Apple Cider Vinegar1 of 11
Raw, unfiltered apple cider vinegar is a Jack of many trades. It lowers glucose levels, promotes healthy bacteria in the gut, encourages alkalinity, and relieves gas, bloating and heartburn, according to the Gerson Institute. Mix 1 tablespoon with a cup of water or herbal tea, or combine it with flaxseed oil for a delicious salad dressing. Apple cider vinegar is also known to be a natural remedy for athlete's foot, if rubbed on the affected area, according to Earth Clinic.
Greek Yogurt2 of 11
Regular yogurt and Greek yogurt are both filled with healthy bacteria, but the Greek varietal has a higher concentration of protein because of the way its filtered and strained. That high protein content (about 15 to 20 grams in 6 ounces) makes it an appealing food choice for athletes. Add it to soups in place of cream; mix it with herbs and use it as a pasta sauce; or combine it with lime juice, garlic and honey for a creamy and healthy salad dressing.
Kefir3 of 11
Kefir assists in calcium absorption, as well as the assimilation of other vitamins and minerals, making it a great post-workout recovery drink. This creamy, drinkable fermented milk contains bacteria and yeast that actually colonize, cleanse, and fortify the intestinal tract, making it more efficient at resisting pathogens, according to NaturalNews.com. Drink kefir by itself or blend it together with fresh fruit and honey.
Kimchi4 of 11
Kimchi has been referred to as "Korea's most affordable health and beauty care product." And Korean athletes laud it for its natural performance-enhancing abilities. This spicy and sour condiment, which is eaten at almost every meal in Korea, is loaded with vitamins A, B and C, as well as the beneficial bacteria lactobacilli. It's also an effective carbohydrate metabolizer. Use it as a topping for meat and veggie dishes.
Kombucha5 of 11
Kombucha is made via a fermentation process that requires a colony of good bacteria and yeast, according to the Mayo Clinic. It’s referred to as a tea, but this gut-healthy drink tastes more like a Belgian lambic. Kombucha's glucuronic acid strengthens the immune system, cleanses impurities in the blood and protects the joints from wear and tear. Drink kombucha as is, or use it as sour mix in your favorite healthy cocktails. Just be sure to buy unpasteurized kombucha to receive the probiotic benefits.
Kumquats6 of 11
Along with vitamins C, A and E, kumquats are a rich source of energy-boosting vitamin B. These half-inch-size citrus fruits also contain polyphenols, which are important for the immune system. To boot, two-thirds of a cup of kumquats contains about 4 grams of protein. Snack on them by themselves or add them to salads.
Lemons and Limes7 of 11
Intense workouts create an acidic environment in the body. If you don't neutralize that acid, your body will get the job done by using calcium from your bones and nitrogen from your muscles, according to Matt Frazier, the No Meat Athlete. Although lemons and limes have a highly acidic pH, that changes during the body's metabolic process and they become alkaline-forming. Squeeze the juice of these sour fruits into your water post-workout.
Rhubarb8 of 11
Prolonged and strenuous exercise can increase the generation of free radicals in the body. Antioxidants found in rhubarb can help neutralize those free radicals. Additionally, rhubarb's vitamin K has been shown to improve bone metabolism. Rhubarb's sour-bitter flavor profile can be tough to get down, so pair the stalks with sweeter fruits such as apples and strawberries. Just don't eat rhubarb's toxic leaves: They contain oxalic acid, a chemical compound found in bleach and other cleaning products.
Sauerkraut9 of 11
The German word "sauerkraut" directly translates to "sour cabbage" in English. Its sour flavor is a result of the lactic acid bacteria that forms in the fermentation process. That fermentation process is also responsible for sauerkraut's gut-friendly probiotics, nutrient-assimilating enzymes and anti-inflammatory isothiocyanates, according to health blogger Nathan Young. Add sauerkraut to soups, stews or your favorite sandwich.
Tamarind10 of 11
The tartaric acid in tamarind is a powerful antioxidant that wards off free radicals in the body and reduces inflammation. And tamarind's sticky pulp is a rich source of fiber as well as B vitamins, such as thiamin and niacin. It's also considered a natural remedy for diarrhea, constipation and nausea, which is good news for athletes who get "sloshy stomach" when running. Add tamarind pulp to marinades and sauces for fish, chicken, noodle dishes and stir-fries.