What Vitamin to Take for Sand Flies? Debunking the Popular Myth

According to a 2022 systematic review of over 100 papers, oral thiamine (vitamin B1) "cannot repel arthropods in any dosage or route of administration". This finding addresses the common misconception about what vitamin to take for sand flies, revealing that traditional methods of protection are still the most reliable.

Quick Summary

The long-held belief that taking vitamin B can prevent sand fly bites is a myth unsupported by science. Effective prevention relies on proven methods like topical repellents, protective clothing, and avoiding active hours.

Key Points

• The Vitamin Myth: The belief that taking vitamin B supplements, particularly thiamine (B1) or B12, can repel sand flies is scientifically unfounded and considered a myth.

• Proven Prevention: Effective sand fly protection relies on using EPA-approved topical repellents containing DEET, picaridin, or oil of lemon eucalyptus (OLE).

• Physical Barriers: Covering up with long-sleeved shirts, pants, socks, and using bed nets provides a critical physical barrier against bites, especially during peak activity hours.

• Avoid Peak Times: Sand flies are often most active during dawn and dusk, so limiting outdoor exposure during these times is a highly effective strategy for avoidance.

• Not a Deficiency Issue: A person's attractiveness to sand flies is influenced by factors like carbon dioxide output, body heat, and unique skin odors—not their vitamin levels.

• Combined Approach: The most successful defense against sand flies involves a combination of repellents, protective clothing, and environmental awareness, rather than a single method.

The Scientific Reality of Vitamins and Sand Flies

For decades, many travelers and outdoor enthusiasts have sworn by taking vitamin B supplements to ward off biting insects like mosquitoes and sand flies. The theory suggests that an excess of vitamin B in the body causes a scent to be excreted through the skin that, while undetectable to humans, is unpleasant to insects. However, modern scientific studies and reviews have systematically disproven this anecdotal claim.

A comprehensive scoping review published in the Bulletin of Entomological Research in 2022 examined 104 different reports and studies regarding thiamine (vitamin B1) as an insect repellent. The analysis concluded that there is no scientific evidence to support the use of thiamine in any form or dosage to repel insects. Controlled experiments measuring insect landing and biting rates showed no difference between subjects who took vitamin B1 and those who did not. The myth, which originated from flawed research in the 1940s, persists despite repeated refutation by entomological experts.

Why Do Sand Flies Bite Some People More Than Others?

Since it's not a vitamin deficiency, what really makes some individuals more attractive to sand flies and other biting insects? The science points to several factors that vitamins do not affect. These include:

• Carbon Dioxide Exhalation: As humans exhale, they release carbon dioxide, which acts as a beacon for insects. Some people release more than others, especially during exercise, making them more noticeable to sand flies.
• Body Heat: Insects are drawn to heat. People with higher body temperatures or those who are exercising produce more heat and are therefore more attractive targets.
• Skin Odor: The unique cocktail of body odor, influenced by genetics, diet, and the specific bacteria on our skin, plays a significant role. Some compounds released through sweat are more appealing to sand flies than others.
• Genetics: An individual's genetic makeup affects their body chemistry and odor, influencing their attractiveness to insects. This is why some people are "mosquito magnets" while others are seemingly ignored.

Effective Strategies for Sand Fly Prevention

Given that supplements are ineffective, a multi-pronged approach using proven methods is the best way to protect yourself from sand flies. No single solution is 100% effective, so combining strategies is key.

• Use Proven Topical Repellents: Products containing active ingredients registered by the Environmental Protection Agency (EPA) are your best defense. The Centers for Disease Control and Prevention (CDC) recommends using repellents with DEET, picaridin, IR3535, or oil of lemon eucalyptus (OLE). Always follow the product instructions for safe and effective use.
• Wear Protective Clothing: Covering exposed skin is a simple and effective physical barrier. Wearing long-sleeved shirts, long pants, socks, and closed-toe shoes is recommended, especially during peak sand fly activity. Lighter colors are often suggested, as sand flies may be more attracted to darker shades.
• Minimize Outdoor Exposure at Peak Times: Sand flies are often most active during dawn and dusk. Planning activities to avoid these times can significantly reduce your risk of being bitten. Local conditions can vary, so it is wise to be mindful of your surroundings.
• Use Barriers and Nets: When sleeping in areas with a high sand fly population, sleeping under an insecticide-treated bed net can provide a crucial physical barrier. Ensuring windows and doors have well-maintained screens also helps prevent them from entering your living space.
• Explore Natural Options: While less potent than chemical repellents, some essential oils can offer a degree of protection. Citronella, lavender, and eucalyptus oils are known to deter insects. These often need to be reapplied more frequently than DEET or picaridin products. For safe use, essential oils should typically be diluted with a carrier oil before being applied to the skin.

Comparing Effective vs. Ineffective Sand Fly Prevention

Method	Effectiveness	Mechanism	Application Notes
Oral Vitamin B (e.g., B1, B12)	Ineffective	None; scientifically debunked.	Safe to take for nutritional reasons, but will not repel sand flies.
Topical DEET Repellent	Highly Effective	Masks human scent, confusing insects.	Apply to exposed skin, follow label directions.
Picaridin-Based Repellent	Highly Effective	Masks human scent; a DEET alternative.	Preferred by some for being less irritating and having a milder smell.
Essential Oils (Citronella, Eucalyptus)	Moderately Effective	Strong scents deter insects.	Requires frequent reapplication; effectiveness varies.
Protective Clothing	Highly Effective	Physical barrier prevents bites.	Simple but crucial defense; light colors are recommended.
Avoiding Dawn & Dusk	Highly Effective	Mitigates exposure during peak activity.	Plan outdoor activities for mid-day when possible.

Conclusion

In the search for what vitamin to take for sand flies, it is crucial to recognize that this common folk remedy is scientifically unfounded. Instead of relying on ineffective oral supplements, effective sand fly prevention requires a combination of proven strategies. By using EPA-approved topical repellents, wearing protective clothing, avoiding peak biting times, and using physical barriers, you can significantly reduce your risk of getting bitten. For reliable information on insect-borne disease prevention, including leishmaniasis transmitted by sand flies, consult authoritative health sources. For further guidance, please visit the CDC website.

Frequently Asked Questions

Question: Why is the myth about taking vitamin B for sand flies so persistent? Answer: The myth persists largely due to anecdotal evidence and folklore that originated from flawed studies in the 1940s. People may associate a lack of bites with their supplement use, but this is likely due to other factors or a placebo effect.

Question: Do sand flies transmit any diseases? Answer: Yes, sand flies can transmit diseases in many parts of the world. The most common is leishmaniasis, a parasitic disease that can cause skin sores or affect internal organs. It is especially important to take proper precautions in endemic areas.

Question: Is it dangerous to take a lot of vitamin B to see if it works? Answer: Taking excessive doses of vitamin B is generally not recommended. While it is water-soluble, meaning the body excretes excess, very high quantities could potentially lead to side effects like gastrointestinal discomfort. Consult a healthcare provider before starting any high-dose vitamin regimen.

Question: How quickly do sand fly bites appear? Answer: Unlike some mosquito bites, which can show up immediately, sand fly bites may not become noticeable for several hours. By the time you feel the itch or see the red welt, the sand fly is long gone, which adds to their annoyance.

Question: Does eating garlic or other strong foods help repel sand flies? Answer: No, like the vitamin B myth, the idea that consuming strong-smelling foods like garlic will repel sand flies is not supported by science. Your body odor may be influenced, but not in a way that reliably deters biting insects.

Question: How does DEET work to repel sand flies? Answer: DEET is thought to interfere with the insect's chemoreceptors, which are used to detect human sweat and carbon dioxide. This confusion effectively makes it harder for the sand fly to locate a host.

Question: Are there any effective natural repellents for sand flies? Answer: While chemical repellents are the most effective, some natural options can provide moderate protection. Repellents containing oil of lemon eucalyptus (OLE) are CDC-recommended and derived from a plant. Other essential oils like citronella and lavender may also offer some relief, but often for a shorter duration.

Question: What should I do if I get a sand fly bite? Answer: To treat a sand fly bite, you should wash the area with soap and water. Applying an ice pack, aloe vera gel, or anti-itch cream can help reduce swelling and discomfort. Avoid scratching, as this can lead to infection.

Frequently Asked Questions

Why is the myth about taking vitamin B for sand flies so persistent?

The myth persists largely due to anecdotal evidence and folklore that originated from flawed studies in the 1940s. People may associate a lack of bites with their supplement use, but this is likely due to other factors or a placebo effect.

Do sand flies transmit any diseases?

Yes, sand flies can transmit diseases in many parts of the world. The most common is leishmaniasis, a parasitic disease that can cause skin sores or affect internal organs. It is especially important to take proper precautions in endemic areas.

Is it dangerous to take a lot of vitamin B to see if it works?

Taking excessive doses of vitamin B is generally not recommended. While it is water-soluble, meaning the body excretes excess, very high quantities could potentially lead to side effects like gastrointestinal discomfort. Consult a healthcare provider before starting any high-dose vitamin regimen.

How quickly do sand fly bites appear?

Unlike some mosquito bites, which can show up immediately, sand fly bites may not become noticeable for several hours. By the time you feel the itch or see the red welt, the sand fly is long gone, which adds to their annoyance.

Does eating garlic or other strong foods help repel sand flies?

No, like the vitamin B myth, the idea that consuming strong-smelling foods like garlic will repel sand flies is not supported by science. Your body odor may be influenced, but not in a way that reliably deters biting insects.

How does DEET work to repel sand flies?

DEET is thought to interfere with the insect's chemoreceptors, which are used to detect human sweat and carbon dioxide. This confusion effectively makes it harder for the sand fly to locate a host.

Are there any effective natural repellents for sand flies?

While chemical repellents are the most effective, some natural options can provide moderate protection. Repellents containing oil of lemon eucalyptus (OLE) are CDC-recommended and derived from a plant. Other essential oils like citronella and lavender may also offer some relief, but often for a shorter duration.

What should I do if I get a sand fly bite?

To treat a sand fly bite, you should wash the area with soap and water. Applying an ice pack, aloe vera gel, or anti-itch cream can help reduce swelling and discomfort. Avoid scratching, as this can lead to infection.