As temperatures drop and daylight fades, pharmacy shelves fill with colorful packaging promising to boost natural defenses, reduce fatigue, and even improve sleep. According to the National Union of Food Supplements (Synadiet), 61% of French people consumed supplements in 2024, with 77% of consumers reporting they take them several times a year. The market was valued at 2.7 billion euros in 2023.
But do these autumn regimens truly deliver on their promises? Dr. Alexandra Dalu, a nutritionist specializing in anti-aging medicine and co-author of L’assiette santé, says it depends entirely on which supplements you choose.
Vitamin C: Largely Overrated
Vitamin C is regularly presented as a miracle cure for preventing colds and respiratory infections. While it is essential for immune and nervous system function, Dr. Dalu insists that supplementation is unnecessary unless you have a deficiency.
According to ANSES, adults need 110 mg of vitamin C daily—the amount found in a single kiwi or bell pepper. Children require between 15 and 45 mg per day depending on age. “Unless you’re deficient, vitamin C supplementation is useless,” she emphasizes.
The doctor acknowledges exceptions exist. Smokers or regular alcohol consumers may need supplementation to compensate for harmful effects, but she stresses the solution is addressing the addiction itself, not increasing vitamin C intake.
Magnesium and Vitamin D: The Better Options
Magnesium stands out as genuinely beneficial during seasonal transitions. This mineral supports energy production and cardiovascular and nervous system function. “If there’s one supplement worth taking when seasons change, it’s magnesium,” Dr. Dalu notes. “It reduces fatigue and stress and promotes more restorative sleep.”
Vitamin D supplementation also makes sense for combating autumn fatigue. Though called a vitamin, it functions as a hormone involved in bone mineralization, muscle function, and immunity. Produced by the skin through sun exposure, levels naturally decline with reduced autumn and winter light.
However, not everyone needs it. French health authorities recommend vitamin D supplementation primarily for children, adolescents, and elderly people prone to deficiencies. A blood test prescribed by a doctor can determine whether supplementation is warranted.
The Danger of Overconsumption
Dr. Dalu’s most critical warning concerns overuse. No supplement can prevent or cure a cold. “If you’re prone to winter infections, it’s important to understand why,” she explains. Rather than self-prescribing supplements, she recommends consulting a doctor for blood work to identify potential deficiencies and their underlying causes.
The doctor also cautions against excessive supplement intake. “The more you consume, the greater your risk of developing kidney failure,” she warns. ANSES echoed this concern in March, reminding consumers that supplements should be taken on healthcare professionals’ advice and that “miracle” products warrant skepticism.
- Vitamin C supplementation is unnecessary without diagnosed deficiency
- Magnesium effectively reduces fatigue and stress during seasonal changes
- Vitamin D benefits specific populations, particularly the elderly and children
- Blood tests should guide supplementation decisions
- Excessive supplement use can cause kidney damage
