To determine whether dietary sulforaphane (SFN), naturally available from eating broccoli, improves pain in people with knee osteoarthritis (OA), the trial will compare broccoli soup (rich in SFN) with a soup, which does not contain broccoli (control), but looks and tastes the same. Sixty-four participants with moderate osteoarthritis, chosen at random, will either have the broccoli or the control soup. The participants will eat the soup once-a-day, for 4 days-a-week for 3 months.

This is the first clinical trial to test the benefits of eating broccoli on pain and physical function in knee osteoarthritis (OA).

Many fruits and vegetables in the normal human diet contain substances that may improve human health or disease. There is increasingly strong laboratory data that indicate that exposure to these substances at the levels found in the diet influence the way in which osteoarthritis develops. Sulforaphane (SFN) is a naturally occurring substance found in vegetables such as broccoli and is known to have helpful effects on cartilage cells. Sulforaphane derived from broccoli, has a potential role in limiting pain and cartilage destruction in OA.

The investigators have shown that:

• SFN can stop inflammation in mice with OA
• SFN blocks the production of the enzymes which break down cartilage in OA, both in cell cultures and in pieces of cartilage
• SFN enters the joint in participants provided with a high broccoli diet ahead of a knee replacement and alters the types of proteins present in the joint fluid

The investigators aim to discover for the first time in man, whether a broccoli-rich diet will improve pain and physical function in participants with knee osteoarthritis. The study will provide the much-needed preliminary data that will allow the investigators to design a clinical trial to prove that broccoli can be recommended as a helpful food for people with OA.

The trial will compare broccoli soup (rich in SFN) with a soup, which does not contain broccoli (control), but looks and tastes the same. Sixty-four participants with moderate osteoarthritis will either have the broccoli or the control soup, chosen at random. The participants will eat the soup once-a-day, for 4 days-a-week for 3 months. The investigators will measure pain and physical function at the start of the trial, at 6 weeks and at 12 weeks and look at the changes in these. The investigators will also take blood samples and collect urine to measure SFN levels.

Inclusion Criteria:

1. Current knee pain, defined as pain in either knee, in the (one) month before Visit 1, for which the patient gives a severity score of at least 4 on a 0-10 numeric rating scale (NRS).
2. The target knee should fulfil the criteria of the American College of Rheumatology (ACR) for knee osteoarthritis defined as knee pain for most days of the prior month and at least one of the following three factors: age over 50 years; morning stiffness of less than 30 minutes; knee crepitus on motion.
3. Kellgren Lawrence grade 2-3
4. Stable analgesic usage (if using) for 4 weeks prior to trial entry and throughout the trial duration
5. Able to adhere to the study visit schedule and other protocol requirements (willing to consume soup intervention).
6. Willing to provide 24 hour urine collection samples (x3)
7. Capable of giving informed consent and the consent must be obtained prior to any screening procedures.

Exclusion Criteria:

1. The presence of any inflammatory arthritis (e.g. gout, reactive arthritis, rheumatoid arthritis, psoriatic arthritis, seronegative spondylarthropathy) or fibromyalgia or metabolic bone disease.
2. Any clinically significant uncontrolled concurrent illness, which, in the opinion of the Investigator, would impair ability to give informed consent or take part in or complete this clinical study.
3. Known or suspected intolerance or hypersensitivity to the investigational product (broccoli) or standardised meal (see section 9.2), closely related compounds, or any of the stated ingredients.
4. Use of an investigational product within 30 days prior to 'run in' period or active enrolment in another drug or vaccine clinical study.
5. Significant knee injury or any knee surgery within the 6 months preceding enrolment in the study.
6. A history of partial or complete joint replacement surgery in the signal knee at any time, listed for knee surgery, or anticipating knee surgery during the study period.
7. Poor tolerability of venepuncture or lack of adequate venous access for required blood sampling during the study period
8. Nutritional deficiency
9. Use of anticoagulant medication (see notes for inclusion exclusion criteria)
10. Use of intra-articular hyaluronic acid in the signal knee within the 3 months preceding enrolment in the study.
11. Use of intra-articular, intra-muscular or oral corticosteroids in the 2 months preceding enrolment.
12. Commencement of non-pharmacological interventions within two months preceding enrolment.
13. Persons less than 50 years
14. Pregnant/lactating women