Our diet and lifestyle can influence our immune responses. Causes of poor immune function and how these can be addressed.

1. DIET AND NUTRITION
Nutrition and
Immunity
By
Dr. Madhumita Sen

2. Learning Objectives
At the end of this lecture the student will
know:
What is immunity?
What are the types of immunity?
How is food related to immunity?
Immune boosting foods.
Food allergy and immunity.

3. Immune System
 An immune system is a system of biological
structures and processes within an organism that
protects against disease.
 In order to function properly, an immune system
must detect a wide variety of agents, from
bacteria and viruses to parasitic worms, and
distinguish them from the organism's own
healthy tissue.
 Immunity deals with the functioning of the immune
system and how it protects our body from harmful
external influences.

4. Immunity is a layered response of
the body.
The 3 main layers of defense are:
1. Surface factors
2. Innate immunity
3. Acquired or adaptive immunity

5.  There is good evidence that probiotic flora, such
as the lactobacilli normally found in
unpasteurized yogurt, helps keep a healthy
balance of microbial populations in intestinal
infections.
 Studies on bacterial gastroenteritis, inflammatory
bowel diseases, urinary tract infection and post-surgical
infections suggest that probiotic bacteria
improves both local and general innate
immunity.
 Probiotic bacteria may also have anti-inflammatory
and anti-cancer properties, as seen
in some recent studies.

7. Diet and immunity
 Adequate nutrition is vital for a healthy
immune system.
 Nutrient deficiencies and excesses can
harm the immune system.
 Both innate and acquired immunity is
affected in malnutrition.
 Some foods can stimulate allergic
reactions in susceptible people.

8. Malnutrition
 It is recognized that malnutrition
and infection are the two major
obstacles for health, development,
and survival worldwide, and
poverty and ignorance are the
most significant contributing factors
 Infection and malnutrition
aggravate each other. In fact,
malnutrition is the commonest
cause of immunodeficiency
worldwide.

9.  There are many causes of increased susceptibility
to infection among the underprivileged,
malnourished community
 Lack of proteins, vitamins and minerals in PEM lead
to changes in immune competence in cell-mediated
immunity, the bactericidal function of
neutrophils, the complement system and the
secretory immunoglobulin A (IgA) antibody
response.
 Also, lack of health education, illiteracy,
contaminated food and water, poor sanitation
and over crowding are important in worsening the
situation.

10. Obesity
 Obesity is associated with adipose tissue
inflammation and increased risk of infection.
 Inflammatory markers secreted by abdominal
adipocytes suppress the replication of both T and B
cells.
 Leptin -- a hormone produced by fat cells, also
supports white blood cell production, which in turn
enhances immune function. Obese people have
high levels of leptin, but their immune cells and
phagocytes have become unresponsive.
 These impairments are reversible with adequate
weight reduction.

11. Other Factors: Hormones
 Hormones can act as immunomodulators,
altering the sensitivity of the immune system.
 Steroid hormones directly suppress B cells and T
cells.
 Female sex hormones are known stimulators of
both adaptive and innate immune responses.
 Estrogens may also influence how some antigens
are processed, and cause autoimmunity.
 Some autoimmune diseases such as lupus
erythematosus(SLE) strike women preferentially,
and their onset often coincides with puberty.

12.  By contrast, male sex hormones such as
testosterone seem to be immunosuppressive.
 This is how excessive exercises, which increase
testosterone levels, can reduce immunity.
 Other hormones appear to regulate the
immune system as well, most notably
prolactin, growth hormone and vitamin D.
 Vitamin D is crucial to activating our immune
defences and without sufficient intake of the
vitamin, T cells will not be able to react to and
fight off serious infections in the body.

13. Sleep
 The immune system is affected by sleep and rest.
 Sleep deprivation is detrimental to immune
function.
 Complex feedback loops involving cytokines,
such as interleukin-1 and tumor necrosis factor
influence and are influenced by sleep.
 Better sleep improves B-cell function, and
inflammation, by itself can reduce sleep.

14. Aging
 Aging is associated with reduction in all lymphoid
tissue in the body. This results in a poorer cellular
and humoral response to infections.
 A progressive decline in hormone levels with age
is also partially responsible for weakened immune
responses in aging individuals.
 Reduced thyroid and sex hormones result in
reduced immunological surveillance.
 Bone marrow production of WBCs also decreases
causing a lower innate immunity response.

15.  The age-related decline in immune function is
also related to dropping vitamin D levels in the
elderly.
 As people age, two things happen that
negatively affect their vitamin D levels.
 First, they stay indoors more due to decreased
activity levels. This means that they get less sun
and therefore produce less cholecalciferol
via UVB radiation.
 Second, as a person ages the skin becomes less
adept at producing vitamin D

16. Role of Different foods
 The function of the immune system, like most
systems in the body, is dependent on proper
nutrition.
 Energy intake seems to have an important
influence on immune activity. Undernourished
people are at greater risk from infections.
Weight reduction schemes using diets with less
than 1200 kcal per day can also reduce immune
function, an excellent reason to avoid unhealthy
"crash diets".

17.  Regular consumption of fermented dairy
products such as yoghurt or kefir may enhance
the immune defences in the gut.
 Recent research results suggest that yoghurts
made with certain bacteria (probiotics) may
have a beneficial effect on the immune system.
 For example, human volunteers who ate yoghurt
every day made with specific probiotic bacteria
showed a higher resistance to microorganisms
that cause food poisoning.

18.  Immune system maintenance requires a steady
intake of all the necessary vitamins and minerals.
 This can be accomplished by eating a well-balanced
diet including plenty of fruit and
vegetables, yoghurt products on a regular basis.
 To date, most studies show that supplements do
not stimulate immune response in healthy, well-nourished
individuals.
 However, a recent study among elderly people
showed that a multivitamin and mineral
supplement may boost their immunity.
 Supplements may also be required in the
recovery phase of malnourishment or in persons
with mal-absorption syndrome.

19.  Specific foods may also affect the immune
system; for example, fresh fruits, vegetables,
and foods rich in omega 3 fatty acids may
foster a healthy immune system.
While an excess of pro-inflammatory trans and
saturated fatty acids can cause an
imbalance in the immune system.

20. Minerals :
 Iron deficiency and excess increase infections.
 Zinc essential for immuno-competence,
especially mucosal immunity.
 An Italian study found that small amounts of
zinc quickly raised blood levels of T-cells in
elderly people to those usually seen in much
younger people

21. Carbohydrates :
 Carbohydrates supply the immune system with
energy so that it can work better and fight
disease.
 However, high blood sugar reduces immunity by
reducing the functioning of immune cells.
 High blood sugar is also a stress factor, increasing
cortisol secretion, and reducing immune function
even further.
 Neutrophil activity can be reduced by 50% by
excess sweet and sugar intake.

22. Proteins:
 Proteins make enzymes and immunoglobulins,
which help the immune cells kill germs, viruses,
bacteria etc.
 They also help keep the GI tract and immune
system healthy.
 Protein lack causes atrophy of lymph organs with
reduction in T lymphocyte production.
 Protein deficiency makes the skin and mucus
membranes brittle and break down easily.

23. Alcohol
 Alcohol ingestion has been shown to severely
depress neutrophils, cells that act as
phagocytes and destroy bacteria and
tumour cells.
 Excess alcohol intake is also usually
associated with other nutrient and vitamin
deficiencies.

24. Foods that boost immunity
 Vegetarian diet.
 A German study, reported in Nutrition and
Cancer, found that the white blood cells of
vegetarians were twice as effective against
tumour cells as those of meat eaters.
 The precise reason is unknown, but may have
something to do with higher levels of
phytochemicals richly available in vegetables
and fruits as well as lower levels of fats in the
diet.

25.  “Vitamin C rich” foods.
While this vitamin's reputation as an immune-enhancer
has fluctuated over time, we do know
that vitamin C boosts antibodies as well as white
blood cell activity.
 Stress of any kind, psychological or physical,
increases our need for this vitamin.
When you think vitamin C, think more than
orange juice.
 Broccoli contains three times as much vitamin C
as citrus. Even baked potatoes are packed with
this helpful nutrient.

26.  Chinese mushrooms.
 Shiitake mushrooms appear to be powerful
immune stimulants.
 They contain an antiviral substance that boosts
T-cells and macrophages, large cells that
engulf and destroy foreign particles.
 This beefy mushroom is becoming more readily
available in many supermarkets as demand for
it increases.

27.  Garlic.
 Several studies indicate that garlic does as much
for our immune systems as it does for our taste
buds.
 It appears to increase not only the numbers of
natural killer cells but also their potency.
 T- helper cells, as well, are stimulated by garlic
intake.

28.  Carotenoids.
 Although beta carotene is best known in the huge
carotenoid family, there is evidence that many
members of this antioxidant group are helpful to
our immune systems.
 Studies indicate that a high intake of carotenoid-rich
foods (orange-coloured vegetables and fruits,
in particular) increase T-cells, natural killer cells,
and antibody response.
 Pumpkins and winter squashes, as well as carrots,
peaches, and cantaloupe, are especially good
sources, though many green vegetables are also
rich in carotenoids.

29.  Herbs and immunity
 Several herbs have extensive histories that
indicate they can help us fight a variety of
diseases.
 And, in the last few decades, laboratory
studies have shown that indeed many of these
herbs contain substances that work specifically
to boost the immune system in various ways.

30.  Echinacea (purple coneflower) is perhaps the best
known of the Western immune-stimulating herbs.
 It was originally a wildflower commonly found in
America.
 Native Americans used echinacea for anything
from blood purification to snake bite.
 Laboratory studies show echinacea to enhance
the immune system through several mechanisms,
most notably through activating T-cells and
increasing virus-fighting interferon.
 It's particularly helpful with the common cold.

31.  Ginger. This pungent root stimulates
the production of interferon, and
has direct anti-inflammatory
properties.
 Licorice root has been used for
thousands of years, in Eastern as well
as Western cultures, by people
wishing to benefit from its medicinal
properties.
 It's particularly helpful in fighting
viruses such as influenza and herpes.
Warning: take licorice in
moderation; too much can cause
the body to retain sodium, causing
oedema.

32. Allergies and the immune system
 Approximately 250 million people in the world
sneeze in the fall, itch when they eat peanuts,
wheeze when they pet cats or exhibit one of the
many other symptoms of allergy.
 Some people are even at risk of dying from severe
allergic reactions to various substances that are
benign or only slightly irritating to most people.
 Even when allergy symptoms like hives, sneezing
and migraine are not life-threatening, they can
certainly affect our ability to enjoy life.

33.  E.g. Like other allergies, a peanut allergy is an
abnormal immune system response.
 The body decides that the proteins peanuts
contain pose an immunological threat, and it
generates Immunoglobulin E (IgE), an antibody, to
fight peanuts the next time they appear in the
body.
 Sometimes it takes multiple exposures to peanuts
to develop IgE.
When someone with a peanut allergy eats
peanuts, it triggers the release of histamines in the
body to fight the peanuts, causing an allergic
reaction.

34. Common allergy symptoms
Sneezing, and itchy eyes.
Hives.
Eczema and other rashes.
Asthma.
Bloating, diarrhea, headaches, usually from food
sensitivities.
Anaphylactic shock, a rare but severe allergic
reaction that can lead to death.
The most common triggers are peanuts, shellfish,
bee stings, and penicillin.

35. Food allergy
 This usually causes mild symptoms, but in some
people, can be life threatening.
 Food allergies (like all allergies) involve an over-reactivity
of the immune system.
 Antibodies that are designed to protect us from
disease for various reasons can react against
proteins in foods, causing injury to our tissues and
symptoms of food allergy such as bloating,
headaches, hives and diarrhea.
 The only important fact to remember here is
complete avoidance of the food.

36.  People with food sensitivities have unusually low
levels of IgA in their blood.
 And stress, besides its many effects on the immune
system, can decrease the amount of IgA.
 This may help explain why allergies are often
worse during high-stress periods.
 There are many other immune system reactions
involving the four major types of antibodies as well
as T-cells that can come into play in food allergies
of various types.

37.  In addition, there are food "sensitivities" that,
although they are not technically allergies,
cause similar symptoms.
 Some foods contain substances such as
histamine or other amino acids that can cause
reactions in the blood vessels, leading to allergy-like
symptoms.

38. Foods that commonly cause allergy-like
symptoms
Casein-rich foods: milk, cheese, ice cream,
other dairy
Histamine-rich foods: sauerkraut, wine, tomato,
spinach
Tyramine-rich foods: cabbage, cheese, citrus,
potato, seafood, dates, figs
Phenylethylamine-rich foods: chocolate
Serotonin-rich foods: banana

39.  Even if we are allergy-prone, there are things we
can do to help lessen the symptoms:
 Quercetin, a natural phytochemical in many
foods, appears to dampen allergic responses by
inhibiting the release of histamine.
 Red grapes, yellow squash, shallots and broccoli
are good sources.
 Onions contain thiosulfinate, a natural chemical
that has a very high anti-inflammatory activity.
And onions also contain large amounts of
quercetin. One study reduced asthma attacks by
50% in subjects who drank onion juice. A few raw
slices of pungent onion on our salads may be a
good idea.

40.  Vitamin C also works to tamp down inflammatory
responses in the body.
 The American Journal of Epidemiology reports
that adults eating the most vitamin C-rich foods
had far fewer asthmatic attacks than those
eating little of these foods.
 A new British study found that children eating an
all-Asian diet had far fewer allergic symptoms
than their schoolmates eating a typical Western
diet. This may be due to the action of Turmeric, a
spice known to reduce inflammation and boost
immunity.

41. SUMMARY
 Immunity can be either natural or
artificial, innate or acquired=adaptive, and
either active or passive.
 Our immune system is influenced greatly by the
quality and quantity of the food we eat.

42. Q?
THANK YOU