Last updated by Dr Sarah Brewer on
The foods you eat and the foods you avoid can have a profound effect on your overall health. While a good diet can promote wellness, a bad diet is at the root of many help problems and niggling symptoms.
Dietary approaches can help to improve or even prevent acne, anaemia, high blood pressure, raised cholesterol levels, indigestion, metabolic syndrome, diabetes, gallstones, gout, menopause, premenstrual syndrome (PMS), irritable bowel syndrome (IBS), osteoporosis, polycystic ovary syndrome (PCOS) and an enlarged prostate, to name just a few.
Among the pages in this category, you will find some pointers on how to eat well to stay well and to improve health issues. There are also a few brief pointers below.
Diet and anaemia
Anaemia literally means lack of blood and occurs when the concentration of the red blood pigment, haemoglobin, falls below normal levels. This can cause symptoms of paleness, dizziness, tiredness, lack of energy, headache and shortness of breath.
The commonest form of anaemia is due to lack of iron which is needed to produce haemoglobin in the body. Iron deficiency can result from excessive loss of blood which may need investigation, a poor diet (eg unbalanced vegetarian diet) or poor absorption of iron from the gut. Similarly, lack of folic acid or vitamin B12 may be due to poor diet – especially an unsupplemented vegan diet – or to a condition known as pernicious anaemia in which the bowel loses its ability to absorb vitamin B12.
A healthy intake of iron helps to prevent iron-deficiency anaemia. Foods rich in iron include seafood, especially mollusks, red meat, poultry, nuts, wholegrains, egg yolk, green vegetables such as spinach and kitchen herbs such as parsley.
The form of iron found in red meat (haem or heme iron) is up to ten times more easily absorbed than non-heme iron in vegetables. Meat eaters are therefore less prone to iron-deficiency anaemia than non-meat eaters. Vitamin C helps to ensure optimum absorption of dietary iron in the gut.
Oily fish – especially sardines – are a good source of vitamin B12, along with meat and dairy products. Beetroot juice is an excellent source of folic acid as are green leafy vegetables, wholegrains, beans and nuts.
Diet and poor circulation
A poor circulation is usually linked with hardening and furring up of the arteries. This may be linked with following a high fat, low fibre diet over a long period of time which lacks fruit and vegetables rich in protective antioxidants. This type of diet is often associated with overweight and lack of exercise which exacerbate circulatory problems.
Following a low fat, high fibre diet and taking regular exercise will help to lose weight and may improve circulation. Oily fish contains essential fatty acids that reduce blood stickiness so circulation is improved. Olive oil, garlic and onions are also beneficial. Research shows that taking garlic powder tablets improves blood circulation to the nail beds by over 50%.
A dietary supplement containing extracts from the leaves of the Ginkgo biloba tree have also been shown to improve circulation to the peripheries and can improve poor memory, reduced circulation in the legs and erectile problems due to blocked arteries.
Milk contains special milk proteins such as casein and a milk sugar, lactose, which can trigger allergic symptoms in some people. Milk protein allergy is mainly found in children and has been linked with diarrhoea and eczema. Most children grow out of it, however, and it is unusual to find milk protein sensitivity in adults.
Lactose intolerance is more common however due to deficiency of a metabolic enzyme, lactase, needed to digest milk lactose before it can be absorbed. Lactase enzyme is released from the lining of the small intestine and acts on a molecule of lactose to break it down into two sugars: glucose and galactose which are immediately absorbed into the blood stream. Lactase deficiency leads to symptoms that can include:
- bloating and wind
- audible bowel sounds (borborygmi)
- abdominal pain
Lactase deficiency can be present from birth (primary lactase deficiency) or can result temporarily after a bout of gastro-enteritis (secondary lactase deficiency). It is therefore usual to advise that children with diarrhoea should avoid milk until symptoms have improved.
The treatment of lactose deficiency involves following a dairy produce or lactose free diet in which soya or low lactose milk products are used in place of cows’ milk products.
- Sheep’ milk contains 4.7g lactose per 100g (avoid)
- Skimmed cows’ milk contains 4.8g lactose per 100ml (avoid)
- Full fat cows’ milk contains 4.6g lactose per 100ml (avoid)
- Goats’ milk contains 4.2g lactose per 100g (avoid)
- Low lactose cows’ milk contains less than 0.3g lactose per 100g
- Soy milk, rice milk, almond milk and oat milk contain no lactose.
NB yoghurt made from cows’ milk has a low lactose content as bacterial fermentation breaks the lactose down.
Some people may be advised to follow a total milk free diet in which all foods containing milk need to be avoided, including cheese, yoghurt and cream. Milk powder is found in many manufactured foods so you will need to check all labels carefully when buying ready-made products.
Avoid foods labeled as containing:
- Hydrolysed casein
- Whey syrup sweetener
- Milk solids
- Non-fat milk solids
- Skimmed milk powder.
These dairy extracts may be found in foods such as breads, cereals, pancakes, potato croquettes, tinned sauces, burgers, luncheon meats, corned beef, sausages and fruit pies so it is important to check all labels.
A variety of soy-based products are available to replace baby milk powder, butter, margarines and low-fat spreads.
If avoiding dairy products, you will need to ensure an adequate intake of vitamin A, vitamin D and mineral calcium from alternative sources, including supplements.
Good dietary sources of calcium other than dairy milk products include:
- calcium enriched soya milk
- green leafy vegetables eg broccoli, spinach
- whitebait and tinned salmon and sardines which include soft bones
- nuts eg almonds, brazils, hazelnuts
- seeds eg sesame, tahini
- pulses such as chickpeas, beans, lentils, soybeans and products (eg Tofu)
- white and brown bread – in the UK, white and brown flour are fortified with calcium by law – but not wholemeal flour.
- dried or fresh figs
- prawns, cockles, mussels
Diet and diabetes
Blood glucose levels are controlled by hormones such as insulin and glucagon which normally keep blood glucose levels within a narrow range, despite wide variations in dietary intake. When resting blood glucose levels rise above a certain level, diabetes mellitus is diagnosed.
A raised blood sugar level occurs when the body’s ability to control glucose levels is impaired. This usually results from decreased production of insulin hormone in the pancreas gland (type 1 diabetes) or from reduced sensitivity of body cells to the effects of insulin hormone (type 2 diabetes).
Good control of blood glucose levels is important to reduce the long term risk of high blood pressure, hardening and furring up of the arteries, coronary heart disease, stroke, kidney and eye problems.
- Type 2 diabetes is often controlled by diet alone, or diet plus tablets that help to lower blood sugar levels.
- Type 1 diabetes usually requires insulin replacement therapy. Unfortunately, insulin cannot be taken by mouth as it is broken down by stomach juices before it is absorbed. Insulin replacement therapy must therefore be given by injection between 1 and 4 times a day.
A diabetes diet is essentially similar to the healthy low fat, high fibre diet that everyone should be eating and it is unnecessary to eat special diabetes foods. It is important to obtain individual nutritional advice from a dietician however, who will show you how to tailor your food intake to your needs. The main principles of a diabetes diet are to:
- Eat foods that have a low to moderate glycaemic index
- Increase fibre intake from wholemeal bread, wholegrain cereals, pulses, fruit and vegetables
- Avoid overindulgence in sugar and food with a high sugar content such as sweets, chocolate, honey, preserves, sweet biscuits, fizzy drinks, sweet alcoholic drinks
- Avoid excess fried and fatty foods
- Avoid excess salt to help protect against high blood pressure
- Eat regular meals and to eat similar amounts of starchy foods each day
- Eat meat, eggs, cheese, fish or pulses at least twice a day for protein
- Maintain a healthy weight.
Diet and cholesterol
Most of the cholesterol in your circulation is made by the liver – cholesterol in foods such as egg yolk actually has little effect on circulating blood cholesterol levels. There are two main types of cholesterol in the bloodstream:
- high-density lipoprotein (HDL) cholesterol that protects against atherosclerosis and CHD by transporting LDL-cholesterol away from the arteries and back towards the liver for metabolism.
- non-HDL cholesterol, such as low-density lipoprotein (LDL) cholesterol, which is linked with hardening and furring up of artery walls (atherosclerosis), high blood pressure and coronary heart disease (CHD)
Research shows that as HDL cholesterol level rise by 1%, the risk of CHD falls by 2%. If the level of LDL-cholesterol is increased however, this increases the risk of CHD. Until recently, eating too much saturated fat was thought to be the sole culprit in raising blood cholesterol levels and triggering atherosclerosis.
Researchers increasingly believe that it is eating too much omega-6 polyunsaturated fatty acids (mainly found in vegetable oils) and not enough omega-3 polyunsaturated fatty acids (mainly found in fish oils) that increases the risk of atherosclerosis. This is especially true if your intake of antioxidants (eg vitamins C, E, betacarotene and mineral selenium) is low.
If you have a high cholesterol level you may be advised to increase the amount of exercise you take, to follow a diet that is relatively low in fat but which supplies good amounts of omega-3 fatty acids (eg oily fish, walnuts) and monounsaturated fatty acids (eg olive oil and rapeseed oils). It is also important to increase fibre intake and to eat at least five servings of fruit and vegetables per day. Foods rich in soluble fibre such as oatmeal help to reduce absorption of fat from the gut. Garlic contains a substance, allicin that has been shown to reduce harmful LDL-cholesterol by as much as 12%. It has such a powerful effect that in Germany, garlic tablets containing the equivalent of 4g of fresh cloves are available on prescription to treat high blood cholesterol levels and high blood pressure.
Diet and heart disease
It’s estimated that one in three deaths from coronary heart disease are due to an unhealthy diet. Losing excess weight by following a low fat, low calorie diet can reduce the risk of coronary heart disease by as much as half for those who are obese.
Aim to eat oily fish (eg salmon, herrings, sardines, mackerel) two or three times per week as research shows this significantly reduces the risk of dying after a heart attack or stroke.
Eat at least five servings of fruit and vegetables per day as these contain fibre, vitamins, minerals and important antioxidants which can lower the risk of coronary heart disease by two thirds.
Reduce salt intake by avoiding obviously salty foods and not adding salt during cooking or at the table. If everyone did this, it is estimated that the incidence of coronary heart disease would be reduced by 15%. Obtain flavour from herbs, spices and black pepper instead.
Interesting new research also shows that those drinking tea are 50% less likely to develop coronary heart disease or have a fatal heart attack than non-tea drinkers. Tea is a rich source of protective antioxidant flavonoids – the other main dietary sources are onions and apples.
Those who have a high intake of vitamin C (including the use of supplements) also have up to a 40% lower risk of coronary heart disease while taking garlic tablets can reduce the risk of coronary heart disease by up to 25%. It is also important to exercise regularly, keep alcohol intake within safe limits and – if you smoke cigarettes – to stop.
Diet and cancer
A poor diet low in antioxidant vitamins, fibre and which is high in saturated fat is linked with over a third of all cancers. You can significantly reduce your risk of developing the disease by stopping smoking, losing excess weight, taking regular exercise, keeping alcohol intake within safe limits and avoiding sunburn.
Follow a low fat, high fibre diet and eat at least five portions of fruit and vegetables per day for the antioxidants such as vitamins C, E and mineral selenium they contain. Those with the highest blood levels of vitamins C, E and selenium have the lowest risk of cancer.
Reduce your intake of salt-cured, salt-pickled and smoked foods as these have been linked with an increased risk. Protective plant chemicals have also been identified in many fruit and vegetables. Broccoli contains sulphoraphane, which has a powerful anti-cancer effect, especially against tumours of the digestive tract, lungs and prostate gland. Cherries, strawberries and grapes contain ellagic acid that helps to protect against cancer by blocking an enzyme needed for growth of cancer cell. Red and black grapes are especially beneficial as they contain antioxidant pigments that are more powerful than vitamins C or E.
Chilies (cayenne pepper) contain antioxidants, including capsaicin, that also protect against coronary heart disease, cancer and premature ageing. Tomatoes contain lycopene, a pigment that is a powerful antioxidant and may protect against cancer. Citrus fruits are an excellent source of vitamin C, a powerful antioxidant while lemons are a rich source of limonene – a phytochemical that protects against cancer.
Studies in China suggest those who regularly eat up to 20g fresh garlic per day have the lowest rate of stomach cancer. Fish oils have also been shown to halt the growth of some cancer cells, reduce the risk of intestinal polyps and reverse weight loss in cancer patients.
Diet and fatigue
Fatigue affects an increasing number of people who admit to feeling tired all the time
If you eat the right types of food, you will gain a natural energy boost from your diet. If you eat the wrong foods however, you will quickly feel bloated, sluggish and fatigued. The foods that can pep you up are also those that are recommended for healthy eating such as:
- Crusty wholegrain bread – especially those with added nuts and seeds
- Wholegrain cereals eg porridge, brown rice, pearl barley, oatcakes, unsweetened breakfast cereals
- Root vegetables eg carrots, parsnip, turnip, swede, potatoes
- Cruciferous plants eg broccoli, cauliflower, Chinese leaves
- Legumes eg lentils, kidney beans, soya
- Fresh fruits eg avocado, banana, melon, plums, grapes, orange, pineapple
- Ready to eat semi-dried apricots, dates, figs, prunes
- Oily fish
- Virgin olive oil
- Nuts – especially walnuts – and seeds
- Honey (in moderation)
Research shows that eating fatty foods for breakfast can leave you feeling tired, sluggish and with poor concentration throughout the morning. If you then have a fatty lunch, you will function below par all day. Foods that can drag you down include:
- fatty, sugary snacks eg doughnuts, pastries
- fatty, salty snacks eg crisps, pork pies, salami pizza
- cakes, biscuits and confectionery
- red meat
- alcohol – try sticking to a maximum of one glass of red wine daily
- caffeine-containing products
Caffeine is now recognised as one of the great energy drainers. In the short term it gives a quick, alerting boost but in the long term it can lead caffeine poisoning with symptoms of restlessness, insomnia, headache, anxiety and fatigue. Caffeine mimics the effects of stress in your body and raises blood levels of stress hormones such as adrenaline and cortisol. It is now also known to take away a natural safety valve by blocking the effects of a calming brain chemical, adenosine. Adenosine also has other actions in the body, including regulating blood flow through coronary arteries, transmission of nerve signals, immunity and the storage and production of energy. Overall, adenosine helps to balance the body’s response to stress. If its actions are blocked by excess caffeine, you will succumb to the effects of stress more quickly and start to feel drained of energy.
The B-group of vitamins are especially important for energy production. Good sources include yeast extract, wheat germ, wholegrain bread and cereals, brown rice, pulses, nuts, dark green vegetables, meat, dairy products and seafood.
Some women are tired because of low iron levels through heavy, frequent periods, pregnancy, poor diet or a poor ability to absorb and store iron. Good sources of iron include red meat, seafood – especially sardines – wholemeal bread and green vegetables. Overboiling vegetables decreases their iron availability by up to 20%. Increasing your intake of vitamin C will help you absorb iron eg drink a glass of fresh orange juice with your breakfast boiled egg. Iron absorption is blocked by tannin, so don’t wash down your iron-containing foods or supplements with a mug of tea.
Diet and food allergies
Food allergy and food intolerance are commonly blamed for a number of chronic illnesses. Food intolerance is defined as a reproducible, adverse reaction to a specific food or ingredient which occurs even when that food is eaten in a disguised form. It is relatively common. In contrast, a food allergy is relatively rare. It is an abnormally excessive and dangerous immune response to a particular food and often involves a type of antibody called Ig E.
There are several medically accepted types of food intolerance and allergy, including:
- Severe anaphylactic reaction – with life-threatening symptoms such as falling blood pressure, difficulty breathing and tissue swelling – which can be triggered by foods such as peanuts.
- Hypersensitivity – with widespread, itchy rash (urticaria), eczema, asthma, vomiting, abdominal pains or diarrhoea – which can be caused by eating foods such as strawberries, eggs or shellfish.
- Food sensitivity – in which chemicals in chocolate, cheese or red wine for example can trigger migraine
- Lactose intolerance – due to the inability to digest lactose sugar in milk, causing bloating, abdominal pain and diarrhoea.
- Gluten intolerance – sensitivity to a protein found in wheat and some other cereals, which causes bloating, abdominal pain, bulky stools, malabsorption and weight loss (coeliac disease).
There is also a more controversial type of food intolerance which some researchers have labelled immuno-antagonism. This is thought to be triggered by food molecules that are absorbed into the blood stream from the gut. Once in your circulation, some of these food particles to which you are sensitive are quickly attacked by the immune system and destroyed by white blood cells called neutrophils.
If you eat too many of the foods to which you are sensitive to, it is thought that your immune system becomes swamped so that food particles are free to roam your body until they are eventually filtered out in the kidneys and destroyed. This challenge to the immune system has been linked with feelings of being tired all the time. Some researchers also believe they set up mild inflammation in parts of the body linked with the chronic illnesses such as:
- pre-menstrual syndrome
- chronic fatigue syndrome
- inflammatory bowel diseases.
If you believe you suffer from a food allergy, it is important to seek medical advice.
Diet and menopause
The menopause signals the end of a woman’s monthly menstrual cycle and her fertility. It is triggered when the ovaries start to run out of eggs so that oestrogen levels fall. This produces symptoms of oestrogen withdrawal, which may include hot flushes, night sweats, vaginal dryness, urinary problems and mood swings. There are three main ways in which your diet and nutritional state affects your hormone balance, through:
- the types of fat and fibre you eat
- the natural plant hormones present in your food.
- the amount of vitamins, minerals and trace elements you obtain.
Researchers have found that following a high-fat, low-fibre diet is associated with relatively high levels of circulating oestrogen. Women who have followed a life-long high-fat, low-fibre diet are more likely to have menopausal symptoms of oestrogen withdrawal – their tissues are used to a relatively high level of circulating hormones, and they seem to tolerate the menopausal drop less well.
Switching to a healthier, low fat, high fibre diet around the time of the menopause may make symptoms of oestrogen withdrawal worse however, by lowering oestrogen levels further, unless your diet is rich in natural plant hormones. Increase intakes of soya bean products, celery, fennel, Chinese leaves and other green or yellow vegetables.
Aim to eat more nuts and seeds, wholegrain cereals and fish.
Cut back on sugar, salt, tea, coffee and caffeinated fizzy drinks.
If hot flushes are a problem, avoid spicy foods and convenience foods. Avoid alcohol and smoking cigarettes which lower oestrogen levels further. Evening primrose oil contains essential fatty acids that act as building blocks for making sex hormones and are often helpful.
Diet and premenstrual syndrome
Pre-menstrual syndrome (PMS) is a common and distressing problem affecting as many as one in two women. Problems start in the two weeks before a period and usually stop quickly once bleeding occurs. Common symptoms include depression, anxiety, irritability, poor concentration, tiredness, bingeing, bloating, breast tenderness, headache and backache. It is thought to be due to a relative imbalance between the two female hormones, oestrogen and progesterone.
Some research suggests that progesterone can’t work properly when blood sugar levels are low. Nibbling regular carbohydrate snacks every 3-hours can help to reduce symptoms.
Evening primrose oil contains hormone building blocks and will help to even out hormonal imbalances, but needs to be taken at doses of up to 3 g a day for at least three months before an effect may be noticed.
Eat more fish, wholegrain cereals, nuts and seeds. Also cut down on intakes of salt, alcohol, caffeine and eat a wholefood diet.