All about Resistant Starch

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What is resistant starch?
Resistant starch (RS) is a type of starch that is not digested in the stomach or small intestine, reaching the colon intact.  Simply put, it “resists” digestion. This explains why we do not see spikes in either blood glucose or insulin after eating resistant starch, and why we do not obtain significant calories from resistant starch.

There are four types of resistant starch:

  • RS Type 1 – Is found in grains, seeds and legumes and resists digestion because it’s bound within the fibrous cell walls;
  • RS Type 2 – Is found in some starchy foods, including raw potatoes and green (unripe) bananas;
  • RS Type 3 – Is formed when certain starchy foods, including potatoes and rice, are cooked and then cooled. The cooling turns some of the digestible starches into resistant starches via retrogradation;
  • RS Type 4 – Is man-made and formed via a chemical process.

However, this classification is not so simple, as several different types of resistant starch can co-exist in the same food.

Depending on how foods are prepared, the amount of resistant starch changes. For example, allowing a banana to ripen (turn yellow) will degrade the resistant starches and turn them into regular starches.

Where to find resistant starch
Resistant starch occurs in a number of natural foods. Some legumes, many tubers such as potatoes, and many fruits, especially unripe bananas and plantains.

There are several supplementary sources such as raw potato starch, plantain flour and tapioca starch. Raw (not sprouted) mung beans are also a good source of resistant starch, so mung bean starch (found often in asian grocery stores) can also work.

Food for your gut
Just like anything other living organism, your gut bacteria requires a food source. They need to eat to survive, and certain food sources are better than others. Simply put, resistant starch is a high quality food for your gut bacteria. This is the very basic, but most important function of resistant starch.

How does it work?

A healthy human gut has hundreds of bacterial species, outnumbering all other cells approximately 10 to 1. The overall balance of these bacteria has an important effect on health and wellbeing. Resistant starch resists digestion until it reaches the colon where it feeds your good bacteria.

The good bacteria feeds on resistant starch and produce short chain fatty acids, with butyrate being the most significant due its beneficial effects on the colon and overall health.  Butyrate is the prefered energy source for the cells lining the colon, it also has a role in increasing metabolism and decreasing overall inflammation.

Below are just some of the health related benefits backed by science to consuming resistant starch.

Improve gut integrity and overall gut function
As mentioned earlier, resistant starch improves the overall quality and functionality of your gut bacteria. It also inhibits endotoxins from getting into circulation and can reduce leaky gut, which could have a positive effect with regards to allergies and autoimmune conditions.

Improved insulin sensitivity
Consuming Resistant starch improves insulin sensitivity, even in people with metabolic syndrome.

Lowers the blood glucose response to food
A popular reason people avoid even minimal amounts of  dietary carbohydrate is the blood glucose response. It’s too high. Resistant starch lowers blood glucose spike after meals. This reduction may carry over to subsequent meals.

Reduces fasting blood sugar
This is one of the most commonly mentioned benefits of resistant starch. With a reduction in blood sugar levels, resistant starch may help you avoid chronic disease and improve your quality of life.

Increases satiety
In a recent human study, a large dose of resistant starch increased satiety and decreased subsequent food intake.

Enhanced magnesium absorption
Most likely because resistant starch improves overall gut function and integrity, resistant starch increases dietary magnesium absorption.

Consuming resistant starch may also have the following benefits:

  • Improved body composition;
  • Improved thyroid function;
  • Improved sleep.

Adding resistant starch to your diet

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In a modern diet a person may only consume about 5g of resistant starch daily, compared to many traditional diets where 20g or 30g was consumed per day. You can add resistant starch to your diet by either consuming it from a food source or through supplementation.

Several commonly consumed foods are high in resistant starch. These foods include, raw potatoes, cooked and then cooled potatoes, yams, green bananas, various legumes, lentils and raw oats.

These foods are commonly high-carbohydrate foods, making them out of the question if you are following a low-carbohydrate nutrition plan. However, even if you are eating a low-carbohydrate diet, you can still see some benefit from consuming some resistant starch.

You can add resistant starch to your diet without adding any dietary carbohydrates. This is where our supplements, such as raw potato starch come in to the equation.

Raw potato starch contains approximately 8g of resistant starch per tablespoon and almost zero digestible carbohydrate.

It is cheap. It does have a fairly bland flavour, but it can be added into your diet in a variety of ways, such as by adding to foods, smoothies or mixing it with water.

Four tablespoons will give you about 32g of resistant starch. Like most supplements, it is important to build up, as too much too soon may have disastrous results.

There doesn’t seem to be any reason to consume much more than that anyway, as excess amounts seem to pass through your body when you reach about 50g per day.

Why you should be eating bananas

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Why it’s a superfood?

  • High in vitamins B6 and C, fiber, potassium, mangansese;
  • Good source of riboflavin, folate, magnesium, copper;
  • Contains antioxidant phenols.

Healthy evidence
One of the reasons eating bananas is beneficial is because bananas are high in potassium. Potassium is an electrolyte and we require it to help our bodies function optimally. One banana contains more than 300mg of potassium. The recommended daily intake according to the National Health and Medical Research Council is 3,800mg per day for males and 2,800mg per day for females.

Bananas are high in potassium, a mineral that promotes heart health and normal blood pressure. This meta-analysis published in 2011, found that a daily consumption of 1,300-1,400mg of potassium is linked to 26% lower risk of heart disease.

In addition, bananas contain antioxidant flavonoids that have also been associated with a significant decrease in the risk of heart disease.

Making the most of Bananas
The high content of heat-sensitive and water soluble vitamins B6 and C means that fresh bananas are the best choice (vitamin B6 may decrease by as much as 50% if heated). For added nutrients, combine bananas with fruit high in vitamin A, such as mango or peach and mix with cottage cheese to add slow digesting protein.

Bananas and athletic performance
The unique mix of vitamins, minerals, and low glycemic carbohydrates in bananas has made them a favorite fruit among endurance athletes.

Bananas have long been valued by athletes for prevention of muscle cramps. Since bananas are a good source of potassium, and since low potassium levels are known to contribute to risk of muscle cramps, it is logical to think that the potassium content of bananas as being a contributing factor for a reduction in muscle cramps whilst conducting physical activities.

When is the best time to eat bananas
Generally, the taste and nutritional value of bananas change as they ripen.

Pre-ripened bananas tend to have greener skins and are less sweet than well-ripened bananas because the starch hasn’t fully broken down into simple sugars. The upside to eating pre-ripened bananas is that you stay full for longer and enjoy the benefits of the resistant starch.

On the other hand, a well-ripened banana with some dark patches on the skin is easier to digest and may give you the energy boost you require before playing sports.