All humans are destined to age because of cumulative damage to cells and tissues. Although genetics plays an important role in determining longevity, people can increase their lifespan by reducing the risks from degenerative diseases through proper nutrition, adequate exercise and a healthy lifestyle.
As people age, calorie requirements generally decrease due to reduced activity. However, in order for the body to work well, a balanced diet, with all the necessary carbohydrates, proteins, fatty acids, vitamins and minerals is still needed. For example, an excessive consumption of animal fats may lead to a partial blockage of the arteries by cholesterol plaques. This could result in tissues and organs getting less oxygen and nutrients, and give rise to many old age diseases.
Inadequate absorption of vitamins and minerals is common among seniors. Deficiencies in vitamin B12 and vitamin D are the rule, rather than the exception. In fact, the U.S. Institute of Medicine has advised people over 50 to take vitamin B12 supplements to compensate for the decrease in absorption as they age.
As for vitamin D, people in their 70s produce only about half of the amount they did in childhood through exposure to sunlight. Vitamin D is needed not only for good bones but also, according to new research, for protection against autoimmune diseases, hypertension and some cancers.
A lack of B vitamins can also lead to depression, as does inadequate vitamin D or omega-3 fatty acids. Low folate levels can increase blood homocysteine levels, which can lead not only to heart disease and stroke, but also to the development of Alzheimer's and Parkinson's diseases.
Mineral deficiencies are responsible for a host of medical conditions from osteoporosis to goitre. For example, anemia results from low blood iron level coupled with insufficient vitamin B12 and folic acid intake. Incidentally, increased iron absorption by the body occurs when food containing vitamin C is also included, one of many examples of nutrients working in conjunction with one another in the body.
Many of the degenerative diseases common in old age, such as cancer and heart disease, are initiated by "free radicals," which can attack DNA, proteins and cell membranes. By destroying free radicals, antioxidants such as vitamins A, C and E, carotenoids, polyphenols and certain minerals can help protect against diseases and may even slow down the aging process.
We should, therefore, maximize our consumption of foods rich in antioxidants: carrots, spinach, citrus fruits, tomatoes, strawberries, blueberries, red grapes, red wine, peppers, broccoli, cabbages, garlic, onions, Brazil nuts, soy and tea.
Many fruits and vegetables, such as bananas, potatoes and oranges, are also rich in potassium, which helps keep blood pressure low. Plus, a new study shows that nuts and grains reduce the risk of prostate cancer.
It's advisable to cut down on animal protein - most people consume too much. Eat lean, white meat and low-fat dairy, with red meat making only an occasional appearance. Avoid bacon, sausage and other high-fat meats.
Stick to complex carbohydrates by eating whole wheat bread, pasta and cereals, bran and brown rice. Avoid cookies, sweets and other foods made with refined carbohydrates (sugar).
Ideally, consumption of saturated, and especially trans fats, should be limited. By eating whole and natural foods, trans fats, which can increase the risk of coronary artery disease even more than saturated fats, are avoided. So, choose trans fat-free margarine and stay away from fast food, commercially-fried food, chips and crackers which are often prepared with trans fats or their close relatives, partially hydrogenated oil and shortening.
A diet should be rich in omega-3 fatty acids, which are found in fatty fish such as salmon, sardines or tuna and in walnuts, flaxseed and other nuts. If contaminants are a worry, such as mercury in large fish, eat sardines and other small fish.
Reduce the intake of omega-6 oils such as those made with corn, sunflower or soybean, using instead monounsaturated fatty acids from olive oil, nuts and avocadoes.
And don't forget the daily glass of red wine! Many studies, including the Physicians Health Study, have found that men and women consuming one drink a day live longer than those who don't drink at all.
Don't overeat, since we are all well aware of the increased risk of diabetes and heart disease associated with being overweight. In fact, calorie restriction, along with the intake of all required nutrients, has been shown to prolong the lifespan of laboratory animals. So, to increase the odds of living a long and healthy life, try to stay thin!
In summary, there's not much people can do about their genes, but a good diet, together with plenty of exercise, may increase longevity.
Dr. Naidoo, is a retired Chemistry professor who now lives in Ladysmith. He is the author of two books, Nature's Bounty: Why certain foods are so good for you and Nature's Bounty: More about foods for a longer and healthier life. You can contact him at firstname.lastname@example.org