Swapping just 1% of plant protein in place of animal protein was associated with significantly less age-related deficit accumulation.
Based on a study of more than 400,000 people, replacing just 3% of calories of animal protein with plant protein was associated with a 10% reduction in overall mortality risk. That simple swap could translate to about an extra year of life. Egg protein—mostly found in egg whites—appeared to be the biggest offender when it came to mortality risk. Swapping 3% of calories from egg protein for plant protein was associated with more than a 20% reduction in overall mortality—greater than the reduction seen when replacing red meat with plant protein. However, it’s not just about adding years to your life, but life to your years. How do changes in dietary intake of animal versus vegetable protein affect unhealthy aging?
Healthy aging is defined as “the process of developing and maintaining the functional ability that enables wellbeing in older age.” No one wants to be vegetative, and you may be able to avoid that by eating more vegetables. A higher intake of vegetable protein was associated with less accumulation of deficits, based on functional impairments, mental health and diseases, self-reported health and vitality, and the use of health services.
Swapping in just 1% of vegetable protein calories for animal protein “led to significantly less deficit accumulation.” Don’t animal protein and animal fat travel alongside each other in the same foods? Is this just a saturated fat effect? No—even after accounting for fat, there still seemed to be something about whether the protein came from animal or plant sources, but it’s still not clear whether the beneficial health effects are due to avoiding the deleterious effects associated with animal foods or from the beneficial effects of plants, though it may be a bit of both.
A recent review in a dermatology journal on the role of a whole food, plant-based diet in preventing and reversing skin aging emphasized this point. A whole food, plant-based diet is not the same as a vegan diet. It’s possible to have a terribly unhealthy vegan diet, filled with sugar, processed oils, and white flour and no fresh fruits or vegetables. As a physician, “vegan” just tells me what a person doesn’t eat, but they actually have to, you know, eat vegetables, too. And when they do, “a whole food, plant-based (WFPB) diet can aid in the prevention, and in some cases reversal, of some of the leading chronic diseases in the United States,” as well as potentially contributing to younger-looking skin, due to telomere lengthening, maximizing our cells’ antioxidant potential, and eliminating harmful carcinogens and aging toxins, known as gerontotoxins, from entering our bloodstream.
It is no wonder “the highest life expectancy of any formally described population” in the world may be the Adventist vegetarians in Loma Linda, California, one of the world’s five original “blue zones.” The average life expectancy of Adventist vegetarian men and women is about 83 and 86 years, respectively, about 10 and 6 years longer than the general population in California. Those who eat a vegetarian diet with nuts, exercise, have a lower weight, and never smoke live about 9 to 11 years longer than people lacking these habits, as you can see below and at 3:22 in my video The Best Diet for Healthy Aging.
That’s like having 10 years of life up for grabs.
Now, “[s]ubstantial gains in life expectancy would only be worthwhile if they were also accompanied by a longer period of good-quality life.” Although overall well-being has not been measured directly, vegetarian Adventists have been recorded taking fewer medications and logging fewer x-ray examinations, surgical procedures, and overnight hospital stays. Their reduced prevalence of several chronic diseases alone would presumably make life more worth living.
The most feared disease associated with getting older is likely Alzheimer’s disease. Dementia is one of the fastest-growing epidemics, affecting 1 in 10 people older than 65 years of age and half of all people older than 85. Alzheimer’s is the main type of dementia, and indeed the most feared. So, when we’re talking about “plant-based diets for healthy aging,” “[p]articularly intriguing is emerging evidence that diet plays a major role in the prevention of age-related cognitive decline and Alzheimer’s disease. It has been shown that a diet rich in fruits, grains, legumes [beans], vegetables, nuts, and seeds may cut the risk of Alzheimer’s disease by more than a half.”
This evidence comes from research on the “MIND diet,” which emphasizes natural plant foods, specifically including berries (the healthiest fruits) and greens (the healthiest vegetables), while limiting the intake of animal foods and high saturated fat foods like meat and dairy.
Strictly adhering to the MIND diet was associated with a 53% reduction in risk for Alzheimer’s disease. In fact, even moderate adherence appeared to cut risk by about a third. Overall, participants with high adherence to the diet had the cognitive function equivalent to someone 7.5 years younger.
No wonder people who ate meat, including poultry and fish, “were more than twice as likely to become demented as their vegetarian counterparts”—and that rises to three times the risk when taking past meat consumption into account. This may be because “[p]lant-based diets are known to preserve body tissues from oxidative stress and inflammation, both hallmarks of chronic-degenerative diseases.” That may be why berries are so protective, since they’re so rich in antioxidants, and in terms of inflammation, those who avoid meat have a higher abundance of anti-inflammatory compounds flowing through their systems and lower levels of proinflammatory indicators like C-reactive protein. “Dietary factors also influence the effect of stress on cognitive decline. Diets characterized by high intake of animal proteins, saturated fats, and refined sugar along with low intake of plant-based foods can increase secretion of corticosteroids,” stress hormones like cortisol from the adrenal glands, which may promote the development of Alzheimer’s disease.
Then there are the gerontotoxins, like AGEs (advanced glycation end products), in our diet that may be a factor in the development of Alzheimer’s. Safe foods—foods that have low AGE content—include starches like whole grains, beans, fruits, and vegetables, whereas the main dietary sources of AGEs are broiled, grilled, fried, or roasted meats. The cooking process is important. Chicken breast has an AGE level of 1,000 KU when boiled in water (for chicken soup, for example), but that same chicken breast jumps up to 9,000 KU when broiled. Below and at 6:53 in my video is a list of the top 40 most AGE-contaminated foods tested, in terms of AGEs per serving.
As you can see, it’s almost all meat: chicken, bacon, hot dogs, and so on. I tell people to choose raw nuts and seeds to avoid AGEs, but even roasted, toasted nuts don’t come close to making the list.
Now, of course, diet is not the only factor when it comes to reducing the risk of cognitive decline. We also need to get adequate sleep, rest, and physical activity. For example, daily brisk walks were associated with a 40% lower risk of developing Alzheimer’s later in life, and smoking may double the risk of developing dementia. But in terms of preventing Alzheimer’s with diet, the key takeaways are the following: reduce added sugars, added salt, saturated fat, animal products, and processed foods in general while eating more plants (especially greens and beans) and fruits (especially berries).
Doctor’s Note
Aging is the topic of my book How Not to Age. Check it out at your local public library.
Some of my popular videos on aging and longevity include:
