Decoding Nutrition: What vitamin gets destroyed by light? And How to Protect Your Nutrients

October 17, 2025 •

5 min read

Up to 80% of Vitamin A can be lost in just six hours of daylight exposure in some medical solutions. This dramatic statistic highlights a critical, yet often overlooked, aspect of nutrition: photolability. Understanding what vitamin gets destroyed by light? is crucial for ensuring you get the maximum nutritional benefit from the foods you eat and the supplements you take.

Quick Summary

Certain vitamins, notably riboflavin (B2), ascorbic acid (C), and vitamin A, are highly sensitive to light exposure and can degrade rapidly. This photodegradation process reduces their nutritional potency in both foods and supplements, making proper storage and handling vital for preserving nutrient integrity.

Key Points

Riboflavin (Vitamin B2) is most sensitive: This vitamin is easily destroyed by visible light, which is why milk and other sources are often packaged in opaque containers.
Vitamin C is also highly fragile: Along with sensitivity to light, Vitamin C is vulnerable to heat and oxygen, requiring careful storage and quick consumption after preparation.
UV rays are a major threat: Vitamin A, among others, is particularly susceptible to degradation from ultraviolet (UV) radiation, making proper packaging critical.
Opaque containers are key: Choosing supplements and foods in amber glass, dark plastic, or foil packaging is one of the most effective ways to protect light-sensitive vitamins.
Proper storage matters: Keep all light-sensitive items in cool, dark environments like a pantry or refrigerator to slow the rate of photodegradation.
Fresh is best: Consuming fruits and vegetables immediately after cutting maximizes their vitamin content, particularly for Vitamin C.
Quick cooking preserves nutrients: To minimize nutrient loss from heat, especially for water-soluble vitamins, opt for quick and gentle cooking methods.

The Primary Victim: Riboflavin (Vitamin B2)

Of all the vitamins, riboflavin, or vitamin B2, is arguably the most sensitive to light. As a water-soluble vitamin, it's vital for energy production, cellular growth, and the metabolism of carbohydrates, fats, and proteins. Its light sensitivity is a major reason why milk, a key source of riboflavin, is no longer primarily sold in clear glass bottles. Exposure to sunlight can cause significant riboflavin loss in milk, which is why modern paper cartons and opaque plastic jugs are used instead.

Research has shown the chemical mechanisms behind riboflavin's photodegradation. When exposed to light, it forms unstable, highly reactive compounds that break down the vitamin. This process occurs even under visible light, and is accelerated by higher temperatures and certain pH levels. For consumers, this means that leaving milk or other B2-rich foods exposed to light, even for a short time, can have a noticeable impact on their nutritional content.

Other Vitamins That Suffer From Light Exposure

While riboflavin is a standout case, other vitamins also fall victim to light-induced degradation:

Vitamin C (Ascorbic Acid): This powerful antioxidant is notoriously fragile and is destroyed by light, heat, and oxygen. Think of an apple slice turning brown when exposed to the air; a similar oxidation process, accelerated by light, degrades Vitamin C. To protect it, food products containing Vitamin C should be stored in cool, dark places and consumed quickly after preparation.
Vitamin A (Retinol): This fat-soluble vitamin is also very sensitive to light, especially UV radiation. A study on parenteral nutrition solutions found a rapid and significant loss of Vitamin A during daylight exposure, demonstrating its vulnerability outside of the digestive tract. The photodegradation of Vitamin A is a key concern in the pharmaceutical industry and for foods containing it.
Vitamin B12: Though typically considered more stable than other water-soluble vitamins, Vitamin B12 is still photolabile, especially in aqueous solutions and when exposed to other vitamins that act as photosensitizers. While some studies show minimal degradation over short periods, light protection is a traditional practice for B12 supplements and medical specimens.
Folate (Vitamin B9): Like other B-vitamins, folate can be sensitive to light and heat. Its degradation can be a factor in some food preparation methods, though proper handling can minimize losses.

The Science Behind Photodegradation

Photodegradation is a chemical reaction caused by the absorption of photons (light particles) by a molecule. This process excites the molecule, making it highly reactive and causing it to break down into other, often inactive, compounds. For vitamins, this leads to a loss of biological activity and, consequently, a reduction in nutritional value.

Key factors influencing this process include:

Wavelength: Shorter, higher-energy wavelengths, such as ultraviolet (UV) light, are more damaging than longer, visible light wavelengths. Amber-colored packaging works by blocking UV and blue light.
Oxygen: The presence of oxygen often accelerates the degradation process. Many vitamins, like Vitamin C, are susceptible to photo-oxidation.
Temperature: Higher temperatures can increase the rate of degradation reactions. This is why storing sensitive vitamins in a cool, dark place is often recommended.

How to Protect Light-Sensitive Vitamins

Protecting your vitamin intake requires conscious decisions about how you store and prepare your food. Here are some practical tips:

Choose Opaque Packaging: When purchasing milk, cereals, or supplements, opt for items in opaque containers like paper cartons, dark-colored plastic jugs, or amber glass bottles.
Store in the Dark: Always keep sensitive foods and supplements away from direct sunlight or bright artificial light. The pantry, refrigerator, or a cupboard are ideal storage locations.
Use Foods Fresh: Eat fruits and vegetables soon after cutting them to minimize exposure to light and air. For example, prepare salads right before serving rather than letting them sit out.
Consider Cooking Methods: Vitamin C and some B vitamins are sensitive to both heat and water. Choose quick-heating methods like stir-frying or microwaving, and avoid boiling vegetables in excessive water.
Refrigerate Properly: Store vegetables and fruits in the crisper drawer of your refrigerator. Some manufacturers even recommend refrigerating certain skincare products containing Vitamin C to prolong their stability.

Light-Sensitive vs. Relatively Stable Vitamins

This table summarizes the light sensitivity of various vitamins and provides key storage takeaways.


Vitamin	Sensitivity to Light	Key Storage Takeaway
Riboflavin (B2)	High	Store in opaque containers like paper cartons; keep away from visible light.
Vitamin C	High	Store in a cool, dark place and use quickly after exposure to air.
Vitamin A	High	Protect from UV radiation; choose dark containers for supplements and foods.
Vitamin B12	Moderate	Keep in dark containers; minimize exposure, especially in liquid forms.
Folate (B9)	Moderate	Minimize light and heat exposure during cooking and storage.
Vitamin K	Low	Relatively stable, not significantly affected by light.
Vitamin D	Low	Primarily synthesized by the body from sunlight exposure; not destroyed by light in storage.

Dietary Habits to Maximize Vitamin Intake

Making small adjustments to your daily routine can make a significant difference in your nutrient intake. When grocery shopping, prioritize items with protective packaging. For fresh produce, choose seasonal fruits and vegetables and consume them promptly. If you’re making a smoothie with ingredients like spinach or kale, blend and consume it immediately to preserve the most Vitamin C. For supplements, be sure to store them as directed, which almost always means in a cool, dark place. By being mindful of these simple practices, you can ensure you're getting the full nutritional value of your food.

Conclusion: Prioritizing Nutrient Preservation

In the grand scheme of a balanced diet, the impact of light exposure on vitamin integrity is often an invisible force undermining our nutritional goals. Riboflavin and Vitamin C are particularly susceptible to photodegradation, but other vital nutrients like Vitamin A also suffer from careless handling. By consciously choosing opaque packaging, storing foods and supplements in dark, cool environments, and being mindful during food preparation, you can effectively counteract this effect. Preserving the potency of these essential micronutrients is a straightforward and highly effective way to optimize your diet and support your overall health.

For more information on vitamin stability and nutrition, you can consult resources like Harvard's School of Public Health website: https://nutritionsource.hsph.harvard.edu/.

Frequently Asked Questions

The main vitamin most easily destroyed by light is riboflavin, also known as vitamin B2. Exposure to both visible and ultraviolet light can rapidly degrade its nutritional content.

Yes, vitamin C is highly sensitive to light, along with heat and oxygen. This is why it's crucial to store foods and supplements rich in Vitamin C in a cool, dark place.

Light energy causes a chemical reaction called photodegradation, which breaks down the vitamin molecules. For many vitamins, this process is accelerated by the presence of oxygen.

Milk is sold in opaque cartons or jugs to protect its riboflavin content from light. Before this packaging became common, milk stored in clear glass bottles lost significant amounts of this essential vitamin.

The best types of packaging are those that block light, such as amber or cobalt blue glass bottles, opaque plastic jugs, and blister packets. For foods, airtight foil or cardboard cartons are effective.

No, not all vitamins are equally sensitive. While vitamins B2, C, A, and B12 are particularly vulnerable, others like Vitamin K and D are much more stable and not significantly affected by light exposure in storage.

You can minimize vitamin loss by storing foods in cool, dark places, choosing opaque packaging, eating fresh produce soon after cutting, and using quick cooking methods that limit heat exposure.