PFAS in diet and other sources: The health risks

 PFAS — per- and polyfluoroalkyl substances — are synthetic chemicals with myriad industrial and cosmetic uses. However, their negative impacts on human health are extensive and continue to be investigated. In this feature, we discuss PFAS, where they are found, their potential health risks, and recommendations on reducing PFAS exposure.

Developed in the 1940sTrusted Source, per- and polyfluoroalkyl substances (PFAS) are a family of over 9,000 chemicals with many industrial and cosmetic uses.

They were a breakthrough in technological advancements at the time, improvingTrusted Source textiles by making them water- and stain-resistant, adding flame retardant properties, and enhancing chemical stability for longer-lasting products.

Their uses have since extended throughout the cosmetic and food industries.

PFAS are foundTrusted Source abundantlyTrusted Source in:

• contaminated drinking water
• non-stick cookware
• food packaging material
• water- and stain-resistant coatings for clothes, furniture, and carpets
• personal care products
• cosmetic products, such as foundation makeup
• fire-fighting foams
• fast foods, meat, fish, and shellfish
• some take-out coffee and tea in the United States
• processed foods including microwave popcorn
• low-fiber, high-fat grain products, such as bread and pasta
• indoor dust.

Safety concerns

Yet PFAS are a double-edged sword — the chemical properties that make them excellent for industrial use are the same properties that threaten environmental and human health.

They have a long half-life, which makes them “persistentTrusted Source” chemicals. This means that they do not easily break down, so they subsequently accumulate throughout the environment, including in animal and human tissues.

Humans become exposed to PFAS predominantly through diet, as well as through contaminated drinking waterTrusted Source, skin contact from cosmetic and personal care products, indoor and outdoor air pollution, and early-lifeTrusted Source exposure during pregnancy or breastfeeding.

Although some researchTrusted Source shows that PFAS may be found in low and potentially non-hazardous levels in the environment, their overwhelming presence in common products and build-up in the human body pose significant safety and toxicity concerns.

In fact, a 2022 reviewTrusted Source indicates that PFAS are found in the blood of nearly all U.S. adults, and they accumulate in the liver.

Health risks

In addition to being persistent chemicals in the environment, PFAS are endocrine-disruptingTrusted Source chemicals (EDCs), which are compounds that interfere with the normal functions of hormones in the body.

Here are some of the documented health risks of PFAS.

Liver damage

In the body, PFAS predominantly accumulate in liver tissue, making liver damage one of the most-researched health effect of PFAS.

The 2022 review mentioned above — which looked at studies in both animals and humans — shows that exposure to PFAS is associated with signs of liver damage and an increased risk of developing conditions like non-alcoholic fatty liver disease (NAFLD), which can in turn lead to more serious conditions such as cirrhosis.

NAFLDTrusted Source is a spectrum of liver disorders and one of the leading causes of chronic liver disease and potentially liver failure.

Its exact mechanism is unclear, but some experts believe that PFAS disrupts fat processing and storage in the body, increasing the deposits of fat in the liver that subsequently damage this organ, and inducing other metabolic disorders.

Endocrine and metabolic disorders

As endocrine-disrupting chemicals, PFAS are associated with metabolic disorders, including obesity, thyroid disorders, and diabetes.

A 2016 reviewTrusted Source suggests that prenatal exposure to PFAS was later associated with excess adiposity and an increased risk of childhood overweight and obesity.

Observational studiesTrusted Source also support the link between PFAS and compromised thyroid health, which, during pregnancy, disrupts glucose and insulin levels, increasing the risk of developing gestational diabetes.

Gestational diabetes occurs when blood sugar levels become too high during pregnancy, and may be harmful to the parent and baby.

Reproductive health

PFAS may disrupt reproductive health from as early as puberty by potentially impairing the function of the ovaries.

A 2020 reviewTrusted Source highlights research that found associations between exposure to PFAS and delayed start of the menstrual cycle, irregular or longer cycles, early onset of menopause, and hormonal imbalances of estrogen and androgens.

In addition, exposure to PFAS during pregnancyTrusted Source poses long-term health risks to the fetus, but may also lead to low birth weight or the life-threatening condition, preeclampsia.

However, findings regarding PFAS and reproductive health have been inconsistent, and more research in humans is warranted.

Other risks

Although there is little evidence to date, ongoing research continues to elucidate the potential role of PFAS exposure in cancer risk and development.

Researchers have already observed associations between PFAS exposure via drinking water and the developmentTrusted Source of testicular and kidney cancers.

Other researchTrusted Source determined that PFAS increase the risk of developing kidney cancer such that the greater the PFAS exposure, the greater the cancer risk, adding to the evidence that PFAS are renal carcinogens.

Avoiding PFAS

Government regulations and changes in manufacturing practices have aimed to reduce human exposure to PFAS.

For instance, the Government of Canada‘s list of prohibited toxic substances includes some classes of PFAS, and in the U.S., the Centers for Disease Control and Prevention (CDC) have listed PFAS in their toxic substance registry.

However, PFAS is a family of over 9,000 chemicals, not all of which have been clearly categorized and researched, making widespread exposure a public health concern.

Regardless, there may still be some steps that you can take to reduce exposure to PFAS and subsequent health risks:

• filter drinking water
• read labels on packages for PFAS chemicals to know what to avoid
• avoid non-stick cookware
• choose PFAS-free food packaging — more likely with recyclable paper, glass, bamboo, or stainless steel
• choose personal care and cosmetic products free of PFAS
• skip water-resistant makeup
• limit or avoid highly processed foods like fast foods and fried meat or fish
• make popcorn on the stove-top or air pop instead of microwave popcorn
• maintain a regular cleaning schedule to avoid dust build-up indoors
• avoid stain- and water-resistant fabric coatings.

Occupational exposures occur, too, such as with fire training. Have a discussion regarding protective gear to avoid skin contact and inhalation of PFAS-containing compounds.

The bottom line

PFAS are a family of over 9,000 chemicals with many industrial uses that offer water- and stain-resistant, adding flame retardant and chemical stability properties to textiles.

They are also found in contaminated drinking water, fast foods, personal care and cosmetic products, and some non-stick cookware.

These PFAS accumulate in tissues in the body and are associated with compromised liver, thyroid, kidney, and reproductive health, and an increased risk of testicular and kidney cancers.

The abundance of PFAS makes them difficult to avoid, but choosing PFAS-free food packages, filtering drinking water, avoiding stain- and water-resistant coatings and makeup, and limiting highly processed foods may reduce exposure and long-term health risks.

Source - Medical News Today

Intermittent fasting: Is it all it's cracked up to be?

 Intermittent fasting is an increasingly popular weight loss dieting strategy. Beyond weight loss however, the diet has promising benefits that may reduce the risk of developing some chronic, lifestyle diseases. In this Honest Nutrition feature, we explain all that you need to know about intermittent fasting, and whether it is worth the hype.

Intermittent fasting is a term used to describe a variety of eating patterns that have alternating periods of fasting — abstinence from foods — and eating.

The fasting period may last from 12 hours per day to several consecutive days, with a consistent, recurring pattern over the course of a week.

The main typesTrusted Source of intermittent fasting are:

• modified fasting or the 5:2 diet — this protocol involves fasting for 2 non-consecutive days of the week, and eating normally for 5 days
• alternate-day fasting — fasting days are alternated with days where foods and beverages are consumed normally, without restrictions
• time-restricted eating — a type of intermittent fasting that limits the “eating window” to 4–12 hours, inducing a daily fasting period of 12–20 hours. Persons eat to satiety during their eating windows without caloric restrictions.

Of these, time-restricted eatingTrusted Source is the most popular, and may be what most people refer to when they mention intermittent fasting.

The 16:8 pattern — eating during an 8-hour window and fasting for 16 hours each day — may be the most recommended time-restricted eating pattern.

The circadian rhythm

Much of the research on intermittent fasting and time-restricted eating considers the impact of fasting on the body’s natural circadian rhythm.

The circadian rhythmTrusted Source, also called the circadian clock, represents the 24-hour cycle of metabolism in the body, including control of the sleep-wake cycle, blood pressure, mood regulation, and hormonal balance, to name a few.

It is influenced by light and darkness over the course of the day, eating behaviors, and the timing of meals.

A growing body of researchTrusted Source suggests that eating for lengthy periods in the day, ranging from 12–15 hours, may disrupt the circadian rhythm and increase the risk of chronic

diseases including heart disease, cancer, and type 2 diabetes.

Thus, a major goal of fasting, specifically time-restricted eating, is to reduce the time spent eating in the day by extending the overnight fasting period.

The study of the relationship between circadian rhythms and food timing is called chrono-nutritionTrusted Source.

Benefits

Many of the benefits of intermittent fasting are attributed to daily fasting periods of no less than 12 hours, although some research suggests that a minimum of 16 hours of fasting may be required.

Generally, during 12–36Trusted Source hours of uninterrupted fasting, the liver glycogen stores become depleted, overall metabolic processes are altered, and positive health effects are observed.

Here are some of the science-backed benefits of intermittent fasting.

1. Improved cholesterol levels

Findings across animal and human researchTrusted Source show favorable changes in cholesterol levels.

Intermittent fasting has the potentialTrusted Source to reduce total cholesterol, triglycerides, LDL cholesterol or “bad” cholesterol, and increase HDL cholesterol or “good” cholesterol.

Elevated total cholesterol, LDL cholesterol, and triglyceride levels are risk factorsTrusted Source for heart disease.

2. Blood sugar control

Intermittent fasting can improve blood sugar controlTrusted Source by reducing insulin resistance, and increasing insulin sensitivity.

This results in lowerTrusted Source fasting blood sugar and glycated hemoglobin — HbA1c — levels.

In fact, experimental research in adult males with type 2 diabetes showed the potential for intermittent fasting as a therapeutic approach that may reduce the need for insulin therapy.

3. Changes in body composition

Changes in body weight and compositionTrusted Source are among the most studied effects of intermittent fasting.

Several studies have shown that weight loss of between 3–7% body weight in an average of 8 weeks was achievable through intermittent fasting. Research also noted that this method could result in fat loss.

Fasting in a 14:10 patternTrusted Source — an eating window of 10 hours and a daily fast of 14 hours — can act on the risk factors of metabolic syndrome, including by reducing waist circumference, body fat percentage, and visceral fat.

Intermittent fasting can thus ease metabolic syndrome, a set of risk factors that increase the risk of heart disease and type 2 diabetes.

4. Other health benefits

A 2015 reviewTrusted Source of 2,650 adult females indicated that reducing calorie intake in the evenings, and fasting for longer periods at night, may lower inflammation and the risk of breast cancer and other inflammatory conditions.

Observational researchTrusted Source of 26,092 adult males over a 16-year period suggested that reducing late-night eating through time-restricted eating may significantly reduce the risk of heart disease.

Other areas of health that intermittent fasting is being explored in include longevityTrusted Source and neurodegenerative conditions like Parkinson’s diseaseTrusted Source.

Potential downsides

Despite the many touted benefits of intermittent fasting, there are also some downsides.

Side effects

Intermittent fasting may be safe for heart and metabolic health, but according to a 2017 reviewTrusted Source, it may induce negative side effects in some people, such as:

• increased feelings of hunger
• heightened irritability
• worsened mood
• increased thoughts about food
• fatigue
• fears of feeling out of control around food
• overeating during eating windows
• difficulty concentrating.

Quality of evidence

Additionally, most of the research on intermittent fasting is based on animal research, with littleTrusted Source long-term human research available.

Furthermore, a 2021 reviewTrusted Source found that only six out of 104 alleged health benefits of intermittent fasting were supported by moderate- to high-quality evidence, and most findings were based on low-quality research.

This means that more rigorous human research on the long-term health benefits of intermittent fasting is warranted.

Alternatives

Intermittent fasting is not the only type of diet to result in the aforementioned benefits.

Calorie restriction

Calorie restrictionTrusted Source involving a reduction of about 25% of daily energy needs without a change in mealtimes had a positive effect on promoting overall health.

Some research suggests that the health outcomes of intermittent fasting are no greater than those observed in calorie restriction diets.

In fact, outcomes for weight and/ or fat loss, body fat percentage, and metabolic risk factors are comparableTrusted Source between the two.

However, research on intermittent fasting shows a greater adherence over longer periods compared to calorie restriction, and suggests that it may be a more sustainable approach.

Mediterranean diet

The Mediterranean dietTrusted Source is a renowned dietary pattern based on the traditional eating patterns of the Mediterranean basin.

Like the potential heart-friendlyTrusted Source benefits of intermittent fasting, research shows that long-term adherence to the Mediterranean diet reduces the occurrence of heart attack and stroke by up to 30%Trusted Source after approximately 5 years.

Additional research on the Mediterranean diet demonstrates its protective nature against the development of colorectal cancerTrusted Source and the loss of nerve cells in Parkinson’s diseaseTrusted Source.

A major benefit of the Mediterranean diet compared to intermittent fasting is that similar results can be achieved without the need for fasting.

The bottom line

Intermittent fasting describes a variety of eating patterns that alternate periods of fasting and eating with a consistent, recurring pattern over the course of a week.

Time-restricted eating is the most popular form of intermittent fasting and uses the principles of chrono-nutrition to lengthen night-time fasting and potentially reduce chronic disease risk.

Intermittent fasting may improve cholesterol levels, blood sugar control, weight and/ or fat loss, lower inflammation, promote longevity, and support neurodegenerative conditions like Parkinson’s disease.

However, most of the research on intermittent fasting is based on animal studies and human research is sparse and often of low quality.

Alternative non-fasting diets that produce similar results to intermittent fasting include calorie restriction and the Mediterranean diet.

Source - Medical News today

Is it better to eat several small meals or fewer larger ones?

 Many of us may have heard that eating several small meals daily can help improve metabolism and achieve optimal health. However, evidence to support this claim is mixed. In this Honest Nutrition feature, we take an in-depth look at the current research behind meal frequency and discuss the benefits of small frequent meals compared with fewer, larger ones.

It is widely accepted in modern culture that people should divide their daily diet into three large meals — breakfast, lunch, and dinner — for optimal health. This belief primarily stems from culture and early epidemiological studiesTrusted Source.

In recent years, however, experts have begun to change their perspective, suggesting that eating smaller, more frequent meals may be best for preventing chronic disease and weight loss. As a result, more people are changing their eating patterns in favor of eating several small meals throughout the day.

Those who advocate for eating small, frequent meals suggest that this eating pattern can:

• improve satiety, or feeling full after a meal
• increase metabolism and body composition
• prevent dips in energy
• stabilize blood sugar
• prevent overeating.

While a few studies support these recommendations, others show no significant benefit. In fact, some research suggests it may be more beneficial to stick with three larger meals.

Here is what the research says.

Meal frequency and chronic disease

Early epidemiological studiesTrusted Source suggest that increased meal frequency can improve blood lipid (fats) levels and reduce the risk of heart disease. As a result, many experts advise against eating fewer, larger meals a day.

Over the years, some studies have supported these findings, suggesting that people who report eating small, frequent meals have better cholesterol levels than those who consume fewer than three meals per day.

In particular, one 2019 cross-sectional studyTrusted Source that compared eating fewer than three meals per day or more than four meals per day found that consuming more than four meals increases HDL (high-density lipoprotein) cholesterol and lowers fasting triglycerides more effectively. Higher levels of HDL are associated with a reduced risk of heart disease.

This study observed no differences in total cholesterol or LDL (low-density lipoprotein) cholesterol. It is important to note, however, that this is an observational study, meaning it can only prove association, not causation.

Additionally, one review published in the American Heart Association’s journal CirculationTrusted Source concluded that greater eating frequency is associated with a reduced risk for diabetes and cardiovascular disease, according to epidemiological studies.

Meal frequency and weight loss

There is a commonly held notion that more frequent meals can help influence weight loss. However, the research on this remains mixed.

For example, one studyTrusted Source compared eating three meals per day or six smaller, more frequent meals on body fat and perceived hunger. Both groups received adequate calories to maintain their current body weight using the same macronutrient distribution: 30% of energy from fat, 55% carbohydrate, and 15% protein.

At the end of the study, researchers observed no difference in energy expenditure and body fat loss between the two groups. Interestingly, those who consumed six smaller meals throughout the day had increased hunger levels and desire to eat compared to those who ate three larger meals per day.

Although calorie intake was controlled in both groups, researchers hypothesized that those who consumed frequent meals would be more likely to consume more daily calories than those who ate less frequently.

Results of another large observational studyTrusted Source suggest that healthy adults may prevent long-term weight gain by:

• eating less frequently
• eating breakfast and lunch 5 to 6 hours apart
• avoiding snacking
• consuming the largest meal in the morning
• fasting for 18-19 hours overnight.

Moreover, according to the United States Department of Agriculture (USDA) Scientific Report of the 2020 Dietary Guidelines Advisory CommitteeTrusted Source, due to inconsistencies and limitations in the current body of evidence, there is insufficient evidence to determine the relationship between meal frequency and body composition and the risk of overweight and obesity.

Does eating frequent meals boost metabolism?

Small, frequent meals are often touted as a cure-all for obesity. Many believe that eating every 2 to 3 hours can help boost metabolism.

Digestion of food does require energy. This is known as the thermic effect of food (TEF)Trusted Source. However, it does not appear that meal frequency plays a role in boosting metabolismTrusted Source.

In fact, some studies suggest fewer, larger meals may increase TEF more than eating frequent meals.

Meal frequency and athletic performance

Although evidence to support increased meal frequency in the general population remains mixed, several experts believe that eating small, frequent meals can benefit athletes.

According to the International Society of Sports NutritionTrusted Source, athletes who follow a reduced-calorie diet may benefit from eating small frequent meals with adequate protein because it can help preserve lean muscle massTrusted Source.

When prioritizing total daily calorie intake, limited evidence suggests that, in athletes, a higher meal frequency may increase performanceTrusted Source, support fat loss, and improve body composition.

Diet quality

People who eat more frequently are more likely to have better diet quality. Specifically, those who consume at least three meals per dayTrusted Source are more likely to have a greater intake of vegetables, greens, legumes, fruit, whole grains, and dairy.

These individuals are also more likely to consume less sodium and added sugars than those who consume two meals per day.

Similarly, another 2020 study published in the British Journal of Nutrition found that increased meal frequency — approximately three meals per day — is associated with higher diet quality.

Researchers found that snack frequency and diet quality varied depending on the definition of snacks.

Is one better than the other?

Based on the presented studies, no substantial evidence supports one eating pattern over the other. Yet many of these studies also have limitations.

For example, there is no universally accepted definition of what a meal or snack consists of. This can have an impact on study outcomes.

With that said, both eating patterns can be beneficial as long the primary focus is on healthful eating habits.

Who should consume small, frequent meals?

A review published in Nutrition in Clinical PracticeTrusted Sourceshows that certain populations may benefit from six to 10 small, frequent meals. These include people who:

• experience early satiety
• are trying to gain weight
• have gastroparesis
• have gastrointestinal symptoms such as nausea, vomiting, or bloating.

If your goal is to lose weight, it is important to be mindful of your portion sizes. Be sure to stay within your allotted daily calorie needs and divide them among the number of meals you consume.

For example, if you need 1,800 calories to maintain your weight and choose to eat six small meals daily, each meal should be around 300 calories.

Small, frequent meals often come in the form of ultra-processed foods and snacks that fall short in many vital nutrients your body needs. Thus, it is essential to focus on the quality of the foods you consume.

Who should consume fewer, larger meals?

People who may benefit from three larger meals per day include:

• those who have difficulty practicing portion control
• those who tend not to eat mindfully
• people who live busy lives and may not have time to plan and prepare several nutritious mini-meals a day.

Again, keeping diet quality in mind and prioritizing whole foods is essential. Fewer meals mean fewer opportunities to get in key nutrients the body needs.

The best diet for optimal health

While we do not have strong evidence to support the importance of meal frequency, substantial evidence supports the overall health benefits of following a well-balanced, nutrient-rich diet.

According to the Dietary Guidelines for Americans 2020–2025Trusted Source, a healthy diet should:

• emphasize fruits, vegetables, whole grains, and low-fat or fat-free milk or dairy products
• include protein from various sources, including seafood, lean meat and poultry, eggs, nuts, seeds, soy products, and legumes
• stay within your allotted calorie needs
• limit added sugars, cholesterol, trans fats, and saturated fats.

The bottom line

Evidence is mixed about the importance of food frequency. While there is no solid evidence to suggest that one eating style is superior to the other, both can offer health and wellness benefits if you follow a healthy eating pattern.

Thus, it ultimately comes down to personal preference and which approach works best for you. Additionally, if you have certain health conditions, one style may benefit you over the other.

As always, consult your healthcare provider before making any significant changes to your diet.

Source - Medical News Today