Therapies for Post-Prandial Dysmetabolism
Promising pharmacologic approaches to the normalization of post-prandial dysmetabolism are evolving. However, resorting to drug therapy for an epidemic caused by a maladaptive diet is less rational than simply realigning our eating habits with our physiological needs.[2] The traditional Mediterranean and the Okinawan diets, which are rich in minimally processed natural foods that are low in caloric density but high in nutrient density, have been associated with improved CV health and longevity.[1,19] These diets are closer to the ancestral hunter-gatherer eating patterns for which modern humans remain genetically adapted.[20] Specifically, diets that include large amounts of fresh unprocessed plants, with moderate levels of lean protein and beneficial fats (such as omega-3 and monounsaturated fats) and low levels of processed carbohydrates and saturated and trans fats, and that are rich in antioxidants substantially improve post-prandial glucose and lipid levels.[19]
Type and Amount of Carbohydrate Consumed
The amount and type of carbohydrate consumed with a meal is a major determinant of the post-prandial glucose excursion.[21] The glycemic index of a food is defined as the incremental increase in the area under the post-prandial glucose curve after ingestion of 50 g of a specific food compared with that noted after ingestion of 50 g of oral glucose. A meal such as white bread and jelly with a glycemic index of 80 will result in a 2-fold higher incremental increase in glucose compared with an isocaloric meal of whole-grain bread and peanut butter with a glycemic index of 40. Most studies show that diets rich in high-glycemic-index, low-fiber foods independently increase the risk of both CV disease and type 2 diabetes.[19,21]
Minimally processed plants such as vegetables, fruits, nuts, seeds, and grains generally increase post-prandial glucose and triglycerides to a lesser degree than do processed foods.[22] Ideal carbohydrate foods for improving post-prandial dysmetabolism include green leafy vegetables such as broccoli and spinach, or fruits such as grapefruits and cherries. Their lower caloric density and glycemic indexes and higher fiber and water content induce less glucose excursion after a meal, whereas their antioxidant phytonutrients dampen down the oxidant stress that is inherently generated when glucose or fatty acids are burned in the Krebs cycle.[2] Dietary antioxidants such as those present in deeply pigmented plant-based foods and drinks such as berries, red wine, dark chocolate, tea, and pomegranates help to protect the vascular endothelium from post-prandial oxidant stress and inflammation independently of their effects on post-prandial glucose and triglyceride levels.[2,23] Cinnamon is a calorie-free herb rich in antioxidants that, when added to a high-glycemic-index meal, significantly reduces the post-prandial glucose excursion, partly by slowing gastric emptying.[24]
Excess intake of processed carbohydrates sets up a vicious cycle whereby the transient spikes in blood glucose and insulin early after a meal trigger reactive hypoglycemia and hunger.[25] The chronic consumption of a diet high in processed carbohydrates leads to excess visceral fat, which increases both insulin resistance and inflammation and predisposes to diabetes, hypertension, and CV disease.[25] In contrast, restriction of refined carbohydrates will improve the post-prandial levels of both glucose and triglycerides and can reduce intra-abdominal fat, particularly in individuals with insulin resistance.[25]
The amount of carbohydrate consumed is equally important as the glycemic index. Small quantities of high glycemic index foods such as white rice, glucose, or potatoes will have a proportionally smaller effect on post-prandial glucose spikes than larger quantities of these foods.[26] On the other hand, even low glycemic index foods such as legumes (e.g., lentils) when consumed in large quantities can cause substantial post-prandial glucose spikes.[26] Thus, portion control is of fundamental importance to the short- and long-term health effects of any diet. The portion size inflation that has transpired in American restaurants in recent decades is not just contributing to the obesity crisis but also is causing immediate toxic effects throughout the vascular system in the person who consumes such a meal.[16]
Dietary fiber is effective at delaying gastric emptying, slowing digestion, and reducing post-prandial excursions of both glucose and triglycerides.[27] Minimally processed plant-based foods are natural sources of soluble and insoluble fiber that improve post-prandial dysmetabolism, reduce oxidant stress and inflammation, and lower the risks of CAD and diabetes.[19,22,27]
Nuts, Olive Oil, and Fish Oil
Nuts, when consumed with a meal, will significantly reduce the post-prandial glucose excursion by slowing digestion. Recent studies show that almonds, pistachios, or peanuts, when eaten along with high glycemic index carbohydrates such as white bread or mashed potatoes, will reduce the post-prandial glucose area under the curve by approximately 30% to 50%[28] (Fig. 4). Importantly, nuts also decrease meal-induced oxidative protein damage because they lower post-prandial oxidative stress and additionally provide antioxidants.[29]
Figure 4.
 Almonds Reduce Post-Prandial Glucose. The post-prandial increase in the area under the curve for glucose was reduced by 58% when 90 g of almonds were added to a high glycemic index meal (p = 0.009). Data from Josse et al.[28]
A recent trial randomized 772 subjects at high risk for CAD to a low-fat diet or a Mediterranean-style diet supplemented with either walnuts (30 g/day) or virgin olive oil (1 l/week). This trial found that after 3 months the Mediterranean diets supplemented with either nuts or olive oil produced clinically significant reductions in systolic blood pressure, fasting glucose, and inflammatory biomarkers compared with the low-fat diet.[1]
Epidemiologic studies consistently indicate that consumption of nuts at least 5 times per week will reduce CAD and diabetes risks by 20% to 50%.[29] Tree nuts are comprised predominantly of monounsaturated fats and are a rich source of antioxidants, fiber, phytosterols, magnesium, and folic acid, which might beneficially influence CV risk. Replacing refined carbohydrates with monounsaturated fats (using nuts and/or olive oil) will reduce post-prandial hyperglycemia and hypertriglyceridemia, increase high-density lipoprotein, and decrease oxidative stress.[1,2] One practical way to accomplish this is to substitute nuts (all of which have very low glycemic indexes) for the sugary and starchy snack foods that are staples in the American diet.
Fish oil (omega-3 fatty acids) lowers post-prandial triglyceride levels by 16% to 40% in a dose-dependent fashion, in part by upregulating lipoprotein lipase activity and accelerating the clearance of chylomicrons.[30] Thus, some of the documented anti-inflammatory and cardioprotective activities of omega-3 fatty acids may be conferred in part by significant improvements in post-meal lipid levels.[31] |
