A study sponsored by PepsiCo showed that adding extra fiber to regular orange juice markedly reduced the usual high rise in peak blood sugar and insulin concentrations in men who were at high risk for diabetes and heart attacks (The Journal of Nutrition, May 11, 2016).
In the study, 36 men, ages 30–65, with high cholesterol or triglycerides, ate a high-fat mixed breakfast. Then on four days, each separated by two weeks, they were then given 8-ounce glasses of either:
1) Tropicana pure premium orange juice without pulp (a PepsiCo brand),
2) The same orange juice with 5.5 grams of orange pomace fiber added,
3) Juice made from lightly blended whole oranges, or
4) A same-calorie, sugar-matched control.
The added-fiber group had significantly lower glucose concentrations after breakfast than the other groups. The added-fiber group also had significantly slower time to reach the peak glucose level, compared to the regular-juice and control groups, but not to the group that drank juice made from blended whole oranges.
Fruit Juice Issues
Regular orange juice can cause a high rise in blood sugar and insulin that increases risk for:
• diabetes (Am J Clin Nutr, published online Jan 30, 2013; Br J Nutr, Sep 14, 2014;112(5):725-34; Diabetologia, Jul 2015;58(7):1474-83)
• heart attacks (Atherosclerosis, August 2012;223(2):491-6)
• weight gain (JAMA, Aug 25, 2004;292(8):927-934)
• some types of cancer (J Clin Invest, Jan 2, 2014;124(1):367–384)
Glycemic Index (GI) and Glycemic Load (GL) are measures of how high various foods raise blood sugar, compared to a serving of straight table sugar, which is assigned a value of 100. Orange juice has a GI of 50 and a GL of 12, while a whole orange has a GI of 40 and a GL of 4. Apple juice has a GI of 44 and a GL of 30, while a whole apple has a GI of 39 and GL of 6.
How Does Fiber Help?
A single orange contains about 2.3 grams of fiber, of which 1.3 grams is soluble fiber. Soluble fiber is a gel-like substance that binds to sugar and reduces its rate of absorption. Juicing an orange removes much of the fiber, including the soluble fiber, so the unbound sugar can be absorbed almost immediately. This study demonstrates that at least some of the benefits can be restored by adding fiber back into the juice.
How About Smoothies?
This study showed that juice from a lightly blended whole orange had slower sugar absorption than either the commercial orange juice or the juice with added fiber. This result would seem to favor home-blended “smoothies” made from whole fruits or combinations of fruits and vegetables, but the study did not make any comparison between the juices and eating a whole (unblended) orange.
Another article in the same issue of the Journal of Nutrition points out that when you make your own smoothies, you are likely to take in extra calories since you can drink a 20-or-24-fluid-ounce smoothie in just a few minutes, compared with the 15 or 20 minutes it would take to eat the same fruits or vegetables whole (J. Nutrition, May 11, 2016). If you buy commercially-made smoothies, be sure to read the list of ingredients, since they often include added sugar, honey or other sweeteners, protein powder that is often sweetened and other ingredients that add calories and raise blood sugar.
What is Orange Pomace Fiber?
Orange pomace is everything that is left over after the orange juice and oil have been extracted from oranges. Generally it is regarded as a waste product at the juice processing plants, but food researchers are experimenting with ways to use it. When dried and ground, it contains 40 percent fiber. The flour-like substance may be used as an ingredient in gluten-free bakery products, and now we can expect that PepsiCo will soon introduce a new “all-orange” high fiber juice. It will be interesting to see what health claims they are allowed to make for the product.
While a fiber-added orange juice such as the one used in this study would be more healthful than ordinary commercial orange juice, I still recommend that you eat whole fruits and vegetables. When you eat whole, unprocessed or minimally-processed foods, you can be sure that you are consuming all of their nutrients and are not taking in hidden ingredients such as added sugars.