Carbs, not saturated fat, increase fatty acid linked to diabetes risk

by Barbara Hewitt on December 15, 2014

Doubling or even nearly tripling saturated fat in the diet does not drive up total levels of saturated fat in the blood, according to a new study.

However, increasing levels of carbohydrates in the diet during the study promoted a steady increase in the blood of a fatty acid linked to an elevated risk for diabetes and heart disease.


Carbohydrates increase a fatty acid linked to an elevated risk of diabetes and heart disease

The finding challenges the conventional wisdom that has demonised saturated fat and extends our knowledge of why dietary saturated fat doesn’t correlate with disease, according to Jeff Volek, professor of human sciences at the Ohio State University in the United States where the study was conducted.

‘It’s unusual for a marker to track so closely with carbohydrate intake, making this a unique and clinically significant finding. As you increase carbs, this marker predictably goes up,’ he explained.

The researchers found that total saturated fat in the blood did not increase and went down in most people despite being increased in the diet when carbs were reduced.

Palmitoleic acid, a fatty acid associated with unhealthy metabolism of carbohydrates that can promote disease, went down with low carb intake and gradually increased as carbs were re-introduced to the study diet.

In the study, participants followed six three-week diets that progressively increased carbs while simultaneously reducing total fat and saturated fat, keeping calories and protein the same.

Volek pointed out that when that marker increases, it is a signal that an increasing proportion of carbs are being converted to fat instead of being burned as fuel. Reducing carbs and adding fat to the diet in a well formulated way, on the other hand, ensures the body will promptly burn the saturated fat as fuel so it won’t be stored.

‘When you consume a very low-carb diet your body preferentially burns saturated fat. We had people eat two times more saturated fat than they had been eating before entering the study, yet when we measured saturated fat in their blood, it went down in the majority of people. Other traditional risk markers improved, as well,’ Volek added.

The 16 adults who took part in the study all had metabolic syndrome, defined as the presence of at least three of five factors that increase the risk for heart disease and diabetes such as excess belly fat, elevated blood pressure, low good cholesterol, insulin resistance or glucose intolerance, and high triglycerides.

After getting them to a baseline reduced carb diet for three weeks, researchers introduced the exact same diets, which changed every three weeks, for 18 weeks. The diets started with 47 grams of carbs and 84 grams of saturated fat each day, and ended with 346 carb grams per day and 32 grams daily of saturated fat.

Each day’s meals added up to 2,500 calories and included about 130 grams of protein. The highest carb level represented 55% of daily calories, which roughly matches the estimated daily percentage of energy provided by carbs in the American diet.

Compared to baseline, there were significant improvements in blood glucose, insulin and blood pressure that were similar across diets. Participants, on average, lost almost 22 pounds by the end of the trial.

Participants’ existing health risks were not a factor in the study because everyone ate the same diet for 18 weeks. Their bodies’ responses to the food were the focus of the work.

‘There is widespread misunderstanding about saturated fat. In population studies, there’s clearly no association of dietary saturated fat and heart disease, yet dietary guidelines continue to advocate restriction of saturated fat. That’s not scientific,’ Volek said.

‘There is no magical carb level, no cookie cutter approach to diet that works for everyone. There’s a lot of interest in personalised nutrition, and using a dynamically changing biomarker could provide some index as to how the body is processing carbohydrates,’ he added.

The opinions expressed in this article do not necessarily reflect the views of the Community and should not be interpreted as medical advice. Please see your doctor before making any changes to your diabetes management plan.

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