I recently received the results of a nutrition study re: raisins and post-meal glucose levels.  This got me thinking…I have learned to be some what savvy when sifting through this type of information, however I can see how it would be very difficult for most people who don’t do this on a daily basis; especially when news outlets pick-up these stories and soon you hear news anchors everywhere extolling the virtues of this or that.

While I have not done the further research yet, when examining study findings such as the ones below, questions pop-up in my head and I thought it might be helpful for you to see how I personally go through articles such as the one below (My comments will be in RED).  I definitely do not claim to be an expert in deciphering research…these are the methods I follow personally.

For this particular study, I noticed immediately that though it came from a Nutrition Website I subscribe to and thoroughly enjoy (Smartbrief for Nutritionists), it had a disclosure on the top of the e-mail stating, “This is a paid advertisement” which got me thinking…who paid for it?


California Raisins Announces New Research Findings (Who funded this research?  Was is California Raisins?)

New research recently debuted at the American Diabetes Association’s 72nd Annual Scientific Session suggests eating raisins three times a day may significantly lower post-meal glucose levels when compared to common alternative snacks of equal caloric value (What specifically were those snack alternatives?  Apples, rice cakes, cheese, chocolate chip cookies, potato chips???).

The study was conducted at the Louisville Metabolic and Atherosclerosis Center (L-MARC) by lead researcher, Harold Bays, MD, medical director and president of L-MARC (Does this doctor have any affiliation with the Raisin Board?)

Key Findings:

The study was conducted among 46 men and women who had not previously been diagnosed with diabetes mellitus, but who had mild elevations in glucose levels. Participants were randomly assigned to snack on raisins or pre-packaged commercial snacks (Again, what specifically were those snacks?) that did not contain raisins or other fruits or vegetables (We now know the other snacks were not produce-related), three times a day for 12 weeks (How big was the portion size?). Findings included:

  • Compared to control snacks (Not sure what they were), raisins significantly decreased mean post-meal glucose levels by 16 percent  
  • Compared to baseline within group paired analysis, raisins significantly reduced mean hemoglobin A1c by 0.12 percent (that is a decrease, but VERY slight and not what I would consider significant…a small fraction of 1 percent)
  • Consumption of the control snacks in the study did not significantly reduce mean post-meal glucose or hemoglobin A1c 

The study was funded by the California Raisin Marketing Board through a grant to the L-MARC Research Center in Louisville, Kentucky (We now know the study was funded by the California Raisin Marketing Board).

“Raisins have a relatively low glycemic index and contain fiber and antioxidants, all factors which contribute to blood sugar control,” said James Painter, Ph.D., R.D., and nutrition research advisor for the California Raisin Marketing Board. “Decreasing blood sugar and maintaining normal hemoglobin A1c levels is important because it can prevent long-term damage to the heart and circulatory system.” This statement is reasonable, however dried fruits are MUCH higher in sugar and MUCH more concentrated in calories than fresh fruit.  My fear would be that people begin ADDING handfuls of raisins into their diets in an attempt to lower their blood sugar and that seems misguided.  

The research is from a two-part study by L-MARC that looked at raisins and possible impacts to blood pressure and blood sugar levels. The first part of the study announced at the American College of Cardiology’s 61st Annual Scientific Session suggests eating raisins three times a day may significantly lower blood pressure among individuals with slightly higher than normal blood pressure, otherwise known as prehypertension.

Visit for further information and summaries of California Raisins’ nutrition research.

Again, I DO NOT have the answers to all of the red flags above…that will take further research; I merely wanted to share the process I go through  with you.

Do any of you have a similar process you go through in your head when reading nutrition information or listening to news stories about nutrition / health?


Filed under Education, Research


  1. I really love this post… not only to encourage folks to question “research” but to also question everything they read and hear… I remember in grad school a very interesting lesson we all learned about interpreting research and how data and statistics can be manipulated… Again – great (and very important) post!!! 🙂 xoxo

    • That’s so true Jodie. I think I first learned that lesson when we were in Speech and Debate…it blew my mind that I could convincingly argue two different sides of the same topic!

  2. Always good to be skeptical.

    Great article.

    I’d add that a sample size of 46 individuals is fairly small. It also says nothing of those individuals’ other diet and exercise habits, nor whether the results were controlled for meals consumed. Imagine if a raisin eater, having eaten something sweet, skips dessert, while a control snacker (having had an unnamed possibly savory snack) feels the need for something sweet and eats a piece of chocolate cake for dessert. The raisins did not cause a comparative decrease in blood sugar – the not eating cake did. Would eating a stevia-sweetened snack have the same effect? Who knows!

  3. What a very useful article! I was actually discussing the difficulty involved in analyzing scientific papers with my friend who is a MD the other day. Herself is facing difficulties and constantly needs to refer back to other studies and previous researches to put the new studies in perspective. Thanks.

  4. HC

    I love this article! I have always been skeptical how they push their agenda (pill companies, processed food products like Special K, etc.). Money speaks volume!

  5. Michael Ford

    I have never seen a nutrition study that was very meaningful to me. Unless you control the calories, food selections, amount of excercise, BMI, metabolism etc., of all of the participants you never know what really caused the differing results between two groups of people. The two groups, unless they are extremely large are very likely to have different results but that doesn’t mean that the food being studied had much if anything to do with it.

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