The most significant link between diet and osteoarthritis is weight.
Being too heavy is one of the biggest risk factors for osteoarthritis because those extra pounds place an extra strain on your weight-bearing joints and encourage painful inflammation.
Put simply then, the best foods to avoid are the ones that cause you to put on weight. A combination of dietary measures and regular exercise can lead to long-term weight loss and a significant associated reduction in osteoarthritis symptoms, according to research from Wake Forest University in the US.
Related: Learn more about lifestyle changes for osteoarthritis
So should I cut down on fat?
Eat too much fatty food and you'll put on weight, which places the joints under increased stress. But it really depends what type of fat we're talking about here. Both saturated fats and trans fats can increase the amount of cholesterol in your blood and cause inflammation.
Saturated fats are found in processed and fatty meat, hard cheeses, whole milk, cream, butter and lard. Trans fats are found in fry-ups, takeaways and sweet snacks such as biscuits and cakes.
However, monounsaturated and polyunsaturated fats – the kind found in olive oil, nuts and oily fish – contain essential fatty acids, which have many health benefits, including anti-inflammatory properties, so still have an important role to play in a balanced diet.
Related: Read our guide to good fats and bad fats
And what about sugar?
Be honest: you know the answer to this one already, don't you? Eat too much sugar and you're pretty much consuming 'empty calories', which can lead you to put on weight and so aggravate osteoarthritis symptoms.
High-sugar diets can also raise levels of chemical messengers known as cytoklines, which encourage inflammation.
So how much is safe? No more than five per cent of our daily calories should come from sugar, according to a recent report from the Scientific Advisory Committee on Nutrition: that's about seven teaspoons.
Unfortunately, most of us currently consume at least twice this amount – partly due to the amount of hidden sugars found in fizzy drinks, sauces and cereals.
Related: 10 ways to eat less sugar
I'm guessing extra salt's off the menu, too?
Yes – excess salt can elevate blood pressure and may encourage inflammation in some people.
Eating less salt can also halt calcium loss, so strengthens the bones. Current NHS guidelines state we should consume no more than 6g salt per day – that's approximately half a teaspoon.
But remember, around 75 per cent of the salt we consume has already been added to processed foods, such as bread, cereal and ready meals.
Related: Find out more about inflammation and how it affects your body
I've heard nightshade vegetables can aggravate osteoarthritis...
Vegetables from the nightshade family – including white potatoes, tomatoes, peppers, aubergines and chillies – contain a chemical called solanine, which some people believe may cause inflammation, and so aggravate osteoarthritis.
However, the evidence for this is largely anecdotal and no formally recognised scientific link has yet been found.
On the contrary, these vegetables are rich in vital antioxidants, so it's not a good idea to cut them out of your diet, according to Arthritis Research UK (www.arthritisresearchuk.org).
Related: Find out more about antioxidants and how they affect your health
Aren't citrus fruits rumoured to be bad, too?
Various claims have been made citing citrus fruits – including oranges, lemons and grapefruit – as a cause of inflammation.
But once again, there's no widely accepted proven link and it's not recommended that you restrict your intake as they're such a rich source of essential vitamins.
Oranges and tangerines, for example, contain an antioxidant called beta-crytoxanthin, which actually discourages inflammation and may help slow the progress of osteoarthritis.
Related: Eat the rainbow – how colourful foods boost your health
Could a food intolerance make things worse?
It's certainly possible. Various studies have shown an improvement in arthritis symptoms after cutting out certain foods. Likewise, some people experience arthritis flare-ups after eating particular dishes.
However, dietary culprits vary from person to person, which may well account for some of those anecdotal claims made about citrus fruits and nightshade vegetables.
The only way to be sure you have a food intolerance is to try an 'exclusion and challenge' diet under the supervision of a registered dietitian. For more information, speak to your GP in the first instance.
Related: Is it something you ate? Food intolerance causes and diagnosis