Intranasal insulin is insulin that is sprayed through the nose. This kind of insulin application helps improve brain function and prevents inflammation. Read below to learn more about its health benefits.
What is Intranasal Insulin?
Intranasal insulin (I-insulin) is a form of insulin that is a spray and inhaled through the nose. The insulin then travels to receptors in the brain [1].
Insulin receptors are located in the olfactory bulb, hypothalamus, hippocampus, cerebral cortex, and cerebellum [1].
Insulin signaling makes new synapses, and it can improve spatial memory [1].
Other pros include: it does not affect blood glucose levels [2], it prevents dopaminergic neuron loss [2], decreases hippocampal neuroinflammation [3] and improves memory in young, healthy humans [3].
Short-term use of intranasal insulin without absorption enhancers was predominantly well tolerated and no objective nasal adverse effects were detected [4].
Benefits & Uses of Intranasal Insulin
1) May Improve Brain Function
Patients with Alzheimer’s disease usually have low brain insulin signaling.
In adults with dementia or Alzheimer’s disease, intranasal insulin improved delayed memory. It also helped preserve general brain function [5].
Daily insulin treatment also increases verbal memory and improves attention [6].
In both young and postmenopausal women, insulin administration enhances working memory tasks [7].
The rapid-acting insulin analog insulin aspart (ASP-I) combined with intranasal insulin administration can improve word list recall even more than the normal insulin by itself [8].
Four months of intranasal insulin treatment improves brain functions in Alzheimer’s patients. However, the results depend on the gender of the patient. Both men and women had improvements in brain function when taking 20 IU of insulin, but only men benefited from the 40 IU dosage [9].
Brain insulin deficiency and insulin resistance can contribute to Alzheimer’s disease. Normal insulin administration in non-diabetics can cause low blood glucose. However, intranasal insulin can directly deliver insulin to the brain and help treat Alzheimer’s while avoiding side effects [10].
It also significantly improves brain function in bipolar disorder patients [11].
The 22q13 deletion syndrome (Phelan-McDermid syndrome) can cause developmental and speech delay and autistic behavior.
Short term intranasal insulin improves motor activities, brain function, and education levels in children. On the other hand, positive long-term effects also included improvements in motor activity, nonverbal communication, brain function, and autonomy [12].
Intranasal insulin administration also improves mood. After insulin treatment, the subjects reported signs of enhanced self-confidence and reduced anger [13].
2) May Help Prevent Obesity
Intranasal insulin affects the hypothalamus, which is the central regulator of metabolism [14].
The brain can rapidly influence whole-body (liver, muscle, and fat tissue) insulin sensitivity through the autonomic nervous system [15].
Hypothalamic neurons are crucial for insulin’s control of peripheral metabolism [15].
Impaired brain insulin action is linked to diabetes, obesity, and brain diseases.
In overweight and obese patients, insulin action is impaired. This may reduce the inhibitory control, which will lead to overeating [16].
Brain insulin can cause anorexic effects in humans and animals. Intranasal insulin increases insulin activity in the brain, which can stop overeating and obesity [16].
Insulin and cortisol regulate energy homeostasis and appetite. Intranasal insulin application to men affects blood flow in the brain and helps regulate eating behavior [17].
Insulin can also help regulate fat metabolism. Intranasal insulin suppresses free fatty acid levels. This can help control the breakdown of fats in healthy humans [18].
In normal-weight men, intranasal insulin administration reduces body fat [19].
8 weeks of intranasal administration in men lead to decreased body weight, fat, waist circumference, and fat levels. However, it did not have the same effects in women [20].
3) May Help Treat Diabetes
Intranasal insulin moderates food intake and activity in the brain. It can help treat excess liver glucose production in diabetes [21].
In humans, the intranasal route allows insulin to reach the brain while maintaining a normal concentration of glucose in the blood [22].
Diabetes can change brain function. Intranasal insulin administration can modify connections between different brain regions. It can help regulate memory and complex brain-behavior [23].
Intranasal application of insulin to the brain impacts the whole-body insulin sensitivity. In lean patients, it can improve insulin sensitivity [24].
4) Improves Sense of Smell
Insulin resistance is linked to diabetes, obesity, and decreased the sense of smell.
Intranasal insulin administration improves nose sensitivity. It helped patients correctly identify odors and improve their impaired sense of smell [25].
In young men, intranasal insulin improves odor-cued reactivation of spatial memory [26].
Interesting details
- I-insulin increases delivery of NMDA receptors to the cell membrane [1].
- Rapid-acting insulin has better intranasal effects than regular insulin because I-insulin goes to all brain regions [1].
- Chronic I-insulin treatment has stronger effects than acute treatment [1].
- I-insulin also increases heart rate variability (increased high-frequency band/parasympathetic activity indicating that vagal outputs are involved) [15].
