The surprising effects of a Paleo diet on diabetic patients
Diabetes is a widely spread disease in modern society, a condition in which the capacity of the body to manage blood glucose is impaired. Type 2 Diabetes (T2D) is associated with many metabolic dysfunctions, such as insulin resistance (the inability of the tissues - mainly muscle and fat - to absorb glucose from the blood in response to the insulin hormone signal), hypertension and dyslipidemia (abnormal amount of lipids in the blood).
T2D depends on both genetic and lifestyle factors: the typical Western diet (processed meat, high-fat dairy products and refined grains) is associated with T2D development1. The so-called Paleo(lithic) diets limit the food intake to items that were most likely consumed by our ancestors during the Paleolithic period (2.5 MYA - 10,000 BP), and are hypothesized to improve T2D and its associated metabolic impairments2,3. Paleo-diets are rich in meats, fish, fruits, vegetables and nuts and they do not include processed foods, dairy products and refined grains. They are alsolower in sodiumand higher in potassium, antioxidants, micronutrients and fiber and have a lower diet acid content.
To investigate if there is an improvement in the metabolism of diabetic people after following a Paleo diet, two groups of diabetic patients were assigned to either the Paleo diet or the standard diet recommended by the Amercian Diabetes Association (ADA)4, for two weeks. The Paleo diet consisted of meat, fish, poultry, eggs, fruit, vegetables, tree nuts, canola oil, mayonnaise and honey. Dairy products, legumes, cereals, grains and potatoes were excluded. The total number of calories of the Paleo and ADA diet was the same. The Paleo diet had a higher content of carbohydrates (437 vs 408 g) and a lower amount of proteins (138.5 vs 152.5 g). The total amount of fat was higher in the ADA diet (96 vs 90 g) and, importantly, the type of fats was different: the ADA diet had a higher amount of saturated fatty acids (21.5 vs 12 g) and slightly lower amounts of monounsaturated and polyunsaturated fatty acids (46 vs 49.5 g and 20.5 vs 21 g, respectively).
Metabolic changes were assessed through a series of measures, mainly lipid blood content and specific parameters of blood glucose control. Blood lipids and cholesterol were lower on all patients after both diets but markedly more so in the group under the Paleo diet. A general improvement in glucose control was also found after both diets but again this was much more evident in the group consuming the Paleo diet. The fact that both diets led to a healthier metabolic frame is likely explained from the fact the subjects were conducting a poor dietary regimen before the trial, and that following the ADA diet also led to an improvement compared to previous habits.
One of the main differences between the two diets that probably contributed to the better health improvement of the group following the Paleo diet, is that in that diet, the fiber content is much higher and it possibly attenuated the after meal glucose rise. Other differences are the higher content of antioxidants, mono- and polyunsaturated fats, low sodium and high potassium in the Paleo diet. Also the source of carbohydrates differed: fruits, vegetables and honey in the Paleo diet, and rice, bread and pasta in the ADA diet.
One month after the two-week diet trial all the patients were examined again and it was found that the improvements observed during the study tended to go back to their initial values, indicating that in order to have stable, long-term effects of a diet, it should be a permanent lifestyle habit rather than a temporary, time-limited intervention. Besides the specific kind of diet, it is important to underline how strongly food habits influence our health.
Masharani U, Sherchan P, Schloetter M et al. Metabolic and physiologic effects from consuming a hunter-gatherer (Paleolithic)-type diet in type 2 diabetes. European Journal of Clinical Nutrition. 2015;69(8):944-948. doi:10.1038/ejcn.2015.39.
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