Learn to Balance Fats for a Healthier Diet, Researcher Argues
By Heidi Silver
Public health guidelines, such as the Dietary Guidelines for Americans, have long emphasized reducing dietary fat intake, but nutritionists and other health scientists now have more recent evidence that not all fats have adverse effects. Dietary fats differ with regard to their effects on health and risk for chronic diseases, particularly in regard to effects on risk for heart disease.
Indeed, some nutrition experts now believe that certain types of dietary fat may even reduce cardiovascular risk. Some dietary fats may lower fats in the blood called triglycerides. They may also increase levels of HDL, or what is known as the "good" cholesterol, and reduce LDL-cholesterol, or the less healthy type of cholesterol, thus improving the HDL to total cholesterol ratio.
Also, many diet plans that do not strictly limit the total amount of dietary fat a person consumes have been associated with better diet satisfaction, weight loss and preservation of muscle mass.
As a research professor in the field of nutrition and dietetics, I am convinced that findings from our work, along with other published current evidence, show that the concept that dietary fat is "toxic" is very much outdated and misguided.
Although there is conclusive evidence that one type of fat, trans fat, has no place in a healthy diet, I believe that consumers should start to learn how to balance the other types of fats in the diet.
A Balancing Act
While not all fats are alike, they do share some things in common. They provide energy with approximately nine calories per each gram of fat, they are all broken down during digestion by enzymes in the gastrointestinal tract, and they are well absorbed as fatty acids, or chains of hydrogen and carbon.
But these carbon chains vary in length and their degree of saturation. As a result, dietary fats vary in their effects on the body.
In some instances, the carbon molecules bind to other carbon molecules. In others, they bind to hydrogen molecules. You likely have heard names for these two types of fats—unsaturated and saturated. Unsaturated fats are those in which carbon molecules bind to other carbon molecules. Saturated fats are those in which carbon molecules bind to hydrogen molecules. Within the two broad types of fat, there are differences still.
Among the unsaturated fats, there are those that are mono-unsaturated, or those that have one unsaturated carbon bond, which are found in olive oil and certain kinds of nuts, and there are those that are poly-unsaturated and are found in such foods as walnuts, plant oils, salmon and sardines.
We also have learned that different kinds of saturated fats affect the body in different ways. For example, the 12-carbon lauric acid, 14-carbon myristic acid, 16-carbon palmitic acid and 18-carbon stearic acid are all saturated fats. But stearic acid does not increase LDL-cholesterol levels like the other saturated fats.
While these differences are not new, the understanding of their effects is new, mostly due to findings from more recent studies like my own.
Thus, the amount of total fat in the diet no longer is the sole measure of the health effects of dietary fat. It's also about the type of fatty acid, how long the carbon chain is, and whether the fat is saturated, mono-unsaturated or poly-unsaturated.
The Link to Heart Health
The scientific discourse about the potentially toxic role of dietary fat and cholesterol on human health started in the late 1950s and early 1960s, when scientists discovered how to analyze fats in the lab. They also discovered the link between dietary fat intake, serum levels of total and LDL-cholesterol and risk for cardiovascular diseases in animals.
Because heart disease has been the leading cause of death in the U.S. since the 1930s, the Nutrition Committee of the American Heart Association in 1968 recommended reducing total and saturated fat intake. The emphasis on lowering dietary fat intake was advanced further in 1977 with the publication of the first Dietary Guidelines for Americans by the Senate Select Committee on Nutrition and Human Needs.
Health care professionals in turn shifted their nutrition counseling efforts toward encouraging a low-fat diet. And, the food industry began to develop and produce of a wide-ranging assortment of "low-fat," "reduced-fat," "light" and "fat-free" items.
In the mid-1980s, advice to consume a low-fat diet also became a strategy for weight control. Evidence from the landmark Framingham Heart Study uncovered that obesity increased risk for heart disease, and national data showed that the entire population was getting heavier.
Americans responded with a substantial reduction in the percentage of calories consumed as fat. But humans have a biological preference for the taste of fat. And with fat off the table, millions increased their consumption of dietary carbohydrates to compensate for the loss in flavor and appeal of foods. As a result, there has been a substantial increase in the waistlines of Americans.
An Alternative Approach
Given the mixed scientific evidence on fat, and the diverse roles of dietary fatty acids in health and disease, about four years ago I designed a diet that is moderately high in fat but the types of fat are proportionally balanced, that is, one-third of total fat comes from saturated fats; one-third comes from monounsaturated fats; and one-third comes from polyunsaturated fats.
Based on this balanced moderately-high fat diet approach, my research team developed a 14-day cycle of menus comprised of three meals and two snacks per day that increases intake of foods high in the 18-carbon monounsaturated fat, oleic acid and the 18-carbon and longer chain polyunsaturated fats (more commonly known as omega-3 and omega-6 fatty acids). To do this, we replaced high simple carbohydrate snacks with nuts, we replaced croutons in salads with avocado slices, and we used salad dressings high in safflower oil, canola oil and olive oil.
We have been studying the effects of this balanced moderately high fat diet in adults who are overweight or obese. In a study with 144 women over a period lasting 16 weeks, we found that study participants had significant reductions in abdominal fat and waist circumference; a 6 percent improvement in blood pressure; reduced blood levels of markers of inflammation; and overall a 6 percent reduction in their five- and 10-year cardiovascular risk.
Study participants reported that they found our diet to be highly palatable, satisfying and economically feasible to adhere to. The firm adherence to our balanced moderately high fat diet in the four-month study was reflected by significant changes in participants' plasma fatty acid profiles (the array of saturated and unsaturated fats in the blood) that reflected the fatty acid composition of the diet menus.
In a follow-up study using more in-depth analysis of the lipid response to the balanced moderately high fat diet, we found a difference in response between Caucasian females and African-American females. While the Caucasian females had improvements in serum triglyceride and LDL-cholesterol levels, African-American females had the most significant improvement in HDL-cholesterol levels. These data support the concept that not all people respond to a dietary approach in the same way and there is no one optimal diet for all people.
In another follow-up study of the response to a higher fat diet, we also found that people with a specific genotype had a stronger response, and that response differed by sex, particularly with regard to improvements in HDL-cholesterol being stronger in females versus males.
Thus, I believe the choice of an effective dietary approach must be determined based on an individual's goals and an individual's clinical and metabolic response to the interaction between genes and environment.
There are limited studies on the strategy of balancing the type of dietary fat. While current scientific consensus is that extremes of dietary fat intake, too high or too low, are unhealthy, I believe that a paradigm shift focusing on the types of dietary fats consumed may offer the opportunity to modify our cardiometabolic risk factors without requiring major changes in the amount of fat or calories we consume.
12 Clean Eating Goals You Should Know https://t.co/9ct25WWeQC #climate #organic #energy https://t.co/31FJIfZjmn— Eco-friendly Tips (@Eco-friendly Tips)1537975643.0
Heidi Silver is an associate professor of medicine at Vanderbilt University.
Disclosure statement: Heidi Silver received funding to study dietary fat from the Atkins Foundation.
Reposted with permission from our media associate The Conversation.
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By Emily Grubert
Natural gas is a versatile fossil fuel that accounts for about a third of U.S. energy use. Although it produces fewer greenhouse gas emissions and other pollutants than coal or oil, natural gas is a major contributor to climate change, an urgent global problem. Reducing emissions from the natural gas system is especially challenging because natural gas is used roughly equally for electricity, heating, and industrial applications.
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What RNG Is and Why it Matters<p>Most equipment that uses energy can only use a single kind of fuel, but the fuel might come from different resources. For example, you can't charge your computer with gasoline, but it can run on electricity generated from coal, natural gas or solar power.</p><p>Natural gas is almost pure methane, <a href="https://www.eia.gov/energyexplained/natural-gas/" target="_blank">currently sourced</a> from raw, fossil natural gas produced from <a href="https://www.eia.gov/energyexplained/natural-gas/where-our-natural-gas-comes-from.php" target="_blank">deposits deep underground</a>. But methane could come from renewable resources, too.</p><p><span></span>Two main methane sources could be used to make RNG. First is <a href="https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks" target="_blank">biogenic methane</a>, produced by bacteria that digest organic materials in manure, landfills and wastewater. Wastewater treatment plants, landfills and dairy farms have captured and used biogenic methane as an energy resource for <a href="http://emilygrubert.org/wp-content/uploads/2019/02/eia_860_2017_map.html" target="_blank">decades</a>, in a form usually called <a href="https://www.eia.gov/energyexplained/biomass/landfill-gas-and-biogas.php" target="_blank">biogas</a>.</p><p>Some biogenic methane is generated naturally when organic materials break down without oxygen. Burning it for energy can be beneficial for the climate if doing so prevents methane from escaping to the atmosphere.</p>
Renewable Isn’t Always Sustainable<p>If RNG could be a renewable replacement for fossil natural gas, why not move ahead? Consumers have shown that they are <a href="https://www.nrel.gov/analysis/green-power.html" target="_blank">willing to buy renewable electricity</a>, so we might expect similar enthusiasm for RNG.</p><p>The key issue is that methane isn't just a fuel – it's also a <a href="https://www.eia.gov/environment/emissions/ghg_report/ghg_overview.php" target="_blank">potent greenhouse gas</a> that contributes to climate change. Any methane that is manufactured intentionally, whether from biogenic or other sources, will contribute to climate change if it enters the atmosphere.</p><p>And <a href="http://doi.org/10.1126/science.aar7204" target="_blank">releases</a> <a href="https://doi.org/10.1016/j.wasman.2019.07.029" target="_blank">will happen</a>, from newly built production systems and <a href="https://theconversation.com/why-methane-emissions-matter-to-climate-change-5-questions-answered-122684" target="_blank">existing, leaky transportation and user infrastructure</a>. For example, the moment you smell gas before the pilot light on a stove lights the ring? That's methane leakage, and it contributes to climate change.</p><p>To be clear, RNG is almost certainly better for the climate than fossil natural gas because byproducts of burning RNG won't contribute to climate change. But doing somewhat better than existing systems is no longer enough to respond to the <a href="https://doi.org/10.1038/nclimate2923" target="_blank">urgency</a> of climate change. The world's <a href="https://www.ipcc.ch/sr15/chapter/spm/" target="_blank">primary international body on climate change</a> suggests we need to decarbonize by 2030 to mitigate the worst effects of climate change.</p>
Scant Climate Benefits<p><a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab9335/meta" target="_blank">My recent research</a> suggests that for a system large enough to displace a lot of fossil natural gas, RNG is probably not as good for the climate as <a href="https://investor.southerncompany.com/information-for-investors/latest-news/latest-news-releases/press-release-details/2020/Southern-Company-Gas-grows-leadership-team-to-focus-on-climate-action-innovation-and-renewable-natural-gas-strategy/default.aspx" target="_blank">is publicly claimed</a>. Although RNG has lower climate impact than its fossil counterpart, likely high demand and methane leakage mean that it probably will contribute to climate change. In contrast, renewable sources such as wind and solar energy do not <a href="https://www.eia.gov/environment/emissions/carbon/" target="_blank">emit climate pollution directly</a>.</p><p>What's more, creating a large RNG system would require building mostly new production infrastructure, since RNG comes from different sources than fossil natural gas. Such investments are both long-term commitments and opportunity costs. They would devote money, political will and infrastructure investments to RNG instead of alternatives that could achieve a zero greenhouse gas emission goal.</p><p>When climate change first <a href="https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html" target="_blank">broke into the political conversation</a> in the late 1980s, investing in long-lived systems with low but non-zero greenhouse gas emissions was still compatible with aggressive climate goals. Now, zero greenhouse gas emissions is the target, and my research suggests that large deployments of RNG likely won't meet that goal.</p>
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By Charli Shield
When an elephant dies in the wild, it's not uncommon to later find its bones scattered throughout the surrounding landscape.
Elephant Burial Grounds<p>Highly social creatures that form deep familial bonds, elephants have long been observed gathering at the site where a peer or family member has died — often spending hours, even days, quietly investigating the bodies or the bones of other dead elephants.</p><p>Although the popular idea that dying elephants are instinctively drawn to special communal graves — so-called "elephant graveyards" — is a myth, their tendency to go out of their way to visit the bones and tusks of the deceased isn't unlike human rituals at graveyards, says animal psychologist Karen McComb.</p><p>"They spend a lot of time touching and smelling skulls and ivory, placing the soles of their feet gently on top of them, and also lifting them up with their trunks," McComb, who's been studying African elephants for 25 years in Kenya's Amboseli National Park, told DW.</p><p>The most striking part of watching an elephant experience loss, Poole recalls, is the quietude. She still remembers one of the first elephant deaths she witnessed; a mother who birthed a stillborn calf. That elephant stayed with its baby for two days, trying to lift it and defending it from vultures and hyenas.</p><p>"I was so struck by the expression on her face and her body. She looked so dejected. It was really like, 'Oh God, these animals grieve…'. It was just so different," Poole told DW. </p>
Witnessing Emotions in Animals<p>Not all scientists are comfortable concluding that elephants grieve. Among the more than 30 reports of elephant reactions to death that Wittemyer co-reviewed in <a href="https://link.springer.com/article/10.1007/s10329-019-00766-5" target="_blank">a study published in November 2019</a> were accounts of "enormous variation and nuance" he says. "It can be incredibly involved and intricate for extended periods or can be relatively cursory checks."</p><p>In Wittemyer's own experience, it can be difficult not to attribute some kind of emotional experience to the more involved interactions between elephants and their dead.</p><p>He shares the story of an "extraordinary event" involving the death of a 55 year-old matriarch in Kenya in a protected area that happened to be near his place of work. She was visited by multiple unrelated families while she was dying, including another matriarch that exerted such enormous effort attempting to lift her to her feet that she broke her tusk, which Wittemyer says, is "like breaking a tooth." </p><p><span></span>"It was a remarkable example of this heightened emotional state, it was very clearly a very stressful interaction," he says.</p>
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