Download Diet and Kidney Disease

Diet and Kidney Disease
Louise Wells Clinical Lead for Renal Dietetics at York Teaching Hospital NHS Foundation
Trust
Diet and lifestyle changes play an important role in the management of Chronic Kidney
Disease (CKD) and in the early stages of CKD, appropriate dietary treatment may help
prevent or slow the rate of the disease progression.
For people with CKD the basic dietary principles are the same as those for the general
population; aimed at achieving and maintaining a healthy weight, improving blood glucose
control for those with diabetes and supporting effective hypertension management.
In more advanced CKD, dietary advice shifts towards the ‘renal specific’ elements. This
requires timely specialist renal dietetic intervention to support good biochemical control,
continued sodium restriction to address salt and water imbalance alongside assessment of
nutritional status and the need to maintain adequate nutrition.
Healthy diet and lifestyle measures for CKD:
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Eat a varied, balanced diet
Maintain a healthy body weight
Reduce salt intake to a maximum of 6g (1 teaspoon) per day
Limit alcohol intake to a maximum of 3 units per day for men and 2 units per day for
women
Eat at least five portions of fruit and vegetables per day
Eat adequate protein for growth and repair but avoid an excessive intake – (A
‘normal’ intake of 0.8-1.0g protein/kg Ideal Body Weight/day is recommended)
Take regular exercise
Effective blood pressure control is essential to the management of CKD, as hypertension is
a major risk factor for further kidney damage and progression of kidney disease.
The importance of diet and lifestyle modification alongside anti-hypertensive medication is
highlighted in several guidelines. The NICE Hypertension Guidelines (2011) recommend a
‘healthy diet’ - reducing sodium intake, reducing alcohol and caffeine intake where
necessary and promoting regular exercise.
The Dietary Approaches to Stop Hypertension (DASH) trial (2001) provided robust evidence
that a combination diet, emphasising a high intake of fruits, vegetables, low fat dairy
products and whole grains, and lower in fat, sugar, salt and meat products, can significantly
reduce blood pressure in populations with normal kidney function. The potential for this type
of diet to be of benefit in hypertension is clear, but there are concerns about its use in more
advanced CKD because of its higher potassium and phosphate content, both of which may
be problematic for some people with reduced kidney function. However, the principles of a
healthy diet, and in particular a reduction in sodium intake to help manage hypertension,
remain valid.
Clinical News, September 2014
Reducing salt intake:
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Avoid adding salt to food at the table
Aim to avoid using salt in cooking
Cut down on high salt and processed foods
Use fresh ingredients where possible
Don’t use salt substitutes
Most of us eat too much salt and only a small amount is needed for good health. The current
advice is that we should aim to have no more than 6g per day. Most of the salt that we eat –
around 75% - is ‘hidden’ salt in processed and ready prepared foods, so the aim is to limit
intake of these and use more fresh products. The salt content of similar foods can vary
greatly so advice on how to interpret the salt, or sodium content on food labels is important.
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To convert sodium to salt, you need to multiply the amount by 2.5
Greater than 0.6g of sodium/1.5g of salt per 100g in food is high.
Less than 0.1g of sodium/0.3g of salt per 100g is low.
Remember that a serving of a food may be more than 100g, e.g. if a food contains 1g of salt
per 100g, but a serving is 300g, this will provide half a day’s salt intake!
From the end of 2014 food labelling guidance changes and only salt content will be
indicated, with sodium no longer used
Salt substitutes are not advised, since they still contain some sodium, as well as being high
in potassium, which can be a problem for some people with CKD. Most importantly, their use
does not help people adjust to a reduced taste for salt. Using herbs, spices and other low
salt flavourings is preferable and can help people adapt to a lower salt intake.
Weight management in CKD:
Obesity is a recognised risk factor for cardiovascular disease and type II diabetes. Weight
reduction in these patient groups has been shown to reduce blood pressure and improve
control of blood lipids and blood glucose. Obesity is also associated with the development
and progression of CKD and obese patients may be required to lose weight prior to
transplantation. Weight loss programmes should be advised where needed, encouraging a
sensible eating plan, combined with regular exercise, in order to achieve a slow, steady
weight loss of 0.5-1kg (1-2lb) per week.
In the later stages of CKD poor appetite and uraemic symptoms can lead to rapid loss of
nutritional status and flesh weight changes may be masked by shifts in fluid balance.
Monitoring nutritional status is essential, since malnutrition in established renal failure is
associated with poorer outcomes and reduced patient survival.
Therefore, sensible weight loss in CKD patients with multiple dietary needs should be
managed by specialist renal dieticians, who can assess the various and sometimes
Clinical News, September 2014
conflicting nutritional requirements of these patients, can determine the priorities and
address nutritional concerns.
Phosphate and potassium control
Phosphate and potassium restrictions are commonly required in the later stages of CKD as
blood levels rise.
Dietary manipulation to control high phosphate and high parathyroid (PTH) levels is a
recognised factor in the effective management of CKD-Mineral Bone Disorder in stage 4 and
5 CKD patients. There is increasing focus on restricting inorganic phosphates, found in food
additives, as a way of controlling phosphate levels without compromising protein intake. A
healthy diet as described above will therefore potentially also help phosphate management.
The UK Renal Association CKD Guidelines propose that dietary advice in this area should
be delivered by renal dieticians and there is now considerable evidence showing
improvements in bone biochemistry with dietetic-led interventions.
Potassium is found in many foods, particularly fruit and vegetables, so over restriction can
conflict with the dietary advice to lower blood pressure. There are many reasons why blood
potassium levels may rise and non-dietary causes should be excluded before focussing on
high potassium foods. Specialist dietetic advice will help to ensure that wherever potassium
restriction is necessary, it can be achieved without affecting the balance or adequacy of a
healthy diet.
Many people diagnosed with CKD may already be aware of the dietary advice
recommended for management of diabetes or high blood pressure. They can be reassured
that making simple changes to achieve a healthy, balanced diet can also support good
management of chronic kidney disease.
Educational resources are available at:
http://www.britishrenal.org/getattachment/CKD-Forum/Educational-Resources/CKD-Nutrition-Leaflet.pdf.aspx
Clinical News, September 2014