Is the Winter Blues Just a "Mental" Issue? — A Doctor Points Out the Surprising Connection Between "Nutritional Deficiency" and Winter Depression —

1. Why Do Moods Drop in Winter?

First, the phenomenon of "feeling somewhat down when winter comes" is a natural reaction that happens to many people.

When daylight hours decrease, the secretion of serotonin, known as the "happiness hormone," tends to decrease in the brain, while the secretion of the sleep hormone, melatonin, tends to increase. As a result,

• difficulty waking up in the morning

• feeling drowsy all day

• tendency to feel gloomy

are states that are more likely to occur.

These recurring depressive symptoms that occur with seasonal changes are called "Seasonal Affective Disorder (SAD)," and organizations like the National Center for Complementary and Integrative Health and the Mayo Clinic explain them as depressive symptoms that increase in winter.NCCIH+1

However,not all winter blues are necessarily "depression."
There are many cases where underlying health issues or nutritional deficiencies result in "mental downturns."

2. The Relationship Between "Nutritional Deficiency" and Mental Health as Pointed Out by Doctors

A British doctor introduced by the Daily Record warns that "behind the winter blues, there may be a nutritional deficiency, particularly a certain 'deficiency.'" The article mentions,

• fatigue

• headaches

• palpitations (feeling of rapid heartbeat)

as symptoms.One News Page

These symptoms are typical signs of iron deficiency anemia, as well as psychological stress or depression. The NHS (National Health Service) also lists "fatigue," "headaches," and "increased heart rate (palpitations)" as representative symptoms of iron deficiency anemia. nhs.uk

Furthermore, recent studies have reported that iron deficiency anemia can be accompanied by mental symptoms such as

• low mood

• anxiety

• restlessness

• headaches and palpitations

.PMC+1

In other words, if you think "my mental state just drops in winter," it might not be uncommon to find that your iron levels were significantly low in a blood test.

Additionally, vitamin D, B12, folic acid, magnesium, and other nutrients are involved in the synthesis and functioning of neurotransmitters (such as serotonin and dopamine) in the brain. A deficiency in these can lead to decreased motivation, anxiety, and poor sleep quality.Healthline

3. Common "Nutritional Deficiencies" That Worsen in Winter

Let's take a closer look at the key nutrients that tend to become problematic in winter.

3-1. Iron Deficiency (Iron Deficiency Anemia)

● Iron is a Mineral That Carries "Oxygen and Motivation"

Iron is a component of hemoglobin in the blood and plays a role in transporting oxygen throughout the body. It is also necessary for the synthesis of neurotransmitters like dopamine and serotonin, which are related to "motivation" and "pleasure."michiganmedicine.org+1

Therefore, when iron is deficient, not only the body but also the mind tends to lack energy.

● Symptoms Likely to Occur Due to Iron Deficiency

Health information sites and medical institution materials list the following as representative symptoms of iron deficiency anemia.Healthline+1

• Lethargy and easy fatigue

• Decreased concentration and feeling spaced out

• Pale complexion, pale inside of the eyelids

• Palpitations and shortness of breath

• Headaches and dizziness

• Prone to feeling cold

• Hair loss and brittle nails

These symptoms overlap significantly with depression and autonomic nervous system disorders and are often dismissed as "just in your head" or "due to stress."

Especially,

• women with menstruation

• people with diseases involving bleeding (hemorrhoids, stomach ulcers, etc.)

• those on a diet or with small or unbalanced meals

• growing children and students engaged in sports

are at high risk of iron deficiency, and symptoms can surface rapidly when combined with the cold of winter.

● Why Iron Deficiency Worsens in Winter

In winter,

• metabolism increases to maintain body temperature

• meals tend to become irregular due to busyness and events

• meals tend to be centered around hot pots and carbohydrates

These factors combine, leading to a tendency to consume less meat and fish containing iron.

As a result, the iron stock that was already on the edge may run out, leading to a sudden feeling of fatigue in winter.

3-2. Vitamin D Deficiency

● Vitamin D is Related to Both "Bones" and "Mental Health"

Vitamin D is well known for aiding calcium absorption and strengthening bones, but recently,

• immune function

• inflammation control

• mood control

have also been noted. There are reports suggesting a connection with Seasonal Affective Disorder (SAD), drawing attention as one of the factors behind winter's "somewhat gloomy" feelings.Veterans Affairs+1

● Many Japanese Are Very Deficient in Vitamin D in Winter

Research investigating the vitamin D status of Japanese people reports that nearly half of adults are "deficient to insufficient" even in summer, with this percentage exceeding 80% in winter.PMC+1

Furthermore, a survey targeting young women reported that over 80% were at deficient levels of vitamin D throughout all seasons,

contradicting the image that "Japan is a sunny country, so vitamin D should be sufficient."

J-STAGE

Especially,

• those who consistently use sunscreen

• those who mainly work in offices and rarely go outside during the day

• those living in regions like northern Japan, where winter daylight hours are short

may experience a significant drop in vitamin D levels in winter, potentially exacerbating feelings of depression and fatigue.

3-3. Vitamin B Group and Other Nutrients

● Vitamin B Group

Vitamins B1, B2, B6, B12, folic acid, and other B vitamins are essential for energy metabolism and nerve function. A deficiency in these can lead to

• easy fatigue

• irritability

• difficulty concentrating

• numbness in the hands and feet

and other symptoms, and their connection to depression and anxiety disorders is being researched.Healthline

● Magnesium, Zinc, Omega-3 Fatty Acids

Magnesium, zinc, and omega-3 fatty acids like EPA and DHA, found in fish oil, are also involved in the synthesis of neurotransmitters and the regulation of inflammation, suggesting a link to mental health.

Although there is currently no definitive solution that "will surely cure winter depression,"the idea that improving nutritional status forms the basis for treatment and preventionis gaining traction globally.Health