-fats-do-they-cause-heart-disease/

 

[bohm2]

This 2017 article is an excellent piece worth reading in full. I'll quote some of hi-lites, in case you have to be a health professional to access to link:

Coconut oil is bad for health!" announced headlines recently when the American Heart Association (AHA) issued a new Presidential Advisory[1] on saturated fats, stating that these fats really do most definitely cause heart disease. As a writer who's spent more than a decade researching the science, and as a cardiologist whose practice is based on the most updated findings, we can say that the AHA paper is an outlier, with at least nine other expert reviews finding weak to nonexistent evidence for this link.

In recent years, however, work by us[5] and others[4] has shed light on these forgotten trials, prompting teams of scientists all over the world to unearth and evaluate this evidence. One set of files was literally hauled out of a basement, reconstructed, and reexamined.[6] And the results? None of these reviews could find any evidence that saturated fats had an effect on cardiovascular mortality or total mortality (Table).[6,7,8,9,10,11,12,13,14] As quite a few of the authors state in their conclusions, the results clearly do not support the current national dietary guidelines which limit saturated fats to 10% of daily calories, or those by the AHA and American College of Cardiology, which further limit those fats to 5%-6% of calories for people with high cholesterol.[15,16]

So much data refute the diet-heart hypothesis that it's a wonder the AHA can ignore it all.

We believe that one reason for the AHA's resistance to this evidence is its significant, longstanding reliance on funding from interested industries, such as the vegetable-oil manufacturer Procter & Gamble, original maker of Crisco Oil, which virtually launched the AHA as a nationwide powerhouse in 1948.[5] Just recently, Bayer, the owner of LibertyLink soybeans, pledged up to $500,000 to the AHA, no doubt encouraged by the group's continued support of soybean oil, which is by far the dominant type of oil consumed in America today. It is striking that the authors of the three review papers supporting the AHA's stance on vegetable oils all report receiving funding from one or more vegetable-oil companies. Indeed, the review paper that most favored these oils was written by a researcher who discloses serving on the scientific advisory board of Unilever, one of the largest manufacturers of vegetable oils in the world.

http://www.medscape.com/viewarticle/882564?src=soc_tw_160817-pm_mscpedt_news_neuro&faf=1#vp_1