5 Supplements You Should Keep in the Fridge, According to Dietitians

When it comes to ensuring your supplements stay fresh and potent, sometimes refrigeration is key. Just like a delicate slice of cheesecake that must be chilled for the perfect taste and texture, certain supplements also benefit from cooler temps. Storing these five supplements in your fridge will keep them at their best. Keep reading to learn more.

Why Some Supplements Should Be Stored in the Refrigerator

The first thing to keep in mind is that you should ultimately defer to the storage directions on the supplement label. That’s because storing supplements correctly is crucial to maintaining their effectiveness and potency. “Environmental factors such as heat, humidity and oxygen can affect the potency and formulation of certain supplements,” says Jamie Adams, M.S., RD, owner of Mamaste Nutrition.

While most supplements are shelf-stable, some should be stored in the fridge because they contain live microorganisms or delicate ingredients that are sensitive to their environment. Not all need the chilled-out treatment, though. In some cases—and this is why reading the label is key—refrigerating a supplement can expose the product to excess moisture, which can degrade the product. 

5 Supplements You Should Be Storing in the Refrigerator

1. Fish Oil

Fish oil contains omega-3 fatty acids, which are prone to oxidation when exposed to heat, light and air. This oxidation process can degrade the quality of the oil, leading to an unpleasant stale smell and taste, as well as a loss of nutritional value. “In general, a cooler temperature protects the delicate oils from becoming rancid, lengthens the life of the potency of the supplement and slows any potential microbial growth,” explains Melissa Groves Azzaro, RDN, owner of The Hormone Dietitian.

2. Probiotics

Probiotics contain live microorganisms that are beneficial for gut health, but they may not do well in temperature fluctuations. “Lactobacillus and Bifidobacterium are both highly sensitive to heat and need refrigeration to survive,” says Carrie Gabriel, M.S., RDN, a California-based culinary dietitian. Exposure to heat can cause these delicate bacteria to die, rendering the probiotic supplement less effective or even useless.

By storing probiotics in the fridge, you ensure that the beneficial bacteria remain effective, so they can support digestive health and immune function and help maintain a balanced gut microbiome. However, not all probiotic strains need to be refrigerated—some are designed to be more stable at room temperature. Always check the label for specific storage recommendations.

3. Liquid Iron

If your provider recommends taking an iron supplement to treat low iron levels, they may in some instances suggest taking it in liquid form. Stash these bottles in the fridge. Adams explains that liquid vitamins, like liquid iron, should be kept in the fridge for freshness and to maintain their potency. Refrigeration helps slow down the oxidative processes that can degrade the iron and reduce its effectiveness. Additionally, keeping liquid iron cold can help preserve its taste and prevent the formation of any unpleasant odors. 

4. Flaxseed Oil Supplements

Flaxseed oil can quickly go rancid. The oil is rich in omega-3 fatty acids, which can easily oxidize in heat, light and air. Refrigeration slows this process, so your supplement stays fresher for longer. Plus, when kept cool, flaxseed oil retains its flavor better, so you can avoid that rancid taste and smell.

5. Vitamin C

Most people have healthy vitamin C levels, but if you opt to take a supplement, there’s one big thing to know: vitamin C is known to be incredibly finicky, in that it can easily degrade in heat, light and air. Storing these supplements in a cool, dark place may help keep them potent. So while refrigeration is not absolutely necessary, it can be beneficial in warmer climates or for long-term storage. 

The Bottom Line

Not all dietary supplements require refrigeration. But for those that do, proper storage is crucial to maintaining their effectiveness. Probiotics, liquid vitamins, fish oils and flaxseed oils are particularly sensitive to heat and light and should be kept in the refrigerator to preserve their potency. Always check the label and follow the manufacturer's storage recommendations. By ensuring that these supplements are stored correctly, you can maximize their benefits and support your overall health.