Introduction 

Definition of food intolerance and nutritional deficiencies

Food intolerance is a term that is used to describe a wide range of adverse responses to foods that cause symptoms after eating some type of food. These include stomach pain, bloating, diarrhoea, irritable bowel syndrome (IBS), rashes,  recurrent mouth ulcers or headaches. Nutritional deficiency is a deficiency of one or more essential vitamins.¹

Importance of understanding the relationship between the two

Food intolerance or sensitivities play an enormous part in the malabsorption of vitamins and minerals, often leading to nutritional deficits. The fact is that most deficiencies are commonly due to gastrointestinal problems leading to poor absorption of food. A person with food intolerance is unable to properly digest and process that food.

Food intolerance

Food intolerance means your gut is sensitive to certain foods and cannot tolerate them. The following are a few examples:

• Lactose: This food intolerance is the most common. It occurs when your body doesn’t make enough lactase enzymes to break down lactose, a sugar found in milk and dairy products which makes you unable to digest lactose²
• Histamine: Histamines are naturally occurring chemicals in foods like cheese, pineapples, bananas, avocados and chocolate. People who are intolerant to histamine do not make enough diamine oxidase enzyme to break down this chemical³
• Gluten: Gluten is a protein in wheat and barley. When you have gluten intolerance, your body has a harder time digesting gluten.⁴

Symptoms and diagnosis

• Abdominal pain
• Diarrhoea
• Bloating
• Headaches or migraines
• Heartburn
• Nausea
• Bloating

Common culprits (dairy, gluten, soy, etc.)

The most common food intolerance is lactose intolerance. 

However, you can be intolerant to any type of food or ingredient in food such as:

• gluten (wheat, rye and barley) – found in foods like bread and pasta
• histamine – found in foods and drinks like wine and cheese
• caffeine – found in coffee, tea and some bubbly drinks
• sulphites – found in cider, beer and wine
• Salicylates are natural, aspirin-like mixtures found in a wide variety of spices, fruits, and vegetables. 
• Reactions to salic monosodium glutamate (MSG) – found in ripened fruits, cured meats and savoury foods
• Irritants: Caffeine and curry are gut irritants that can trigger indigestion in some people⁵

Nutritional deficiencies

Nutritional deficiency refers to a condition where the body lacks essential nutrients, like vitamins, due to an insufficient or imbalanced diet. Some common nutritional deficiencies include:

Vitamin D deficiency

Vitamin D can be acquired through dietary sources, like fish and fish oils (which contain the highest proportion of available vitamin D), eggs, liver, and fortified foods (like orange juice and milk). Vitamin D insufficiency causes hypocalcemia and hypophosphatemia, which lead to osteomalacia among grown-ups and rickets among children.

Iron deficiency

Iron deficiency is the most popular nutritive insufficiency, with adolescents and premenopausal women at the topmost threat of iron deficiency. Iron insufficiency could affect development, actions, learning capabilities, and growth during childhood. Iron insufficiency is basically caused by insufficient dietary iron intake, blood loss during periods, intestinal blood loss or blood loss due to tumours, and the regular use of medicines like aspirin.

Calcium deficiency

Calcium deficiency, or hypocalcemia, is characterised by low serum calcium levels. It could lead to cataracts, dental changes, brain alterations, osteoporosis, and rickets.

Vitamin C deficiency

Vitamin C (ascorbic acid) is considered an essential nutrient and is basically absorbed from the diet. Deficiency of Vitamin C causes scurvy and could also lead to behavioural and mood changes.

Humans are unable to synthesise vitamin C, so they completely depend upon dietary vegetables and fruits for sufficient intake and storage. Good vitamin C sources can be obtained from citrus fruits, tomatoes, strawberries, potatoes, and green leafy vegetables.^6,7

Causes 

• Limited financial resources
• Limited access to nutritious foods
• Medical conditions that make eating difficult, such as nausea or difficulty swallowing
• Medical conditions such as chronic diarrhoea or cancer.
• Physiological changes or situations such as during pregnancy, breastfeeding or childhood
• Mental health conditions such as depression or dementia.
• Eating disorders such as anorexia and bulimia
• Malabsorption disorders such as pancreatic insufficiency or inflammatory bowel disease.
• A condition that requires long-term intravenous feeding 

Symptoms

• Low body weight, prominent bones, depleted fat and muscle
• Weakness, faintness and fatigue
• Irritability, apathy or inattention
• Dry, inelastic skin, rashes and lesions
• Brittle hair, hair loss and hair pigment loss
• Frequent and severe infections
• Low body temperature, unable to get warm
• Low heart rate and blood pressure^6,7

Importance of proper nutrition

Proper nutrition is important for good health. It protects against numerous habitual non-infectious diseases, such as heart disease, diabetes, and cancer. Eating a variety of food and consuming less salt, sugars, saturated and industrially produced trans-fats are essential for a healthy diet.⁸

The connection between food intolerance and nutritional deficiencies

Nutrients are necessary for adequate growth, development, and good health at all stages of life. Whether someone has one or multiple food intolerances, their diet will be restricted in some shape or form, which puts them at risk for nutritional deficiencies. 

The most common cause of food intolerance is enzyme deficiency.

This can happen if you don't eat enough foods containing vitamins like B-12 and folate or if your body has trouble absorbing or processing these vitamins. Without these nutrients, the body produces red blood cells that are too large and do not work properly, reducing their ability to carry oxygen.

Diagnosis 

• Blood tests

This is specifically for testing for coeliac disease and for gluten intolerance. A specific IgE test measures the quantity of IgE antibodies to a questionable food in the blood. 

• A special diet

You avoid eating the food you might be intolerant to see if your symptoms get better, then  after a few weeks, you start eating the food again to see if your symptoms return

• A hydrogen breath test

During this test, you drink a lactose-containing liquid and breathe into a balloon-like vessel every 30 minutes for some hours. If you are lactose intolerant, the undigested lactose will cause high levels of hydrogen in your breath.

There is no test for gluten sensitivity or histamine intolerance. An allergy test can detect food allergies but not food intolerance. Your healthcare provider may ask you to keep a food diary to track meals and symptoms.

Treatment

The treatment includes:

• Identifying Triggers
• Avoid and Replace: Substitute with alternatives
  • Lactose-free milk or plant-based options for lactose intolerance
  • Gluten-free grains for gluten intolerance
• Correct Deficiencies: Address missing nutrients with fortified foods (e.g., plant milk for calcium, beans for iron) or supplements as advised
• Monitor Progress: Regular blood tests and dietitian consultations ensure proper nutrient intake.
• Dietary changes and supplementation⁹

If you have a food intolerance, you should try to avoid or reduce eating the food you are intolerant to, including foods where you are intolerant to any of the ingredients. However, it may be necessary to talk with a general practitioner or dietitian if food intolerance happens in a child to prevent the child from missing out on certain vitamins and minerals which are important for growth and development.¹⁰

Conclusion

Summary of key points

Food intolerance and nutritional deficiencies can have severe health consequences if left undiagnosed or mismanaged. Early detection and treatment can significantly improve symptoms and quality of life. Nutritional deficiencies can lead to conditions like anaemia, osteoporosis, and impaired cognitive function. However, awareness and proper management are crucial for preventing long-term health complications. Patient education and awareness are key to successful management and prevention of food intolerance and nutritional deficiencies. 

Importance of awareness and proper management

Awareness of food intolerance and nutritional deficiencies can lead to early detection and treatment, preventing long-term health complications. Awareness also helps to reduce the risk of chronic diseases and the costs of healthcare associated with habitual diseases linked to nutrition scarcities. Early awareness and proper management will help to promote eating habits, help patients make informed food choices and prevent complications like osteoporosis, anaemia, and impaired cognitive function.

Frequently asked questions (FAQs) 

What is food intolerance?

Food intolerance occurs when the digestive system cannot digest certain foods, leading to adverse reactions such as bloating, diarrhoea, and headaches.

What are nutritional deficiencies?

Nutritional deficiency is a deficiency of one or more essential vitamins. 

Is there a link between food intolerance and nutritional deficiencies?

Yes - Food intolerance can lead to poor nutrient absorption, increasing the risk of deficiencies in essential vitamins and minerals.

What foods commonly cause intolerance?

Common foods include dairy (lactose intolerance), gluten and soy.

How can I manage food intolerance and nutritional deficiencies?

Managing these conditions involves avoiding problematic foods, making dietary adjustments, and sometimes taking supplements to address deficiencies.