Cold sores are caused by the herpes simplex virus, usually HSV-1. While some people believe that certain foods can trigger a cold-sore outbreak, there isn’t enough proof to back this up.

Many people believe that certain foods can trigger cold sore outbreaks. However, there’s little to no evidence behind this claim.

Cold sore outbreaks are typically triggered by:

  • exposure to hot sun or cold wind
  • a cold or other illness
  • a weakened immune system
  • stress
  • hormone fluctuations
  • dry, cracked lips

People also want to know if certain foods can prevent or reduce the duration of cold sore outbreaks.

We’ll take a look at what the research says about how diet affects the activity of herpes simplex virus, as well as what works — and what doesn’t — for preventing cold sore outbreaks.

If you were diagnosed with the herpes simplex virus, especially type 1 (HSV-1), cold sore outbreaks may be common. While the virus may remain dormant during certain periods, when it’s triggered, you can expect to see cold sores.

While some people believe that food can trigger cold sore outbreaks, environmental factors are more likely to trigger an outbreak than anything else.

Exposure to hot sun, cold wind, a cold, or other illness is usually the cause of an unexpected cold sore outbreak. Fluctuating hormones might also be to blame.

There’s no known cure for the herpes simplex virus or its symptoms. However, certain foods may boost your body’s ability to fight off the virus.

Here’s what the research says about diet-related remedies that may prevent, or reduce, the duration of cold sore outbreaks.

Upping your intake of lysine

Older laboratory research of studies performed in vitro showed that lysine — an essential amino acid that you get from food — may be able to help prevent cold sores. Lysine is also available as an oral supplement and as a cream.

Lysine is thought to prevent against cold sore outbreaks because it reduces the activity of arginine, an amino acid needed by the herpes simplex virus to replicate.

The richest sources of lysine are foods that are high in protein, such as:

  • meat, specifically beef, chicken, and pork
  • cheese, especially parmesan
  • fish, particularly cod and sardines
  • soybeans
  • spirulina
  • fenugreek seed

However, a review of the evidence remains inconclusive about lysine’s ability to prevent cold sore outbreaks, and emphasizes the need for further research.

The jury is also still out on the effectiveness of lysine supplements to ward off cold sores.

Avoiding foods high in arginine

Some small evidence also points to restricting foods that contain a lot of arginine, as a way to prevent cold sore outbreaks. However, research is inconclusive.

Foods rich in arginine include:

  • certain meats
  • peanuts and other nuts
  • legumes
  • whole grains

More research is needed to determine whether upping your intake of lysine and lowering your intake of arginine can prevent cold sore outbreaks.

Eating foods that boost your immune system

Anecdotal evidence suggests that eating certain foods may boost your immune system, which in turn can help prevent cold sore outbreaks.

Here are some immune-boosting suggestions:

  • Antioxidants. Eating vegetables and fruits rich in antioxidants, like cauliflower, spinach, kale, berries, and tomatoes, can boost your immune system.
  • Vitamin C. Some research shows that vitamin C may help treat and prevent cold sores. Try upping your intake of vitamin C-infused fruits and vegetables like bell peppers, oranges, and strawberries.
  • Zinc. Foods high in zinc may reduce the number of outbreaks you have. Rich sources include wheat germ, chickpeas, lamb, and pork.
  • Vitamin B complex. B vitamins may also help to boost your immune system. You can get them from green beans, eggs, spinach, and broccoli.
  • Probiotics. Taking probiotics may help strengthen your immune system. In addition, a certain strain of probiotic has been shown to fight herpes in vitro.

Cold sores develop as a result of a herpes simplex virus infection, usually the HSV-1 strain. Although certain foods are often thought to be a trigger for cold sore outbreaks, there’s no definitive proof of this claim.

Eating foods that help to boost your immune system — like antioxidant-rich fruits and vegetables — may help stave off cold sore outbreaks. Some studies have also shown that eating foods rich in lysine, or avoiding foods with arginine, may also help to prevent cold sore outbreaks.

However, more research is needed to confirm the link between diet and the herpes simplex virus.

The best way to prevent an outbreak is to avoid factors that are known to trigger the virus, such as acute or prolonged illness, extremes in weather, and emotional or physical stress.

Keep these common triggers in mind if you’re looking to steer clear of a cold sore outbreak.