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Tag: saturated fat

Published on Leave a comment on Butter Is No Longer Taboo

This is huge. Decades long advice dietary advice to Americans was wrong. New research finds that the medical advice to replace saturated fat in the diet with vegetable oils rich with linoleic acid lowers cholesterol, but does not lead to a lower risk of death from coronary heart disease or other causes. It may even lead to increased rates of death from coronary heart disease, and cardiovascular disease (2013 study). Vegetable oils rich in linoleic acid are corn oil, sunflower oil, safflower oil, cottonseed oil, and soybean oil.

Other recent articles written on this topic have pointed out that research evidence opposing the prevailing medical view of what is "heart healthy" (low-fat foods, and substitute vegetable oil for butter) was suppressed for decades and the researchers ridiculed. In the past few years a number of other studies have found health benefits from whole fat foods (such as high-fat dairy foods) and not from low-fat or zero fat foods or vegetable oils. From Medical Xpress:

Researchers unearthed more evidence that replacing butter with vegetable oils does not decrease risk of heart disease

A research team led by scientists at the UNC School of Medicine and the National Institutes of Health has unearthed more evidence that casts doubt on the traditional "heart healthy" practice of replacing butter and other saturated fats with corn oil and other vegetable oils high in linoleic acid. The findings, reported today in the British Medical Journal, suggest that using vegetable oils high in linoleic acid might be worse than using butter when it comes to preventing heart disease, though more research needs to be done on that front.

This latest evidence comes from an analysis of previously unpublished data of a large controlled trial conducted in Minnesota nearly 50 years ago, as well as a broader analysis of published data from all similar trials of this dietary intervention. The analyses show that interventions using linoleic acid-rich oils failed to reduce heart disease and overall mortality even though the intervention reduced cholesterol levels. In the Minnesota study, participants who had greater reduction in serum cholesterol had higher rather than lower risk of death.

Along with corn oil, linoleic acid-rich oils include safflower oil, soybean oil, sunflower oil, and cottonseed oil. The belief that replacing saturated fats with vegetable oils improves heart health dates back to the 1960s, when studies began to show that this dietary switch lowered blood cholesterol levels. Since then, some studies, including epidemiological and animal studies, have suggested that this intervention also reduces heart attack risk and related mortality. In 2009, the American Heart Association reaffirmed its view that a diet low in saturated fat and moderately high (5-10 percent of daily calories) amounts of linoleic acid and other omega-6 unsaturated fatty acids probably benefits the heart.

However, randomized controlled trials - considered the gold standard for medical research - have never shown that linoleic acid-based dietary interventions reduce the risk of heart attacks or deaths. The largest of these trials, the Minnesota Coronary Experiment (MCE), was conducted by researchers at the University of Minnesota between 1968 and 1973. It enrolled 9,423 patients in six state mental hospitals and one state-run nursing home.....The investigators reported then that a switch to corn oil from butter and other saturated fats did lower cholesterol levels but made no difference in terms of heart attacks, deaths due to heart attacks, or overall deaths.....But they also found that.... the corn oil group had almost twice the number of heart attacks as the control group.

In a much-cited study published in 2013, however, Ramsden, Zamora and colleagues were able to recover unpublished data from a smaller trial, the Sydney Diet Heart Study, and there they also found more cases of heart disease and death among patients who received a linoleic acid intervention (safflower oil), compared to controls.

Why linoleic acid-containing oils would lower cholesterol but worsen or at least fail to reduce heart attack risk is a subject of ongoing research and lively debate. Some studies suggest that these oils can - under certain circumstances - cause inflammation, a known risk factor for heart disease. There is also some evidence they can promote atherosclerosis when the oils are chemically modified in a process called oxidation.

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These results go against the medical advice we've been hearing for years (why am I not surprised?). The new advice: High-fat dairy  yes, low-fat dairy no. I also think processed meat (with nitrates) should not be lumped together with unprocessed meat. From Science Daily:

Consumption of high-fat dairy products associated with lower risk of developing diabetes

People with the highest consumption of high-fat dairy products -- eight or more portions per day -- have a 23 percent lower risk of developing type 2 diabetes (T2D) than those with the lowest consumption -- one or less per day, a new study shows.

The study included 26 930 individuals (60% women), aged 45-74 years, from the population-based Malmö Diet and Cancer cohort. Dietary data was collected with a modified diet history method. During 14 years of follow up, 2860 incident T2D cases were identified. 

The researchers found that high intake of high-fat dairy products was associated with a 23% lower incidence of T2D for the highest consuming 20% of participants (or quintile) (median=8 portions/day) compared with the lowest consuming 20% (median=1 portion/day).

In contrast to these findings, there was no association found between intakes of low-fat dairy products and risk of developing type 2 diabetes.

High intakes of meat and meat products were, regardless of fat content, associated with increased risk, but the increased risk was higher for lower fat meats (increased risk of type 2 diabetes for high fat meats 9%, for low fat 24%), both referring to the risk in the highest-consuming versus lowest-consuming 20%). The highest consuming group for the high-fat meat had 90g or more per day, and for the low-fat meat 80g per day.

Same research, some extra details in write-up. From Medscape:

Big Intake of High-Fat Dairy May Be Protective for Diabetes

Previous research led by Nita Forouhi, MD, program leader and public-health physician at the MRC Epidemiology Unit, University of Cambridge, United Kingdom, published in August this year, suggested that molecules with odd numbers of carbon atoms (15 and 17), which are found in dairy products such as yogurt, cheese, and milk, appeared to have a protective effect.

This contrasts with evidence suggesting that even-chain saturated fatty acids, as found in alcohol or margarine, are associated with a greater risk for type 2 diabetes.

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Again, more support for eating a mainly plant based diet and lowering intake of saturated fat. From MedlinePlus:

High-Fat Diet May Boost Breast Cancer Risk

For more than three decades, experts have debated whether eating a high-fat diet increases breast cancer risk. Now, new research suggests it might boost the chances of three common types of breast cancer.

In a large European study evaluating more than 337,000 women in 10 countries over 11 years, researchers found that women who ate the most saturated fat were about 30 percent more likely to develop breast cancer than those who ate the least. The study is published April 9 in the Journal of the National Cancer Institute.

Sieri and her team found that a high intake of total fat and saturated fat was linked to an increased risk of breast cancer subtypes known as estrogen receptor-positive (ER-positive) and progesterone receptor-positive (PR-positive). High-fat diets also were tied to a raised risk of developing HER2-negative breast cancer, the investigators noted.

The breast cancer subtypes linked with fat intake are common, she said. "The majority of breast cancers in the U.S. and Europe are ER-positive, PR-positive, HER2-negative," she noted.

In the new study, women answered questions about their fat intake and other habits that could affect risk, including smoking, age at first period, pregnancy history, use of hormone therapy and their body mass index (a measurement of body fat based on height and weight). To correct for measurement errors in the diet questionnaire, the researchers interviewed a random sample of 8 percent of the women, asking for a 24-hour dietary recall.

After an average follow up of 11.5 years, just over 10,000 women were diagnosed with breast cancer.When the cases of cancer were compared with fat intake, "we found an association between exposure to saturated-fat intake and breast cancer," Sieri said.

Women in the group eating the most saturated fat averaged 48 grams a day, compared to 15 grams in the group eating the least. The link can't be explained with certainty, Sieri said, but it's possible that the high-fat intake raises the levels of the body's own estrogen, which can stimulate the growth of breast cancer cells.

Until more study is done, Sieri tells women: "In general, it is recommended that the percent of total calories from saturated fat should not exceed 10 percent for women." Gaudet agreed. "If you have a mainly plant-based diet, that is going to help you keep your fat intake low."