As we grow older, decades of stress and unhealthy eating really begin to take a toll on our health, says fitness expert Tosca Reno, author of Your Best Body Now. "Diseases including cancer, heart disease, multiple sclerosis, Parkinson's, and more begin to take hold in the body," she says.
 

Still sitting on the couch eating chips? Don't despair — it's not too late to change your habits and reap the health benefits. "Even if you haven't started preventive measures, it's never too late to boost your immunity and begin a lifestyle in order to give yourself the best fighting chance against some of these crippling diseases," says Reno.
 

Follow these six simple health strategies to boost your immune system:
 

• Get enough vitamin E. Vitamin E is a fat-soluble compound that reduces the oxidative damage that increases with age. According to Reno, it's essential to help prevent cancer and Alzheimer's, as well as to enhance memory and brain function. It's found in eggs, nuts, vegetable oils, wheat germ oil, and whole grains. Although the RDA is only 15 IU, some experts advise taking up to 800 IU daily. If you choose supplements, choose a vitamin E complex, which contains both tocopherols (alpha, beta, gamma, and delta) and tocotrienols (alpha, beta, gamma, and delta) —all are essential to fight disease. Pass up supplements that contain only alpha-tocopherol.
 

• Eat goji berries or take supplements. Goji is a super-fruit that studies have shown increases bone density and fights heart disease. Experts believe its power is due to the positive effects it has on estriol, a form of estrogen that promotes good bone and heart health. Reno advises a 500 mg supplement daily.
 

• Avoid table salt. Cutting sodium will decrease the risk of heart disease, says Reno. Instead, season with spices and herbs. "They boost flavor without adding fat and may be linked to fighting certain health conditions, including cancer and heart disease," she says. When you use salt, she advises, choose sea salt since it has 82 minerals while table salt has only sodium chloride.  
 

• Eat natural appetite suppressants. Foods that increase the amount of the neurotransmitter dopamine in your system are natural appetite suppressants. They include apples, spinach, unsalted almonds, egg whites, and carrots.
 

 • Take fish oil to fight depression. The omega-3 fatty acids found in fish oil fight depression and also act as powerful anti-inflammatories. Even if your diet is high in fish, Reno suggests supplementing with 1,000 to 2,000 milligrams daily for the maximum amount of mood-boosting omega-3s. "For a triple punch, make sure you're also getting enough vitamin D and magnesium glycinate," Reno suggests.
 

• Get a good night's sleep naturally. L-tryptophan is an amino acid that's found in turkey and is responsible for your after-dinner drowsiness at Thanksgiving. It is necessary for the production of serotonin, which is responsible for regulating sleep cycles. Natural sources of L-tryptophan include meat, pumpkin seeds, and milk and dairy. Boost your body's level of L-tryptophan by taking supplements. Follow instructions on the bottle.
 

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