Coach Sugahara's
Citrus Research Report

As part of Ehime Citrus Club's work to promote citrus from Ehime Prefecture, Professor Sugahara from Ehime University's Graduate School of Agriculture explains things like the functional components contained in citrus, and what their effects and benefits are—all in terms of the science of food's functions. The report also introduces results of the professor's research.


Takuya Sugahara

Professor at the Graduate School of Agriculture, Ehime University

Head of the Food and Health Sciences Research Center at Ehime University's Graduate School of Agriculture

Ehime Citrus Club Coach(2020)

Tell Us, Coach Sugahara!


Fitting enthusiasm for the captain.
If I start talking about the power of citrus, I won't be able to stop, so let's just talk here about the main functional components contained in citrus.
Citrus contain a number of functional components that help you stay healthy.
1Vitamin C (ascorbic acid): Keeps skin and mucous membranes healthy (helps with skin problems, etc.)
2 β-Cryptoxanthin: Keeps bones healthy (prevents osteoporosis, etc.)
3Citric acid: Helps you recover from fatigue, etc.
4Hesperidin: Improves blood circulation (reduces cold sensitivity, etc.)
5Dietary fiber: Prevents constipation, suppresses rises in low-density lipoprotein cholesterol (LDL), etc.
6Nobiletine: Has anti-allergic and anti-inflammatory effects (helps prevent lifestyle-related diseases, alleviates hay fever, etc.)
7Auraptene: Improves cognitive functions, etc.

As you can see, they contain a wealth of components that help our bodies stay healthy both inside and out. As Ehime Citrus Club's captain, please spread the word about what makes citrus so wonderful!

Note: What are functional components?
These are components that can have various functional effects that help us stay healthy. For example, there are ones that can alleviate allergies, reduce inflammation, prevent high blood pressure, or boost immunity.


It sure is rough when you can't get rested, right?
Fatigue is said to be caused by a buildup of the fatigue substance (lactic acid) in the body.
The component that breaks this down is citric acid.
Citrus contain lots of this citric acid, so I recommend them for recovering from fatigue.


Have you ever heard of the word "antioxidation?"
It comes up a lot when talking about aging and anti-aging care.
When cells get oxidized, it can lead to premature aging. This can cause a variety of diseases.
"Antioxidation" is the action that inhibits cell oxidation.
Vitamin C has this antioxidant effect and citrus are rich in it, so they'll help keep your skin and mucous membranes healthy.
Consequently, because they contain vitamin C, citrus are often said to be good for keeping your skin beautiful.


Immune strength is said to be important for keeping other diseases at bay besides colds.
It's the ability to eliminate harmful things like bacteria and viruses from the body.
Our research has found that the components β-cryptoxanthin and auraptene contained in citrus can boost the immunity.
We're still at the stage of conducting experiments with fish and small animals at the moment, but are expecting to see similar effects in humans as well in the future.


You might be surprised to hear it, but citrus peel is bursting with nutrients.
In particular, lots of the functional components like dietary fiber and auraptene are contained in the peel.
So, if you want to get as many of the nutrients as you can, you should eat the peel.
However, be sure to wash thoroughly with water first, because the citrus sold generally might have had pesticides or wax used on them.

Coach Sugahara's Citrus Column


The Immunity Boosting Effects of β-cryptoxanthin
β-Cryptoxanthin is an orange pigment component. It's a carotenoid. Unshu mikan are particularly rich in it compared to other fruits. This is true of both the peel and the flesh (including the segment skin).

It's also been attracting attention in recent years as a component involved with foods with function claims, and can be effective for promoting bone metabolism and supporting blood pressure.
In addition, research by Ehime University has confirmed that β-cryptoxanthin can boost immunity, verifying the effects using culture cells, through oral administration to mice, and by feeding mikan extracts to yellowtails, red sea bream, and other fish.
In addition, analysis of fish called seven-band groupers that had been fed unshu mikan peel extract showed that besides having enhanced immunity toward infectious diseases, they also had increased levels of free amino acids (including components related to sweet and savory flavors).

Based on this, seven-band groupers farmed using himeka mikan were successfully branded as "himeka-raised". Research will continue to study the further potential of citrus.

The Main
Nutrients in Citrus

Vitamin C (ascorbic acid)
Effects Through its antioxidant effects, vitamin C helps keep skin and mucous membranes healthy, and alleviate skin problems, etc.
Varieties All varieties
Effects By boosting bone metabolism, this component keeps bones healthy and can help prevent osteoporosis.
Varieties All varieties (Especially abundant in unshu mikan, setoka, and ponkan)
Citric acid
Effects Citric acid helps you recover from fatigue by breaking down the lactic acid in your body that causes it. It also inhibits oxidation of the blood, and improves blood circulation and excretion of waste products.
Varieties All varieties
Effects This component reduces cold sensitivity by protecting capillaries, strengthening blood vessels, dilating peripheral blood vessels, and improving circulation.
Varieties All varieties (Particularly abundant in unshu mikan, dekopon, and iyokan)
Dietary fiber
Effects Large amounts of dietary fiber are contained in the internal skin (segment skin). It's not absorbed by the body, instead being expelled from the bowel along with harmful substances. Consequently, it can prevent constipation. It can also suppress rises in low-density lipoprotein cholesterol (LDL).
Effects Through its anti-inflammatory effects, nobiletine can prevent lifestyle-related diseases, dementia, and other conditions. It can also alleviate allergies.
Varieties All varieties (Particularly abundant in ponkan)
Effects This component can improve cognitive function. It does this by inhibiting excessive activation of glial cells, which attack neurons.
Varieties All varieties (Particularly abundant in kawachi bankan)