Hyaluronic Acid (Oral) Simply Explained

1. What It Is About

Hyaluronic acid is a substance that occurs naturally in the body: in connective tissue, in joint fluid and in the skin. Connective tissue is the tissue that holds organs and muscles together. Joint fluid is the fluid in the joint that lubricates the bone ends. Hyaluronic acid binds water and keeps tissue elastic. For preparations it is usually obtained from cockscombs or produced with bacteria. It is available for application to the skin, for injection into the joint and for oral intake. When taken orally, one point is important: hyaluronic acid is not absorbed in the intestine as a whole substance, but is broken down into smaller fragments. Whether these fragments then act throughout the body or only in the intestine has not yet been clarified. In the studies, moreover, hyaluronic acid molecules of different sizes are used; a molecule is the smallest building block of a substance. Some preparations contain the unchanged form, others a form broken down into smaller parts. Therefore, studies on oral intake are not readily comparable with studies on injection or topical application.

2. What Studies Show

The knee joints are the best studied. In a study with 60 people with knee osteoarthritis, the participants took hyaluronic acid for twelve months and additionally performed exercises to strengthen the thigh muscles. Osteoarthritis is the wear and tear of the joint. In participants up to 70 years of age, symptoms improved more markedly than in the group that received a placebo 4. A placebo is a preparation without an active ingredient; it is used by researchers to check whether a substance achieves more than expectation alone. The participants’ self-reported pain and everyday movements were observed, not the joint itself on X-ray. In a further study with 40 overweight people with knee osteoarthritis, reported pain intensity improved after three months and mobility increased. In addition, values that play a role in inflammation decreased in blood and joint fluid 1. These are laboratory values; whether their reduction contributed to the reported improvements was not examined. For the skin there is a study with 129 women. After two to eight weeks the skin was moister, after four to eight weeks skin tone appeared lighter, and after twelve weeks the epidermis was slightly thicker 2. How much hyaluronic acid the women took and how large the molecules were is not stated in the paper. In dry eye, a study examined 54 patients who took hyaluronic acid in addition to treatment with hyaluronic acid eye drops. After one and after three months they reported fewer symptoms and the measurement values for the ocular surface improved 3. It is not possible to separate here which share came from oral intake and which from topical application. For joints and skin there are therefore indications of perceptible improvements, but they are not yet confirmed.

3. What Remains Unclear

None of the controlled human studies has so far been able to show that more hyaluronic acid is present in blood or tissue after oral intake. This is the greatest open question. It is therefore discussed whether the observed improvements act via the intestine, for example via the intestinal barrier or via the bacteria in the intestine. This is so far only a hypothesis. The studies also use very different preparations: molecules of different sizes, unchanged or fragmented hyaluronic acid and different amounts per day. A comparison of these forms is still outstanding. Likewise, a study lasting more than twelve months is still outstanding; whether an effect persists with longer intake is therefore open. And whether the joints themselves change was not examined in the controlled human studies — mainly questionnaires and laboratory values were measured.

4. What This Means in Everyday Life

Anyone reading the studies finds reports of less pain, more mobile knees and moister skin. What was measured were the participants’ self-assessments or what a device showed on the skin surface. A difference between an improved feeling and a changed joint structure cannot be inferred from this. Nor can it be inferred from the studies which preparation produces which effect, because the studies are too different for that. The observed improvements also occurred only in certain groups in some cases, for example in osteoarthritis patients up to 70 years of age who also trained. The next step would be a study that measures the fragments of hyaluronic acid after oral intake in blood and tissue and at the same time compares images of the joint with the participants’ reports.

All details with study numbers and sources: detailed page on hyaluronic acid (oral). For children: Hyaluronic acid (oral) for children.