Wednesday, March 26, 2008

Dietary nutrient intakes and skin-aging appearance among middle-aged American women

Nutritional factors play a key role in normal functioning of the skin, the body's largest organ. However, little is known about the effects of diet on skin-aging appearance. Recent research indicates that higher intakes of vitamin C and linoleic acid and lower intakes of fats and carbohydrates are associated with better skin-aging appearance.

Using data from the first National Health and Nutrition Examination Survey (NHANES I), scientists examined associations between nutrient intakes and skin aging in 4,025 women between the ages of 40 and 74 years. Clinical examinations of the skin were conducted by dermatologists. Skin-aging appearance was defined as having a wrinkled appearance, dryness associated with aging (senile dryness), and skin atrophy (shriveling or shrinking).

Higher vitamin C intakes were associated with a lower likelihood of a wrinkled appearance. Higher linoleic acid (an omega-6 essential fatty acid) intakes were associated with a lower likelihood of senile dryness and skin atrophy. A higher than average fat and carbohydrate intake also increased the likelihood of a wrinkled appearance and skin atrophy. These associations were independent of age, race, education, sunlight exposure, income, menopausal status, body mass index, supplement use, physical activity, and energy intake.

Elevated intakes of vitamin C and linoleic acid and reduced intakes of fats and carbohydrates are associated with better skin-aging appearance. Promoting healthy dietary behaviors may have added benefit for the appearance of skin in addition to other beneficial health outcomes in the population.

Source: Dietary nutrient intakes and skin-aging appearance among middle-aged American women, Cosgrove et al, American Journal of Clinical Nutrition Vol. 86, No. 4, 1225-1231, October 2007

Wednesday, March 19, 2008

Meta-analysis of glycemic index and glycemic load effects on chronic disease‏

Due to inconsistent findings from observational studies, there is controversy over the effects of dietary glycemic index (GI) and glycemic load (GL) on the risk of certain chronic diseases. A recent meta-analysis showed that diets high in GI and/or GL increase the risk of certain chronic, degenerative diseases.

The American Journal of Clinical Nutrition recently published a meta-analysis to evaluate the association between GI, GL, and chronic disease risk. A total of 37 prospective cohort studies of GI and GL and chronic disease risk were included. In 4 to 20 years of follow-up across studies, a total of 40,129 incident cases of degenerative diseases were identified.

For the comparison between the highest and lowest quantiles of GI and GL, significant positive associations were found for type 2 diabetes, coronary heart disease, gallbladder disease, breast cancer, and all diseases combined. Low-GI and/or low-GL diets are independently associated with a reduced risk of certain chronic diseases. Relating to cardiovascular disease and type 2 diabetes, the protection is similar with that seen in diets high in whole grains and fiber.

The findings support the hypothesis that higher GI and GL diets, and their resulting increases in postprandial (after meal) blood glucose levels, increase the risk of several chronic, degenerative diseases.

Source: Glycemic index, glycemic load, and chronic disease risk—a meta-analysis of observational studies, Barclay et al, American Journal of Clinical Nutrition, Vol. 87, No. 3, 627-637, March 2008

Monday, March 17, 2008

Vitamin E Deficiency

The Untold Epidemic Vitamin E Deficiency by Ladd McNamara, M.D.

It is clear that there is an epidemic vitamin D deficiency (see posting about vitamin D below). Few people are aware that there is also a serious epidemic deficiency of vitamin E. An editorial that accompanied the largest study on vitamin E in medical history (Am J Clin Nutr 2006 Nov;84(5):1200-7) stated 93% of American men and 96% of American women do not obtain the [pathetically low] recommended dietary allowance of 15 IU of vitamin E per day. It is clear that we should be taking at least 30 to 50 times that level (400 to 1000 IU/day) to reduce the risk of chronic diseases. Taking this much vitamin E in the correct form and balance with other vitamins, is both safe and effective; more than the pharmaceutical companies would have you believe. However, it is in the economic interest of pharmaceutical companies to dissuade the public from taking supplements so that they can be on medications which often do little to nothing to reverse disease. Other health practitioners make their living by “educating” others that they can get everything they need from their food alone. The medical research indicates otherwise. The amount of vitamin E, as well as other important vitamins, required to reduce the risk of chronic diseases can only be obtained through supplementation.

Tragically many doctors and the lay person have the misconception that vitamins, such as vitamin E supplementation may be harmful. There seems to be continued misinformation put out in news media and health magazines, regarding the “dangers” of supplementation. Either they are not aware of the medical research, or they are purposefully misleading the public for their own gain. This non-stop attempt to persuade people not to supplement, but to get all their antioxidants from their food alone is at minimum unethical, at worst dangerous. Vitamin E seems to be in these detractors line of fire more than any other nutrient, probably because it is the most common supplement used today. With the thousands of medical studies showing the benefits of supplemental vitamin E, how is it that there is still controversy and confusion? The doses of vitamin E that research has shown to be of benefit can ONLY be obtained through proper supplementation.

Almost weekly a new study about the benefits of vitamin E is published. Almost all show health benefits or potential health benefits. Because vitamin E is one of the most popular supplements, it is only when a medical study or report showing a possible negative effect it is reported by the media, either to make headlines, and/or to scare people away from taking this incredible vitamin. The negative findings regarding vitamin E of a few medical reports have either shown to be excessively biased, restricting other important vitamins that work synergistically with vitamin E, poorly designed, or bearing no cause and effect of vitamin E to a detrimental health impact. The studies of vitamin E that have shown a true potential negative impact are few, but of more importance it has given us clarity regarding the synergistic impact of various vitamins as well as the importance of the formulation of vitamin E.

Vitamins must work together for optimal benefit:

Studies published many years ago showed that for vitamin E to continue to function as an antioxidant within the body, adequate levels of vitamin C must be present to regenerate (donate more electrons) to vitamin E so that it can continue to prevent oxidation of lipids. Any study about vitamin E that restricts the participants from also taking vitamin C is setting up the study to show nothing more than how vitamin E is quickly “used up,” and not regenerated to continuously provide an antioxidant benefit. It tells us nothing about the real benefits that can be obtained from proper supplementation.

The correct formulation of vitamin E is critical:

Vitamin E is a family of nutrients; alpha, delta, and gamma-tocopherols and tocotrienols. There is a difference between the synthetic (petroleum-derived) vitamin E, dl apha-tocopherol , and the natural (food-based ) vitamin E, d alpha-tocopherol. Gamma-tocopherol is a critical form of vitamin E needed to reduce the oxidation of lipids (cholesterol) in conjunction with alpha-tocopherol. (J Am Coll Cardiol. 1999 Oct:34(4):1208-15, Pro Natl Acad Sci USA, 1993 Mar 1:90(5):1771-5) In addition, studies have shown that people who supplement solely with vitamin E in the alpha-tocopherol form are at risk to lower the blood levels of a critical form of vitamin E, gamma-tocopherol. (J Nutr. 2003 Oct:133(10):3137-40; J Nutr.1985 Jun:115(6):807-13) The average American’s blood-stream is five times more rich in alpha-tocopherol than gamma-tocopherol, and that difference jumps 20-fold among people who take vitamin E as alpha-tocopherol without gamma tocopherol.

In 2007, a negative study about vitamin E (that lingers as the “justification” for the case against vitamin E) highlights the way the public can be mislead to make some poor decisions about supplementation. (JAMA Feb 27, 2007). This was a flawed study with flawed data that concluded that vitamins A and E “significantly increased the risk of mortality.” This meta-analysis (report) did very little to help us understand the benefits of vitamin E, but showed us just how data, and the public’s opinion, can be manipulated. The authors of this meta-analysis (which is not a study per se, but a review of previous published studies) considered 815 prior studies regarding antioxidants, but included the results of only 68 of these studies for analysis. Some of the studies excluded from their report showed significant benefits and reduction of mortality from taking supplements. Selection bias was glaringly evident. The authors essentially “cherry-picked” the studies they wanted, and ignored others, so that they could come to their desired conclusion: vitamin E can kill you!

The authors were unable to establish any cause and effect between supplementation with vitamin E and an increased risk of death, making this a poorly designed study. The elderly people who died could have just as easily died from accidents, medications, surgery, etc. …who knows? One noted researcher described this report a kin to “doing a cholesterol-lowering study without ever measuring cholesterol levels.” Furthermore, the average duration of the reviewed studies was 2.7 years, so the ridiculous conclusion that the authors wanted the public to believe was that vitamin E could kill you (somehow) in less than 3 years!

The others ignored many studies showing significant benefits derived from supplemental vitamin E. One such study that was ignored by these researchers was the November 10, 2006 study published in the American Journal of Clinical Nutrition which is the largest study on vitamin E in medical history measuring alpha-tocopherol in male smokers. (Am J Clin Nutr 2006 Nov;84(5):1200-7) This study followed 29,000 patients for over 19 years, and included over 13,000 deaths, …making possible a significant and fair analysis of vitamin E and the risk of death.

This study showed a significant reduction in overall mortality in those patients with the highest blood levels of alpha-tocopherol. Specifically, over a 19-year period men with the highest blood levels of alpha-tocopherol showed the following reduction in causes of death:

  • Prostate Cancer 32% Reduction of Death
  • Ischemic Stroke 37% Reduction of Death
  • Hemorrhagic Stroke 35% Reduction of Death
  • Lung Cancer 21% Reduction of Death
  • Respiratory Illness 42% Reduction of Death

The authors of this significant and powerful study stated: “As a primary fat-soluble antioxidant that protects lipids from peroxidation, alpha-tocopherol is able to scavenge mutagenic free radicals and inhibit the oxidation of LDL-cholesterol, and the abilities have important implications for the prevention of carcinogenesis and atherosclerosis ….alpha-tocopherol also has several important functions that are independent of its antioxidant activity, including modulation of gene expression, enhancements of immune responses , an suppression of tumor angiogenesis.”The researchers further elaborated that although the patients who enjoyed the greatest health benefits had higher blood levels of alpha-tocopherol, these same subjects also had the highest levels of gamma-tocopherol, meaning that these people were taking the natural formulation of vitamin E, not dl-alpha-tocopherol without gamma-tocopherol and the tocotrienols. This study, and other significant studies are ignored by the media, and obviously by doctors who are continually visited and educated by pharmaceutical companies.

Certainly, there are tens of thousands of studies reporting the benefits of various nutritional supplements. They are both safe and effective. If doctors and the public were simply made aware of the poorly designed analyses that denigrate vitamin E supplementation, and the significant studies about the benefits of taking vitamin E, in the form of alpha-tocopherol and gamma-tocopherol (along with delta-tocopherol and the mixed tocotrienols) along with vitamin C and vitamin K, which replenishes the antioxidant abilities of vitamin E, then I believe that not only would people need less medication and reduce the economic crisis in the health care industry, but more importantly people could enjoy the true health and happiness that can be obtained by eating right, exercise, and proper supplementation with a full spectrum of quality vitamins and minerals.

Vitamin E, in the natural form (as described above), appears to be safe up to at least 2000 IU per day. I personally take 800 IU per day of the full spectrum of vitamin E. When I was in medical practice, I recommended at least that much (if not up to 1200 IU of vitamin E) to patients with diabetes. The natural form of vitamin E, along with co-enzyme Q10, the red grape extract (grape seed extract and resveratrol) and a full spectrum of other antioxidants (quercetin, alpha lipoic acid, turmeric extract, olive extract, green tea extract, etc.), vitamins (B, C, D, and K), and minerals in the chelated form, all contribute to safely and significantly reduce the risk of heart disease, stroke, cancer, Alzheimer’s disease, lung diseases, and almost every other chronic degenerative disease, as well as slow the aging process, all without the side-effects of drugs.

Source: Ladd McNamara, M.D. - expert in nutraceutical and anti-aging medicine, Dr Ladd MacNamara blog,

Friday, March 14, 2008

Omega-3 fatty acids in pregnant women and early visual acuity in infants

Docosahexaenoic acid (DHA), an omega-3 fatty acid found most commonly in fish oil, is important to neural development. It is speculated that DHA intakes are low enough in some pregnant women to impair infant development.

A new study published in the American Journal of Clinical Nutrition compared eye development scores among infants of women who supplemented DHA versus infants of women with typical diets. Supplemental DHA at 400 mg/day or a placebo was consumed by the women from 16 weeks of gestation until delivery. Researchers determined maternal red blood cell fatty acids, dietary intakes at 16 and 36 weeks gestation, and infant visual acuity at 60 days of age.

Infant visual acuity was related to sex and maternal DHA levels. More infant girls in the placebo than in the DHA group had a visual acuity below average and maternal red blood cell fatty acids were inversely related to visual acuity in both boys and girls.

These results suggest that some pregnant women in the study population were DHA-deficient.

Source: Essential n–3 fatty acids in pregnant women and early visual acuity maturation in term infants, Innis and Friesen, American Journal of Clinical Nutrition, Vol. 87, No. 3, 548-557, March 2008

Friday, March 07, 2008

Calcium supplementation increases bone mineral content in adolescent girls

A new clinical trial (reported in the February 2008 issue of the American Journal of Clinical Nutrition) found that supplementing adolescent girls with calcium led to significantly increased bone mineral content in the short term. However, long-term benefits were only maintained with continual use.

A recent meta-analysis raised doubt as to whether calcium supplementation in children benefits spine and hip bone mineral density (BMD). A recent study had a different conclusion. The trial was an 18 month trial of calcium supplementation (792 mg/d) with follow-up two years after supplement withdrawal. Subjects included 96 adolescent girls with low calcium intakes.

State-of-the-art measures of bone were used to determine the change in total-body, lumbar spine, and total hip bone mineral content (BMC) during supplementation and then two years after supplement withdrawal. Over the eighteen-month period, girls who received supplemental calcium showed significantly greater gains in bone mineral content (with the exception of the hip), and bone mineral density was greater at all sites compared with the group that received a placebo. Indicators of bone loss were significantly lower in the supplemented group than in the control group after 18 months. However, after 24 months (or two years without supplements), the differences between groups were no longer observed.

Contrary to the conclusion of the recent meta-analysis, this study indicates that calcium supplementation does indeed enhance bone mineral accumulation in teenage girls, but the effect is short-lived. The likely mechanism for the effect of the calcium is suppression of bone turnover, which is reversed upon supplement withdrawal. Therefore, calcium supplementation must be consistent and life-long to achieve full bone health benefits.

Source: Calcium supplementation and bone mineral accretion in adolescent girls: an 18-mo randomized controlled trial with 2-y follow-up, Helen L Lambert, Richard Eastell, Kavita Karnik, Jean M Russell and Margo E Barker, American Journal of Clinical Nutrition, Vol. 87, No. 2, 455-462, February 2008