Read about how your body responds to different forms of sugar - fructose vs sucrose vs glucose - in this article by Time. The original scientific article is available here.
Scientific American reports that there is"More Evidence that Refined Carbohydrates, not Fats, Threaten the Heart." Slate Magazine provides a thorough summary of recent evidence. If you'd like to really delve into the history of dietary recommendations and the evidence - or lack thereof - check out Gary Taubes' book Good Calories, Bad Calories.
How do these studies translate to the kitchen? Let's look at the sweeteners that are commonly available, and how they break down. It is difficult to locate consistent numbers for this data, so I've summarized what I was able to find here, with sources. If you're not familiar with the glycemic index, it is a rating of how foods affect blood sugar levels, with glucose as the standard at 100.
|Evap Cane Juice||100||55||3|
|Honey||50||44||62||varies by type|
|Brown Rice Syrup||3||45-50||25||1,2,3|
|Barley Malt Syrup||2||16||6||76||42||1,3,5|
|HF Corn Syrup-55||55||45||87||2|
Agave nectar is often touted as a healthy alternative sweetener - but given the results of the study cited above regarding fructose, I don't plan to experiment with it. Brown rice syrup is another favorite of some whole foods cooks - but it is half maltose, which has a very high glycemic index. I have a jar of barley malt syrup in the fridge for bread, and I won't purchase that again, given its high maltose content. Given that no sweeteners are actually healthy, it looks like my current strategy of just limiting sugar is probably best.
Now, let's look at the other highly refined food in our diet: flours vs grains. "Whole grain" everything is available now, but often it's made from whole grain flour, not actual whole grains. Is there a difference? It seems logical to consider that grinding grains into tiny pieces (flour) would make the body digest it faster. Dr. Andrew Weil says:
Grains in their natural form have a low glycemic index, while processed carbohydrates, including those made with flour or puffed grains, have a high GI. The reason is that it takes longer for digestive enzymes to reach the starch inside whole grains or grains cracked into large pieces, slowing down the conversion of starch to sugar... when grains are pulverized into flour, whether whole or not, their surface area expands dramatically, providing a huge, starchy surface area on which the enzymes can work. Consequently, the conversion to sugar happens very quickly.
Here's some data on glycemic index measurements for actual whole grains, and for breads made with flour:
|Whole grain rye||34-48|
|Whole wheat flour bread||71|
|Whole rye flour bread||68-88|
|Wheat bread with 50% cracked wheat||58|
|Rye bread with 80% kernels||41|
- The glycemic index of brown rice is nearly the same as white rice. White rice is missing the nutrients, but the fact that my daughter and husband won't eat brown rice isn't as bad as I had thought, since we don't eat rice that often anyway.
- Using actual whole grains in bread has a big impact on the glycemic index; simply subbing whole grain flour for refined flour makes little difference in how it affects blood sugar.
Since my experimental gluten-free month, I've been limiting things made with flour, and that seems like a sound strategy according to these press releases and the GI data. My next baking experiment will be adding more real whole grains to our bread.