Sicca

What the research found.

• One trial gave 104 people with Sjogren's disease omega-3 or a placebo, with neither side knowing which. Over two months, dry eye symptoms on an 18-point scale fell from 10.44 to 4.85, against 10.70 to 8.27 on placebo, at a P value of 0.001. The two starting scores didn't differ, at 0.767.

  Al-Rawi and colleagues, Mediterranean Journal of Rheumatology, 2025

• In that trial, dry mouth on the xerostomia inventory fell from 2.83 to 1.91, against 2.81 to 2.35 on placebo, at a P value of 0.017. Tear production improved in both groups. Saliva flow on omega-3 reached only 0.053, which is the weak half of the result.

  Al-Rawi and colleagues, Mediterranean Journal of Rheumatology, 2025

• One study looked at 114 people with Sjogren's at one moment, where Mediterranean diet scores ran opposite to the ocular surface disease index. The rho was minus 0.73. The mean index was 13 in the good adherence group and 33 in the poor or moderate group.

  Chaaya and colleagues, Medical Sciences, 2025

• Across nine studies, people with primary Sjogren's syndrome slept worse than controls, reporting more broken sleep, more daytime sleepiness, and more waking at night. Obstructive sleep apnea ran at 64 percent against 28 percent. The P value was 0.03.

  Hackett and colleagues, Rheumatology, 2016

What the word means

Sicca means dryness, and in rheumatology it means dryness of the eyes and mouth in particular, because you make less tear and less saliva. It's the defining symptom group of Sjogren's disease, which is why the two words often turn up together. The dryness is the symptom, and Sjogren's is one condition that produces it.

That difference is worth holding onto. Dryness like this happens in other settings as well, one of them being a side effect of a number of common medicines, and this site holds no source on the other causes, so this page can't list them. Somebody with new dry eyes and a dry mouth has a question worth asking rather than a diagnosis.

Most of the confusion about treating dryness comes from mixing those two halves up. How dry things feel gets measured with symptom questionnaires, while how much you make gets measured with its own separate tests. A treatment can move one of those without moving the other at all, which is what happened in the trial below.

The one properly blinded trial

Our source set holds one good nutrition trial in Sjogren's disease. People were assigned at random to omega-3 or a placebo, and neither the patients, the staff, nor the investigators knew which. It ran in 104 people who finished, over two months, and this page won't print what dose they took. That's a stronger design than most nutrition research in these conditions.

The symptom results separated clearly. Dry eye symptoms sit on an 18-point scale, where omega-3 took them from 10.44 to 4.85 while placebo took them from 10.70 to 8.27, at a P value of 0.001, and the two starting scores didn't differ, at 0.767. Dry mouth sits on the xerostomia inventory, and it fell from 2.83 to 1.91 against 2.81 to 2.35, at 0.017.

Single eye symptoms moved too. Itching improved by 0.65 against placebo, mucous discharge by 0.42, and light hurting the eyes by 0.55, and all three reached significance. So on how people felt, this trial is a positive result from a reasonably well run study.

Where that trial is weakest

The measured results are the problem, and they're the reason this page doesn't say omega-3 treats dryness. Tear production gets measured with a Schirmer's test. On omega-3 it improved from 2.38 to 6.63 millimeters, at a P value below 0.001, and on placebo it improved too, from 2.68 to 5.58 millimeters, at 0.01.

A measure that improves a great deal on placebo can't count for much, because the improvement in the treatment group may not be the treatment's doing. Saliva flow tells a similar story from the other side, rising from 0.99 to 2.07 milliliters per 15 minutes on omega-3. That reached only a P value of 0.053.

Three further limits belong here. The trial ran two months at a single center, the paper doesn't state who paid for it, and it reported no side effects at all, which is a real hole in a supplement trial. So symptoms improved against placebo, the secretion measures largely didn't separate, and the result deserves a longer and larger repeat.

What the rest of the field looks like

The map of diet research in Sjogren's disease is nearly empty. This site holds one nutrition trial in this disease and nothing else of any size, and what else gets written about is mostly single case reports or small series rather than trials. The things tested included vitamins and minerals, gluten-free and plant-based diets, liquid diets, herbal supplements, and omega-3.

The encouraging things you'll read about here rest on very small reports, of a few people, with no control group and no way to tell a real effect from chance. Those are hypotheses rather than findings. It's a useful distinction to hold on to when a headline arrives.

That isn't a negative finding about diet, and it's a description of how little has been done in the area so far. Nobody has shown that eating differently helps sicca, and nobody has shown that it doesn't. What is true is that confident diet advice about this condition circulates anyway, resting on nothing at all.

The Mediterranean correlation, read carefully

One study looked at 114 people with Sjogren's at a single moment, where Mediterranean diet scores ran opposite to the ocular surface disease index at a rho of minus 0.73. The mean index was 13 in those with good adherence and 33 in those with poor or moderate adherence. Fatty acid intake against the same index came out at minus 0.67.

Those are strong correlations, and the design can't turn them into a treatment claim. Data from one moment can't separate a diet improving symptoms from feeling better making it easier to shop, cook, and eat well. The authors themselves list that limit.

There's a further caution worth stating. Both of those measures are self-reported, one a food questionnaire and the other a symptom questionnaire, and a correlation that strong between two forms like that may partly come from the method, because people who report their diet favorably may report their symptoms favorably too. So eating a Mediterranean picture is a reasonable thing to do, and this study isn't evidence that it reduces dryness.

The problem sitting alongside it

Sleep is worse in this condition, and it's a separate matter from dryness, which is worth saying because the two get mixed together when a dry mouth wakes somebody at night. Across nine studies, patients with primary Sjogren's syndrome slept worse than controls. They reported more broken sleep, more daytime sleepiness, and more waking at night.

Obstructive sleep apnea ran at about twice the rate, at 64 percent against 28 percent, at a P value of 0.03, and total sleep time across the included groups ran from 5.2 to 7 hours. The authors of that review concluded that treatments aimed at sleep are needed. That's a large enough difference to raise as its own item at a visit.

Treating the dryness and treating the sleep are different problems, and an apnea rate that high isn't something a saliva substitute addresses. This page holds nothing on the treatments for dryness itself, including artificial tears, saliva substitutes, punctal plugs, and secretagogues. No reference in our set covers any of them.

Common misconceptions.

Related terms.

• Sjogren's and diet, where the omega-3 trial is set out in full.
• Living with Sjogren's, for the condition sicca defines.
• Omega-3 index, the measurement behind the supplement question.
• Inflammation, and the difference between the kind you can measure and the kind you have.

Questions patients ask.