advanced diploma in principles of nutrition€¦ · treatment: complete avoidance of cow’s milk...
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ADVANCED DIPLOMA IN PRINCIPLES OF NUTRITION
@ShawPhotoTomCourse Educators: Thomas Woods, William Eames
BY LAUREN OWENS RD
BSC (HONS) Human Nutrition and DIetetics
BY LAUREN OWENS
Course Educator:
Lauren OwensBSc (Hons.) Human Nutrition and Dietetics
Special Diets Semester : Lesson 2Food Allergies and Intolerances
@ShawNutrition [email protected]
Lesson 2 Learning Outcomes
Food Hypersensitivity
Food Allergy e.g.
• Cow’s Milk Allergy
Food Hypersensitivity Diagnosis
Food Exclusion diets
More than 30% of the world’s population is affected by allergies with approx. 250 million people thought to
be affected
1 in 13 children under 18 suffer from food allergies
Number of people with food allergies is growing but with no clear reason
as to WHY?!
Every 3 minutes, a food allergy sends someone to the emergency department
GeneticsYour risk of having food allergies is higher if you have a parent who suffers from any type of allergic disease
(asthma, eczema, food allergies, or environmental allergies such as hay fever)
Facts and Statistics
Environment
• The Hygiene Hypothesis- Inadequate exposure to environmental micro-organisms may therefore result in the immune system of atopic children developing a tendency towards allergy.
• Epigenetics- genes turned on and off by environmental factors e.g food
Food Hypersensitivity
Are food allergy and food intolerance the same thing??
Question Time???
Answer…….NO
Food Hypersensitivity
Estimated Prevalence
1. Peanut- 0.6-1.3%2. Tree nuts- 0.4-0.6%3. Fish- 0.4%4. Crustacean shellfish (crab, crayfish, lobster,
shrimp) 1.2%5. All seafood: 0.6% in children and 2.8% in adults6. Milk and egg: approx. 1-2% for young children
and 0.2-0.4% of the general population
Top Food Allergens
8 foods account for 90% of all food-allergic reactions
'inappropriate response by the body to a perfectly harmless substance'.
Triggers immune response
T-cell lymphocytes, which recognise allergens and react by producing cytotoxic substances or triggering inflammatory
Production of inappropriately high titres of antibodies (IgE) – B cell lymphocytes
IgE antibodies which attach to 'mast' cells and, in turn, precipitate a release of histamine
Why Do Allergies Occur?
Histamine- causes a contraction of the
muscles around the air passages (an
attack of breathlessness or asthma),
local swelling and skin irritation, and, if
the attack is serious enough, a drop in
blood pressure
Why Do Allergies Occur?
Most extreme form of allergic reaction
Obvious symptoms (throat swelling/ hoarseness, wheezing, fainting & low blood pressure)
Treated with Adrenaline/ Epinephrine
Teenagers and young adults with food allergies are at the highest risk of fatal food-induced anaphylaxis
Rapid in onset and may cause death
Anaphylaxis
Often confused with allergic reactions
No immunological mechanism involved
Similar symptoms - vomiting, diarrhoea, rashes
Also called food intolerance/ sensitivities
Often manifest as a result or symptom of another medical condition or illness
The acute effects can be severe - in some cases hypotension and anaphylactic reactions can occur
Non-allergic Food Hypersensitivity
Intolerance
Usually comes on gradually
Significant amounts of the food may need to be eaten
May only happen when you eat the food often
Usually not life threatening
Allergy
Comes on suddenly
Triggered by small amounts of food
Happens every time you eat the food
Can be life threatening
Food Allergy or Intolerance?
Clinical History
Diagnostic tests
Food Exclusion
Diagnosis of Food Hypersensitivity
Skin prick test- Measures specific IgE attached to mast cells in the skin
Detects IgE mediated food allergy
A positive (histamine) and negative (saline) control should always be used
Size of the wheel caused by food allergen should be interpreted in relation to the size of the negative control
Easy method to screen for patients with IgE mediated sensitivity to foods
In general, wheal size >3mm- considered positive
Diagnostic Tests
IgE test - determines levels of circulating specific IgE to allergen in circulation
Patch test - used for diagnosis of more delayed reactions such as allergic dermatitis
Other diagnostic tests - still in experimental stage and not routinely used in the diagnosis of Food hypersensitivity
1. Single exclusion diet: excludes all sources of a single food
Can be very difficult in practice Patients require clear but comprehensive information
detailing both obvious and less obvious sources of the food
Require information on reading labels Guidance on suitable alternatives for excluded food
2. Multiple food exclusion diet: excludes a number of foods at the same time
Used when a dietary link is suspected but not identified
No set rules on which foods to exclude Practice varies by centre
Food Exclusion Diets
More restrictive than a multiple exclusion diet
Provides rapid symptom relief
Excludes most foods Foods included are those which rarely
provoke sensitivity Practice varies between treatment centres Usually comprise 1 or 2 meats, a selection
of starchy foods, vegetables ad some fruits
Few Foods Diet and Monitoring
Both socially and nutritionally restricting Requires considerable commitment from
patient Do not continue for more than 2-3 weeks
Once symptom relief is obtained, foods reintroduced singly
Monitoring- degree of effectiveness Keep a daily record of symptoms Record details of frequency and severity
Few Foods Diet and Monitoring
To diagnose and treat hypersensitivity Complete avoidance can be difficult Avoidance of one type of food-little nutritional
significance if similar food can be eaten Exclusion of entire food group can have major
impacts nutritionally Some single foods can have a large knock on effect
e.g. nuts present in lots of food Food exclusions should be reviewed as they can
remit with time Need to establish each patient’s tolerance levels
Food Exclusion in the Management of Food
Hypersensitivity
Medically supervised food challenge
Open food challenges
Single-blind placebo-controlled food challenge
Double-blind placebo-controlled food challenge
Confirmation of Diagnosis
Allergic disease such as asthma, rhinitis, eczema and food allergies increasing in both developed and developing world
Different factors related to development of allergic diseases:
1. Genetics2. Exposure to allergens3. Development of the immune response4. Family history- individual more at risk of
developing allergic diseases
Prevention of Food Allergy
Role of maternal diet during pregnancy and breastfeeding and weaning in development of allergies - still uncertain
Some research suggests that avoiding “allergens” during pregnancy may have a negative effect
Promising research that probiotics may be helpful - to be confirmed
Prevention of Food Allergy
American Academy of Paediatrics
Advice for infants at risk - where both parents or parent and sibling have documented disease
Exclusive breastfeeding for up to 6 months
Alternatives if breastfeeding not possible/sufficient, use a formula with proven reduced allergenicity - this must be confirmed with GP advice
Goat’s and soya formula NOT suitable replacement for babies
Breastfeeding does have some protective effect on the development of allergic disease and that this effect is greater when there is a family history of atopic disease
Up to1/3 of infants will develop cow’s milk allergy during exclusive breastfeeding
Allergy Prevention Advice
The American Academy of Paediatrics recommend:For High Risk Infants:
Do not introduce solid food until 6 months Do not introduce cow’s milk until 1 year Do not introduce egg until 2 years Do not introduce peanuts, tree nuts and fish
until 3 years
Breastfeeding and Weaning Guidelines
For Allergy Prevention
For mothers of infants at high risk of developing atopy (During breastfeeding) :
No evidence of benefit from avoiding specific foods
May be helpful to avoid peanuts whilst breastfeeding
Eat a healthy, balanced diet
More information is needed regarding n-3 fatty acid consumption, probiotics, and vitamin and mineral intake in the prevention of allergic disease
Breastfeeding and Weaning Guidelines
Characterised by gastrointestinal symptoms: Vomiting Diarrhoea Irritability Failure to thrive
Sometimes more severe reactions: Anaphylaxis (life-threatening allergic reaction) Facial swelling, hives (red itchy lumps) on the body, streaming
nose, sickness and vomiting, or diarrhoea, Wheezing/ coughing/ breathing problems
Usually develops in early infancy
More delayed response: Eczema/ colic, poor growth, diarrhoea/ constipation
Can be IgE-mediated food allergy, non-IgE-mediated food allergy or non-allergic food hypersensitivity (e.g. lactose intolerance)
Cow’s Milk Allergy
Treatment: complete avoidance of cow’s milk protein
Ensure provision of suitable formula alternative - soya not recommended
Soya should never be introduced before 6 months of age
Secondary lactose intolerance is common but temporary
Goat’s and sheep milk not suitable alternatives Specialised formulas available for babies - prescribed
by Doctor Risk of nutritional deficiency (energy and calcium)
when milk is eliminated from the diet Delayed growth can occur Important that diet remains free of cow’s milk protein -
from obvious and less obvious sources
Management of Cow’s Milk Allergy
Exclude Examples of foods to exclude Notes
Cow’s milk Liquid whole, semi-skimmed or skimmed milk
Evaporated or condensed milk
Dried full-fat or skimmed milk powder
UHT powder
Goat’s and sheep milk should not be used as an
alternative to cow’s milk. They are unsuitable for
people requiring total exclusion of lactose or
galactose
Dairy products Butter, margarine or fat spreads containing milk
derivatives
Cheese and cheese spreads
Yoghurt
Fromage frais, crème fraiche, cream, ice cream
Butter and hard cheeses can be used by people
with mild/moderate lactose intolerance
Milk or milk
derivatives in
manufactured
foods
May be described on ingredients lists as:
Milk, milk solids, non-fat milk solids, milk protein,
skimmed milk, skimmed milk powder, casein or
caseinates, hydrolysed casein, whey, whey solids,
buttermilk lactose, milk sugar, whey sugar, whey
syrup sweetener
It may not be necessary to exclude lactose and
other milk sugars in all cases of cow’ milk allergy
but, for practical purposes, their presence is
usually taken as indicative of the presence of
milk, and foods containing them are excluded.
Lactose in flavourings and medications may be a
problem to some severely allergic patients
Exclusion of Cow’s Milk
General Guidance
1. Read all food ingredient labels and look out for allergy information- check every time as sometimes company’s change their ingredients
2. Avoid foods which are sold loose or without a label where you are unsure if it contains milk
3. Avoid foods with “may contain traces of milk”
4. Avoid cross contamination with milk when preparing food
5. Ensure the diet contains adequate calcium from other non-milk sources
6. Remember cow’s milk allergy is different to lactose intolerance so just because it is “lactose free” does not mean it will be cow’s milk free
Tips For a Milk Free Diet
Cow’s milk allergy is often transitory
Should be challenged every 6-12 months
In the majority of cases cow’s milk allergy will have resolved by 3 years
Should be carried out under MEDICAL SUPERVISION
Reintroduction of Milk
Food hypersensitivity can have both an allergic (immune response)
and non-allergic response (food intolerance)
Allergens should be excluded from the diet to prevent allergic response which can be life threatening
Allergen diagnosis tests should always be done under medical supervision
In Conclusion
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Further reading links are available if you wish to learn more
Next Steps
Further Learning
To expand upon the subjects covered in todays lesson:
• Basic nutrition- Diploma in Nutrition
• Weight loss- Ultimate weight Loss Programme
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Further Reading
1) Manual of Dietetic Practice, 4th edition, edited by Briony Thomas and Jacki Bishop
2) http://www.ncbi.nlm.nih.gov/pubmed/21236480
3) http://www.foodallergy.org/document.doc?id=194
4) http://www.who.int/mediacentre/factsheets/fs297/en/
5) http://www.cancerresearchuk.org/cancer-info/cancerstats/world/cancer-worldwide-the-global-picture