The Best Diabetes Diet (According to the Research) “What should I eat?” This question get asked here more than any other. The answers are often given with an almost religious devotion. “We need to eat like our hunter gatherer ancestors!” “Cut out all carbs and limit protein!” “Eat lots of fruits and vegetables!” “Eat like the [fill in group with low diabetes rates]!” “Go vegan!” “Drink only fish oil!” Often the American Diabetes Association (ADA) gets pummeled for promoting high carbohydrate diets. Although as we’ve covered before, the ADA does not even have an official diet. There is no recommendation that x% of calories come from carbohydrates. Their official positions its that “each person with diabetes should receive an individualized eating plan.” Yet surely there must be some research that can offer us guidance? Our best current answer may be in the February edition of Diabetes Care. It features a comprehensive research review of the last decade of nutritional studies. So let’s dig in, clear up the misconceptions, and figure out the truth. How the Diets Were Evaluated The the authors of the review gathered all of the studies on diabetes nutrition and then excluded those that only lasted a few days or had few participants. Ultimately, they evaluated 92 studies on their ability to: Maintain good blood sugar levels Reduce the risk of vascular disease Prevent and treat other chronic complications Address individual nutritional needs (including personal preferences, culture and willingness to change) Maintain the pleasure of eating by only limiting food choices when indicated by scientific evidence. The review begins with a warning that it’s very difficult to draw conclusions because the impact of carbohydrates, proteins and fats can be difficult to isolate, especially when weight loss or medication is involved. The Definition of a Low Carb Diet There are no standard definitions for phrases like “low-carbohydrate”, “low-GI” and “low-fat” presents further problems. For the purpose of the review, the authors classified the studies into categories: very-low-carbohydrate: 21-70 grams per day moderately low-carbohydrate: 30-40% of calories from carbs moderate-carbohydrate: 40-65% of calories from carbs high-carbohydrate diet: >65% of calories from carbs For those who eat a lot of calories, the first two categories overlap in some cases. The Verdict on the Diets Low-Carbohydrate Diets The authors looked at the impact of 11 low and moderately-low-carbohydrate diets on those with type 2 diabetes. (None of the type 1 studies fit the review’s criteria.) In 60% of the diets, the participants saw a lower HbA1c. In many cases, fasting blood sugars, average blood sugars, and average insulin use all went down. In a few of the studies, participants saw a significant increase in HDL cholesterol, which reduces risk for cardiovascular disease. Other studies saw decreases, but they were not statistically significant. Moderate or High-Carbohydrate Diets The review found a wide range of outcomes for moderate and high-carbohydrate diets. In one group, those with the higher-carbohydrate diet had lower HbA1cs. In a few of the moderate-carbohydrate groups, there were substantial reductions in HbA1cs. For the rest, there was no difference between the groups following the diet and the control groups. For heart health, the higher-carbohydrate diet resulted in much lower LDL cholesterol levels. The lower-carbohydrate diets results in much lower triglycerides. Are Low Glycemic Index Foods Better? According to the ADA, the “glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health.” Here the evidence is limited but generally positive. The review found that low GI diet results ranged from moderate impact to no impact on HbA1cs. Do Fiber Supplements Help Control Blood Sugars? Very little. Do Low Fat Diets Work? There was no evidence that cutting out fat improved blood sugar control or decreased the risk for cardiovascular disease. The different types of food also had no impact on post-meal blood sugars. Some studies found that taking omega-3 fatty acid supplements improved triglycerides, although they didn’t improve blood sugars. Do High Protein Diets Work? For those without kidney disease, eating a higher protein diet (30% of calories) had a limited impact on HbA1cs but improved risk factors for cardiovascular disease. For those with kidney disease, lowering protein intake from normal levels had little impact on blood sugars, cardiovascular disease risk factors, or the amount of protein spilled. However, switching to soy-based proteins may help improve cardiovascular disease risk factors. Do the Mediterranean or Vegetarian Diets Work? The Mediterranean-style diet is based on eating more vegetables, whole grains, fruits, legumes, nuts and fish along with less red meat. This style of eating had no impact on blood sugar levels. There’s not enough research on Vegetarian diets to make any conclusions, although there’s some evidence that they might help with blood sugars and cardiovascular risks. How Do Different Foods Impact Blood Sugars? Some of the studies look at how diets rich in a particular food source impacted blood sugars. Here are the general conclusions: Nuts have little impact but may improve cardiovascular disease risks. Whole grains have little impact but may reduce inflammation. Soy bean supplements didn’t help. Fruit and Vegetable supplements had mixed results. Dairy supplements had no impact. Meat, poultry and fish - there were not enough studies to draw broad conclusions. In general, there is very little research on how various foods affect people with diabetes. This is not a very satisfying answer, but it’s where we are today. SO WHAT SHOULD I EAT?!?! The bottom line is that different diets are working for different people. Many of the low-carbohydrate diets had high dropout rates and 40% that stick with it don’t see better blood sugars. But 60% can make it work with great results. On the flip side, some successfully reduced their HbA1cs on high carbohydrate diets.
Posted on: Sat, 15 Mar 2014 04:30:01 +0000
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