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April 2016

Topics:

Vitamin C and cataract
Dietary fruit lowers heart risks
Exercise for brain and muscle mass
High fiber intake and lung function
General Information

Vitamin C and cataract

Aside from its many other benefits as an antioxidant and anti-inflammatory agent that helps support the immune system, vitamin C also helps protect vision. A recent study shows that it can help with the prevention of cataracts in the lens of the eye. Based on genetic studies, the researchers estimated that inherited factors contributed about 35 percent of the risk of cataract, but the remaining 65 percent of the risk was due to environmental factors, including nutrition. In particular, dietary intake of vitamin C and the trace mineral manganese.

The researchers gathered dietary measurements for 2,054 white female twins in the United Kingdom. They evaluated their nutrition using food frequency questionnaires and compared that data to the incidence of cataracts. They then followed as many as they could for an average of 9.4 years. At the end of the follow-up period, they had available cataract measurements for 324 of the twins.

Dietary vitamin C was protective against nuclear cataract at baseline and the progression of nuclear cataract during the term of the study. At baseline, subjects with the highest intake of vitamin C had a 19 percent lower risk of cataract compared to those with the lowest intake. These subjects also had a 33 percent lower risk of progression of their cataracts during the course of the study. Manganese and dietary supplements of other micronutrients were protective at the start of the study, but no further benefit was seen at the end of the study. Subjects with the highest manganese intake had a 20 percent lower risk of cataract at baseline, but no protection against progression of their cataracts. (Yonova-Doing E, et al., Genetic and dietary factors influencing the progression of nuclear cataract. Ophthalmology. 2016 Mar 15. pii: S0161-6420(16)00114-7. doi: 10.1016/j.ophtha.2016.01.036.)

The researchers noted that they found no statistically significant association between taking micronutrients in supplemental form and progression of nuclear cataract. At least one news article made this appear to be an important conclusion, but this would be misleading. The authors noted that only about 10 percent of their subjects reported taking supplements (a surprisingly low number) so the lack of statistically significant associations only means that they did not have enough subjects to make a meaningful evaluation of supplements.

Other studies have shown cataract protection from supplements, or from high serum levels of nutrients, which are usually found primarily in people who take supplements. (Wei L, et al., Association of vitamin C with the risk of age-related cataract: a meta-analysis. Acta Ophthalmol. 2016 May;94(3):e170-6.) A variety of nutrients have been shown to prevent a few eye conditions, including macular degeneration, dry eye syndrome, and cataract. They include lutein, zeaxanthin, vitamin C, vitamin E, zinc, copper, and omega-3 fatty acids (EPA and DHA). These authors reported that these nutrients “remain the most proven nutritional therapy for reducing the rate of advanced macular degeneration…” (McCusker MM, et al., An eye on nutrition: The role of vitamins, essential fatty acids, and antioxidants in age-related macular degeneration, dry eye syndrome, and cataract. Clin Dermatol. 2016 Mar-Apr;34(2):276-85.) However, not all studies show that vitamin C supplements protect against cataracts, but as there is no risk from taking extra vitamin C, is it worth waiting until all of the information is in agreement?

Practical guidelines:

It is best for a host of reasons to eat a diet that contains a lot of vitamin C from fruits and vegetables. These foods contain a wide variety of nutrients and fiber in addition to their vitamin C content. Examples of vitamin C-rich foods include bell peppers, leafy greens, papaya, broccoli, berries, pineapple, citrus fruits, and kiwi fruit. I also take quite a lot of vitamin C in supplement form (usually 6000 mg per day) for anti-aging, anti-inflammation, and immune support.

Dietary fruit lowers heart risks

Fruit consumption confers a lot of health benefits. Among them is a reduction of the risk of dying from cardiovascular disease. Fruits contain a lot of vitamins, minerals, nutritional phytochemicals (including antioxidants), and fiber, in addition to the contribution they make to your water intake (most fresh fruits are 80 to 90 percent water). All of the nutrients protect tissues and slow the aging process.

In a new study from China, researchers recruited 512,891 adults from 30 to 79 years of age and evaluated their fruit consumption. They followed them for over five years. In their 3.2 million person-years of follow-up, they reported 5173 deaths from cardiovascular disease, 2551 major coronary events (both fatal and non-fatal), 14,579 ischemic strokes, and 3523 brain hemorrhages. They then correlated the mortality and event data with fruit consumption (this does not prove cause and effect, just correlation, but it is probably the best that research can do with such studies).

Overall, only 18 percent of the participants reported daily fresh fruit consumption. Compared to those participants who rarely or never ate fresh fruit, those who ate it daily had lower blood pressure and lower blood glucose levels. The fruit eaters had a 40 percent lower risk of cardiovascular death and a 34 to 36 percent lower risk for coronary events, ischemic stroke, and hemorrhagic stroke. The risk reduction was directly proportional to the amount of fruit eaten. The results were the same across all of the ten regions that they studied and among all of the subgroups of participants. (Du H, et al., Fresh fruit consumption and major cardiovascular disease in China. N Engl J Med. 2016 Apr 7;374(14):1332-43.

Practical guidelines:

Aside from all the health benefits, fruits are delicious. I eat them daily. Among my favorites are watermelon (rich in lycopene), cantaloupe, all varieties of berries (very high in protective phytochemicals), cherries, peaches, nectarines, bananas, apples, pears, grapes, mangoes, papayas, pineapples, and citrus. When I can not find organic ones fresh, I’ll buy them frozen.

It is especially important to choose organic berries, peaches, nectarines, and apples. On the other hand, pineapples, watermelons, mangoes, and papayas are unlikely to be contaminated with pesticides. Consumer Reports has a good guide to purchasing fruits and vegetables at this link: http://www.consumerreports.org/cro/health/natural-health/pesticides/index.htm It gives information about risk levels of pesticides and which country of origin is most likely to be safe and when you should choose organic. You find other information at the Environmental Working Group (www.ewg.org) in their “Dirty Dozen” and “Clean Fifteen” lists of the most and least contaminated produce. This does not give quite as much information as the Consumer Reports list, which shows country of origin of the least contaminated foods.

Exercise for brain and muscle mass

In evaluating the quality of muscles, researchers evaluate the number of functioning motor units (MU) and their neuromuscular transmission stability. As people age they lose MUs and the decline is typically precipitous for people in their 70s and 80s. Canadian researchers had already shown that 65-year-old masters runners had more MUs than age-matched controls. They then set out to evaluate the number and stability of MUs in masters athletes who were around 80 years old and compared them to otherwise healthy age-matched controls. They used the tibialis anterior muscle (the muscle in the front of the lower leg; the one that allows you to raise your foot toward your knee) to evaluate the amount of muscle, the strength, and the transmission stability.

The masters athletes had a 14 percent greater active muscle mass than the controls. They also had 28 percent more functioning MUs than the controls. The neuromuscular stability was also greater than the controls (indicated by lower “jitter” and “jiggle” values, believe it or not). This all indicates that regular exercise helps to maintain muscle mass and keeps the muscles younger at the cellular level even into the 80s. (Power GA, et al., Motor unit number and transmission stability in octogenarian world class athletes: can age- related deficits be outrun? J Appl Physiol (1985). 2016 Mar 24:jap.00149.2016. doi: 10.1152/japplphysiol.00149.2016. [Epub ahead of print])

It is hard to overestimate the value of exercise at any age, and as people reach advanced years, maintaining function becomes even more important to help with routine activities of daily living and recreational activities, as well as maintaining balance and preventing falls. Another study shows the value of exercise for maintaining mental function as people age. This also helps to prevent falls by improving concentration and focus. Leisure time physical activity (LTPA) is protective against dementia.

As part of the Northern Manhattan Study, researchers evaluated LTPA for 1,228 subjects at the start of the study and used a standard neuropsychological examination (NPE) to assess cognition. The NPE was repeated five years later. LTPA was classified as none to light intensity versus moderate to heavy intensity. Mental function subcategories included processing speed, semantic (word) memory, episodic memory, and executive function.

At the start of the study, low to no physical activity was associated with worse executive function, semantic memory, and processing speed. However, the researchers noted that this difference might have been due to the difference in vascular risk factors (of course, these may also be influenced by the lack of exercise). Those who were in the moderate to high LTPA levels maintained more of their cognitive function over the next five years in processing speed and episodic memory. The benefits were most notable in those who were normal at the start of the study, suggesting that the sooner you start exercise the more likely you are to derive the most benefit. Waiting to start until the onset of cognitive decline puts you at a significant disadvantage.

According to the authors, those who had little to no LTPA showed an extra 10 years of cognitive decline (brain aging) compared to those in the moderate to high LTPA group. (Willey JZ, et al., Leisure-time physical activity associates with cognitive decline: The Northern Manhattan Study. Neurology. 2016 Mar 23. pii: 10.1212/WNL.0000000000002582. [Epub ahead of print])

Practical guidelines:

Regular exercise is possibly the most important activity for health. I suggest any combination of walking, cycling, tennis or other racquet sports (I am liking pickle ball at the moment), swimming, dancing, stationary cycling, rowing, stair or elliptical machines at the health club, and some strength training are all good, and you don’t have to do a lot for it to be worthwhile. The more you can do the better, but regularity is the key. For strength training, I find one home gym particularly good. It is called the Smart Gym (www.smartgym.com) and it takes up virtually no space in the home, is very inexpensive, and provides a wide variety of strength training options. When traveling in the summer, I walk everywhere and take some elastic exercise bands with me (many are available online for about $10, and I use a FlexActive set of 5 different resistances, which is great for travel as the whole bag is about the size of your fist).

High fiber intake and lung function

Fiber is the non-digestible portion of food that passes through the intestinal tract mostly unchanged (some is fermented by organisms in the lower colon). However, fiber is by no means unimportant. It helps bowel function, cleansing the colon, adsorbing toxins, and making you feel full to help control appetite. High fiber diets are associated with a reduction in many diseases, which may be partly related to the fiber itself and partly to the many other nutrients found with foods high in fiber. High fiber foods include whole grains, beans, vegetables, fruits, and seeds (such as sesame, sunflower, and pumpkin seeds).

As part of the National Health and Nutrition Examination Surveys (NHANES) information collected included dietary intake and spirometry measures of lung function. Researchers evaluated 1,921 participants who had both spirometry measurements and fiber intake data available. One lung test is the FEV1, (forced expiratory volume 1, or the amount of air that can be forced out in the first second of expiration). Another test is the total volume of air that can be forced out with a complete exhale (FVC, or forced vital capacity).

Those subjects with the highest fiber intake had an FEV1 that was 82 mL higher than the than those with the lowest fiber intake. They also had an FVC that was 129 mL higher than the low fiber group. FVC has been associated in the past with predictions of longevity (better lung function predicted longer life). In the overall analysis, higher fiber intake was associated with a higher percentage of those with normal lung function and a significant decline in the proportion of participants with airflow restriction. (Hanson C, et al., The relationship between dietary fiber intake and lung function in NHANES. Ann Am Thorac Soc. 2016 Jan 19. [Epub ahead of print])

Practical guidelines:

Western diets typically contain 10 to 15 grams of fiber. Guidelines suggest trying to get 25 grams of fiber a day. The native African diet that Denis Burkitt studied in the 1950s contained about 100 grams of fiber (of course they ate a large volume of food because of their highly physically active lives). The staples of their diet were potatoes, bananas, corn meal, and beans, all high fiber foods. Animal products have no fiber. I haven’t eaten meat or chicken since 1975. When I eat my organic, non-fat yogurt, I try to make up for the lack of fiber by including bananas and berries (blueberries, raspberries, and strawberries) and often walnuts or almonds. High fiber foods contain many other nutrients that may account for all of part of the health benefits seen.

General Information

 


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From September to June, I see patients in New Smyrna Beach, Florida.
Call 386-409-7747, or send an email to to make arrangements.

In summer, I have a variable schedule, and I see patients in offices at the
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Information herein is not medical advice or direction. All material in this newsletter is provided for information only. Its contents should not be used to provide medical advice on individual problems. Consult a health care professional for medical or health advice.

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