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 lauren.owens@shawacademy.com

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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Practical lesson 2 will continue on this subject

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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