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Resistant Starch: Why Local diet is good for your Health

Mr. Gaye TheVoice

By Prof. Raphael Nyarkotey Obu

Being a Professor of Naturopathy with an interest in African Naturopathy, especially in the African context, I found something interesting throughout my research on our local foods. What I found is that our local diets are highly nutritious and beneficial to our health. But it appears we have succeeded in demeaning them at the expense of foreign foods. We have shifted our studies to the negative aspects of our local foods and praising foreign delicacies. Our scientific community and medical professionals appear to buy into some of this brainwashing without conducting studies to ascertain the facts. This keeps me thinking and worrying.

Recently, I chanced on Prof. Badu Akosa’s video lamenting why we have neglected our local oils such as Palm oil, coconut, etc at the expense of industrially manufactured oils. Recently, the Daily Graphic reported that data available to the Ministry of Health indicates that approximately 35 percent of the adult population of the country is hypertensive, the disease described as a silent killer if not controlled, with many more affected people unaware of their condition or undiagnosed.

This is a disturbing situation coupled with wrong medical information. Wrong health information is a disease!

Recently, I wrote about the science of eating gob3 in Ghana which drew huge attention and some controversies. Others argued that the ingredients in gob3, are loaded with starch hence it creates a problem for our health. However, they did not recognize the fact that I highlighted that the starch content in gari and beans is a type of starch known as resistant starch. Well, this was expected as the thought of starch in Ghana is linked to bad eating practices. We have inherited and been indoctrinated that starches are unhealthy and should be avoided at all costs, especially for lovers of good health.

What we forget to know is that not all starch is created equally, however. In one article by Links, R(2018), the author explained that resistant starch, for example, is a beneficial type of starch that can have a multitude of positive effects on health. Links, R(2018) further explained that resistant starch diets support weight loss and blood sugar control. This article aims to espouse the scientific benefits of eating local foods loaded with resistant starch. It also aims to bring to the public domain the importance of resistant starch and ultimately to educate the public that not all starch foods are bad as had been advocated for years.

History, Resistant Starch

Links, R(2018) in one of her articles explained that the ideal surrounding resistant starch emanated from the 1970s and hence has been regarded or considered to be one of the three major types of starch, including the already known digested starch and slowly digested starch. Hence, the idea surrounding resistant starch is relatively new as nutrition advocates have supported the consumption of whole grains and legumes as part of staple ingredients in a healthy, well-rounded

diet. For instance, The Commission of the European Communities, the organization responsible for policy-making for the European Union, began funding and supporting research on resistant starch in 1996, and a review entitled “Nutritional Implications of Resistant Starch” was published in Nutrition Research Reviews, this review brought the concept and definition of what constitutes resistant starch and the mechanism of action. This also paved the way for recent studies on resistant starch by many researchers on the health benefits of this health-promoting compound, which led to the discovery that resistant starch consumption stabilizes blood sugar, and promotes digestive health and weight loss.

What is Resistant Starch?

Link, R(2018) article defined resistant starch as a type of starch that isn’t completely broken down and absorbed in the stomach or small intestine. Instead, it passes through to the colon and is converted into short-chain fatty acids, which act as prebiotics to help feed the beneficial bacteria in the gut. Another unique thing about resistant starch is that it is processed and metabolized the same way as dietary fiber, which comes with many health benefits. Due to this; studies consider it diabetic friendly, aids satiety, and aids digestive health. Web med also defined Resistant starch as a type of carbohydrate that doesn’t get digested in your small intestine. Instead, it ferments in your large intestine and feeds beneficial gut bacteria.

Additionally, due to the way it aids satiety, some also regard it as a keto-support diet especially those considering a low-carb diet as it resists digestion or goes through the body undigested without raising blood sugar levels.

Types of Resistant Starch

Different resistant starches exist. Sajilata et al.(2006) found four types which were highlighted in Gunnars, K(2018) article:

Though Corn has a GI of 52, which is on a low glycemic diet and is also a source of resistant starch. However, most commercial varieties of corn products may be composed of 40–60% resistant starch. The remainder is mostly digestible starch. This could pose challenges to diabetics. Besides, studies have been mixed on certain corn-related diets such as Banku and Kenkey.

Diabetics can still eat white rice in this manner by allowing it cool for a longer period to increase its resistant starch contents before eating.

Additionally, what I also found from the literature is that resistant starch tends to coexist in the same food. For instance, the way foods are cooked or prepared can change the outlook or the amount of resistant starch in a particular food. This was demonstrated in how banana ripening (turning yellow) will degrade the resistant starches and turn them into regular starches.

This is why one study by Ogbuji et al.(2013) found that the average glycemic index for ripe plantain is 54.6 and 45.3 for unripe plantain. They also noted that the glycemic index values for fried, boiled, and roasted ripe plantain are 56,54 and 55 respectively. Another study by Kouamé et al.(2017) in Côte d’Ivoire found plantain chips(unripe) to have a GI of 45 which is within the low range. The study did not support consuming Banane braisée(Charcoal –roasted light green stage plantain) which has a GI of 89 and uses the roasting method. The other cooking method for plantains such as chips used deep frying with major ingredients being salt, and refined palm oil.

A previous study by Ayodele and Godwin(2010) in Nigeria found no difference between boiled plantain (Bp), fried plantain (Fp), roasted plantain (Rp), boiled and pounded plantain (BPp), and plantain flour. The study found that roasted plantain gave the lowest glycemic index and the value was significantly lower than the other test foods.

This has lost its resistant starch content

Mechanism of Action

Studies have found that resistant starches function similarly to fermented fiber. This was demonstrated in an old study by Englyst et al.(1996) which found that resistant starch penetrates the stomach and small intestine undigested, and gets into the colon where it feeds the friendly gut bacteria. Sears, C(2005) study found that human intestine bacteria(gut flora) overshadow the body’s cells 10 to 1 — this means we are only 10% human.

One review and one comparative study(Macfarlane, S. 2006; Brown et al. 1997) explained that when we eat most foods feed only 10% of our cells, whereas fermentable fibers and resistant starches feed the other 90%. This study is very interesting. Our local foods are loaded with resistant

starches which are beneficial to us yet we forgo them. Forgoing our local foods means we are losing a lot as Africans.

Additionally, two studies(Guarner and Malagelada, 2003; Cryan, and O’Mahony, 2011) also found that the intestine is loaded with hundreds of diverse species of bacteria. The researchers found that the number and type of bacteria have the potential to influence our health.

Two studies(Wang et al. 2001; Topping et al. 2003) confirmed that resistant starch feeds the friendly bacteria in our intestines, thus taking a positive effect on the type of bacteria and their number.

Two reviews (Topping and Clifton. 2001; Wong et al. 2006) found that in event that the bacteria digest resistant starches, they form several compounds, including gases and short-chain fatty acids, most especially butyrate.

Resistant starch, Science Lowers Blood Sugar

When we consume local foods from cassava-related, plantain, corn-relate, beans, seeds, legumes, etc, the resistant starch nature has been confirmed in scientific studies to control blood sugar. For instance, two clinical trial and a review(Raben et al. 1994; Higgins, 2004; Maiarz et al. 2017) found that eating resistant starch help sustain normal blood sugar levels and aids glycemic control to avert any blood sugar spike and prevent diabetes naturally. Another clinical trial by Johnston et al. 2010) also found that resistant starch may also improve insulin sensitivity.

One study by Brighenti et al. (2006) also found resistant starch has a second meal effect, this implies that if you eat resistant starch with breakfast, it can also lower your blood sugar spike at

lunch. This reminds me of the days when we used to eat the leftovers fufu early in the morning in the village before going to the farm. This is supported by two studies (Robertson et al. 2005; Maki et al.2012) found that this has a huge effect on glucose and insulin metabolism. The researchers when participants eat these foods had a 33–50% improvement in insulin sensitivity after four weeks of consuming 15–30 grams per day.

Gut Health

There are trillions of bacterial cells in our gut microbiome. One of the significant aspects of eating resistant foods is that it benefits your gut health. Two studies (Jacobasch et al. 1999; Brouns et al. 2002; Lynnette et al.2009; Donohoe et al. 2011) found that when we eat resistant starch foods, they go straight into our large intestine, where the bacteria digest them and convert them into what we called short-chain fatty acids or butyrate.

Butyrate is used as the primary source of fuel by the good gut bacteria in our colon. Resistant starch both feeds the friendly bacteria and indirectly feeds the cells in your colon by increasing the amount of butyrate. The result is that butyrate improves the health of our gut microbiome, enhances digestive health, and supports the treatment of conditions such as inflammatory bowel disease, Crohn’s, and ulcerative colitis. For instance, Two clinical trials(Hylla et al. 1998; Zimmerman et al. 2012) established that resistant starch lessens the pH level, is effective against inflammation, and decreases colorectal cancer.

Additionally, resistant starch consumption benefits extend outside the colon. For instance, one animal study and a review (Gao et al. 2009; Hamer et al. 2007)found that the short-chain fatty acids which remain in the colon and are unused further move to the bloodstream, liver, and the rest of your body, and function to support them. One review by Bird et al,( 2000) found that due to

the therapeutic effects on the colon, resistant starch support numerous digestive illnesses such as inflammatory bowel diseases like ulcerative colitis and Crohn’s disease, constipation, diverticulitis, and diarrhea. Two animal studies( Morais et al. 1996; Younes et al. 2001) confirmed that resistant starch consumption further improves the absorption of minerals.

Weight loss

Resistant starch has fewer calories than regular starch — two vs four calories per gram. The higher the resistant starches content in a food, the fewer calories it will have. Maybe, this could also explain why some communities in preparing banku add more cassava dough as compared to maize flour. I saw this method in my village when I was a young boy. Our forefathers knew exactly what they were doing but could not explain it to us in scientific terms. This could also mean that our forefathers were practicing science without documentation. Anyways, two clinical trials (Salas- Salvadó et al. 2008; Ramos et al. 2011) justified this and found that soluble fiber supplements can aid weight loss, because they can make one full and lessen our appetite. Resistant starch appears to be in the same line as soluble fiber. Hence, when we include it in our diet, it makes us full and allows people to eat fewer calories according to three clinical trials( Anderson et al. 2010; Bodinham et al. 2010; Willis et al.2009)

Fights colon cancer

A previous clinical trial study by Hylla et al. (1998) in 12 healthy volunteers for two-4 weeks found that consuming resistant starch modified the metabolism of certain bacteria in the colon to aid in cancer prevention.

Zimmerman et al.(2012) in vitro study found that butyric acid, one of the compounds formed by the breakdown of resistant starch, may be effective in reducing inflammation in the colon and blocking the growth of cancer cells.

Other studies also opined that resistant starch might block the growth and spread of colon cancer cells and support the digestive system.

Warnings

Anything with positive also has some negative side. For an instance, supplements made from corn known as Hi-Maize flour, have lower beneficial nutrients than whole-food corn-related sources of resistant starch. Also, Potato starch, for example, contains less of the calories and carbs in potatoes, but it also contains a lower amount of essential nutrients, vitamins, and minerals found in the potato nutrition profile as well. Too much can also trigger serious gastrointestinal issues. Eating high amounts can act as a laxative in the body and can cause side effects such as abdominal pain, excessive flatulence, and bloating.

Resistant Starch vs. Fiber vs. Starch-difference

Well, there are so many controversies surrounding this. But what is starch? Starch is a type of carbohydrate which consist of many units of sugar joined together by glycosidic bonds. We normally get them in starchy foods, such as peas, corn, and potatoes. Links, R(2018) a renowned registered international dietician explained the difference and similarities:

Resistant starches, on the other hand, are not digested in the small intestine and instead travel to the large intestine where they are converted into short-chain fatty acids. My question is if fufu and konkonte are in the class of resistant starch and they do not digest; how come we are told that it takes about 7 or whatever hours for fufu to digest?

Besides, I could not get any sound literature to support this. Also if resistant starch foods such as fufu or konkonte resist digestion, it means resistant starch doesn’t cause blood sugar to increase the same way as regular starch and boasts a much longer list of health benefits.

Meaning, that I will personally choose to eat fufu or konkote at even 8 pm as compared to white rice or what they term light food at 8 pm. This is because this white rice which is not even cooled or light food is going to digest and cause sugar spikes when resistant starch food such as fufu or konkonte will not as they resist digestion. Unless probably, these light foods at 8 pm have undergone the retrogradation process to form resistant starch before I will personally eat them.

Fiber meanwhile is another type of carbohydrate that is indigestible and comes with many of the same benefits. Much like resistant starch, fiber can promote gastrointestinal health, support weight loss, improve digestive health, and protect against chronic disease and colon cancer. Include both as part of a healthy, well-rounded diet to reap the multitude of benefits that each has to offer.

Although resistant starch is a term that’s been coined just within the last century, resistant starch foods have long been used in many forms of holistic medicine.

Links further held that Traditional rice varieties commonly consumed on an Ayurvedic diet, such as basmati, contain a higher amount of resistant starch than heavily processed white rice. “Other resistant starch foods, such as potatoes, also work well on an Ayurvedic diet and are believed to have grounding, sedative properties that can help satisfy the stomach and alkalize the body”.

Links also opined that in Traditional Chinese Medicine, rice is used to soothe and nourish the stomach, plus strengthen the spleen and relieve indigestion. “Meanwhile, other resistant starch foods like oats are used to reduce blood pressure, decrease diarrhea and stop spontaneous sweating”.

Resistant Starch Foods

One can get resistant foods in two ways: foods or take a supplement.

Cooked and Cooled Potatoes

Many controversies surround sweet potato consumption by diabetics. The debate centered on potatoes’ high glycemic index, a measure of how much a food raises blood sugar levels( Atkinson et al. (2008).

Muraki et al.(2016) opined that higher potato consumption has been associated with an increased risk of diabetes, this could be caused by processed forms like French fries rather than baked or boiled potatoes. Studies have found that how potatoes are processed could impact your health. For example, cooling potatoes after cooking can considerably increase their amount of resistant starch. For instance, Muir and O’Dea (1992) found that cooling potatoes overnight after cooking tripled their resistant starch content. Another study by Raben et al.(1994) in 10 healthy adult men found that the higher amounts of resistant starch in potatoes led to a smaller blood sugar response than carbs with no resistant starch.

Retrogradation is the process when potatoes are cooked and then cooled, this allows the sweet potatoes to acquire a higher amount of resistant starch. Renowned dietitian Links(2018) explained that though there is resistant starch in sweet potatoes and other tubers, white potatoes are heavily loaded with resistant starch. Other ingredients like raw potato starch are gotten from potatoes they also contain resistant starch.

Also, take note that raw potato starch contains about 8 grams of resistant starch per tablespoon and almost no usable carbohydrate. Four tablespoons of raw potato starch can load you with 32 grams of resistant starch. However, too much of it can also cause flatulence and discomfort. There’s no point in taking much more than that since excess amounts seem to pass through your body when you reach 50–60 grams per day. It may take 2–4 weeks for the production of short-chain fatty acids to increase and for you to notice all the benefits — so be patient. Chen et al.(2010) found that raw

potato starch for instance is one of the most concentrated sources of resistant starch, with about 80% of the starches in it being resistant. Additionally, due to the high content of resistant starch, one needs 1–2 tablespoons per day. Potato starch is often used as a thickener or added to:

The best is to not heat the potato starch. Instead, prepare the meal and then add the potato starch once the dish has cooled. A lot of people use raw potato starch as a supplement to boost the resistant starch content of their diet.

Cooked and Cooled Rice

Links(2018) also explained that resistant starch rice includes any type of rice that has been cooked and then cooled. Links further advised we opt for brown rice over white rice in other to also acquired the needed vitamins, minerals, and fiber content. This means that white rice has a high glycemic index and is not good for diabetics, one can eat white rice only if is cooked and further allowed to cool for some time before eating. The longer the white rice is allowed to cool the higher the content of resistant starch content one can get. One popular preparation method is to cook large batches for the entire week.

Sonia et al. (2015) study compared freshly cooked white rice to white rice that was cooked, refrigerated for 24 hours, and then reheated. The rice that was cooked and then cooled had 2.5 times as much resistant starch as the freshly cooked rice.

Researchers also examined what occurred when both types of rice were eaten by 15 healthy adults. They found that eating the cooked and then cooled rice led to a smaller blood glucose response. Though more studies are needed, another rat study by Ha et al.(2012) found that eating rice that had been repeatedly heated and cooled led to less weight gain and lower cholesterol.

Also a recent study by Strozyk et al.(2022) in 32 patients with type 1 diabetes where each participant in the study consumed two standardized test meals consisting of long-grain white rice. One of the test meals was served immediately after preparation, and another was cooled for 24 h at 4 °C after preparation and reheated before being served.

The study concluded that the consumption of rice subjected to the cooling process results in a lower increase in blood glucose in subjects with type 1 diabetes. Also, two recent studies by (Liu et al. 2021; Cheng et al. 2022) also found that microwave reheating of cold rice increases the resistant starch content as it destroys the digestible starch content. A previous study by Ordonioa and Matsuokab(2016) also found that increasing rice-resistant starch is good for our health.

Beans and Legumes

Oats

Khoury et al.(2018) found that Oats are an excellent source of resistant starch, and they also contain beta-glucan, a type of soluble fiber that may be beneficial in the treatment of conditions like obesity and metabolic syndrome. Chen et al.(2010) also found that three-and-a-half ounces (100 grams) of cooked oatmeal flakes can be loaded with 3.6 grams of resistant starch. Oats, and whole grains, are also high in antioxidants. Additionally, to get more resistant starch in oatmeal, you should allow cooked oats to cool for several hours — or overnight before eating as this process can increase the resistant starch even more.

Green Bananas

Links(2018) explained that unripe bananas are loaded with resistant starch. Green bananas can be baked, boiled, or added to smoothies for a hearty dose of resistant starch. The study also opined that as bananas ripen, the resistant starch transforms into simple sugars such as:

Hence. It is advisable to buy green bananas and eat them within a couple of days if you want to maximize your resistant starch intake.

Hi-Maize Flour

This type of resistant starch-rich flour is made from corn and can be used to boost the fiber content of your favorite foods and baked goods.

Other Starches

Due to the process of retrogradation, other cooked and cooled starches can also contain resistant starch, such as resistant starch pasta. This was found in one comparative study by Yadav et al.(2009) found that cooking and cooling other starches will increase their resistant starch content. Hence, for lovers of Konkonte, as it cools the higher the resistant starch content. You can also select whole-grain varieties and pair them with generous portions of veggies, protein foods, and healthy fats to up the nutritional content of your meals.

Also, some ingredients contain high amounts of resistant starch, but only when consumed raw such as sprinkled on food or adding it to water or smoothies. The resistant starch content is lost when it is heated such as when used for baking or cooking.

Take Home

There’s no formal recommendation for the intake of resistant starch. However, in four studies (Birt et al. 2013; Wang et al. 2019; Maziarz, M. 2013; Maki et al. 2012) where the Study participants naturally received 10–60 grams per day. Significant health impacts were found with a daily intake of at least 20 grams, but an intake as high as 45 grams per day was also marked as safe.

Additionally, (Birt et al. 2013; Maki et al. 2012) also found that among Americans, several people get about 5 grams each day, some Europeans may get 3–6 grams, and the daily intake for Australians ranges from 3–9 grams.

Two studies (Chen et al. 2010; O’Keefe et al. 2015) also agreed that the average daily intake for Chinese people is about 15 grams. For rural South Africans 38 grams of resistant starch per day.

In Africa and Ghana, one article by Yakubu, T (2015) explained that people who consume whole grains and unrefined food products are likely to consume about 30-40 g/day. It is estimated that the acceptable daily intake of resistant starch may be as high as 45 grams in adults, an amount exceeding the total recommended intake for dietary fiber of 25-38 grams per day. The dietician encouraged individuals to have greater consumption of foods that naturally contain resistant starch. This call is necessary in our part of the world especially because people are increasingly resorting to more refined foods rather than unrefined ones.

From the literature, I found that though these are all high-carb foods as we know in the Ghanaian foods, for those on a very low-carb diet, you can avoid them. Additionally, some still can eat some especially if they are on a low-carb diet with carbs in the 50–150-gram range. However, for considering weight loss, having high blood sugars, and digestive problems, then resistant starch appears good for you.

The health benefits of resistant starch have engineered many people to opt for them now. Resistant starch is a type of nutrient that can boost digestion, prevent diseases, and promote weight loss. While most starches are digested and broken down, resistant starch will pass through you unchanged. My question: if resistant starches according to studies do not digest; where is the science supporting the digestion time of foods such as fufu; konkonte, banku, Akpele, etc.?

Resistant starch keeps your colon healthy. The good bacteria in your large intestine act to turn resistant starch into short-chain fatty acids, the most important of which is butyrate.

Cooking potatoes, pasta, beans, and rice and allowing them to cool in the refrigerator before eating are good. Reheating these items after they have cooled off won’t affect the levels of resistant starch. Apart from already espoused as resistant starch, we can as well get more resistant starch in our Ghanaian diets by cooking other starchy foods and allowing them to cool before eating.

Wang et al.(2015) found that resistant starch occurs when some starches lose their original structure due to heating or cooking. If these starches are later cooled, a new structure is formed. The new structure is resistant to digestion and leads to health benefits. Sonia et al.(2015) research has shown that resistant starch remains higher after reheating foods that have previously been cooled. However, you may feel that these foods taste best freshly cooked. In that case, find a compromise that works for you. You might choose to sometimes cool these foods before eating them, yet other times eat them freshly cooked.

NB:

Prof. Nyarkotey has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations to justify his write-ups. My articles are for educational purposes and do not serve as Medical advice for Treatment. I aim to educate the public about evidence-based scientific Naturopathic Therapies.

The author is a Professor of Naturopathic Healthcare and President of Nyarkotey College of Holistic Medicine & Technology (NUCHMT)/African Naturopathic Foundation. E-mail: collegeofholisticmedicine@gmail.com.

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