Obesity and immune system function: link to cancer, impaired immunity

For people severely overweight, also known as being obese, the health epidemic been tied to many cancers for years. A recent study conducted by researchers from Harvard Medical School and Princeton University, published in the journal Cell, used mouse models and found that when the mice were exposed to a high-fat diet, which led to obesity, the cancer cells got into a tug-of-war against T cells for lipids. Basically, when obesity is introduced, it gives cancer cells more power—illustrating that there are many links between obesity and immune system function.

We also spoke with Theresa DeLorenzo, RD, of Logan University. She’s the dietitian for USA Paralympic Powerlifting as well as the owner of Nutrition for Optimal Performance. We asked her how obesity is linked to cancer, and obesity and immune system function.

Why is obesity has been linked to a number of health problems?

Obesity is caused by several risk factors including diet, lifestyle, and genetics. Regarding the diet correlated with developing obesity, it is often a diet high in polyunsaturated fats and low in fruits and vegetables.

Polyunsaturated fatty acids contain numerous double bonds, which are unstable. This makes them susceptible to oxidative damage. Fruits and vegetables contain antioxidants which help stabilize the fatty acids but commonly, an obesogenic diet does not contain them. Oxidative damage is a precursor to the development of cancer cell development.

How does obesity affect the immune system and cause impairment of its function? What happens in the body for this to occur?

Vitamin D is a prohormone that is linked with improved immune function. Unfortunately, vitamin D becomes sequestered into fat stores with excess adiposity and unavailable to assist with immune function.

Vitamin D deficiency is very common. In America 70% of people are deficient in vitamin D due to reasons including obesity, lack of outside activity, and use of sunscreen. Vitamin D deficiency is linked with many disease states due to its involvement with the immune system including asthma, cardiovascular disease, diabetes, multiple sclerosis, and cancer!

Can losing only a certain amount of weight prevent obesity and immune system function that is compromised?

Absolutely! Firstly, there is no perfect weight, as everybody is different.

Losing weight by increasing exercise, decreasing processed foods — which are the primary source of the aforementioned polyunsaturated fatty acids — and increasing fruits and vegetables will decrease the oxidative stress associated with cancer development and release vitamin D from storage to assist with obesity and immune system function that may be compromised.

What helps prevent this more — diet changes? Exercise?

Both. It is very hard to lose weight with only diet or exercise. It is important to employ both. Decreasing the intake of processed foods, increasing the intake of fruits and vegetables, and incorporating exercise like yoga for stress management is the best approach.

If someone is attempting to lose weight, it’s important to choose a diet and exercise plan they can stick to long periods of time. Avoid fad diets, as they are difficult to commit to long-term, making them less beneficial. For example, many people turn to keto or paleo, which increase foods that are linked with the development of chronic disease like cancer and don’t focus on increasing foods that are beneficial. Moderation in all foods is my approach.