According to a 2015 Centers for Disease Control and Prevention (CDC) study, 30.9 million Americans suffer from diabetes. On average, individuals with diabetes inject themselves with insulin two to four times per day. This means that every single day, Americans are injecting anywhere from 61,800,000 to 123,600,000 doses of insulin. It’s not surprising, then, that there’s a high demand for new, less painful methods of administering insulin.
For many years now, researchers looking into new modes of insulin delivery have focused on the oral method—in other words, an insulin pill. And while great strides have been made toward this effort, after decades of trying, some researchers have declared such a method of insulin delivery impossible. But Chemical Engineering Associate Professor Kathryn Whitehead and her team have now shown that such a feat is possible.
Not only is oral insulin delivery possible, but its secret lies in an unlikely place: strawberries.
“The problem with insulin,” says research assistant Nicholas Lamson, “is that it’s a protein. The human stomach is very adept at breaking down proteins—such as with food. But in order for insulin to be therapeutic, it needs to be absorbed intact by the small intestine. This requires the insulin to be protected as it passes through the stomach.”
Researchers have developed many ways to encapsulate insulin molecules so that they can make it to the small intestine. But it’s what to do with them once they’re there that has been the biggest sticking point in this field. Allowing the proteins to pass into the small intestine fully undigested means the insulin is too large to be absorbed through the intestine and into the blood stream. And while compounds already exist that can open the pores of the small intestine, few can do it without lasting damage.
This is where Whitehead’s strawberries come in.
We took around 110 fruits and vegetables and screened them for an ability to open up the gaps between the cells of the intestine wide enough to allow the insulin to pass through.Kathryn Whitehead, Associate Professor, Chemical Engineering
“We took around 110 fruits and vegetables and screened them for an ability to open up the gaps between the cells of the intestine wide enough to allow the insulin to pass through,” Whitehead says. “It turns out that the same chemical that makes strawberries red—pelargonidin—can also dilate these intestinal pores in a nontoxic way that later allows them to shrink back to normal.”
Combine this molecule with an encapsulated insulin package and voila—an insulin pill that can help diabetics manage their blood sugar with no negative side effects. But though the research team has proven the pill’s efficacy in mice, there is still a long way to go before an insulin pill is made available to human diabetic patients.
“A number of challenges must still be addressed,” says Lamson, “one of the biggest being the necessity of variable dosage. Diabetics must test their blood sugar throughout the day and administer an insulin dose appropriate for their blood sugar levels. This is easy to do with an injection, but much more difficult to do with a pill. This is the next challenge we’ll have to overcome.”
While this research can help make the oral delivery of insulin in diabetic patients a reality, that’s not all it can do. Whitehead’s lab is interested in the oral delivery of proteins in general, and her team plans to extend their strawberry technology to proteins other than insulin. That means this technology can potentially be used with other protein therapies, many of which are used to treat conditions like leukemia, osteoporosis, and autoimmune disease.
Such an advance would revolutionize healthcare as we know it, removing the pain of injections and improving the daily lives of millions of patients.