With age, the human immune system becomes less effective at tackling infections and less responsive to vaccinations. At the same time, the aging immune system is associated with chronic inflammation, which increases the risk of almost all conditions linked to old age.

The good news is that exercising and adopting the right diet may help a person maintain healthy immunity into older age.

Chimpanzees and gorillas, our closest primate relatives, live for only 10–15 years in the wild once they have reached maturity. After the human evolutionary lineage split from theirs, our ancestors’ life expectancy doubled over the next 5 million years.

Scientists believe that it remained relatively stable into the 18th century. In the 250 years between then and now, however, life expectancy more than doubled again due to improvements in sanitation and healthcare.

We live in a time of high average life expectancies. However, our long evolutionary history has adapted us for different lifestyles (and even life expectancies), and these have changed drastically.

As a result, immunity not only weakens in older age; it also becomes imbalanced. This affects the two branches of the immune system — “innate” immunity and “adaptive” immunity — in a double whammy of “immunosenescence.”

“Innate” immunity, which is our first line of defense against infections, fails to resolve after the initial threat has passed, causing chronic, systemic inflammation.

“Adaptive” immunity, which is responsible for remembering and attacking particular pathogens, steadily loses its ability to defend against viruses, bacteria, and fungi.

Chronic, low-grade inflammation is associated with almost all conditions linked to older age, including type 2 diabetes, cardiovascular disease, cancer, and dementia. It also plays a leading role in certain autoimmune conditions that are more common in older adults, such as rheumatoid arthritis.

Meanwhile, the loss of adaptive immunity that comes with older age not only makes people more susceptible to infections; it can also reactivate dormant pathogens that were previously suppressed.

In addition, the weaker adaptive immunity of older adults means that their bodies respond less strongly to vaccinations, such as the annual flu shot.

Aging and innate immunity

Researchers have dubbed the persistent, low-level inflammation that is implicated in almost all conditions associated with older age as “inflammaging.”

“While inflammation is part of the normal repair response for healing, and essential in keeping us safe from bacterial and viral infections and noxious environmental agents, not all inflammation is good. When inflammation becomes prolonged and persists, it can become damaging and destructive.”

After an initial infection or injury, younger people’s immune systems switch to an anti-inflammatory response. This does not appear to happen as effectively in older adults. This is due to the accumulation of aged, or “senescent,” immune cells.

Senescent cells have shorter telomeres, which are the protective caps at the tips of chromosomes. Just as the plastic caps on the ends of shoelaces prevent them from fraying, telomeres prevent vital genetic material from becoming lost when the chromosome is copied during cell replication.

Telomeres get a little shorter every time a cell divides, until, eventually, division has to stop completely. If the cell survives, it becomes steadily more dysfunctional.

Senescent immune cells produce more immune signaling molecules called cytokines, which promote inflammation. Specifically, they churn out more interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha).

Scientists have linked high levels of IL-6 and TNF-alpha to disability and mortality in older adults. They have a particularly strong association with type 2 diabetes, cardiovascular disease, neurodegenerative disease, and cancer.

As the number of pro-inflammatory cells increases, there is an increase in the number of immune cells called M1 macrophages (more pro-inflammatory) and a decrease in the number of M2 macrophages (more immunoregulatory).

These changes in the frequency of M1 and M2 cells seem to be associated with an increased risk of developing plaques comprising fat and debris, which block the arteries in atherosclerosis.

Aging and adaptive immunity

Through adaptive immunity, the immune system learns to recognize and neutralize particular pathogens.

A type of immune cell known as a T cell plays a crucial role in adaptive immunity. In the course of an infection, “naïve” T cells learn to recognize the specific pathogen involved. They then differentiate into cells that are specialized to mount future immune responses against the same pathogen.

The total number of T cells remains constant throughout our lifetime, but the pool of naïve, undifferentiated cells steadily shrinks over the years, as more and more cells commit to tackling specific infections.

As a result, the bodies of older adults become less able to mount effective immune responses to new infections. For the same reason, vaccinations provoke weaker responses from the aging immune system and, therefore, provide less protection.

Ironically, a lifetime of influenza vaccinations may, in itself, diminish the efficacy of the annual vaccine later in life. Indeed, research suggests that repeated influenza immunizations could lead to reduced antibody responses.

Many older adults harbor a latent infection of human cytomegalovirus. This viral infection is very common and persistent, and it usually produces few (if any) symptoms. However, in older adults, this infection may steadily deplete their immune resources, making them more prone to other viral infections and reducing the effect of influenza immunizations.

In addition to this slow decline in immunity with age, senescent T cells also produce more pro-inflammatory cytokines, such as IL-6. These, in turn, stoke the chronic, systemic inflammation of inflammaging.

Holding back the years

Although nothing can prevent aging, there are certain lifestyle changes a person can make to stay healthy into older age.

The sections below will look at these factors in more detail.

Getting regular physical activity

Exercise has a profound effect on the immune system, according to a recent overview of research in the journal Nature Reviews Immunology.

Inevitably, people become less physically active as they age, but there is evidence to suggest that getting as much exercise as possible can slow or even reverse some of the effects of immunosenescence.

Skeletal muscle produces a range of proteins called myokines that reduce inflammation and preserve immune function. Therefore, it makes sense that maintaining muscle mass through exercise protects against infection and conditions such as type 2 diabetes and cardiovascular disease, which are closely linked to chronic inflammation.

One study found that aerobic fitness among 102 healthy males, aged 18–61 years, was inversely proportional to the number of senescent T cells in their blood after adjusting for age. In other words, increased physical fitness was associated with less immunosenescence.

The fittest males not only had fewer senescent T cells but a greater number of naïve T cells.

Another study compared the immune responses of 61 healthy males, aged 65–85 years, to a flu vaccination. Around one-third of the males were intensively active (though participation in running or sports), one-third were moderately active, and one-third were mostly inactive.

After adjusting for their age, the researchers found that the intensively and moderately active males produced more antibodies in response to vaccination than the least active males.

Remarkably, the more active males had higher serum concentrations of antibodies to some flu strains even before they underwent vaccination.

A range of other studies have identified similar benefits, not only from long-term physical activity but also from single bouts of exercise before vaccination.

“Taken together, these studies suggest that the emergence of certain features of immunosenescence and the extent of immune remodeling is likely to be heavily influenced by insufficient physical activity as humans age.”

It is important to note that the majority of the research into the relationship between exercise and immunity in older adults has involved “cross-sectional” studies. This type of study investigates relationships between variables at a single point in time.

To confirm the benefits of physical fitness, the authors of the review above call for more “interventional” studies, which would follow participants over time.

Adopting the Mediterranean diet

For now, there is no direct evidence to suggest that making dietary changes can slow the rate of immunosenescence in older adults. However, there is plenty of indirect evidence.

In particular, research suggests that diet helps determine older adults’ risk of developing sarcopenia. This condition causes a loss of muscle mass, strength, and functionality.

There appears to be a two-way relationship between skeletal muscle and the immune system. Muscles produce anti-inflammatory myokines, but recent evidence suggests that chronic inflammation also accelerates the muscle loss in sarcopenia.

Taking dietary supplements that reduce the risk of sarcopenia — such as vitamin D and polyunsaturated fatty acids — may help, due to their anti-inflammatory properties.

A growing body of evidence also suggests that people who eat a Mediterranean diet are less likely to become “frail” in older age, such as by losing muscle strength, walking slowly, and tiring easily.

The Mediterranean diet comprises:

• large amounts of fruit, leafy vegetables, and olive oil
• moderate amounts of fish, poultry, and dairy
• low amounts of red meat and added sugar

Previous studies have linked this diet to a lower risk of obesity, cardiovascular disease, type 2 diabetes, and cancer.

A 2018 review of observational studies, which Medical News reported on, found that people who adhered the most closely to the Mediterranean diet were less than half as likely to become frail over a 4-year period, compared with those who followed it the least closely.

Among other possible explanations, this may be a result of the diet’s anti-inflammatory properties. The authors write:

“Frail individuals have higher levels of inflammatory markers, and inflammation is considered to be closely associated with frailty. A Mediterranean diet is associated with low levels of inflammatory markers and may reduce frailty risk through this mechanism.”

Maintaining a moderate weight

Although muscle plays a role in reducing inflammation in older adults, fat, or “adipose,” tissue may have the opposite effect.

Normal aging often leads to weight gain, due to an accumulation of adipose tissue beneath the skin and around the organs. According to a roundup of research on the aging immune system, adipose tissue may make a significant contribution to inflammaging.

Up to 30% of the pro-inflammatory cytokine IL-6 in the bloodstream may originate from adipose tissue. Therefore, having obesity or overweight in older age may significantly contribute to chronic inflammation.

In addition, animal and human studies suggest that the immune system of people with obesity may produce fewer antibodies in response to the flu vaccination.

Exercising and eating a healthful diet appear to counter the effects of immune aging. In part, this might be due to the way that these two lifestyle factors prevent excessive weight gain.

Studies have suggested that older adults who exercise regularly and have a moderate weight have fewer senescent T cells and lower levels of pro-inflammatory cytokines in their blood.

However, whether or not diet, exercise, and weight loss can reverse immunosenescence remains an open question for future research.

In the short-term, eating too much sugar may contribute to acne, weight gain, and tiredness. In the long-term, too much sugar increases the risk of chronic diseases, such as type 2 diabetes and heart disease.

According to the Centers for Disease Control and Prevention (CDC), people in the United States consume too much added sugar. Added sugars are sugars that manufacturers add to food to sweeten them.

In this article, we look at how much added sugar a person should consume, the symptoms and impact of eating too much sugar, and how someone can reduce their sugar intake.

How much sugar is too much? 

According to the Dietary Guidelines for Americans 2010-2015, on average, Americans consume 17 teaspoons (tsp) of added sugar each day. This adds up to 270 calories.

However, the guidelines advise that people limit added sugars to less than 10% of their daily calorie intake. For a daily intake of 2,000 calories, added sugar should account for fewer than 200 calories.

However, in 2015, the World Health Organization (WHO) advised that people eat half this amount, with no more than 5% of their daily calories coming from added sugar. For a diet of 2,000 calories per day, this would amount to 100 calories, or 6 tsp, at the most.

Symptoms of eating too much sugar

Some people experience the following symptoms after consuming sugar:

• Low energy levels: A 2019 study found that 1 hour after sugar consumption, participants felt tired and less alert than a control group.
• Low mood: A 2017 prospective study found that higher sugar intake increased rates of depression and mood disorder in males.
• Bloating: According to Johns Hopkins Medicine, certain types of sugar may cause bloating and gas in people who have digestive conditions, such as irritable bowel syndrome (IBS) or small intestinal bacterial overgrowth (SIBO).

Risks of eating too much sugar 

Consuming too much sugar can also contribute to long-term health problems.

Tooth decay

Sugar feeds bacteria that live in the mouth. When bacteria digest the sugar, they create acid as a waste product. This acid can erode tooth enamel, leading to holes or cavities in the teeth.

People who frequently eat sugary foods, particularly in between mealtimes as snacks or in sweetened drinks, are more likely to develop tooth decay, according to Action on Sugar, part of the Wolfson Institute in Preventive Medicine in the United Kingdom.

Acne

A 2018 study of university students in China showed that those who drank sweetened drinks seven times per week or more were more likely to develop moderate or severe acne.

Additionally, a 2019 study suggests that lowering sugar consumption may decrease insulin-like growth factors, androgens, and sebum, all of which may contribute to acne.

Weight gain and obesity

Sugar can affect the hormones in the body that control a person’s weight. The hormone leptin tells the brain a person has had enough to eat. However, according to a 2008 animal study, a diet high in sugar may cause leptin resistance.

This may mean, that over time, a high sugar diet prevents the brain from knowing when a person has eaten enough. However, researchers have yet to test this in humans.

Diabetes and insulin resistance

A 2013 article in PLOS ONE, indicated that high sugar levels in the diet might cause type 2 diabetes over time.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) add that other risk factors, such as obesity and insulin resistance, can also lead to type 2 diabetes.

Cardiovascular disease

A large prospective study in 2014 found that people who got 17–21% of their daily calories from added sugar had a 38% higher risk of dying from cardiovascular disease (CVD) than those who consumed 8% added sugars. For those who consumed 21% or more of their energy from added sugars, their risk for CVD doubled.

High blood pressure

In a 2011 study, researchers found a link between sugar-sweetened beverages and high blood pressure, or hypertension. A review in Pharmacological Research states that hypertension is a risk factor for CVD. This may mean that sugar exacerbates both conditions.

Cancer

Excess sugar consumption can cause inflammation, oxidative stress, and obesity. These factors influence a person’s risk of developing cancer.

A review of studies in the Annual Review of Nutrition found a 23–200% increased cancer risk with sugary drink consumption. Another study found a 59% increased risk of some cancers in people who consumed sugary drinks and carried weight around their abdomen.

Aging skin

Excess sugar in the diet leads to the formation of advanced glycation end products (AGEs), which play a role in diabetes. However, they also affect collagen formation in the skin.

According to Skin Therapy Letter, there is some evidence to suggest that a high number of AGEs may lead to faster visible aging. However, scientists need to study this in humans more thoroughly to understand the impact of sugar in the aging process.

How to eat less sugar

A person can reduce the amount of added sugar they eat by:

1. checking food labels for sweeteners
2. reducing foods with added sugar
3. avoiding processed foods in general

Checking food labels

Added sugar and sweeteners come in many forms. Ingredients to look out for on a food label include:

• brown sugar
• fructose
• glucose
• sucrose
• maltose
• honey
• corn sweetener
• corn syrup
• high fructose corn syrup
• raw sugar
• molasses
• malt syrup
• evaporated cane juice
• agave nectar
• maple syrup
• invert sugar
• fruit juice concentrates
• trehalose
• turbinado sugar

Some of these ingredients are natural sources of sugar and are not harmful in small amounts. However, when manufacturers add them to food products, a person might easily consume too much sugar without realizing it.

Reducing foods that contain added sugar

Some food products contain large amounts of added sugars. Reducing or removing these foods is an efficient way to reduce the amount of sugar a person eats.

The Dietary Guidelines for Americans 2010–2015 state that soda and other soft drinks account for around half a person’s added sugar intake in the U.S. The average can of soda or fruit punch provides 10 tsp of sugar.

Another common source of sugar is breakfast cereal. According to EWG, many popular cereals contain over 60% sugar by weight, with some store brands containing over 80% sugar. This is especially true of cereals marketed towards children.

Swapping these foods for unsweetened alternatives will help a person lower their sugar intake, for example:

• swapping soda for water, milk, or herbal teas
• swapping sugary cereals for low sugar cereal, oatmeal, or eggs

Avoiding processed foods

Manufacturers often add sugars to foods to make them more appealing. Often, this means people do not realize how much sugar a food contains.

By avoiding processed foods, a person can get a better sense of what their food contains. Cooking whole foods at home also means someone can control what ingredients they put into their meals.

When to see a doctor

People should see their doctor if they experience the symptoms of high blood sugar. According to the NIDDK, symptoms include:

• increased thirst and urination
• increased hunger
• fatigue
• blurred vision
• numbness or tingling in the hands or feet
• unexplained weight loss
• sores that do not heal

These symptoms may indicate a person has diabetes. A doctor can test for diabetes by taking a urine sample.

People should also speak to a doctor if they experience other symptoms after eating sugar, such as bloating.

Summary

Consuming too much added sugar has many adverse impacts on health, including tiredness and weight gain, and more severe conditions, such as heart disease. Added sugars are present in many processed foods and drinks.

People can reduce their sugar intake by knowing what to look for on food labels, avoiding or reducing common sources of sugar, such as soda and cereals, and prioritizing unprocessed whole foods.

If a person is concerned about weight gain, symptoms that may indicate diabetes, or other symptoms they experience after eating sugar, they should speak to a doctor.

Type 2 diabetes is the most common form of diabetes. It happens when blood sugar levels rise due to problems with the use or production of insulin.

It can appear at any age, but it is more likely to occur after the age of 45 years.

It affects over 30 million Americans, according to the United States Centers for Disease Control and Prevention (CDC), and it accounts for 90–95 percent of diabetes cases.

What is type 2 diabetes?

People with type 2 diabetes do not make or use insulin correctly.

Insulin is a hormone that regulates the movement of blood glucose, or sugar, into cells, which use it as energy.

When sugar cannot enter cells, this means:

• too much glucose collects in the blood
• the body’s cells cannot use it for energy

A doctor may diagnose diabetes if a person’s blood sugar levels are 126 milligrams per deciliter (mg/dl) or above after fasting for 8 hours.

Symptoms

The symptoms of high blood sugar in type 2 diabetes tend to appear gradually. Not everyone with type 2 diabetes will notice symptoms in the early stages.

If a person does experience symptoms, they may notice the following:

• Frequent urination and increased thirst: When excess glucose builds up in the bloodstream, the body will extract fluid from tissues. This can lead to excessive thirst and the need to drink and urinate more.
• Increased hunger: In type 2 diabetes, the cells are not able to access glucose for energy. The muscles and organs will be low on energy, and the person may feel more hungry than usual.
• Weight loss: When there is too little insulin, the body may start burning fat and muscle for energy. This causes weight loss.
• Fatigue: When cells lack glucose, the body becomes tired. Fatigue can interfere with daily life when a person has type 2 diabetes.
• Blurred vision: High blood glucose can cause fluid to be pulled from the lenses of the eyes, resulting in swelling, leading to temporarily blurred vision.
• Infections and sores: It takes longer to recover from infections and sores because blood circulation is poor and there may be other nutritional deficits.

If people notice these symptoms, they should see a doctor. Diabetes can lead to a number of serious complications. The sooner a person starts to manage their glucose levels, the better chance they have of preventing complications.

Symptoms in children and teens

Type 2 diabetes is more likely to appear after the age of 45 years, but it can affect children and teens who:

• have excess weight
• do not do much physical activity
• have high blood pressure
• have a family history of type 2 diabetes
• have an African American, Asian American, Hispanic American, or American Indian background

The following symptoms may occur:

• weight loss, despite increased appetite and hunger
• extreme thirst and dry mouth
• frequent urination and urinary tract infections
• fatigue
• blurred vision
• slow healing of cuts or wounds
• numbness or tingling in hands and feet
• itchy skin

If caregivers notice these symptoms, they should take the child to see a doctor. These are also symptoms of type 1 diabetes. Type 1 is less common but more likely to affect children and teenagers than adults. However, type 2 diabetes is becoming more common in young people than it was in the past.

Symptoms in older adults

At least 25.2 percent of people aged 65 and above have type 2 diabetes in the United States. They may have some or all the classic symptoms of type 2 diabetes.

They may also experience one or more of the following:

• flu-like fatigue, which includes feeling lethargic and chronically weak
• urinary tract infections
• numbness and tingling in the hands, arms, legs, and feet due to circulation and nerve damage
• dental problems, including infections of the mouth and red, inflamed gums

Early signs

Most people do not experience symptoms in the early stages, and they may not have symptoms for many years.

A possible early sign of type 2 diabetes is darkened skin on certain areas of the body, including:

• the neck
• the elbows
• the knees
• the knuckles

This is known as acanthosis nigricans.

Other early symptoms include:

• frequent bladder, kidney, or skin infections
• cuts that take longer to heal
• fatigue
• extreme hunger
• increased thirst
• urinary frequency
• blurred vision

A person may have mild or subtle symptoms for many years, but these can become in time. Further health problems can develop.

Prediabetes and diabetes prevention

A person with blood sugar levels of 100–125 mg/dl will receive a diagnosis of prediabetes. This means that their blood sugar levels are high, but they do not have diabetes. Taking action at this stage can prevent diabetes from developing.

According to a 2016 report published in The Journal of the American Board of Family Medicine, 33.6 percent of people aged 45 years and older had prediabetes in 2012.

The CDC estimate that around 84 million American adults have prediabetes, but most do not know they have it.

Complications

Diabetes may cause a number of health complications if people do not manage it properly. Many of these are chronic, or long-term, but they can become life-threatening. Others need immediate medical attention as soon as they appear.

Emergency complications

Complications can arise quickly if blood sugar rises or falls too far.

Hypoglycemia

If blood glucose dips below 70 mg/dl, this is hypoglycemia, or low blood sugar.

This can happen if a person who uses insulin takes more than they need for a particular time.

A home blood glucose test can check for hypoglycemia.

It is vital to know the early signs of hypoglycemia, as it can progress quickly, resulting in seizures and a coma. In the early stages, however, it is easy to treat.

Symptoms of hypoglycemia include:

• confusion
• dizziness
• feeling faint
• heart palpitations
• rapid heartbeat
• mood changes
• loss of consciousness
• sweating
• clamminess

If symptoms are mild, a person can often resolve low blood sugar levels by consuming:

• a few pieces of hard candy
• a cup of orange juice
• a teaspoon of honey
• a glucose tablet

The person should then wait 15 minutes, test their blood sugar, and if it is still low, they should take another glucose tablet or sweet.

When levels return to above 70 mg/dl, the person should eat a meal, to stabilize their glucose levels.

If they remain low for 1 hour or longer, or if symptoms worsen, someone should take the person to the emergency room.

Anyone who has frequent or severe hypoglycemic episodes should speak to their doctor, as they may need to adjust their treatment plan.

Hyperglycemia and diabetic ketoacidosis (DKA)

If blood sugar levels rise too far, hyperglycemia can result. If a person notices increased thirst and urination, they should check their blood sugar levels.

It the level is above the target level that their doctor recomends, they take appropriate action.

Without treatment, high a person with hyperglycemia can develop diabetic ketoacidosis (DKA), which happens when high levels of ketones collect in the blood, making it too acidic. For this reason, the person should also test their ketone levels.

Ketoacidosis can lead to:

• difficulty breathing
• a fruity smell on the breath
• a dry mouth
• nausea and vomiting
• coma

It can be life-threatening. A person with these signs and symptoms should seek immediate medical attention.

People who regularly experience high blood sugar should speak to their doctor about adjusting their treatment plan.

People should check with their doctor how often they need to test.

Long-term complications

Keeping blood glucose within target levels can prevent complications that can become life-threatening and disabling over time.

Some possible complications of diabetes are:

• heart and blood vessel diseases
• high blood pressure
• nerve damage (neuropathy)
• foot damage
• eye damage and blindness
• kidney disease
• hearing problems
• skin problems

Effective management of blood glucose levels can reduce the risk of complications.

Diagnosis and treatment

A doctor can diagnose type 2 diabetes with blood tests that measure blood glucose levels. Many people discover they have high blood sugar during a routine screening test, but anyone who experiences symptoms should see a doctor.

Treatment aims to keep blood glucose levels stable at a healthy level and prevent complications. The main ways to do this are through lifestyle measures.

These include:

• following a healthful diet
• reaching and maintaining a healthy weight and body mass index (BMI)
• doing physical activity
• getting enough sleep
• avoiding or quitting smoking
• taking medications or insulin as the doctor recommends

Outlook

There is currently no cure for diabetes, but most people with the condition can lead a healthful life by managing their condition properly.

People who maintain a healthy weight, follow a healthful diet, and do regular exercise may not need medication. Taking these steps can help manage blood sugar levels.

Routine screening can alert a person to high blood sugar levels in the early stages, when there is still time to slow, stop, or reverse the progress of diabetes.

Current guidelines recommend regular screening from the age of 45 years, or younger if an individual has other risk factors, such as obesity. A doctor can advise on individual needs.

It is important to have support from people who understand what it is like to receive a diagnosis and live with type 2 diabetes.