Carbohydrates and insulin response
Simple vs. complex carbohydrates:
To achieve stable insulin levels, the important thing is to take into account the speed at which a carbohydrate raises blood sugar and therefore, this hormone.
In the body, carbohydrates are broken down into smaller units of sugar, a process that is delayed by consuming complex and fibrous carbohydrates. But when consumed in their simple or refined form, they immediately spike blood glucose, creating a spike in insulin.
Simple and refined carbohydrates are popularly known for their “empty calories,” since they rarely have any nutritional value and also, as we will develop here and in the coming blogs, they are directly related to diabetes, obesity, heart disease and certain cancers.
If we were to put carbohydrates in order according to the impact they have on the insulin response, the ranking from the healthiest to the unhealthiest would be as follows:
(Note: It is important to clarify that when we talk about healthy or “unhealthy” vegetables, we refer to the response they create in insulin and not to other factors … which are many.
The idea that vegetables are always healthy, is a very complex and controversial subject that deserves its own book)
- Non-starchy vegetables.
- Vegetables rich in resistant starches.
- Unadulterated starches.
- Refined starches.
- Monosaccharides and disaccharides.
1. Non-starchy vegetables:
Non-Starchy vegetables generally contain very few carbohydrates and many of these come from the fiber.
(Note: Dietary fiber can be beneficial because it doesn’t raise glucose levels and also, it can slow down the absorption of other carbohydrates, but its benefits may have been overestimated. For example, people who lack good diversity of intestinal microbes may have more harm than good.
Also, it is worth mentioning that even if fibers may increase intestinal traffic, science has shown that for constipation, they can be counterproductive (1,2)
Unlike sugars and starches, fibers are not absorbed in the small intestine and are not converted to glucose. Instead, they pass to the large intestine relatively intact, where they are converted into hydrogen, carbon dioxide, and fatty acids.
In addition, they slow down the absorption of other carbohydrates, which makes them the best option to maintain stable insulin levels and, together with low-glycemic vegetables that are rich in resistant starches, to reverse certain pathologies associated with insulin resistance.
Some examples of these would be herbs, celery, lettuce, broccoli, cabbage, spinach, and chard.
2. Resistant starches:
Science has made it clear that complex carbohydrates should be obtained from unprocessed vegetables, since those contained in processed foods such as bread or pasta quickly break down into glucose, creating a potential unhealthy insulin spike.
As we have mentioned, the difference between these is the speed at which they are absorbed, but the metabolic pathway is the same. In contrast, resistant starches follow a completely different metabolic pathway.
Resistant starches are carbohydrates that behave more like fiber.
These starches resist digestion (hence their name) and instead of being absorbed in the upper half of the gastrointestinal tract, they are fermented by microbes in the large intestine (3,4,5,6,7), generating short chain fatty acids as a by-product.
Short chain fatty acids could have a therapeutic potential to treat insulin resistance, as they have anti-inflammatory and antidiabetic effects by suppressing the signaling of this hormone, inhibiting fat storage and reducing it (5,4,6,8). Also, they increase the release of hormones and peptides from enteroendocrine cells, giving greater satiety and reducing the search for food (9).
Of course, if we are looking for stable insulin levels to reverse a pathology, resistant starches should come from low glycemic index vegetables, as they are also present for example in rice or potatoes, which are not the best option for this particular purpose.
Some examples of vegetables with a high content of resistant starches and a low glycemic index are tapioca, sweet potatoes, yucca and celery root.
(Note: With respect to resistant starches, it is also worth mentioning that although they can have an effect on the production of short chain fatty acids, diets based on animal foods have also been shown to generate good levels as well (10)
3. Unadulterated starches:
Starchy vegetables provide a variety of beneficial nutrients and can be a healthy addition to the diet when consumed in moderation. But for many nutrients they contain, compared to non-starchy vegetables, they are a much higher source of carbohydrates and calories.
For this reason, if we want to keep insulin peaks in the blood to a minimum and especially if we are trying to reverse pathology, we should consume those that are richer in resistant starches and minimize those that have the greatest impact on blood sugar.
Some examples of those with the highest glycemic index and therefore, those that we should consume in moderation or in some cases not at all, are white rice and corn.
(Note: Some vegetables in particular are high in lectins, a special class of proteins that can be potentially problematic in some conditions. A topic that we will develop in future blogs)
4. Refined starches:
As we have just seen, grains in general should be consumed in small quantities or better yet (in my opinion), exceptionally. But refined grains should be completely avoided.
These vegetables rich in lectins and stripped of all bran, fiber and nutrients are digested quickly and their high glycemic index causes large spikes in blood sugar.
Insulin spikes create a vicious cycle, because you feel hungry shortly after a meal. Leading to an even greater quest for sugary refined carbohydrates and therefore to excesses that lead to weight gain and the potential to create insulin resistance.
The high consumption of this type of starch is also related to high blood pressure, heart disease, obesity, hyperactivity and mood disorders.
Most of these factors are well known, but what is not talked about, is the latter.
A sudden spike in your blood sugar, followed by an exaggerated insulin response, leads to acute hypoglycemia (11), which is closely related to symptoms of depression (12) and most likely, the reason that links diabetes to suicide (13).
An eventual plate of pasta or a pizza from time to time, could be “the prize” for a healthy lifestyle, but unlike what has been said for years, or the base of the famous nutritional pyramid of the 80s ‘, under no circumstances should they be part of a balanced diet.
Some examples of these are white bread, pizza dough, pasta, and most breakfast cereals.
5. Monosaccharides and disaccharides:
Monosaccharides and disaccharides, also called simple carbohydrates or sugars, are found in a variety of natural foods, such as honey, fruits and vegetables (fructose and / or glucose) or milk (lactose).
Our biology is prepared to process a certain amount, as long as it comes from unadulterated food like the ones we just mentioned, but the big problem in today’s society is that we usually get it in its refined form.
Some examples of monosaccharides are glucose and fructose and of disaccharides, lactose and one of the great protagonists of the metabolic disaster of the last six decades… table sugar.
The rest of the blogs about carbohydrates will be dedicated to table sugar, a molecule that deserves its own book. So, in the most summarized way possible, we will see why based on the evidence, we could conclude that this sweet, which for years was classified as innocent, may be the main responsible (along with vegetable seed oils), of the epidemic of metabolic diseases of the last decades.
To do this, we will delve into its composition, the way it is metabolized, its addictive potential and its relationship with various dysfunctions, including diabetes, vascular diseases, metabolic syndrome (fatty liver, high blood pressure, triglycerides, etc.) and cancer.
Also, we will see how the dangers of this molecule were known more than six decades ago, but have been hidden in a history of cover-ups and bribery.
References:
1 – Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms.
2 – Water-holding by dietary fibre in vitro and its relationship to faecal output in man.
4 – Glucose: Chemistry and Dietary Sources.
7 – Insights into digestion and absorption of major nutrients in humans.
8 – Functional interactions between the gut microbiota and host metabolism.
10 – Diet rapidly and reproducibly alters the human gut microbiome.
13 – Risk of Psychiatric Disorders and Suicide Attempts in Emerging Adults With Diabetes.