(800) 545-4772
Sign In
ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, What Is the Relationship Between Poor Nutrition and Disease?

What Is the Relationship Between Poor Nutrition and Disease?

Reading Time: 6 minutes 61 seconds


DATE: 2021-08-26

One of the biggest concerns with diet is how it might affect one's weight. Eat too many high-fat, high-calorie foods and your weight can go up. Make healthy food a priority and it can come down. A balanced diet and physical activity assist with effective weight maintenance.

Healthy eating also serves another important purpose. It helps promote a stronger immune system.

Understanding Immune System Function

As humans, we have two basic types of immunity. The first is called innate immunity. This refers to the body's natural ability to protect itself from harmful pathogens.

An example of innate immunity is the mucus in your nose. This slimy substance helps trap airborne particles that aren't good for the body. Dust, mold, and germs are all stopped from being inhaled. This prevents them from harming your lungs. Mucus also contains protective proteins designed to kill bacteria and viruses. This reduces your risk of infection.

The other type of immunity is acquired or adaptive immunity. This is the part of our immune system that responds to new pathogens. When it identifies a potentially harmful substance, it increases immune cells to destroy it. It does this by creating antibodies. The body then retains these antibodies in case it encounters that substance again.

How Nutrition Impacts the Immune System

The foods we eat can affect whether our immune system functions as designed. Harvard explains that a poor diet can impair the body's ability to produce and/or activate immune cells and antibodies. This can occur in cases of malnutrition or acute malnutrition.

Immune system function can also be reduced if poor nutrition leads to excess weight. This is because obesity and chronic inflammation often co-exist. When the body is inflamed, it doesn't respond as well when exposed to pathogens.

Obesity has been connected with a variety of health conditions. The Centers for Disease Control and Prevention (CDC) shares a few. Among them are high blood pressure, heart disease, type 2 diabetes, and cancer. Thus, healthy eating can help reduce one's weight. In turn, this helps lower one's risk of these types of disease.

What is the Relationship Between Poor Nutrition and Disease?

One of the concerns of an unhealthy diet is a lack of nutrition. The immune system doesn't get the nutrients it needs to function at optimal levels. This can happen in cases of malnutrition or undernutrition.

Science has proven this repeatedly. Studies have connected vitamin D deficiency with an increased risk of juvenile arthritis. Other pieces of research have linked low vitamin C with cardiovascular disease.

The body relies on both macro and micronutrients to function efficiently. When a nutrient is lacking due to poor nutrition, it can have a detrimental effect.

It goes the other way too. Disease can also cause malnutrition. Some digestive conditions can keep the body from absorbing nutrients, for instance. Crohn's disease and celiac disease are two. Research also connects chronic kidney disease with malnutrition. A 2013 study adds that disease-related malnutrition is "a worldwide problem." And it is one that has costly consequences. It results in billions of dollars in expenditures per year.

Johns Hopkins adds that overnutrition is also a concern. Overnutrition can occur from eating too much. It can also be a result of eating foods low in nutrients or taking too many supplements. This can lead to obesity, and obesity can further increase the risk of disease.

Nutritional Status and Chronic Disease

One of the potential consequences of a poor nutritional status is chronic illness. This includes heart disease, cardiometabolic disease, and type 2 diabetes. Cancer and autoimmune disease also fall into this category.

Several health agencies agree that correcting a suboptimal diet can have a positive impact. For example, the American Heart Association calls healthy eating one of the "best weapons to fight cardiovascular disease." The National Institute of Diabetes and Digestive and Kidney Diseases has the same message when it comes to diet and diabetes.

Certainly, not all diseases can be avoided. But many health agencies stress that diet is an important component. This is because proper nutrition can help prevent these types of conditions. It can also potentially help treat them.

For example, research reports that a diet can help with the management of type 2 diabetes. This type of diet includes whole grains, fruits, veggies, nuts, and legumes. Stanford Health Care adds that a high-protein diet can be beneficial during cancer treatment.

Effects of Poor Nutrition on Infectious Disease

Eating a nutrient-rich balanced diet can also help your body fight off infectious diseases. A 2020 study suggests that diet may impact the one infection that threatened the health of people worldwide: COVID-19. Authors point to dietary choices as a possible risk factor for this virus. They also state that, since obesity increases the risk of death from this disease, nutrition plays a key role.

Some research suggests that diet impacts infectious disease through the gut microbiome. It reports that diet can reduce parasitism. Parasitism is when one organism lives inside another, potentially doing harm. Other studies point to diet's ability to promote healthy bacteria. This, in turn, can improve health.

Dietary Habits that Promote Optimal Immune Function

Eating a balanced diet helps ensure that the body gets the vitamins and minerals it needs for healthy immune cells. It also reduces the risk of disease caused by malnutrition or undernutrition.

A balanced diet includes foods from all major food groups. It also involves eating a variety of foods within each one. This can help prevent a micronutrient deficiency as different foods supply different nutrients.

Let's look at how this works with fruit. Strawberries and oranges in your diet supply the body with vitamin C. Apples and bananas provide vitamin A. Watermelon and kiwi supply the nutrient calcium. By incorporating different fruit into your diet, you get a variety of vitamins and minerals. This can help reduce your risk of disease.

Since obesity increases disease risk, it's also important to watch your saturated fat intake. The USDA's 2020-2025 guidelines recommend keeping saturated fat under 10% of your daily calories. This type of fat is often found in baked goods, fatty cuts of meat, butter, chips, and crackers.

Improved Immune System Function Equals Increased Health

Tending to these dietary factors can improve immune system function. They can also increase overall health and wellness. And not just by reducing disease and infection. They also give the body the energy it needs to support greater physical activity.

Diet has a major impact on physical performance. Eating the right about of carbs and protein can lead to a better HIIT workout. Post-workout meals can also replenish muscle protein. This can help clients recover between training sessions.

Because exercise further promotes physical health, diet serves a dual purpose. It reduces disease risk both directly and indirectly. That makes it even more critical to higher levels of health. It helps reduce dietary risks of disease. It also supports healthy physical function.

So, How Can You Help Clients Build a Healthier Lifestyle?

As a health coach, you're someone who supports and guides clients in making better food and lifestyle choices to improve nutrition and health. Rather than putting every client on the same diet, you work with individuals to learn their strengths, weaknesses, and goals, and craft individualized plans.

Health coaches educate clients. You provide guidance, plans, structure, and motivation, but you also teach clients about health, wellness, and food. Rather than simply giving clients a shopping list for the grocery store, a good health coach will teach them how to shop and make smarter choices in the store.

A health coach helps clients find their motivation. Clients may seek you out because they want to lose weight or need guidance making healthier food choices. A good coach does more than just give them a diet plan. You help clients understand the reasons they want to make changes on a deeper level.

As a health coach, you'll also guide and empower change. This is what it all comes down to: a coach is there to be a guide to lasting, positive health changes. They empower with education and by listening to and understanding the clients' needs and challenges. They guide with information, accountability, and advice.

Are you truly passionate about helping people build better habits to support a long and healthy life? Check out ISSA's Health Coach Certification. You'll learn how to provide the guidance needed to help clients with health conditions and develop programs that empower these individuals—providing insight, accountability, and motivation to make lasting positive change.


"Nutrition And Immunity". 2021. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/.

"The Health Effects Of Overweight And Obesity | Healthy Weight, Nutrition, And Physical Activity | CDC". 2021. Cdc.Gov. https://www.cdc.gov/healthyweight/effects/index.html.

Comak, E., M. Koyun, S. Özdem, C.S. Dogan, A. Uslu Gokceoglu, and S. Akman. 2013. "AB1137 Association Between Vitamin D Deficiency And Disease Activity In Juvenile Idiopathic Arthritis". Annals Of The Rheumatic Diseases 71 (Suppl 3): 702.20-702. doi:10.1136/annrheumdis-2012-eular.1135.

Tveden-Nyborg, Pernille, and Jens Lykkesfeldt. 2013. "Does Vitamin C Deficiency Increase Lifestyle-Associated Vascular Disease Progression? Evidence Based On Experimental And Clinical Studies". Antioxidants & Redox Signaling 19 (17): 2084-2104. doi:10.1089/ars.2013.5382.

Iorember, Franca M. 2018. "Malnutrition In Chronic Kidney Disease". Frontiers In Pediatrics 6. doi:10.3389/fped.2018.00161.

Freijer, Karen, Siok Swan Tan, Marc A. Koopmanschap, Judith M.M. Meijers, Ruud J.G. Halfens, and Mark J.C. Nuijten. 2013. "The Economic Costs Of Disease Related Malnutrition". Clinical Nutrition 32 (1): 136-141. doi:10.1016/j.clnu.2012.06.009.

"Malnutrition". 2021. John Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/malnutrition.

"The American Heart Association Diet And Lifestyle Recommendations". 2021. Www.Heart.Org. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/aha-diet-and-lifestyle-recommendations.

Information, Health, Diabetes Overview, & Physical Activity Diabetes Diet, & Physical Activity Diabetes Diet, and National Health. 2021. "Diabetes Diet, Eating, & Physical Activity | NIDDK". National Institute Of Diabetes And Digestive And Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/diet-eating-physical-activity.

Ley, Sylvia H, Osama Hamdy, Viswanathan Mohan, and Frank B Hu. 2014. "Prevention And Management Of Type 2 Diabetes: Dietary Components And Nutritional Strategies". The Lancet 383 (9933): 1999-2007. doi:10.1016/s0140-6736(14)60613-9.

"Cancer Diet During Treatment". 2021. Stanfordhealthcare.Org. https://stanfordhealthcare.org/medical-clinics/cancer-nutrition-services/during-cancer-treatment.html.

Bousquet, Jean, Josep M. Anto, Guido Iaccarino, Wienczyslawa Czarlewski, Tari Haahtela, Aram Anto, and Cezmi A. Akdis et al. 2020. "Is Diet Partly Responsible For Differences In COVID-19 Death Rates Between And Within Countries?". Clinical And Translational Allergy 10 (1). doi:10.1186/s13601-020-00323-0.

Harris, Erica V., Jacobus C. de Roode, and Nicole M. Gerardo. 2019. "Diet-Microbiome-Disease: Investigating Diet'S Influence On Infectious Disease Resistance Through Alteration Of The Gut Microbiome". PLOS Pathogens 15 (10): e1007891. doi:10.1371/journal.ppat.1007891.

"Dietary Guidelines For Americans, 2020-2025 And Online Materials | Dietary Guidelines For Americans". 2021. Dietaryguidelines.Gov. https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials.

Featured Course

ISSA | Certified Health Coach

ISSA's Health Coach certification is for personal trainers and other health professionals who want to help clients overcome physical and mental health barriers to achieve their optimal wellness.

Sign Up & Stay Connected

Receive $50 off your purchase today!

I consent to being contacted by ISSA.