Apples are rich in two plant compounds called catechins, and quercetin. These compounds help to prevent strokes, heart disease and cancer, according to research published in the the Nutrition Journal.
Quercetin has also been shown to improve the firmness of collagen, which helps the skin to keep its elasticity. Apples are also rich in the soluble fibre pectin, which helps to lower blood cholesterol.
Lastly, the flesh of apples contains the mineral boron, which helps to prevent calcium loss and provides some protection against osteoporosis.
One medium apple (about 100g) contains:
- Calories: 52
- Protein: 0.3g
- Carbohydrates: 13.8g
- Sugar: 10.4g
- Fibre: 2.4g
- Fat: 0.2g
Avocados contain an amino acid called glutathione, a compound made up of antioxidants glycine, glutamine and cysteine. Known as 'the mother of all antioxidants', glutathione strengthens your defences against heart disease and cancer. If you aren't a fan of avocados another good source is asparagus.
Avocados are also rich in vitamin E, a powerful antioxidant important for good skin condition and wound healing.
Avocados are also a good source of monounsaturated fat, which is linked to lower risk of heart disease. Just watch out for the fat content if you're watching your weight.
Half an avocado (about 100g) contains:
- Calories: 160
- Protein: 2g
- Carbohydrates: 1.8g
- Sugar: 0.66g
- Fibre: 6.7g
- Fat: 15g
Find out more about the healthy fats you need in your diet
Whole-grain barley - or "pot barley" - and other whole grains, such as rye and oats, contain phytic acid which has been shown to inhibit the growth of cancers. Barley is particularly rich in chemicals called protease inhibitors, which also have properties that combat cancer, including breast and bowel cancer.
Whole grains are also high in fibre, which helps to keep the digestive and circulatory systems healthy.
Half a cup of uncooked pearl barley (about 100g) contains:
- Calories: 352
- Protein: 9.9g
- Carbohydrates: 78g
- Sugar: 0.8g
- Fibre: 16g
- Fat: 1.2g
Find out how much fibre you need for a healthy diet
Blackcurrants are one of the richest natural sources of vitamin C, at around 130mg per 100g when stewed. Vitamin C is an important antioxidant which helps keep the immune system healthy, keeps the skin in good condition and helps wounds and fractures to heal. High levels of vitamin C are linked with the lowest risk of heart disease.
Blackcurrants also contain other implant compounds such as lutein (see Broccoli) and anthocyanins (see Blueberries), and the oil from their seeds has been shown to have anti-inflammatory effects, relieving arthritic pain. Vitamin C from foods may offer more protection than supplements.
100g of blackcurrants contain:
- Calories: 63
- Protein: 1.4g
- Carbohydrates: 15g
- Sugar: 7g
- Fibre: 3.5g
- Fat: 1.2g
Find out more with our guide to vitamins and minerals
Discovered in recent tests to be the most powerful antioxidants of all, blueberries have the strongest potential to prevent the diseases of old age. It has been found that 100g a day can stimulate the growth of new brain cells and may help prevent memory loss.
Blueberries are also rich in a plant chemical group called anthocyanins, which help oxygenate the skin and keep it looking young. Many other red, purple and blue berries have similar properties.
Find out more about antioxidants
Broccoli is high in antioxidant carotenoids, vitamin C and indoles, which help fight lung, breast and colon cancers. It is rich in lipoic acid, a fatty acid linked with increased brain power and energy.
As well as high levels of lutein and zeaxanthin, which help keep vision healthy, it's the best vegetable source of vitamin E which is linked with protection against Alzheimer's disease. It is rich in fibre, and a natural source of chromium, which helps to regulate blood sugars.
Carrots are the best source of carotenes - compounds which have a strong antioxidant effect that is important in helping to prevent cancers.
Regular carrot intake can also help protect against macular degeneration and cataracts, help minimise night blindness and reduce harmful cholesterol.
Carotenes also protect the skin from sun damage and cancers. Eating carrots cooked with a little oil or fat encourages carotene absorption.
Celery is renowned for reducing blood pressure, possibly because it contains the plant chemical 3-n-butyl phthalid, as well as apigenin, one of the flavonoid plant chemicals.
It is also an excellent source of potassium, a mineral that balances body fluids and can lower blood pressure in some.
Celery also has anti-inflammatory properties and can help reduce pain from arthritis, as well as helping to beat fluid retention. One study found that celery is one of the vegetables most strongly linked with protection from bowel cancer.
Fresh, organic eggs that are certified salmonella-free are an excellent food. They contain high levels of selenium which may be lacking in the diet and have cancer- and heart disease-fighting qualities.
They're a good source of iodine, which can help to promote healthy thyroid activity and also contain lecithin, a substance that can help to prevent heart disease and gallstones.
Eggs are rich in vitamins and minerals, including vitamin E and zinc - both lacking in many older people's diets - as well as the B group, which helps nerve health and stress, and protein.
Aim to have about four eggs a week unless you have specifically been told to avoid cholesterol in your diet.
Ten reasons to eat more eggs
Flax seeds - sometimes called linseeds - are tiny golden seeds from the flax plant. They are one of the few plant foods rich in alpha-linolenic acid which the body converts to the fatty acids EPA and DHA. These fats have a host of important anti-ageing properties - they help to prevent blood clots, stroke and heart disease, may improve brain power and lift depression, can help arthritis, improve insulin sensitivity and are vital in retaining smooth skin.
Flax seeds also contain lignans - oestrogen-like plant compounds that may reduce menopausal symptoms.
The health properties of seeds
Fresh garlic contains several compounds, the most important of which is allicin. This has been shown to protect against high blood pressure, infections, candida, indigestion, stomach ulcers and bowel disorders.
Several studies have shown that it can reduce harmful cholesterol by about 12 per cent, and inhibits new growth of plaque in the arteries that can lead to heart attack or stroke.
Garlic may also inhibit the growth of cancer cells and strengthen the immune system.
Leafy dark green vegetables, such as Savoy cabbage, kale, and spring greens, are good sources of two carotenoids which have been shown to help prevent age-related macular degeneration and cataracts.
Greens are also a good source of easily absorbed calcium to help maintain strong bones, and are rich in potassium, which helps protect against calcium loss. In addition, they're a good source of vitamins C and E.
Several herbs are strong antioxidants, even when used in small amounts. Thyme, oregano, rosemary, sage, basil and coriander all contain high levels of phyto-chemicals, which can help ward off heart disease and cancers.
How herbs can help your health
Nuts are a good source of magnesium, which is vital for energy levels. Magnesium can help keep muscles supple and prevent aches and pains, and may also lower the risk of osteoporosis.
Almonds, Brazils and peanuts are good for helping to build or maintain muscle mass and help protect against glaucoma, diabetes and high blood pressure.
Research in the USA has shown that just two 25g portions of fresh nuts a week reduced death from heart disease in men by up to 47 per cent.
Ten reasons to eat more nuts
Oily fish such as salmon, herring, mackerel and sardines are the main source of the important fats called omega-3s. Two of them - EPA and DHA - are not found in any other foods.
These fats have a variety of benefits, including offering some protection against the decline of brain power and diseases such as Alzheimer's and Parkinson's.
They are also anti-inflammatory, helping to minimise the pains of arthritis and rheumatism. In addition, they can help prevent blood clots, coronary disease and strokes.
Ten reasons to eat more fish
Although olive oil is almost 100 per cent fat, it is rich in nutrients and compounds that can help protect against age-related disease.
It is high in monounsaturated fats, which lower levels of harmful LDL cholesterol while protecting the levels of "good" HDL cholesterol, and thus helps fight heart disease and stroke.
Olive oil also contains squalene and oleuropein, which are powerful antioxidants, protecting blood cholesterol from oxidation.
This antioxidant effect may also reduce the risk of some cancers, particularly of the breast and colon. Top-quality, cold-pressed oils contain more of the protective compounds.
Discover the health-boosting properties of different oils
The onion family, including garlic and leeks, are good detoxifiers and are also antiseptic and antibacterial.
The sulphur compounds they contain are also linked with protection against strokes, high blood pressure, heart disease and cancers. Just 1g of onion a day is enough to help strengthen the bones.
Onions are rich in flavonoids and potassium, which can reduce blood pressure and keep the arteries healthy, and the onion family may also help to keep blood sugar levels even by regulating insulin production.
Most spices are strong antioxidants and have a variety of beneficial effects.
Ginger is an anti-inflammatory and can help ease the pain of arthritis.
Chillies contain the plant chemical capsaicin, which is a great reliever of general aches and pains, and coriander seeds can lower blood pressure.
Learn about the health-boosting properties of spices
Soya beans contain high levels of plant oestrogens and magnesium, both of which may help to minimise menopausal symptoms.
Soya beans are high in soluble fibre, and have also been shown to help reduce the risk of heart disease.
Soya protein helps build and maintain collagen and elastin, both important for keeping skin in youthful condition.
Read our guide to minimising menopausal symptoms
Tomatoes are rich in the carotenoid lycopene, which provides some protection against cancer and heart disease.
Recent trials have found that women who eat a lot of lycopene have lower risks of ovarian or breast cancer, while in men it helps prevent prostate cancer.
Tomatoes are also a good source of lipoic acid, which helps increase energy levels and improve brain power in some people.
Small, ripe tomatoes tend to contain the highest levels of lycopene and cooking them helps absorption.
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