Not all saturated fats are equal when it comes to heart health
Cardiovascular risk of diets rich in saturated fats found in meats and the benefits of plant-based and dairy alternatives
January 28, 2019
Science Daily/Elsevier
The type of saturated fats we eat can affect our risk of a heart attack, according to a study published in the International Journal of Cardiology. People whose diets contain relatively little palmitic and stearic acid -- saturated fats composed of 16 or more carbon atoms (longer-chain saturated fats) that are typically found in meats -- and eat plant-based proteins instead have decreased chances of myocardial infarction. Moreover, individuals who eat more saturated fats with 14 or fewer carbon atoms (shorter-chain saturated fats) that are typically found in dairy products have lower risk of myocardial infarction.
"Our analysis of the diets of large groups of individuals in two countries over time shows that the type of saturated fats we consume could affect our cardiovascular heath," explained lead investigator Ivonne Sluijs, PhD, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands.
The study investigated whether saturated fats with chains varying in length from 4 to 18 carbon atoms are associated with the risk of developing a myocardial infarction. Data from approximately 75,000 people in the UK and Denmark were analyzed. Of these two groups, nearly 3,500 people experienced myocardial infarction in the period between the study's initial outreach and follow-up 13 years later (in Denmark) and 18 years later (in the UK).
"We found that eating relatively little of the longer chained saturated fatty acids and consuming plant-based proteins instead was associated with a lowered risk. Substitution of those saturated fats with other energy sources such as carbohydrates did not affect the risk to develop myocardial infarction," said Dr. Sluijs. Although diets vary by nationality and other factors, the most frequently consumed saturated fat is palmitic acid, with 16 carbon atoms, followed by stearic acid, with 18 carbon atoms, both of which are found in meat products. Consumption of saturated fats that have shorter carbon atom chains and are present in dairy products is less prevalent.
Since the 1960s, when diets high in saturated fat were linked to elevated "bad" LDL cholesterol and coronary heart disease, dietary guidelines recommended restricting saturated fatty acids across the board. In recent years, research studies have raised some questions about what was considered established evidence. Inconsistent findings have pointed to the possibility that different types of saturated fats have different effects on cholesterol levels and the development of coronary heart disease. Despite the fact that their study's findings support this hypothesis, Dr. Sluijs and her fellow investigators recommend proceeding with caution before changing dietary guidelines:
"Our study only allowed us to draw conclusions on the level of associations between saturated fatty acids and the development of myocardial infarction. We do not know whether those fatty acids are actually the cause of differences between the occurrences of myocardial infarction we observed. To further explore this, we need experiments in which the consumption of saturated fatty acids is more controlled and, for instance, compared with consumption of unsaturated fatty acids," she noted.
"The study is applaudable for its large size, prospective cohort study design, and detailed assessment of diet and lifestyle factors. In addition, it is among the few studies that specifically examined individual saturated fatty acids in relation to coronary heart disease risk and compared with different macronutrients," commented Jun Li, MD, PhD, and Qi Sun, MD, ScD, both at the Harvard T.H. Chan School of Public Health, Boston, MA, USA, in an accompanying editorial. They also noted a few limitations of the study and thus called for cautious interpretation of the overall null results for the primary saturated fatty acids.
Dr. Li and Dr. Sun advise that shifts in fat intake should align with the recommended healthy dietary patterns, which emphasize limited intakes of red and processed meat and added sugars, lower salt intake, replacement of refined grains with whole grains, and higher consumption of fruits and vegetables.
https://www.sciencedaily.com/releases/2019/01/190128105230.htm
How diet impact health and well-being
November 2, 2018
Science Daily/University of California - Santa Barbara
From the standpoint of heart health, the Tsimane are a model group. A population indigenous to the Bolivian Amazon, the Tsimane demonstrate next to no heart disease. They have minimal hypertension, low prevalence of obesity and and their cholesterol levels are relatively healthy. And those factors don't seem to change with age.
Also minimal is the incidence of Type-2 diabetes. Which leads scientists to consider the role of diet in the Tsimane's cardiovascular health -- and how it might be impacted over time as the population becomes more exposed to globalization and market forces.
That's where UC Santa Barbara anthropologists Thomas Kraft and Michael Gurven come in. They are part of the Tsimane Health and Life History Project, supported by the National Institutes of Health, which conducted the first systematic study that examines what the Tsimane consume on a regular basis and compares it to that of the Moseten, a neighboring population with similar language and ancestry, but whose eating habits and lifeways are more impacted by outside forces. The researchers' findings appear in the American Journal of Clinical Nutrition.
"Our prior work showed that the Tsimane have the healthiest hearts ever studied, so naturally there's a lot of interest in understanding why and how," said Michael Gurven, a professor of anthropology at UC Santa Barbara, co-director of the Tsimane Health and Life History Project and the paper's senior author. "The obvious first contender is, what are they eating? And are they eating what we think is best for heart health?
"We conducted a detailed analysis of the Tsimane diet and then compared it to what modern Americans typically eat, and to the diets that claim to be heart healthy," he continued. "Maybe the Tsimane just happen to follow one of those without knowing about them." These diets -- Paleo, Okinawan and DASH, among others -- are often promoted because of their proposed health benefits, and in the case of Paleo, that our bodies have evolved to benefit from particular types of food.
The connection to the Moseten is an added benefit of the study. Ethnolinguistically and genetically very similar to the Tsimane, the Moseten, an isolate in Bolivia, are much more acculturated in a number of ways than are the Tsimane. "They provide a forecast of what Tsimane health might look like 20 years from now," Gurven said. "They represent what is happening to many indigenous populations over time. To what extent may changes in their diet increase the prevalence of heart disease and diabetes?"
Using the same measurement strategy employed by the U.S. Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey, the researchers interviewed 1,299 Tsimane and 229 Moseten multiple times about everything they had eaten or drunk in the previous 24 hours. Using published and their own nutritional estimates for all items, and a variety of methods to estimate portion size, they provided a detailed breakdown of daily food intake.
The high-calorie (2,433-2,738 kcal/day) Tsimane diet was characterized by high carbohydrate and protein intake, and low fat intake (64, 21 and 15 percent of the diet, respectively). In addition, the Tsimane don't eat a wide variety of foods, relative to the average U.S. or Moseten diet. Almost two-thirds of their calories are derived from complex carbohydrates, particularly plantains and rice. Another 16 percent comes from over 40 species of fish, and 6 percent from wild game. Only 8 percent of the diet came from markets.
Despite the low dietary diversity, the researchers found little evidence of micronutrient deficiencies in the Tsimane's daily intake. Calcium and a few vitamins (D, E and K) were in short supply, but the intake of potassium, magnesium and selenium -- often linked to cardiovascular health -- far exceeded U.S. levels. Dietary fiber intake was almost double U.S. and Moseten levels.
Over the five years of study, the researchers saw the Tsimane's total energy and carbohydrate intake increase significantly, particularly in villages near market towns. Their consumption of food additives (lard, oil, sugar and salt) also has increased significantly. The Moseten, the researchers noted, consumed substantially more sugar and cooking oil than did the Tsimane.
The conclusion: A high-energy diet rich in complex carbohydrates is associated with low cardiovascular disease risk, at least when coupled with a physically active lifestyle (Tsimane adults average 17,000 or so steps per day, compared to Americans' 5,100). Moving away from a diet that is high in fiber and low in fat, salt and processed sugar represents a serious health risk for transitioning populations. Evidence of nutrition transition in Bolivia parallels trends in increasing body fat and body mass index among Tsimane, suggesting the low prevalence of cardiovascular disease -- as among the Tsimane -- may not persist.
According to Gurven, avoiding the pitfalls of changing diets and lifestyles will be critical for groups like the Tsimane. Many other indigenous populations in South America, Africa and Southeast Asia are in similar situations. And rates of obesity, type-2 diabetes and heart disease are high among indigenous groups whose lifeways are no longer traditional -- including many North American Indian and Australian aboriginal populations.
And for the Tsimane, change is not far on the horizon. "This is a key time," said Thomas Kraft, a postdoctoral researcher in anthropology at UC Santa Barbara and the paper's lead author. "Roads are improving in the area, as is river transport with the spread of motorized boats, so people are becoming a lot less isolated compared to the past. And it's happening at a pretty rapid pace."
Anecdotally, Gurven added, the Tsimane Health and Life History Project's biomedical team is seeing more diabetic patients among the Tsimane than they have previously. That's likely due to the increased regular intake of refined sugar and fat that occurred over the course of the study. As Kraft noted, with the Tsimane's ability to buy large kilo bags of sugar and liters of cooking oil, the researchers calculated a 300 percent rise in consumption of those products. "They're basically deep frying and adding lots of sugar to drinks when they can," he said.
And consuming a lot of calories. "But they're also physically active -- not from routine exercise, but from using their bodies to acquire food from their fields and the forest," added Gurven, "which is also an important lesson. You can't look at what you're eating irrespective of what you're doing with your body. If you're physically active, you can probably get away with more flexibility in the diet."
Calorie count aside, the high carbohydrate content of the Tsimane diet isn't "unprecedented," according to Kraft. "One of the other artery-protecting diets is the Okinawan diet from Japan. It comes out at about 85 percent carbohydrate. But a common feature they share is that pretty much across the board, they're complex carbohydrates -- it's sweet potatoes in the Okinawan diet; here it's plantains and manioc."
The Moseten diet has fewer total calories and less carbohydrates than the Tsimane diet, but the Moseten eat a broader range offoods, including more fruits, vegetables, dairy and legumes. The Moseten also buy more of their food, including soda, bread, dried meat and processed items. The Moseten diet could provide insight into the Tsimane diet of the future, the researchers suggest. "We're still analyzing their health indicators, but we expect the Moseten to show more risk factors related to diabetes and heart disease," said Gurven.
In addition to finding that the Tsimane consume more calories per day than the Moseten do, the researchers note the Tsimane are also more physically active (with much of their labor devoted to the hard work of slash and burn farming, hunting, fishing and foraging). They expend more energy activity, but may also have a higher resting energy expenditure due to higher rates of infection and persistent immune activity.
Overall, the findings suggest that no single diet protocol offers the key to health. The picture is much more complicated. "It definitely sheds light on the diversity of diets that are compatible with good cardiovascular health," said Kraft.
Added Gurven, "We're at a unique point in history where for many of us, our daily decisions are more about what not to eat. We have to work hard not to overeat. Throughout most of human history, it was the opposite. It was so hard to get those calories we needed to survive."
And in terms of the Tsimane's eagerness to incorporate sugar and other additives into their diets despite the associated health risks, "Telling folks to watch what they're eating, don't eat too much of this or that -- that mentality is hard to convey when getting food is unpredictable and a daily grind," Gurven continued. "Getting calories cheaply with less effort -- who wouldn't?"
https://www.sciencedaily.com/releases/2018/11/181102180757.htm