The Odd Couple: HIV and Bacteria

There are more than a thousand types of bacteria that live in our bodies -- on our skin, in our mouths, and in our gut. Of those bacteria, only 50 are known to be harmful. The rest, what we will call "healthy bacteria", have important roles in the body and are needed to keep people functioning well. This may be particularly true for people with HIV.

HIV affects the immune system, and a large part of the body's immune system is located in the intestines and gut. During the early stages of HIV infection, the virus can upset the balance of healthy bacteria in the gut, leading to health issues. This article will look into some of these complications and the ways people can change their diet to reduce their occurrence.

History of Healthy Bacteria

The idea that bacteria can be helpful dates back to 1907, when the Russian scientist Elie Metchnikoff postulated that bacteria might provide health benefits. He observed that regularly eating certain dairy products, such as yogurt, was associated with better health and longer life. Because of this, he drank sour milk every day until he passed away at age 71. Though he didn't have the ability to prove his theory, today scientists are discovering that healthy bacteria can positively affect health, both in the gut and beyond.

Scientists think the human diet once contained several thousand times more bacteria than it does today. With the advent of cleaner water, better sewage systems, antibacterial soaps and antibiotic drugs, the amount of bacteria that people are exposed to has decreased. High standards of hygiene kill bad bacteria but also kill healthy bacteria. Some experts think that reduced exposure may have a negative effect on our health and may disrupt the immune system's ability to function at its best. This is called the "hygiene hypothesis".

Certain healthy bacteria that help the immune system are less frequent or in some cases completely absent in both our environment and in our diets. This is particularly harmful for people with HIV whose immune systems are already negatively affected by the virus. Research shows that germfree animals have a low number of intestinal B and T-cells, the very cells HIV-positive people need in high numbers. The study also showed, however, that shortly after healthy bacteria exposure, the animals' population of T-cells normalized.

In addition to helping the immune system, healthy bacteria help digest food into nutrients that our bodies can absorb, and are useful in the body's defense against other infections in the intestine. Recent data further suggest that there may be a specific bacterium that helps with T-cell development.

Healthy bacteria and other microscopic organisms like yeast are called probiotics because when eaten in the right amount, they help people stay healthy. These probiotics have also been associated with better immune function in people with HIV. Several studies from different countries suggest that probiotics may be able to delay damage to, or help preserve, the immune function of people with HIV. They may do this by stimulating natural killer cell activity, lowering the rate of infection from other harmful bacteria, and possibly lowering inf lammation, but different studies have found different results when looking at this.

Good sources of healthy bacteria include foods such as yogurt, sauerkraut, miso, tempeh, Kombucha tea, and fermented vegetables. These are all "fermented foods", meaning they have undergone a chemical process in which the bacteria change the original food into a simpler and more easily digestible form. For example, yogurt is basically fermented milk. The process of fermentation actually helps preserve the food as well, so it takes longer to spoil. When these healthy bacteria-rich foods are included in one's diet, health benefits may occur in the gut, and possibly in the immune system.

One study examined 24 HIV-positive women with CD4 counts over 200 and diarrhea. Half of the women took probiotic yogurt every day for 15 days and the other half did not. The women who did not eat the yogurt saw their CD4 counts drop, while those who did eat it had an increase in their CD4 counts, and also experienced improvement in their diarrhea. But the study was so small and short it's hard to say whether the results were real or due to chance.

Similarly, another study examined 68 HIV-positive women in Tanzania over a three-year period. This study saw an increase in CD4 counts and concluded that the introduction of probiotic yogurt was significantly associated with an increase in CD4 counts.

Yet another study looked at 77 HIV-positive children and found that healthy bacteria may have improved the immune systems of children who ate fermented foods. Children who ate yogurt regularly saw a small increase in their T-cells. And those with diarrhea saw a slight improvement in their symptoms. Once again, the study was small as were the benefits -- so this type of study just proves that we need more research.

A major barrier to building up healthy bacteria in people with HIV is heavy use of antibiotics, which kill bacterial infections. Antibiotics are over-prescribed and overused in American culture. They are frequently given to people with HIV, either to prevent or treat an infection. Since healthy bacteria are vital for the immune system, it is worth questioning whether or not liberal use of antibiotics is bad for one's health. For example, it's critical that people with HIV and a CD4 count below 200 take meds like Bactrim to prevent PCP. But one study showed that it can take the healthy bacteria in the gut four years to recover from one round of antibiotics. Of course, people at risk for PCP need antibiotics to prevent this deadly disease. But as more research emerges on how healthy bacteria help the immune system, we should study how to minimize the effect antibiotics have on them.

One Man's Story

Sandor Katz

Sandor Katz has been fermenting foods for the past 17 years. He says his goal is to promote fermented foods in our culture and "spread the word about the glorious nutritional and healing powers of live fermented foods." As a self-proclaimed "fermentation fetishist", he eats fermented foods regularly. He has also been living with HIV for over 20 years. He takes his meds and knows that he wouldn't be alive without them, but he also claims much of his good health is due to regularly eating fermented foods.

At his sickest, Sandor weighed less than 100 pounds. He experimented with veganism (not eating meat or dairy products). When that didn't help, he switched gears and began eating fermented foods. He thinks these foods have been an essential part of his healing, and have strengthened his ability to tolerate the side effects of the HIV meds.

Sandor has published a book, Wild Fermentation, and travels around the country giving lectures and fermentation demonstrations. He praises the benefits of healthy bacteria, and believes that they may prevent other diseases, such as cancer. But he is clear to say "that doesn't mean sauerkraut cured my AIDS." Fermented foods certainly aren't miracle foods in the sense that they can cure disease. But they may help improve health and better manage illnesses.

Species and Strains

Not all healthy bacteria are created equal. There are several different kinds that work in different ways to improve health. Studies show that some strains are particularly helpful for the immune system, while others are more helpful for treating intestinal problems, such as bloating, constipation, or diarrhea. Most fermented foods will say on their labels which specific species or strains of healthy bacteria are present.


Some question the safety of eating healthy bacteria or taking a food supplement if HIV-positive. Though people with HIV are at greater risk of opportunistic infections, there is no published evidence that eating foods that contain healthy bacteria increases that risk. Two studies have been conducted to assess the safety of healthy bacteria in patients with HIV, and the findings support their safety.

At the moment, our understanding of how best to use healthy bacteria to enhance or maintain immunity is at an early stage. There is still much to learn, and researchers are looking into the reasons why certain bacteria are helpful. This may lead to a better, more personalized way of eating healthy bacteria and lead to better health outcomes.

Food supplements containing healthy bacteria are not FDA regulated, and one study found that many commercial products did not contain the amount or type of probiotics their labels claimed. For this reason, they should be purchased with caution. A sensible recommendation would be for people with HIV to include more fermented foods in their diets, to boost healthy bacteria intake naturally.

Many fermented foods are "pre-digested", making them better tolerated. For example, some people are lactose intolerant, which means they can't digest dairy products. But often those who are lactose intolerant can tolerate yogurt. This is because the lactose in yogurt is fermented, making it more digestible.


There is still a lot to learn about the relationship between the human body and healthy bacteria. Though the role, safety, and effectiveness of healthy bacteria in people with HIV needs more research, much of what has been discovered is promising. Currently, registered dietitians recommend that people with HIV eat a variety of fruits, vegetables, whole grains, protein, and healthy fats. Fermented foods are not officially on that list, but they should be. Sandor Katz serves not only as an inspiration, but as evidence of the positive effects that these foods can have on people with HIV. As he says in his book, "the [real] health benefits have only encouraged my devotion to fermentation."

Sarah Robertson is the Coordinator of Nutrition and Meals at GMHC and is the treasurer of the Infectious Diseases Nutrition Dietetic Practice Group of the American Dietetic Association.