Lack of sleep, too much stress, a crazy work schedule—it's common knowledge that none of this is great for your health. But what about that new diet you're on? Or even the medication you take? Turns out, you may be chipping away at your immune system without even knowing it. The good news: A few lifestyle changes or new habits can help you rebuild your body's defenses against illness, infections, and disease. Check out these 7 ways you're making your immune system weaker—and how to fix them.

1.    You pop antacids.

In addition to the lymph nodes in the neck, most of our immune system—70 percent of it, in fact—resides in the gut in the form of lymphoid tissue along the entire digestive tract. Therefore, according to Dr. Susan Blum, author of “The Immune System Recovery Plan” and founder and director of Blum Center for Health, it's important to try to avoid things that damage the gut immune system, which will harm the overall immune system.

Taking antacids—particularly the stronger prescription kinds—could have a negative effect on your immune system for a number of reasons. Blum explains that some antacids, like Tums, absorb acid, but the stronger prescription ones—called proton-pump inhibitors (PPIs)—actually alter the pH of your stomach, which is supposed to be incredibly acidic in order to sterilize all the food you eat. When your stomach can't properly sterilize your food, you end up bringing more infections into your body, which places additional stress on the immune system in your gut. One Mayo Clinic study found that people who regularly take PPIs have less diversity in their gut bacteria and are at increased risk of illnesses like Clostridium difficile infections and pneumonia.

Another problem is that some vitamin deficiencies have been associated with taking PPIs, and it's hypothesized that this is because certain nutrients aren't properly absorbed in a low-acid environment. Blum says that people taking PPIs long-term tend to be deficient in nutrients such as B12, zinc, vitamin C, and iron, and these deficiencies can wind up impairing the immune system. (Sign up to get healthy living tips, weight loss inspiration, slimming recipes, and more delivered straight to your inbox!)

What to do: Blum cautions against taking antacids for longer than a 3-month period, and suggests addressing your underlying symptoms by trying an elimination diet—cutting out potentially triggering foods and then reintroducing them one at a time to determine, and then subsequently eliminate, the ones that are causing the reflux.

2. You take certain pain medications.

In addition to antacids, Blum said that some pain medications like steroids and NSAIDs can damage your intestinal lining and cause leaky gut syndrome, which is characterized by increased intestinal permeability. As a result, infections and undigested particles of food can make their way through the intestinal wall and into your body, which then stresses the immune system and decreases its ability to function properly.

What to do: Blum points out that chronic, not occasional, use is most likely to cause problems. But remember that "chronic" isn't just daily pill-popping: It means routinely taking pain medication several times a week or in any kind of regular way.

2.  You're on antibiotics.

Antibiotics can also contribute to a weakened immune system, said Dr. Shilpi Agarwal, a board-certified family medicine and integrative and holistic medicine physician. And women, who are more susceptible to getting things like urinary tract infections, which are frequently treated with antibiotics, are especially at risk.

"These women end up taking antibiotics multiple times a month, maybe 5 to 6 days every few weeks, and it can be really damaging to the intestinal lining," she said.

Being on these medications for too long can wipe out both the unhealthy and healthy bacteria in the gut. When healthy bacteria are not present to protect the intestinal lining, she explains, the weakened barrier allows toxins to be reabsorbed, resulting in a weakened immune system.

What to do: If you frequently come down with UTIs or other chronic infections, Agarwal recommends exploring alternatives to antibiotics. For example, in the case of a UTI, she suggests talking to your doctor about trying vitamin C or cranberry supplements, which will acidify the urine, making it harder for bacteria to survive.

MORE: 4 Things You Should Never Do To Your Vagina

4. You binge drink.

Chronic binge drinking suppresses bone marrow production of red and white blood cells, Agarwal said, which, over time, will hurt your immune system. She cites the definition of binge drinking for women as consuming about four drinks over the course of 2 hours, but says any time you drink enough to feel drunk in a short period of time could be called binge drinking. (Here are 6 sneaky signs you drink too much.)

What to do: You don't have to give up drinking altogether, but try alternating alcoholic beverages with sparkling water with lime to space out the booze and rehydrate.

5. You're a fan of juice cleanses.

Sometimes even your efforts at healthy eating could wind up backfiring. Agarwal finds that people who are on any sort of extreme diet that's very low carb or very calorically restricted tend to get sick more often. She believes that's because these diets are lacking in certain vitamins and minerals like zinc, selenium, and magnesium that you get from eating well-balanced meals. You can have a greater risk of getting sick even from following popular diets like Paleo, South Beach, and Atkins or doing frequent juice cleanses, she says.

What to do: If you're eating well-rounded meals, adding a green juice won't hurt.

"But it's the people who are constantly doing these juice cleanses to slim down and lose weight fast that really miss out on a lot of vital nutrients," she said.

Focus on balanced meals that include healthy fats, she said, which research shows are good for the skin and the immune system.

6. You travel a lot for business. 

Agarwal sees a lot of women who travel for work who report feeling chronically run-down and having a lowered immune system. The main reason, she says, is that they're being exposed to germs and pollutants that their bodies aren't used to on planes and in hotels. But other factors, like not getting enough rest, straying from your regular diet, and being out of your routine, also contribute to the toll on your immune system.

What to do: Agarwal advises her patients to try to maintain as much routine as possible even when on a trip. Since exercise boosts immunity, make sure to move for at least 15 to 20 minutes a day. And try your hardest to eat well; pack your carry-on with healthy, immune-boosting snacks like tangerines, mixed nuts, or even dark chocolate, which is a good source of beneficial magnesium.

7. You're lonely.

Studies show that chronic loneliness, for periods of many months or years, could wreak havoc on your immune system and put you at risk of a host of diseases. And chronic loneliness is more widespread than you might expect. Steve Cole, PhD, a genomics researcher and professor of medicine at UCLA, estimates that 20 percent of Americans feel a "persistent, protracted sense of significant loneliness or isolation from others, detachment from the rest of humanity."

Chronic loneliness, Cole explains, actually changes people's immune system biology, causing their cells to show increased expression of genes involved in inflammation and decreased expression of genes involved in defending against viral infections.

What to do: How Cole defines loneliness in his studies may surprise you.

"It's possible to be lonely in a room full of people and, conversely, to feel connected with other people even when they're not around, like our friends and family in distant cities," he said. (Here are 8 friends every woman should have.)

So rather than looking at the state of being physically isolated from other people, he measures the feeling of being detached from the rest of humanity.

Because of this, simply making social plans or forcing yourself to interact with others isn't likely to get to the root of the problem. To decrease loneliness, it's necessary to foster a sense of safety around others to get rid of the insecurity or fear that causes feelings of isolation. While this is definitely a complex issue to address, he says that there's some evidence that stress-reduction practices like meditation, mindfulness, and yoga, even though they don't specifically target loneliness, can wind up reducing it by helping people to feel more at peace with their experiences and emotional states, and more secure and connected with others. Consequently, these practices have been shown to have a favorable impact on the immune system.

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