Friday, April 23, 2010

Health News and a Whole Foods Diet

A couple of studies in the news provide more evidence for a whole-foods based diet.

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.

Fructose Glucose Sucrose Maltose Glycemic Index Notes

Evap Cane Juice

55 3
Turbinado Sugar

65 3
Honey 50 44

62 varies by type
Fructose 100 0


100 3
Maple Syrup 1 4 95
54 3
Brown Rice Syrup
45-50 25 1,2,3
Molasses 23 21 53
55 3
Barley Malt Syrup 2 16 6 76 42 1,3,5
HF Corn Syrup-55 55 45

87 2
Corn Syrup 0 20-98

Agave Nectar 50-90 50-40

15-30 3

100 105 Wikipedia:Sucrose






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:
Item Glycemic index
Wheat berries 40-59
Whole grain rye 34-48
Brown rice 55-79
White rice 58-83
Barley 25-36
Oatmeal 48-58
Steel-cut oats 42
Millet 71

Whole wheat flour bread 71
Whole rye flour bread 68-88
White bread 73
Wheat bread with 50% cracked wheat 58
Rye bread with 80% kernels 41

Observations on this data:
  • 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.
One thing I've never understood is why pasta seems to measure so low on the GI scale... any thoughts out there? It's basically flour mixed with water, then dehydrated, then rehydrated by cooking. Perhaps the starch that comes out in the cooking water makes a difference.

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.

1 comment:

  1. I am currently experimenting with my bread recipe to lower the white flour content, by adding wheat bran and soy flour, plus seeds. It's been very hard to completely eliminate white flour and have good results. But I'll keep trying! :-)

    Thank you for your research!